Astrophysics for Galaxy Zoo Talk - simple explanations of redshift z PhotoZ spectra emissions AGN
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Budgieye
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If you want to learn more about galaxies, here are links to useful information from Talk, Forum and the SDSS website and other places
PAGE 1 (this page) see below for finding information in Talk Galaxy Zoo https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp
PAGE 2 Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
PAGE 3 Spectra guide for SDSS images in Galaxy Zoo Talk https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef2ee3d5a77490c0001b6
PAGE 4 Redshift image chart of GOODS full-depth galaxies https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=4
PAGE 5 Redshift image chart of CANDELS 2-epoch galaxies
https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=5
Galaxy Zoo Talk
New to Galaxy Zoo? Want Help? Read this! by vrooje admin, scientist : overexposed stars, red / green /blue lines of satellite trails , strange shapes, red / green / blue asteroids, overlaps and mergers, voorwerpjes, bulgeless AGNs https://talk.galaxyzoo.org/#/boards/BGZ0000003/discussions/DGZ1006byh
#1 How do I : Find out more information about the galaxy I have classified? https://talk.galaxyzoo.org/#/boards/BGZ0000005/discussions/DGZ0000lv2 click to get to Examine, SDSS page, zooming in and out, navigating to other galaxies, going into the NED (Nasa Extra-galactic Database) and SIMBAD (star database) to find scientific papers.
Galaxy Zoo Forum
There is much good information on the Galaxy Zoo Forum.https://www.galaxyzooforum.org/ which is the forum that we used before Talk. The forum is now locked, and is read-only, and some of the links are broken.
It was used during Galaxy Zoo 1, 2, 3, Hubble Zoo, and 4 which had the images enhanced by infrared from UKIDSS. It used the SDSS objects numbers (58..............) (82..............) (12..............) and various other project numbers to identify the galaxy image, not Galaxy Zoo 4 AGZ....... number. The galaxy is often not centered in the image, and there are sometimes many ObjIDs in a galaxy.
WOW WHAT'S THAT? LOOK HERE FIRST! images that cause confusion : satellite trails, overexposed stars, nebula, star clusters, square boxes https://www.galaxyzooforum.org/index.php?topic=276702.msg397290#msg397290
Zooite Guide to SDSS Spectra colours of stars and galaxies and their spectra, redshift, star-forming blue galaxies, peas, emission spectra http://www.galaxyzooforum.org/index.php?topic=274815.0
Colours of Galaxies in SDSS : Redshift chart https://www.galaxyzooforum.org/index.php?topic=277142.0 estimate the distance of galaxies by their colours, star-forming, peas, AGN, quasars, spectral charts, There is a newer version on Talk using SDSS PAGE 2 Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
measure the size and distance of galaxies using a redshift calculator Friday 8th January, 2010. Two galaxies, the same size? https://www.galaxyzooforum.org/index.php?topic=277034.msg416504#msg416504
Zooite Guide to Strong Gravitational Lenses lens explanation, dark matter, SDSS images, lensed quasars, Hubble lenses
https://www.galaxyzooforum.org/index.php?topic=275811.Tuesday April 19 2011 Which PhotoZ should I pick? use photometric redshift when there is no spectral chart https://www.galaxyzooforum.org/index.php?topic=279108.msg542377#msg542377
Note: Here are objects that cannot be seen in our images
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Black holes - are smaller than a pixel, and anyway are surrounded by
hot bright gas see 3.7 Black holes and Super Massive Black Holes ( SMBH ) https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=3&comment_id=53d8b91b0d43f77bb6000f96Galactic jets - can be seen in several close galaxies, all the galaxies we look at are too far away. see 3.6 relativistic jets in optical and radio https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=3&comment_id=53d8b92adb90c76710000f93
Information from SDSS
Sloane Digital Sky Survey, from which we get the images from Galaxy Zoo 1, 2, and 3.
SDSS typical spectra from stars, galaxies and quasars https://www.sdss.org/DR7/algorithms/spectemplates/index.html
Redshift Gallery: Quasars how quasars change colour with increasing distance https://www.sdss.org/gallery/gal_zqso.html
SDSS easy astrophysics https://cas.sdss.org/dr7/en/proj/basic/
SDSS harder astrophysics , includes colour of stars, spectral types, Hertzsprung-Russell Diagram, quasars, https://cas.sdss.org/dr7/en/proj/advanced/
SDSS challenging astrophysics, includes quasar spectra and HII regions https://cas.sdss.org/dr7/en/proj/challenges/
How to find more info on your Hubble galaxy? The short answer is that you can't. You are at the frontiers of knowledge These Hubble galaxies are extremely distant, and dim blobs in other telescopes. You can go into the references cited in NED, and maybe come out with a small spectrum. It will be a lot of work for little information. I look at the lists of references, and if it says "emission galaxies" or "Lyman break galaxies" it gives me a clue about what the galaxy might be. The best you can do is learn about other galaxies and use your experience to guess the characteristics of this one, using shape and colour as clues.
Have you looked through the featured discussions?
Astrophysics for Galaxy Zoo Talk - redshift z PhotoZ spectra emissions AGN https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp
#1 How do I : Find out more information about the galaxy I have classified? (for the SDSS images)
https://talk.galaxyzoo.org/#/boards/BGZ0000005/discussions/DGZ0000lv2Explore data, do science, and share findings with Zoo Tools https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ00005b7 Basically just click on "Open in Tools" on the Image page, or play with the filters in the Examine page. This can be used for looking for UV light, which indicates a high energy event. This is good for the CANDELS images, but not the GOODS image like this, the filter information is not fed into it.
Look on the old Galaxy Zoo forum, https://www.galaxyzooforum.org/ and Hubble forum https://www.galaxyzooforum.org/index.php?board=33.0
other sources
Redshift calculator from wolframalpha
Redshift calculator from wolframalphaChandra scale and distance calculator use Example 3 for distant galaxies
Chandra scale and distance calculatorGoogle scholar https://scholar.google.co.uk/schhp?hl=en-GB a search engine for scientific papers
Wednesday, 19th December, 2012: Pixel Ruler https://www.galaxyzooforum.org/index.php?topic=280563.msg625684#msg625684
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Budgieye
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Page 1-2 Current, finished or inactive projects
current projects are in https://www.zooniverse.org/
and past projects below, see also Wikipedia https://en.wikipedia.org/wiki/Galaxy_Zoo
2014 Radio Galaxy Zoo current
: in search of erupted black holes https://radio.galaxyzoo.org/?utm_source=Zooniverse Home&utm_medium=Web&utm_campaign=Homepage Catalogue
2015 Feb-May Hubble GOODS and CANDELS
PAGE 4 Redshift image chart of GOODS full-depth galaxies https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=4
PAGE 5 Redshift image chart of CANDELS 2-epoch galaxies
https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=52014 January-May Infrared Zoo, Galaxy Zoo 4
Finished with Galaxy Zoo: UKIDSS by Kyle Willett https://blog.galaxyzoo.org/2014/05/29/finished-with-galaxy-zoo-ukidss/
70,000 images classified, galactic bars are often more prominent in the infrared
2013 Quench Galaxy Zoo help research why some galaxies have lost their hydrogen and cannot form more new stars
eg red spirals https://quench.galaxyzoo.org/#/https://blog.galaxyzoo.org/2013/08/02/gz-quench-classification-complete-now-the-real-fun-begins/
The Green Valley is a Red Herring https://blog.galaxyzoo.org/tag/red-spirals/
Spacewarps .. find gravitational lenses
Part 1 CFHT Canada France Hawaii telescope
https://talk.spacewarps.org/#/subjects/ASW0000c0w
READ THIS FIRST ! Guide to Information on SpaceWarps Talk https://talk.spacewarps.org/#/boards/BSW0000002/discussions/DSW0000301
The colours of lensing and lensed galaxies https://talk.spacewarps.org/#/boards/BSW0000002/discussions/DSW000044z
SpaceWarps Spotter's Guide https://spacewarps.org/#/guide
Part 2 the VICS82 survey ... pasting infrared data onto image to catch redshifted light.
