Smooth galaxy / unlabelled peak
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Budgieye
moderator
I am looking for your extinction data. Can you post the link to where you saw it?
Galaxy Extinction is when a galaxy is redder than might be expected, and the redness makes some of the distance calculations wrong. This unexpected redness can be due to dust in space between us and the object.
The dust can be
dust in our galaxy, the Inter Stellar Medium, ISM, which affects
galaxies too close to the plane of our own Milky Way galaxy. This galaxy doesn't look as if it is near the galactic plane, there are not many stars and no brownish swirley areas.or
around the object
https://en.wikipedia.org/wiki/Extinction_(astronomy)
DECaLS browser
http://legacysurvey.org/viewer/jpeg-cutout/?ra=146.0796&dec=-0.6812&zoom=16&layer=decals-dr2
http://legacysurvey.org/viewer?ra=146.07941312635975&dec=-0.680955274889875&zoom=14&layer=decals-dr2
SDSS
SDSS skyserver
http://skyserver.sdss.org/dr9/en/get/specById.asp?id=299515241090279424z =0.067 error 0.00002
photoz 0.088 zErr 0.02
The spectral chart shows that it has an even number of blue, white and red stars. So not too old and not newly formed.
It has some dust in the spectrum, as there are absorption areas, eg Mg and Na. So we might be looking at the galaxy slightly edge on, so the light from the nucleus is slightly absorbed.
Some light is getting through from the nucleus, as there is an emission peak at about 7600 Å which to me is likely to be the hot hydrogen peak Hα from a slightly active nucleus. The black hole is eating some hydrogen.
The computer software has not identified any of the peaks, and has tried to assign it to some tiny peak, leaving the big peak .
The absorption valleys seem correctly identified.
Looking at the colour of the galaxy in SDSS, it is yellow not orange or red, I would think the redshift z is about....... 0.2
Am I correct? Let us see.
At z=0.2 I would expect to see some detail of spiral arms. I don't see any detail, maybe it is an elliptical? or a confused spiral?
The boring spectrum rules out it being an exotic starburst elliptical. Dust can't totally hide huge emission peaks.
So what is the big peak? An artifact?
Why can't I see spiral arms? Is it an elliptical?
Astrophysics for Galaxy Zoo Talk Galaxy Redshift Chart for SDSS http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=2
SIMBAD
Object of unknown nature http://simbad.u-strasbg.fr/simbad/sim-coo?Coord=09+44+19+-00+40+51.4&Radius=1.0&Radius.unit=arcmin&CooFrame=FK5&CooEqui=2000&CooEpoch=2000&jsessionid=CF8BA69DD78403D8986F32262BD5F57C
Determining spectroscopic redshifts by using k nearest neighbor regression http://www.aanda.org/articles/aa/full_html/2015/04/aa24801-14/aa24801-14.html
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elsie22
wow that's amazing. that's what I would like to be able to do. what I did was go to the sdss data. on the left hand side you can choose various options. I chose one that said .....
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elsie22
right. so I looked in the SDSS Sky viewer. clicked on 'all spectra' on the left hand side halfway down. two entries came up. I clicked on the second one and the went to 'search on NED' . then it takes me to the NED resource which gave me a 'source list '. so I clicked on the first . the closest one. titled 2MASXi J0944190-004051. does that help
I dont know how to send you the linkPosted
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elsie22
I did wonder what the spike was on the graph that isn't labelled at about 7500 angstroms....?
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Budgieye
moderator
copy the link from the address bar at the top of the screen eg https://talk.galaxyzoo.org/#/boards/BGZ0000004/discussions/DGZ00020dp
(but I don't know about mobile apps)
Here is the link
FOREGROUND GALACTIC EXTINCTION for 2MASXi J0944190-004051
Yes, this is computer generated data for how close the galaxy is to the messy dusty plane of the Milky Way galaxy. I suppose these numbers allow correction to the light from the galaxy. I don't know much about dust, but here goes.
4.2 Milky Way Galaxy and Andromeda Galaxy and nearby http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=4&comment_id=53d8b9890d43f776b0001093
Talk: Zone of Avoidance http://talk.galaxyzoo.org/#/boards/BGZ0000006/discussions/DGZ0001962?page=1&comment_id=54de46566975263491000620 galaxies are hard to see through the dust of our Milky Way galaxy
3.7 Spectra of absorption galaxies http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef71025c6427998000057
What dust does to spectrum, it absorbs the blue and leaves the red
http://cas.sdss.org/dr7/en/get/specById.asp?id=376558677236121600
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elsie22
have I picked up the correct object and done what I've done correctly so far?
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Budgieye
moderator
Sorry, I got carried away with the dust. 😃 Yes, you have found the correct galaxy in SDSS
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237650795146248304
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elsie22
so what do I classify the image as
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Budgieye
moderator
I would say smooth and oval.
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mlpeck
This has to be an overlapping pair with quite different redshifts. The peaks in the spectrum at ∼7