Stargazing Live 2014 Jan 19 2014 BBC Stargazing Live 2014 Finding Hidden Galaxies https://www.galaxyzooforum.org/index.php?topic=281569.msg649790#msg649790
https://talk.spacewarps.org/#/subjects/ASW0009io9
Lens Toy Try putting a small blue galaxy behind these massive yellow ones...simple and fun to play with lenses, but doesn't work with all search engines Firefox seems OK https://slowe.github.io/LensToy/
Merger Zoo ended June 2012 Merger Resources - Links and articles helping us understand Mergers. https://www.galaxyzooforum.org/index.php?topic=278369.msg501369#msg501369
https://mergers.galaxyzoo.org/gallery2
https://news.bbc.co.uk/1/hi/sci/tech/8376566.stm
2010 Hubble Zoo - classifying distant galaxies fromHubble Space Telescope, including clumpy ones, to learn about galaxy formation. You can find some of the images in the old forum, they are in 2 colours - amber and cyan ( yellowish orange and greenish blue)
https://www.galaxyzooforum.org/index.php?topic=278750.msg520491#msg520491
Redshift of Hubble galaxies, with spectra https://www.galaxyzooforum.org/index.php?topic=277967.0
Tues Jan 11 2011 Finding more information about a galaxy https://www.galaxyzooforum.org/index.php?topic=278750.msg520491#msg520491
https://www.galaxyzooforum.org/index.php?topic=277967.msg480171#msg480171
2011 Hunting for gas clouds illuminated by AGN... We call them voorwerpjes, because they're sort of like Hanny's Voorwerp but a lot smaller
https://wavwebs.com/GZ/voorwerpje/Hunt.cgi
https://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587732483292266549
2008 The Irregulars Project
Do it Ourselves Science https://www.galaxyzooforum.org/index.php?topic=273410.0
https://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587725471203459169
Peas project https://www.galaxyzooforum.org/index.php?topic=270633.0
https://en.wikipedia.org/wiki/Pea_galaxy
https://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587736915687964980
2012
look for radiation from AGN ionizing gas in neighboring large galaxies, so we can trace the pattern of escaping radiation from obscuring material around the AGN corehttps://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587733081347063838
2007 overlapping galaxies
Saturday, 14th January, 2012: A Toast to the Overlap Zooites https://www.galaxyzooforum.org/index.php?topic=279829.msg578237#msg578237
Wednesday, 31 December 2013: overlaps and the ultraviolet https://www.galaxyzooforum.org/index.php?topic=281543.msg648519#msg648519
Stripe 82, 84, 86 detailed images recycled from a supernova surveillance study
Tues Dec 28, 2010 Stripe 82 to dr7 SkyServer https://www.galaxyzooforum.org/index.php?topic=278703.msg517660#msg517660
Galaxy Zoo 2 detailed classification of 200,000 of the brightest SDSS galaxies
https://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587735661547290798
Galaxy Zoo 1 elliptical and spiral, clockwise and anticlockwise July 2007 one million of the nearest galaxies from SDSS (Sloane Digital Sky Survey)
Galaxy Zoo (first project in 2007) https://zoo1.galaxyzoo.org/Project.aspx
In the eye of the beholder? https://blog.galaxyzoo.org/2008/01/10/in-the-eye-of-the-beholder/
https://zoo1.galaxyzoo.org/Tutorial.aspx
but also found and posted in Forum: peas, rings, overlaps, lenses
Hanny's Voorwerp Wednesday 25th June: Hanny's Voorwerp https://www.galaxyzooforum.org/index.php?topic=270620.msg139008#msg139008
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Budgieye
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Galaxy redshift chart is on page 2
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Budgieye
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Astrophysics for Galaxy Zoo Talk Galaxy Redshift Chart for SDSS https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=2
How colour changes with redshift.
Redshift is a calculation of the change of the wavelength light from distant galaxies. It is correlated with distance, so we use it as a measure of distance.
On this page 2-7 at the bottom More information on galaxy colours and spectral charts
Ionization colours of hydrogen and oxygen are explained on next page 3.9 Spectra Guide : Physics and biology of colour
All these object have a spectral chart: Do Ctrl + click on blue link to open the link in a new tab, or Shift + click to open in a new window.
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page 2-2 Galaxy Redshift Chart for SDSS z = 0.000 to 0.005
at z=0.000 the star or nebula is in our galaxy
z=0.000 ...white light...............blue light.................starburst UV...............Hot Oxygen ...........Hot hydrogen
z=0.000
z=0.000
z=0.000
white star ..................
blue star.............
white dwarf star.............
Owl nebula...........
Orion nebula
z=0.001 About 10 million light-years away. Close galaxies: The Messier galaxies eg M31 , and closer NGC galaxies
z=0.001
z=0.001elliptical galaxy............
spiral galaxy ........
compact galaxy..
star-forming in NGC 5457.....
hydrogen in M82
z=0.005 About 50 million light-years away. Galaxies usually have an NGC, UGC or other designation
z=0.005
z=0.005
elliptical galaxy.............
spiral...............
blue compact..............
blue pea...........
green near nucleusPosted
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Budgieye
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Page 2-3 Galaxy Redshift Chart Galaxies from z= 0.01 to 0.09
.................white light...............blue light............... .....starburst UV.......Hot Oxygen ...........Hot hydrogen
z=0.01 About 100 million light-years away
z=0.01
z=0.01
elliptical galaxy ............
spiral.................
compact galaxy.......
blue pea galaxy..
green near nucleus
z=0.02 about 250 million light-years away
z=0.02
z=0.02
elliptical galaxy............
spiral galaxy.......
blue compact.......
blue pea galaxy..
green near nucleus
z=0.03 About 400 million light-years away
z=0.03
v
z=0.03
elliptical.............................
spiral.......................
compact........
blue pea galaxy......
AGN with jet
z=0.04 About 500 million light-years away
z=0.04
z=0.04
elliptical..........................
spiral.........................
compact...........
blue pea galaxy..............
AGN
z=0.05 About 700 million light-years away
z=0.05
z=0.05
elliptical............................
spiral...................
compact.............
purple pea galaxy....
Seyfert 1 quasar
z=0.06 About 800 million light-years away
z=0.06
z=0.06
elliptical.........................
spiral.......................
compact............
purple pea galaxy...
Seyfert 1 quasar
z=0.07 About 900 million light-years away
z=0.07
z=0.07
elliptical..........................
spiral.....................
compact................
purple pea............
Seyfert 1 quasar
z=0.08 About one billion light-years away
z=0.08
z=0.08
elliptical..........................
spiral...................
star-forming............
purple pea..............
AGN cloud
z=0.09 About 1.2 billion light-years away
z=0.09
z=0.09
elliptical..................
spiral.....................
star-forming................
purple pea.............
Seyfert 1 quasar
We are now about 1/10 of the way to the "edge" of the Universe
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Page 2-4 Galaxy Redshift chart for SDSS z= 0.1 to 0.9
................white light...............blue light.................starburst UV..........Hot Oxygen ...........Hot hydrogen
z= 0.1 About 1.3 billion light-years away. Galaxies are moving away from us at 10% the speed of light, or more accurately, the universe between us and the galaxy is expanding at 10% the speed of light.
z=0.1
z=0.1
elliptical...........................
spiral.....................
compact.................
white pea............
Seyfert 1 quasar
z=0.2 About 2.4 billion light-years away
z=0.2
z=0.2
elliptical.........................
spiral.....................
starburst....................
green pea............
blue quasar
z-0.3 About 3.4 billion light-years away
z=0.3
z=0.3
elliptical?.............
spiral seen by HST....
post starburst............
green pea............
blue quasar
z-0.4 About 4.3 billion light-years away
z=0.4
z=0.4
elliptical + lens....
spiral? no spectrum...
post starburst...........
yellow pea.............
blue quasar
z=0.5 About 5 billion light-years away
z=0.5
z=0.5
elliptical..................
spiral from HST.......
post starburst.............
red pea...................
blue quasar
z=0.6 About 5.7 billion light-years away
z=0.6
z=0.6
elliptical?....................
radio source...........
post starburst.............
red pea..................
quasar
z=0.7 About 6.3 billion light-years away
z=0.7
z=0.7
elliptical?..........
barred spiral from HST...
post starburst...........
pea?........................
quasar
z=0.8 About 6.9 billion light-years away
z=0.8
z=0.8
elliptical or star........
spiral from HST...
lensed starburst............
pea..........................
quasar
This is now halfway to the "edge" of the observable Universe
z=0.9 About 7.3 billion light-years away
z=0.9
..................................
z=0.9
.................................
spiral from HST.........
lensed starburst.........
pea......................
quasar
The shape of some of these galaxies was verified in Hubble Space Telescope images.
z=0.937 GRB 080319B was a gamma-ray burst (GRB) detected by the Swift satellite at 06:12 UTC on March 19, 2008. The burst set a new record for the farthest object that was observable with the naked eye: http://en.wikipedia.org/wiki/GRB_080319B
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Page 2-5 Galaxy Redshift Chart for SDSS z=1 to 6
.................white light...............blue light.................starburst UV..........Hot Oxygen ...........Hot hydrogen
z=1 About 7.8 billion light-years away
z=1
z=1
elliptical.........................
spiral....................
clumpy ring................
pea 0.97...............
quasar z=1.5
z= 1.4 Light left galaxy 9.1 billion years ago.
Distant galaxies further away than z=1.4 are travelling away from us greater than the speed of light
or more accurately, the Universe between us and the galaxy is expanding faster than the speed of light.
We can still see these galaxies because their light left when the universe wasn't expanding as fast.
Light leaving these galaxies today can never reach us.
z=2 About 10.4 billion light-years away
z=2
...................................................................
..................................
z=2
......................................................................
lensed starburst................................................
quasar z=2.3
z=3 About 11.5 billion light-years away
z=3
.........................................................................................................................................
z=3
.........................................................................................................................................
quasar z=3.2
We are now about 9/10 of the way to the "edge" of the Universe
z=4 About 12.1 billion light-years away
z=4
.....................................................................................................................................
z=4
......................................................................................................................................
quasar z=4.096
z=4.2
.....................................................................................................................................
z=4.2
.........................................................................................................................................
quasar z=4.2
z=4.59
........................................................
New class of galaxy Luminous Infrared Galaxies or LIRGs, starforming and dusty
WISE J224607.57-052635.0 http://skyserver.sdss.org/dr10/en/tools/explore/summary.aspx?id=0x112d1f76208b024f&spec=&apid=
z=5.2
....................................................................................................................................
z=5.2
.........................................................................................................................................
quasar z=5.2
z=6.3 .....................................................................................................................................
z-6.3 .................................................. J0100+2802 in Talk................................................... hyperluminous quasar z=6.3
z=6.4
......................................................................................................................................
z=6.4
.........................................................................................................................................
quasar z=6.4
At z=6.4 That is as far as we can see using visible light in SDSS since even UV light is redshifted into the IR, which SDSS doesn't detect.
To see further, we must use telescopes that detects IR (Infrared Radiation) such as Hubble IR or the upcoming James Webb Telescope,which must be done from space, since IR doesn't penetrate Earth's atmosphere, or we must use radio waves (the big dishes).
Also, there are transient objects: Gamma Ray Burst supernova , probably where neutron stars or black holes collide or collapse of a hypergiant star which produce X -rays and afterglows.
z=6.6 Gamma Ray Burst 060116 16 Jan 2006) 895 million years after the Big Bang
z=6.96 a galaxy IOK-1 corresponding to just 750 million years after the Big Bang.
z=6.7 Gamma Ray Burst 080913 in 2008, 825 million years after the Big Bang.
z=7.1 The most distant known quasar, ULAS J1120+0641
z= 7.5 (2014) z8_GND_5296,http://candels-collaboration.blogspot.co.uk/2014/02/breaking-galaxy-distance-record.html
z=7.7 (2015) the most distant spectroscopically confirmed galaxy in the universe EGS-zs8-1, found in the CANDELS survey by Hubble, and confirmed by spectroscopy by Keck http://www.nasa.gov/feature/goddard/astronomers-set-a-new-galaxy-distance-record
z=8.2 Gamma Ray Burst 090423 in 2009, 600 million years after the Big Bang
z=8.6 a galaxy iUDFy-38135539 at a redshift of corresponding to just 600 million years after the Big Bang. Imaged by Hubble, small but intensely star-forming, http://en.wikipedia.org/wiki/UDFy-38135539, no independent confirmation by spectroscopy
z=9.4 Gamma Ray Burst 090429B (a supernova) in 2009, 500 million years after the Big Bang, the most distant object confirmed by spectroscopy.
z=6 to 20 Reionization. The stars or quasars or something (research is ongoing !) warm the interstellar hydrogen , the hydrogen ionizes and can no longer absorb light. Space becomes transparent and stars can transmit light. through space. http://en.wikipedia.org/wiki/Reionization The supernova produce oxygen and carbon which make Population II stars, small and long-lived stars. As more oxygen, carbon and higher elements are made, Population I stars (like our Sun) are formed.
z= 20 to 100 The yet-to-be-observed first light from the *oldest Population III stars These are huge stars made of just hydrogen, helium and lithium) http://en.wikipedia.org/wiki/Redshift
James Webb telescope to look for the first stars http://jwst.nasa.gov/firstlight.html and the first galaxies http://jwst.nasa.gov/galaxies.html and the Extremely red objects (EROs)
z=20 to 1089 This is called the Dark Ages. At first, there were no sources of light, so it was dark. When stars began to form, any light from them was absorbed by interstellar hydrogen atoms, so the Universe was still dark. Large stars might only live for a million years, so here can be many generations of stars forming and exploding and reforming from hydrogen gas clouds. in a time span of 400 million years in this darkness.
z=1089 the Cosmic Microwave Background ( CMB ) 380,000 years after the Big Bang when protons and neutrons formed stable atoms of hydrogen, helium and lithium. The process released UV light, which becomes redshifted as it travels towards us, which astronomers detect as radio waves. "The universe at that time would already have had a diameter of around 90 million light years"
z=1089 to 100000000000 universe is full of light energy and sub-atomic particles
z=100000000000 the cosmic neutrino background from about two seconds after the Big Bang predicted by physics but not presently observable
z=10000000000000000000000000 the cosmic gravitational wave background emitted directly from inflation which occurred a tiny part of a second after the Big Bang, predicted by physics but not presently observable
[note: a gravitational wave from colliding black holes was detected Feb 11 2016, so scientists are closer to detecting this]
By some calculations, inflation increased the size of the universe by a factor of around 1026 during that tiny fraction (far less than a trillionth) of a second, expanding it from smaller than the size of a proton to about the size of a grapefruit.
z= ∞ (infinity ) The Big Bang , the "edge" of our Universe
"So you might imagine that the current radius of the observable universe is 13.7 billion light years. However, during this time the universe has been expanding, so the current position of the matter that emitted that photon will now be 46.5 billion light years away. ([...]This gives a diameter of the current observable universe of 93 billion light years. Note that as time passes, the size of the observable universe will increase."
distant redshift details from wiki http://en.wikipedia.org/wiki/Redshift
http://www.physicsoftheuniverse.com/topics_bigbang_inflation.html
http://physics.stackexchange.com/questions/32917/size-of-universe-after-inflation
You Tube:Shape of the Universe Orange Theory by Cristian Bredee https://www.youtube.com/watch?v=iIapX8jhCI0 The Universe is a 12 dimensional torus.
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2-6 Complicated examples
Sometimes a galaxy has characteristics of several types of galaxies.
So it isn't so easy.
a white pea galaxy?
The colours in the images are in these areas on the chart
blue light 4000-5500 Å green light 5500-7000 Å red light is 7000-8500 Å
This "white pea" has a blue rise at 4000 Å and a small blue OII peak, and a green OIII peak
Normally, this would make a green pea. But the nucleus is active, making a Hα peak in the red.
So, blue + green + red = white
1237657401341771853 587731680116867174 posted by starry nite
a white nucleus?
This is a star-forming galaxy, making blue light. It should have a yellow nucleus (yellow is green+red mixed together)
But the nucleus is also a blue pea, as seen by the OIII peak in the blue area of the spectrum. So the nucleus is white (white=blue+green+red)
0.0321237661361843339457 588017115595145398 posted by StephanieC
a purple galaxy?
This should be a blue compact galaxy, but it has an active nucleus, adding red to make a purple colour1237662268611166284
587736547386261566 posted by c_cld
a yellow pea?
At z=0.2 this should be a green pea (OIII peak in green) , but it has an active nucleus (Hα peak in the red), so it is yellow. (green+red=yellow)
1237664870825459894
587738946670035133
posted by iathro
a brown? starburst?
This is a blue- green starburst, but it has an active nucleus (red), so it becomes white (blue+green+red=white) with a some yellow-brown colour
1237662683069022334
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posted by LizPeter
a white quasar?
At the distance of =0.3, quasars are magenta (blue rise at 4000 + red Hα peak) , but ithis quasar is also a green pea, so it is white (green+blue+red=white)
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posted by laithro
Quasars at z=0.6 are usually dark blue (blue rise at 40000), but this quasar is also a red pea, which lightens the shad of blue. In dr7 it is magenta.
588009372300804174 posted by liathro
Quasars should be blue at z=0.7
This is mostly a blue quasar, but it is possibly also an ageing starburst, which adds a red colour to make magenta.dr10 doesn't have the spectrum, possibly it has been withdrawn. This spectrum is from dr7
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posted by c_cldPosted
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Budgieye
moderator
2-7More information on galaxy colours and spectral charts
post under construction
Different types of galaxies have different colours.
The colour of the galaxy changes with redshift, which is an indication of distance away.
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white light elliptical galaxies - have white stars which produce white light (ie blue, green and red light)
blue light spiral galaxies - have blue stars which produce more blue light than elllipticals.
***starburst UV *** galaxies- produce lots of UV and blue light from its young stars (star-forming galaxies)
hot oxygen - produce narrow peaks of light from OII and OIII emission from hot oxygen from supernova explosions.
hot hydrogen - produce narrow peaks of light from hot hydrogen alpha (Hα) emission lines
Almost all the examples posted have a spectrum available.
Other colour charts
liathro's colour survey (peas)
liathro's A little previously unknown objects gallery
OOTD Fri Jan 19 2009 Rick Nowells Markarian peas montage
Redshift Gallery: Quasars
starry nite's OIII galaxy catalog
lianthro's OIII object categories
pea chart
Rick Nowell list of ccardamone's peas for the publication
Rick Nowells list of Markarians
Rick Nowells list of Wolf-Rayets
I can't take much credit for the chart: it is the work of thousands of Zooites.
Thank you to the Zooites who posted objects on the forum, all pretty and organized, so all I had to do was choose examples.
Thank you to the Zooites and astronomers who took time to share their knowledge,
and the moderators, and ZooKeepers, and SDSS for the images.This chart was created for using SDSS dr10 data.
updated from Galaxy Zoo forum Colours of Galaxies in SDSS : Redshift chart which uses SDSS dr7 data Colours of Galaxies in SDSS : Redshift chart
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Budgieye
moderator
2-8 PhotoZ
Here is what SDSS says about PhotoZ.
http://skyserver.sdss.org/dr7/en/help/docs/algorithm.asp?key=photozTo me, it looks like the photoz error of -1000 looks like a math operation error.
With the huge error margins in photoz, I think anyone who is not colour blind can do an equally good job. I look at the target galaxy and think, " fuzzy detail so at least z=0.1, turning orange so z=0.2, but too too orange, so not 0.3. With the smaller galaxy, I think "Well, it looks about the same"
The accurate way of estimating the distance of a galaxy is by doing a spectral chart, which is time-consuming and costs money. Only a million and half spectra have been done !!! but there are a billion objects to be looked at. http://www.sdss3.org/dr9/
So no spectral data is available for the less interesting galaxies.But if someone is going to do a computer search of yellow-orange galaxies, they can't put "yellow-orange" in the search parameters, they need a number. So for a computer
yellow-orange is photoz 0.1-0.3
galaxy is "a source which is not round"
Unfortunately, it might be mean two orange stars close together, or a extremely distant orange quasar near something else.
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Budgieye
moderator
2-9 empty
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Budgieye
moderator
2-10 empty
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Budgieye
moderator
Page 3 Spectra Guide for Galaxy Zoo Talk
http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3(this page) UNDER CONSTRUCTION
3.2 Colours of stars http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef69b3d5a77490c0001f3
3.3 Spectra of stars http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef6d225c6427998000054
3.4 Spectra of galaxies http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef6e325c64267cc00111c
3.5 Distance of galaxy, using the spectral break to calculate redshift z http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef6dd3d5a77313f0013fb
3.6 Emission galaxies http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef70425c6427998000056
3.7 Spectra of absorption galaxies http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef71025c6427998000057
3.8 Spectral analysis of 6 round green objects: See how much information is in a spectrum. http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef7033d5a77420900023e
3.9 Physics and biology of colour Here is the stuff that you should have read first. 😃 http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef74525c64253c80003ac
3.10 How colour is presented to you on the computer screen http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef74c25c642799800005c
updated from Galaxy Zoo Forum: Zooite Guide to SDSS Spectra http://www.galaxyzooforum.org/index.php?topic=274815.0
Sloane Digital Sky Survey, from which we get the images from Galaxy Zoo 1, 2, and 3.
SDSS typical spectra from stars, galaxies and quasars http://www.sdss.org/DR7/algorithms/spectemplates/index.html
Redshift Gallery: Quasars how quasars change colour with increasing distance http://www.sdss.org/gallery/gal_zqso.html
SDSS easy astrophysics http://cas.sdss.org/dr7/en/proj/basic/
SDSS harder astrophysics , includes colour of stars, spectral types, Hertzsprung-Russell Diagram, quasars, http://cas.sdss.org/dr7/en/proj/advanced/
SDSS challenging astrophysics, includes quasar spectra and HII regions http://cas.sdss.org/dr7/en/proj/challenges/
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Budgieye
moderator
**3.2 Spectra Guide : Colours of stars
http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef69b3d5a77490c0001f3
white dwarf star
a white dwarf star emits mostly UV and some blue, green, yellow, red, far red, and near IF light
surface temperature: 150,000 degrees or cooler,
ultraviolet star would be more accurate name, star is the remnant of a supernova explosion
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=2240&mjd=53823&fiber=584
blue star
A blue star emits some UV, ** mostlly BLUE**, some green, yellow, red, far red, and near IR
surface temperature: 30,000 K
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=2216&mjd=53795&fiber=196
white star
a white star emits some UV, blue, LOTS OF GREEN, yellow, red, far red, IR
surface temperature: 9,000 K
interactive spectrum p://dr10.sdss3.org/spectrumDetail?plateid=2072&mjd=53430&fiber=170
yellow star
A yellow star emits UV, blue, mostly GREEN, red, far red, and IR
surface temperature: 5,500 K
yes, it looks green, see "How colour is presented to you on the computer screen" below, this is what our Sun would look
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=845&mjd=52381&fiber=498
red giant star
a red giant star emits some green and yellow, but mostly red and some far red and infrared
surface temperature: 3,500 K
These are short-lived large stars that are in a late stage of evolution, they will "soon" explode.
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=276&mjd=51909&fiber=402
red dwarf star M8
A red dwarf star emits yellow, red, far red but mostly IR (Infrared)
surface temperature: 3,000 K
These are small stars that emit small amounts of dim red light, and will stay red dwarfs for longer than the universe has existed.
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=1311&mjd=52765&fiber=253
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?ra=14:16:24.0&dec=13:48:26.7
https://en.wikipedia.org/wiki/SDSS_J1416%2B1348
Brown dwarf T
http://skyserver.sdss.org/dr12/en/tools/explore/Summary.aspx?id=1237648705141410053
http://iopscience.iop.org/article/10.1086/312619/fulltext/005075.text.html
brown dwarf Y2
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237648721210507746
https://en.wikipedia.org/wiki/WISE_0855−0714
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Budgieye
moderator
3.3 Spectra Guide : Spectra of stars
Here are the same seven stars, arranged from hottest to coldest, and their spectra.
 **white dwarf star**
 **blue star**
 **white star**
 **yellow star**
 **red star**
 **red dwarf star M8**
**brown dwarf star L5**
**brown dwarf Y
The numbers across the bottom of each spectra shows the colour of the light.
less than 4200 Å is violet and ultraviolet
4200-5000 blue
5000-5500 green
5500-6000 yellow
6000-7000 red
7000-9200 far red
over 9200 infrared
The numbers on the side is the amount of light: 3 is small and 1000 is big.
For example, a spectrum with high numbers at the blue end will have come from a hot object such as a blue star.
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Budgieye
moderator
3.4 Spectra Guide : Spectra of galaxies
Things to look for in galaxy spectra
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Ratio of young blue stars to old white stars
Distance of galaxy, using the spectral break (a big jump at 4000Å) to calculate redshift z
Emission of light from hot gas produced by the nucleus, collisions,
or by supernova explosions.Absorption of light between light leaving the galaxy, and arriving at
the telescope.
Ratio of blue stars to red stars
spiral galaxy
There is lots of blue light at 4000-500 Å so you can deduce that this spiral has many blue stars. The spectra has been taken at the red box in the middle.
lenticular galaxy
No much blue light, so less star formation.
What is a lenticular galaxy? It looks like an elliptical but has some structure inside. Here, there a blue ring around the nucleus.
A spectrum sample is taken from the area indicated by the red box, and here the area sampled is at the center of the nucleus, and does not include the blue area in the sample. If the sample had included the blue ring, there would be more blue in the spectrum.
http://skyserver.sdss.org/dr7/en/get/specById.asp?id=609061545153921024
 **elliptical galaxy**
The elliptical has less blue light, so fewer blue stars, so not much star formation. The spectra was taken in the middle of the nucleus.
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Budgieye
moderator
3.5 Specta Guide : Distance of galaxy, using the spectral break to calculate redshift z
One way to measure the distance of a galaxy, is to look for its spectral break, also known as the 4000 Å break.
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=2216&mjd=53795&fiber=196
This is the spectrum of a blue star in our galaxy.
Look at the 4000Å break in the spectral chart of this star. At 4000 Å the values make a step upwards, in this case from 60 to 75.
The 4000Å spectral break is at 4000Å, so it has a redshift of zero, or z=0.000
An object with a redshift of zero must be in our galaxy, or very close to our galaxy. The stars in our galaxy have a redshift of zero.
In the spectra of galaxies, the spectral break occurs at values greater than 4000Å The spectral break is found closer to the red end of the spectrum ie towards the right of the chart.,
The redshift (z) value measures how far towards the red end of the spectrum the break is shifted, and tells us how far away the galaxy is.
[warning: there is another z on the data page, with u,g,r,i,z which is the measurement of colour in each filter. don't use this value]
z=0 in our galaxy
z=0.01 nearby galaxies
z=0.1 distant galaxies
z=1.0 can't see galaxies in visible light, must start using infrared telescope
For a tour of the Universe at varying redshift (z) see
Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
z=0 interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=2216&mjd=53795&fiber=196
z=0.05
z=0.05 spectral break at 4150 Å 1237648705123647505
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=299&mjd=51671&fiber=459
z=0.1
spectral break at 4500 Å
z=0.1 1237663457778925938
 **z=0.5**
z=0.5 The spectral break is at 6000 Å 1237667322182238495
-----------------------------------------0.7--------------------------------
 **z=0.7**
z=0.7 spectral break at 6700Å , it is a poor chart though, object is very dim 1237659324408857244
Redshift is a measure of how the expansion of the Universe stretches the wavelengths of light of galaxies that are receding from us, but we also use it to describe the distance of a galaxy.
Explanation of redshift by NGC3314 in Tutorial bits on galaxy spectra
The redshift is caused by the expansion of the Universe. This galaxy moving away from us at high speeds which stretches the wavelengths of light.
We can use the redshift to estimate distance.
Explanation about z here on the z thread
A redshift to distance calculator http://www35.wolframalpha.com/input/?i=redshift+z%3D0.5
OOTD Friday 20th February, 2009 Systems : are galaxies interacting?Galaxies are much, much further away than stars, and the wavelengths of light coming from it are shifted towards the red end of the spectrum: this is called the redshift z. (Caution! There is another z in galaxy description, the Z is also the amount of far red light.
SDSS telescope can't see galaxies that have a red shift greater than about z=1.2 The light from these galaxies is being shifted off the end of the chart far into the infrared. Some distant active galaxies, such as quasars, emit lots of X-rays and UV light, and these can be redshifted down to visible light, and therefore we can still see them on SDSS.
The redshift value is the z value on the SkyServer Object Explorer (the red z)
Negative Redshift, or Blueshift
A nearby galaxy can have a negative redshift if it is coming towards us. You can see this in Object of the Day . The galaxy M90 has a negative redshift, z=-0.0008. The light we see coming from this has been blueshifted, or moved to the left in the chart. So M90 is coming towards us.
OOTD Friday 27th March 2009: Too close for comfort? lists 18 galaxies that are moving towards the Milky Way.
OOTD Tuesday 13th Jan 2009 They are coming for us
OOTD Wednesday 21st October, 2009 Blueshift irregulars http://www.galaxyzooforum.org/index.php?topic=276488.0Posted
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Budgieye
moderator
3.6 Spectra Guide : Emission galaxies
Spectra of emission galaxies
Some galaxies are have lots of hot hydrogen or hot oxygen. The hydrogen and oxygen make peaks on the spectra.
Hot hydrogen = a feeding black hole or a galaxy collision.
Hot oxygen = star formation and supernova explosions.
Just like the 4000 A break, these peaks can be used to determine the distance of the galaxy. As the distance increases, the peaks are redshifted to the right, until they fall off the end of the x-axis. There are new peaks of iron and Lyman-alpha appearing from the left. The colour on the image depends on where the peak falls in the filter.........
SDSS images assigns colour from these wavelengths of light :
blue 4000-5500 green 5500-6000 red 6000-85000 Å
z=0
Huge oxygen emission OII [4959Å] and the hydrogen peak Hα[6500Å]
Image: blue is hot oxygen, green is hot hydrogen.
This is a supernova remnant left by an exploding star in our galaxy, the Owl Nebula,
Exploding stars synthesize lots of elements, but oxygen is easily seen.
z=0.001
Big hydrogen-alpha Hα peak at 6600 Å
Image: M82 galaxy hot hydrogen gas, shown in green, being forced out of the galaxy
OIII peak at 5007 Å indicates many supernova explosion so much star formation, small amount of hot hydrogen Hα at 6560
image: "blue pea" ,starburst galaxy, oxygen is blue, hydrogen is green
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=962&mjd=52620&fiber=551
z=0.034
oxygen OIII at 5007 and hydrogen Hα
image:
It is IC 1182, a nearby quasar with a relativistic jet . We are not seeing the amazing part of the quasar, since the jet is point away to the left, and the nucleus is hidden by dust and stars.
z=0.067
"purple pea" starburst galaxy.
Lots of oxygen OIII so lots of star formation. There is some hydrogen alpha Hα , probably from an active nucleus,
Image: oxygen appears blue and hydrogen is now showing up as red in the image, since that light is at 7000 Å making the galaxy appear purple or magenta.
 z=0.085
spectrum taken at the nucleus: double oxygen peak OIII shows star formation and hydrogen-alpha shows active nucleus
image: The nucleus is red, which shows that this is an active nucleus (AGN). But there are red loops near the nucleus, which is unusual. These are AGN-illuminated clouds.
interactive spectrum http://dr10.sdss3.org/spectrumDetail?plateid=1708&mjd=53503&fiber=620
Here is a green quasar .
by Zutopian http://www.galaxyzooforum.org/index.php?topic=4767.msg567459#msg567459 "ATel #3474; E.O. Ofek, A. Gal-Yam, P. Groot on 5 Jul 2011; 23:43 UT
EMISSION SPECTRA
Emitted light makes bright lines in a spectrum, which are drawn as peaks "^" in a spectral chart.
The orbits of electrons of atoms and molecules can emit and absorb light
They use the same wavelengths of light (the same colour) whether they are emitting or absorbing.
If you can determine the line or wavelength, you can find what atom or molecule is involved.Compare a spectrum of hot hydrogen with a spectral chart of a galaxy with hot hydrogen in it.
See how 4 of the bright lines of the spectrum correspond to some of the peaks on the spectral chart from the galaxy.http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587729386083582038
We can conclude that there is hot hydrogen in this galaxy.For the quantum theory of light emission see
OOTD Saturday 17th October 2009 Hot hydrogen.. a billion light-years awaySee this OOTD Thursday 2nd April 2009 for examples of emission spectrum.
Normal stars are not hot enough to have emission lines!!!
Galaxies which consist of only normal stars will not have emission lines either!!!From NGC3314: "Normal stars have either no emission lines or emission lines so weak that they do not show up in data of this spectral sampling.
Emission lines generally come from excited gas, either:
gas illuminated by hot stars,
gas outflowing from stars,
gas shocked by supernova explosions, or
gas lit up by the hot surroundings of a black hole."
gas heated by merging of galaxies
Picture of galaxy with gas temperature of millions of degreesThe most common gas is hydrogen gas, so hydrogen will produce the main peaks.
They are the hydrogen alpha (Hα), the hydrogen beta (Hβ) and then hydrogen gamma (Hγ) peaks.Posted
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Budgieye
moderator
3.7 Spectra Guide : Spectra of absorption galaxies http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef71025c6427998000057
work in progress, until then see the old version Re: Zooite Guide to Spectra Part 5 Emission and Absorption Spectra http://www.galaxyzooforum.org/index.php?topic=274815.msg300404#msg300404 though there are broken links
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Budgieye
moderator
3.8 Spectra Guide : Spectral analysis of 6 round green objects
See how much information is in a spectrum.
Image Gallery: SDSS Spectra http://classic.sdss.org/gallery/gal_spectra.html
work in progress , until then see the old version Re: Zooite Guide to Spectra Part 7 A spectral analysis of 6 round green things http://www.galaxyzooforum.org/index.php?topic=274815.msg300406#msg300406 though there are broken links.
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Budgieye
moderator
3.9 Spectra Guide : Physics and biology of colour
Here is the guide in the Forum. It is prettier, but some of the links need repair and I cannot update them.
Re: Zooite Guide to Spectra Part 2 How SDSS shows star colours http://www.galaxyzooforum.org/index.php?topic=274815.msg300398#msg300398The physics lesson
Galaxies are made of stars, so let us start simply and look at the colour of stars.
Stars come in different colours:
Ultraviolet, Blue, white, yellow, orange, red
The colours are similar to the rainbow spectrum.
violet, indigo, blue, green, yellow, orange, red.
In addition to these rainbow colurs, SDSS also “sees” ultraviolet (UV) and infrared (IR).
ultraviolet (UV), violet, indigo, blue, green, yellow orange, red, far red, near IR
The colour of a star is its principal colour, but it emits other colours as well.
A white dwarf star emits,,,,UV,,,,,blue,,,,green,,,yellow ,,,,red....far red...near IR
A blue star emits......................BLUE ...green....yellow...red....far red...near IR
A white star emits..................blue.....GREEN...yellow..red.....far red...near IR
A yellow star emits..........................green.....YELLOW..red....far red...near IR
A red star emits ............................................yellow...RED...far red..near IR
A red dwarf emits.......................................................red.......Far RED..near IR
A brown dwarf emits............................................................far.red......NEAR IR
Light is made of electromagnetic waves. Each colour of light has its own wavelength, measured in Angstroms (Å).
Here are the main wavelengths of lightGamma rays......less than 1 Å
X-rays approx 1 Å
A hydrogen atom 1 Å
UV filter in SDSS 3551 Å
Violet 3800-4200 Å
Blue 4200-5000 Å
Green 5000-5500 Å
Yellow 5500-6000 Å
Red 6000-7000 Å
IR 7000-9200 ÅMicrowaves are 300,000 Å
A human hair is 1,000,000 Å wide
Radiowaves are the width of a human hair to kilometers long
The range of each colour is shown in SDSS system response plot (the filters)
So we end up with 5 black and white images taken through 5 different filters. It can only send 3 of these 5 colours to our eyes, because computer screens only receive 3 colours, ie they have red, green and blue pixels.
SDSS takes pictures in 5 colours u g r i z
which corresponds to UV green red far red near IR
with wavelengths (Å) of 3551Å 4686Å 6165Å 7481Å 8931ÅThe range of each colour is shown in SDSS system response plot (the filters)
The biology lesson
So many colours, but a problem..... our eyes only see 3 colours, red, green and blue (RGB)
(WHAT? our eyes only see three colours? That is silly !! We can see lots of colours!)
The other colours we see are actually seen with our brains. http://en.wikipedia.org/wiki/Color_vision
Quick biology lesson on how our eyes see colour:
if we see blue + green + red light mixed together, we see white (take a magnifying glass to your computer screen)
if we see …….....green + red light mixed together, we see yellow
if we see blue +............red light mixed together, we see magenta
if we see blue + green.........light mixed together, we see cyan
Vary the amounts of RGB light and we see lots of colour hues.
We cannot see violet properly
Our eyes cannot see the colour violet. Our blue cones can just see it as dark, dark blue, but through some trick, the powerful violet light can activate the red cones too. So we see violet as blue + red, which appears purple, or magenta. People who have had the lens in their eye replaced can see further into the ultraviolet, but they report that it just looks blue.
"Violet and purple look very similar; but violet is a true color, with its own wavelength on the spectrum of visible light, while purple is a composite color, made by combining blue and red." http://en.wikipedia.org/wiki/Violet_(color)
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Budgieye
moderator
3.10 Spectra Guide : How colour is presented to you on the computer screen
The technology lesson
A TV set, or computer screen, has only three colours RGB or red, green blue. Since our eyes only see these three colours, it would be pointless to make equipment to shine colours into our eyes that eyes don't detect anyway.
shine red green and blue (RGB) light on a white wallThere is only red, green and blue light in this image. There is no yellow, no cyan, no magenta, and no white. These colours are made in your brain by measuring the relative amounts of red, green and blue light coming in
![RGB tv] (http://upload.wikimedia.org/wikipedia/commons/b/b0/LCD_pixels_RGB.jpg) computer screen has red, green and blue pixels., the RGB system.
TV screens and computer screens have only three colours, red green and blue. All the other colours, eg. white. yellow, cyan, magenta, olive green, sea green, grass green, lime green, and the other million colours are made in your brain. If you don't believe, watch a black and white movie and look at the screen with a magnifying glass. Or..,go into some computer paint program eg. Paint, Colors, Edit , Define custom colours, and try mixing some yellow. The mix is red 255 and green 255
http://en.wikipedia.org/wiki/RGB_color_model
When we see nearby stars from Earth
Red galaxies produce red light, which is shown on the red pixels on the screen.
Green stars (white stars) produce mostly green light which is shown on the green pixels on the screen. (Green stars look white to us, they produce blue + green + red , which mixes to form white in our brains.
Blue stars produce blue light which is shown on the blue pixels on the screen
The light from distant galaxies is redshifted, but the telescope surveys compensates the redshift to make the colours look "normal"
Infrared (or far red) is assigned to the red pixels.
Red is assigned to the green pixels.
Green is assigned to the blue pixels.
Galaxy Zoo in 2005-2010 used the Sloan Digital Sky Survey(SDSS) to present a picture of a galaxy for classification.
[EDIT in 2010:see Re: Zooite Guide to Spectra Part 2 How SDSS shows star colours http://www.galaxyzooforum.org/index.php?topic=274815.msg300398#msg300398
Distant galaxies are best observed in redder wavelengths, because the images are better and anyway, the light is getting redshifted. There are five filters that could be put in front of the incoming light, and SDSS uses the g. r and i because they give the best results. It also starts to compensate for redshifting.
SDSS takes pictures in 5 colours......u................g.............r...............i ................z
which corresponds to ......................UV...........green.......red...........far red......near IR
with wavelengths (Å) of ...................3551Å .....4686Å .....6165Å .....7481Å .....8931Å
The blue light is not used in our current images.
Blue galaxies also produce green light (g) which is shown on the blue pixels of the screen.
White galaxies produce red light (r) which is shown on the green pixels of the screen
Red galaxies produce far-red light (i) which is shown on the red pixels of the screen.
So they galaxies have their nornal appearance when we look at them, blue spirals and red ellipticals.
For Galaxy Zoo Hubble in 2010 which is now finished, Galaxy Zoo usrfHubble pictures which use wavelengths further into the infrared. Hubble Space Telescope can see infrared because it is up in space. Infrared doesn't penetrate the earth's atmosphere . To save time and money, the images were taken in only 2 colours. They have amber and cyan (red and blue) speckles. They sometimes have spectral charts. The spectral charts are more red-shifted, because the objects are further away and sample a smaller range of wavelengths.]
The 2 colour images are difficult to work with. see
Redshift of Hubble galaxies, with spectra http://www.galaxyzooforum.org/index.php?topic=277967.0
In 2013 Galaxy Zoo started looking at CFHT images which infrared 6.5 Infrared data CFHT (Canada France Hawaii Telescope) http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=6&comment_id=53d8badb0d43f77b9e000fab
In 2015 Galaxy Zoo started to use Hubble 3 colour images. See this link for good explanation.
These objects are far away, and their light gets redshifted. This is a simplified explanation.
Blue galaxies produce blue light, which gets redshifted to far-red (i) and is shown on the blue pixels of the screen.
White galaxies produced mostly green light, which gets redshifted to near infrared (j) and is shown on the green pixels of the screen.
Red galaxies produced red light, which gets redshifted to infrared light (k) and is shown on the red pixels of the screen.
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Budgieye
moderator
Page 4 Redshift image chart of GOODS full-depth galaxies Talk http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=4
Different kinds of galaxies produce different colours (wavelengths) of light. Distant galaxies have their colours redshifted so the UV becomes, blue, green, red, and infrared, until it is no longer detectable by infrared telescopes. Galaxy IDs under the chart.
red light..............red ellipticals (red and dead)
blue light............ blue spirals
UV light...............star-forming, starburst, Wolf-Rayet galaxies, compact galaxies, clumpy galaxies
hot oxygen...........emission lines of oxygen emitted OIII OII Oiii, "peas" which are starburst galaxies
hot hydrogen...... emission lines of hydrogen, HII regions, feeding black holes, AGN (Active Galactic Nucleus), quasars, galaxy collision, M82 type gas loss.
z=0 red star............... blue star................UVstar........ supernova remnant ........ HII region
elliptical, spirals, starburst , AGN , quasars
z=0.1 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.2 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.3 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.4 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=0.5 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.6 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.7 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.8 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.9 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=1 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=2 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=3 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=4 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=5 red light.............blue light................UV light................hot oxygen...............hot hydrogen
z=5 red light.............blue light...............Lyman break galaxy................hot oxygen...............quasar
z=6 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=7 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=8 red light.............blue light................UV light................hot oxygen...........hot hydrogen
see Highest redshift http://talk.galaxyzoo.org/#/boards/BGZ0000006/discussions/DGZ0001cnq
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Budgieye
moderator
red light..............red ellipticals (red and dead) in GOODS full-depth
red star z=0http://talk.galaxyzoo.org/#/subjects/AGZ0007zxf posted by jameywilliams
http://skyserver.sdss.org/dr12/en/tools/explore/Summary.aspx?id=1237655464306475013
SDSS J123652.95+620726.9 12h36m52.9s +62d07m27s * ... ... 15.5g
z=0.214 http://talk.galaxyzoo.org/#/subjects/AGZ00081bj RA: 189.3653455, DEC: 62.1767506 photoz 0.45
http://talk.galaxyzoo.org/#/subjects/AGZ00082l5 z=0.52852 http://talk.galaxyzoo.org/#/subjects/AGZ000829d RA: 189.5449189, DEC: 62.2714919 z=0.738 spiralhttp://talk.galaxyzoo.org/#/subjects/AGZ00084oe
z=0.910 spiralhttp://talk.galaxyzoo.org/#/subjects/AGZ000821b
z=0.910 spiral GOODS full-depth GDS_N_30559
z=0.946 spiralhttp://talk.galaxyzoo.org/#/subjects/AGZ000816h z=0.946
z=1.098http://talk.galaxyzoo.org/#/subjects/AGZ000839u RA: 53.0734014, DEC: -27.8745785 COMBO-17 24123 z=1.098
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Budgieye
moderator
UV light...............star-forming, starburst, Wolf-Rayet galaxies, compact galaxies, clumpy galaxies in GOODS full-depth
photo\ 0.114http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00082d 1posted by floortap
COMBO-17 38307 03h32m01.9s -27d45m34s G >30000 0.114000 PHOT 23.8R 0.004 7
Hubble ID: GDS_S_707
http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ000844f posted by ramberts
PEARS 097655:[SPM2009] KNOT 01 03h32m27.4s -27d45m41s PofG >30000 0.543000 1LIN ...
COMBO-17 38101 03h32m27.4s -27d45m40s G >30000 0.544200 23.9R 0.005
http://talk.galaxyzoo.org/#/subjects/AGZ00082lv
GOODS-CDFS-MUSIC 13699 03h32m08.0s -27d44m23s G >30000 0.470000 PHOT 23.5V 0.000
z=0.069 starbursthttp://talk.galaxyzoo.org/#/subjects/AGZ00080zf SDSS J123719.58+621204.7
0.45http://talk.galaxyzoo.org/#/subjects/AGZ00082sy
photoz 0.77http://talk.galaxyzoo.org/#/subjects/AGZ00085sp posted by tomaskindah
COMBO-17 38790 03h32m49.2s -27d45m25s G >30000 0.776000 PHOT
z=1.61 starburst clumpyhttp://talk.galaxyzoo.org/#/subjects/AGZ000846c
z= 2.48 starburst clumpyhttp://talk.galaxyzoo.org/#/subjects/AGZ0007z6w
clumpy Lyman Break Galaxy z=4.695http://talk.galaxyzoo.org/#/subjects/AGZ000824o posted by ramberts
GOODS J123757.51+621719.1 12h37m57.5s +62d17m19s G >30000 4.695000 25.3R
green Lyman break galaxy z=4.823 AGNhttp://talk.galaxyzoo.org/?&_ga=1.191612650.1523008579.1427367225#/subjects/AGZ00082gn posted by ramberts
http://www.galaxyzoo.org.s3.amazonaws.com/subjects/standard/goods_full_s_1478_standard.jpg
COMBO-17 35297 03h32m05.1s -27d46m56s G >30000 4.823700 25.2R 0.004
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Budgieye
moderator
hot oxygen...........emission lines of oxygen, OIII OII Oiii, peas in GOODS full-depth
pea? photoz 0.1http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00085mv
pea photoz 0.46http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00081og
green in SDSS http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00081og
pea? 0.6http://talk.galaxyzoo.org/#/subjects/AGZ00082yd #AGN possible #merger by wtaskew
GALEXASC J033213.22-274241.0 03h32m13.2s -27d42m41s G >30000 0.607200 20.1R 0.006 65
z=3.47http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00083rv posted by spceoddity
COMBO-17 25193 03h32m23.3s -27d51m57s G >30000 3.470000
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Budgieye
moderator
hot hydrogen...... emission lines of hydrogen, HII regions, feeding black holes, AGN (Active Galactic Nucleus), quasars in GOODS full-depth
z=0.365http://talk.galaxyzoo.org/#/subjects/AGZ000863j http://www.galaxyzoo.org/#/examine/AGZ000863l
RA: 53.2360814, DEC: -27.887916
z=0.320 quasar at righthttp://talk.galaxyzoo.org/#/subjects/AGZ0007znp
Z=0.79http://talk.galaxyzoo.org/#/subjects/AGZ0007ypi
GOODS J123658.46+620850.0 12h36m58.5s +62d08m49s G >30000 0.791140
z=0.83 quasar bottom righthttp://talk.galaxyzoo.org/#/subjects/AGZ0008536 quasar in bottom right corner
quasar z_spec 0.959http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ0007z6j posted by leonie van vliet, quasar ID by C_cld
Hubble ID: GDS_N_10431
SDSS J123636.62+621346.7 12h36m36.6s +62d13m47s G >30000 0.958800 21.5R 0.031 39
z=1.248http://talk.galaxyzoo.org/#/subjects/AGZ00085q7
bottom right, quasar z=1.37http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ0007xsq
SDSS J123553.13+621037.3 12h35m53.1s +62d10m37s G >30000 1.370910 21.8g
z=4.62http://talk.galaxyzoo.org/#/subjects/AGZ00084xw posted by rollingronnie ID by ramberts
GOODS-CDFS-MUSIC 09220 03h32m36.3s -27d47m59s G >30000 4.620000 29.4B 0.014 11
z=5.18quasar in upper left
http://talk.galaxyzoo.org/?&_ga=1.147340599.1250538510.1430670718#/subjects/AGZ0007zou posted by liometopum ID by ramberts
GOODS J123647.96+620941.7 12h36m47.9s +62d09m42s G >30000 5.186000 24.6 0.026
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Budgieye
moderator
references for GOODS
6.3 HST (Hubble Space Telescope) data http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=6&comment_id=53d8bae1db90c7673f001033
How to find more info on your Hubble GOODS galaxy? The short answer is that you can't. You are at the frontiers of knowledge. These Hubble galaxies are extremely distant, and dim blobs in other telescopes, so they won't be included in other surveys, such as SDSS.
You can go into the references cited in NED, and find a distance. A redshift z is determined by a spectra chart.. Redhsifts are usually correct when looking at emission galaxies, which have a big spike that the software can lock onto. Maybe not so good for galaxies with a flatter spectrum such as red ellipticals.
PHOT is a photoz which is a guess of the redshift by a software algorithm. It can be correct or wildly wrong.
I look at the lists of references, and if it says "emission galaxies" or "Lyman break galaxies" it gives me a clue about what the galaxy might be. The best you can do is learn about other galaxies and use your experience to guess the characteristics of this one, using shape and colour as clues. It doesn't help much to look at the article, they only have graphs, no images, and rarely talk about individual galaxies, and often have 20,000 objects that they have looked at. Some of the references you would need to pay for, some seem to give it out free in .pdf and some let you see and copy from computer-readable scientific papers.
You can go though the references, maybe come out with a fuzzy spectrum. It will be a lot of work for little information. Some of us are good at searching databases or making their own FITS images, I'm not one of them. Eventually I hope that the link to spectrum in NED will be connected to the databases.
You can try the search engine Google scholar www.google.com/scholar https://scholar.google.co.uk/ but it will probably take you back to the same references as NED.
The database SIMBAD is mostly for stars, and it has only the brighter galaxies, and it has the annoying habit of showing you the next closest object, so you think you have found your galaxy.
5.4 Galaxy Zoo 3 Hubble images http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=5&comment_id=53d8ba58db90c70a2a000bf6
Comparison of the different sets of images from the GOODS survey taken with the Hubble Space Telescope. The left shows shallower images from GZH with only 2 sets of exposures; the right shows the new, deeper images with 5 sets of exposures now being classified.
: the GOODS images are made from more HST orbits and are deeper, so you should be able to better see details in a larger number of galaxies compared to HST.
http://blog.galaxyzoo.org/2015/03/27/new-images-on-galaxy-zoo-part-1/
by vrooje ADMIN, SCIENTIST in response to JeanTate's comment
In what bands/filters were the two CANDELS and five GOODS data ('exposures') taken?The GOODS images were taken in 4 bands of the HST Advanced Camera for Surveys (ACS): B, V, I, and z'. In the HST ACS instrument handbook these would be called F435W, F606W, F775W, and F850LP, respectively. (Note: some other surveys use F814W for their I band instead.) Those filter names contain information about the central wavelength and the width of the filter: for example, B is centered at 435 nm, and is a wide-band filter. z' is centered at 850 nm and is a "long pass" filter, which is wider than W.
The 5-epoch images are created by combining all 4 filters into an RGB image. @kwwillett has the details on the precise numbers used, but it was an asinh stretch and I think it was B for blue, V for green, and an average of I and z' for red (Kyle can correct me if I've remembered wrong - this is off the top of my head).
Surrounding the GOODS-South field is another, much larger field called the GEMS field, which observed at a much shallower depth in only the V and z' bands. In the GEMS data release they wanted to include the GOODS-South area, but they didn't re-observe it, because it had already been observed at a deeper total exposure than their larger field. For continuity of image depth GEMS used only the first epoch of the GOODS-South observations in only those bands in their survey. The GEMS survey images, including those that were actually in the GOODS-South field, were transformed to RGB color images using just the V and z' filters and added to Galaxy Zoo: Hubble when that project started. The full-depth GOODS-South images were not added, and the GOODS-North images only used the V and z' bands to make their color images.
The recent addition to GZ is that the full-depth images have been added in both GOODS-North and GOODS-South using all 4 bands to make the color images.
http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/boards/BGZ0000001/discussions/DGZ0001c5t?page=1&comment_id=553698928362d65115000180 correction to filters.
Scale of images
GOODS FULL N
.....................................................................................................This GOODS N Full image is about 25" (arcsec) across, or 0.41 arcmin
So any object more than 0.25 arcmin away from the target will be off the image.
http://skyserver.sdss.org/dr12/en/tools/explore/Summary.aspx?id=1237655369825845399
http://talk.galaxyzoo.org/#/subjects/AGZ000823p
GOODS S on Google Sky https://www.google.com/sky/#latitude=-27.879765057414705&longitude=-126.84814453125&zoom=10&Spitzer=0.00&ChandraXO=0.00&Galex=0.00&IRAS=0.00&WMAP=0.00&Cassini=0.00&slide=1&mI=-1&oI=-1
Chart of colour of Lyman Break Galaxies in the GOODS S field.
http://iopscience.iop.org/0004-637X/695/2/1163/article
"Figure 6. Redshift distribution of the LBGs spectroscopically confirmed in the GOODS-S field. Upper panel: the redshift distribution of all sources at redshift beyond 3 discovered during the FORS2 campaign is shown. The dotted area represents the sources with lower spectral quality (QF = C). Middle panel: the redshift distribution (continuum line) of the FORS2 sample with the highlighted categories B435-, V606-, and i775-band dropouts (blue hatched "/" lines, green hatched "" lines, and red horizontal lines, respectively) is shown. Bottom panel: the redshift distribution has been calculated counting the number of sources in a redshift bin of 0.1 and moving it with a step of 0.003 up to redshift 6.5 (the shaded region is the FORS2 spectroscopic sample and the continuum line histogram include the spectroscopic data from the literature (see the text)). The three segments indicate the interval of cosmic time for dz = 0.1 at the mean redshift of each category."
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Budgieye
moderator
Page 5. Redshift image chart of CANDELS 2-epoch galaxies
https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=5
Different kinds of galaxies produce different colours (wavelengths) of light. Distant galaxies have their colours redshifted so the UV becomes, blue, green, red, and infrared, until it is no longer detectable by infrared telescopes. Galaxy IDs under the chart.
red light..............red ellipticals (red and dead)
blue light............ blue spirals
UV light...............star-forming, starburst, Wolf-Rayet galaxies, compact galaxies, clumpy galaxies
hot oxygen...........emission lines of oxygen, OIII OII Oiii, peas
hot hydrogen...... emission lines of hydrogen, HII regions, feeding black holes, AGN (Active Galactic Nucleus), quasars
z=0 red star.....................blue star............white (UV) dwarf
z=0.1 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.2 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.3 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.4 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=0.5 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.6 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.7 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.8 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=0.9 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=1 red light...............blue light................UV light................hot oxygen...........hot hydrogen
z=2 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=3 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=4 red light.............blue light................UV light................hot oxygen...........hot hydrogen
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Budgieye
moderator
z=5 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=6 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=7 red light.............blue light................UV light................hot oxygen...........hot hydrogen
z=8 red light.............blue light................UV light................hot oxygen...........hot hydrogen
green blob http://talk.galaxyzoo.org/?_ga=1.104757952.1310713284.1428668940#/subjects/AGZ00087i6
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Budgieye
moderator
red light..............red ellipticals (red and dead) of CANDELS 2-epoch
star z=0http://talk.galaxyzoo.org/#/subjects/AGZ00086ya posted by Pythagora
EIS J033220.92-274646.9 03h32m20.9s -27d46m47s * 0 0.000000
Hubble ID: GDS_14713
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Budgieye
moderator
blue light............ blue spirals of CANDELS 2-epoch
spiral? z=0.288http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00086fy posted by rockcake
COMBO-17 32423 03h32m19.2s -27d48m30s G >30000 0.288000 21.9R 0.005
Survey: CANDELS 2-epoch
Hubble ID: GDS_11401
z=0.67 spiralhttp://talk.galaxyzoo.org/#/subjects/AGZ00086lf posted by graham d
COMBO-17 33471 03h32m43.2s -27d47m56s G >30000 0.668400 22.3R 0.002
Hubble ID: GDS_12520
photoz 1.33http://talk.galaxyzoo.org/#/subjects/AGZ00087nj
COMBO-17 27741 03h32m14.8s -27d50m39s G >30000 1.330000 PHOT 25.2R 0.002 7
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Budgieye
moderator
UV light.....star-forming, starburst, Wolf-Rayet galaxies, compact galaxies, clumpy galaxies of CANDELS 2-epoch
white dwarf star? z=0
http://talk.galaxyzoo.org/#/subjects/AGZ0007xyv I don't know what this is, so I'll just put it here for a while.
HDF:[CCH2004] r-31865 12h36m03.4s +62d06m25s VisS
http://www.galaxyzoo.org.s3.amazonaws.com/subjects/standard/GDS_8542_2epoch_standard.jpg
http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00087wa posted by C-cld
GLARE 3000 03h32m38.8s -27d49m54s G >30000 5.080000 ? 25.4z 0.003 12
green blob in upper left photoZ = 5.89http://talk.galaxyzoo.org/?_ga=1.104757952.1310713284.1428668940#/subjects/AGZ00087i6 posted by ramberts
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Budgieye
moderator
hot oxygen.....emission lines of oxygen, OIII OII Oiii, peas of CANDELS 2-epoch
pea? photoz=0.69http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00087tw posted by Sundog1a
*GOODS-CDFS-MUSIC 06764 03h32m27.0s -27d50m02s G >30000 0.690000 PHOT 24.3V 0.001
COMBO-17 29084 03h32m27.0s -27d50m03s G >30000 0.701000 PHOT 23.9R 0.002
I haven't looked at a spectral chart - this is a guess.
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Budgieye
moderator
hot hydrogen...... emission lines of hydrogen, HII regions, feeding black holes, AGN (Active Galactic Nucleus), quasars of CANDELS 2-epoch
z=0.5440http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00086qk posted by Sundog1a
http://talk.galaxyzoo.org/#/boards/BGZ0000004/discussions/DGZ0001dp5 RA: 53.03609848022461, DEC: -27.79290008544922
quasar on right photoz=0.85http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ000883u posted by ramberts
COMBO-17 30588 03h32m14.9s -27d49m21s G >30000 0.858000 PHOT 21.9R 0.011
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Budgieye
moderator
information about CANDELS 2-epoch
6.3 HST (Hubble Space Telescope) data http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=6&comment_id=53d8bae1db90c7673f001033
5.4 Galaxy Zoo 3 Hubble images http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=5&comment_id=53d8ba58db90c70a2a000bf6
Images from the CANDELS survey with the Hubble Space Telescope. Left: deeper 5-epoch images already classified in GZ. Right: the shallower 2-epoch images now being classified.
The new CANDELS images, however, are slightly shallower than before. The main reason that these are being included is to help us get data measuring the effect of brightness and imaging depth for your crowdsourced classifications. While they aren’t always as visually stunning as nearby SDSS or HST images, getting accurate data is really crucial for the science we want to do on high-redshift objects, and so we hope you’ll give the new images your best efforts.
New Images on Galaxy Zoo, Part 1 March 27, 2015 by karenlmastershttp://blog.galaxyzoo.org/2015/03/27/new-images-on-galaxy-zoo-part-1/
CANDELS makes use of the near-infrared WFC3 camera (top row) and the visible-light ACS camera (bottom row). Using these two cameras, CANDELS will reveal new details of the distant Universe and test the reality of cosmic dark energy.
IR filter on CANDELS
We can access different wavelengths in Examine
http://candels.ucolick.org/About.html
CANDELS mostly uses a different camera on HST to perform its imaging: the WFPC3/infrared channel. It takes images in 2 filters: what we call J and H, or F125W and F160W. Note that in this case 125 actually refers to 1250 nm, and 160 to 1600 nm. (I know; don't shoot the messenger! 😃) To make a 3-color image set for GZ, those images were combined with the ACS I-band images from each field as the blue channel. Between the new CANDELS images and the ones that have already been classified by the volunteers, only the depth is different -- the color prescription didn't change.
Also, given that its the Hubble which took the data in both programs, why does the resolution seem so much better? As far as I know, longer exposures (integration times) will change resolution only marginally (resolution is set by the size of the telescope mirror and the wavelength of the band/filter). What am I missing?
You're right that the resolution isn't actually better between the left and right columns in the image above -- I think it just looks that way because the noise is greatly reduced in the deeper images, and the extra color information probably helps too.
Blog: CANDELS: The new data in Galaxy Zoo September 12, 2012 by Harry Ferguson, CANDELS Co-Principal Investigatorhttp://blog.galaxyzoo.org/2012/09/12/candels-intro/ "The Hubble pictures in Galaxy Zoo: Hubble were taken with the Advanced Camera for Surveys (ACS), which was installed by NASA astronauts in 2002...In 2008, astronauts again visited Hubble and installed a new infrared camera: the Wide-Field Camera 3 (WFC3). they reveal light from older stars (2) they penetrate dust better than visible-light images and (3) they have the potential to discover more distant galaxies. Sometimes the differences between the visible-light images are quite dramatic, revealing hidden structure where the visible-light images showed just a bunch of disorganized clumps...you will be looking at images that are three-color composites: one taken through a long-wavelength filter on the ACS camera, and two taken through infrared filters on WFC3.
website: CANDELS Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey http://candels.ucolick.org/
data access http://candels.ucolick.org/data_access/Latest_Release.html
tile maps http://candels.ucolick.org/survey/Field_Maps.html#visits
Magazine articles: CANDELS:
http://iopscience.iop.org/0067-0049/197/2/35/article
http://adsabs.harvard.edu/abs/2011ApJS..197...35G
http://iopscience.iop.org/0067-0049/197/2/35/suppdata/apjs412820t1_lr.gif
Those round galaxy / stars that we wonder about in CANDELS http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0001e4y
Compact galaxies. This is what another survey did with those annoying round star galaxy images. They classified them as compact / unresolved.
I suggest we use the hashtag #compact.They are probably peas? or some extreme star-forming type of galaxy? Or maybe some are stars.
CANDELS Visual Classifications: Scheme, Data Release, and First Results http://arxiv.org/pdf/1401.2455v1.pdf
image in page 7
a number of the brightest objects in our sample are point sources page 8
Obscured quasars in CANDELS ,done by our own Kevin Schawinski, one of the founders of Galaxy Zoo.astronomers are uncovering an underlying population of fainter quasars that thrive in normal-looking spiral galaxies. They are triggered by black holes snacking on such tasty treats as a batch of gas or the occasional small satellite galaxy.
http://www.nasa.gov/mission_pages/hubble/science/quasar-snacks.html
Credit:
NASA, ESA/Hubble, and K. Schawinski (Yale University, USA)
STarlight Absorption Reduction through a Survey of Multiple Occulting Galaxies (STARSMOG) HST Proposal 13695
posted by C_cld
see Highest redshift http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/boards/BGZ0000006/discussions/DGZ0001cnq?page=0
Images of quasars and the surrounding galaxy from publication, with our very own Brooke Simmons as second author. The quasars have refraction spikes.
from http://arxiv.org/pdf/1504.02111v1.pdf
copied from http://talk.galaxyzoo.org/#/boards/BGZ0000006/discussions/DGZ0001cnq
red quasars and mergers paper, red quasars and mergers paper, THE QUASARS LOOK LIKE SPIKEY STARS!
http://arxiv.org/pdf/1504.02111v1.pdf p5
http://arxiv.org/abs/1504.02111
Major Mergers Host the Most Luminous Red Quasars at z ~ 2: A Hubble Space Telescope WFC3/IR Study
Eilat Glikman (1), Brooke Simmons (2), Madeline Mailly (1), Kevin Schawinski (3), C. M. Urry (4), M. Lacy (5) ((1) Middlebury College, (2) Oxford University, (3) ETH Zurich, (4) Yale University, (5) NRAO Charlottesville)
http://arxiv.org/pdf/1504.02111v1.pdf p5
http://arxiv.org/abs/1504.02111
Major Mergers Host the Most Luminous Red Quasars at z ~ 2: A Hubble Space Telescope WFC3/IR Study
Eilat Glikman (1), Brooke Simmons (2), Madeline Mailly (1), Kevin Schawinski (3), C. M. Urry (4), M. Lacy (5) ((1) Middlebury College, (2) Oxford University, (3) ETH Zurich, (4) Yale University, (5) NRAO Charlottesville)
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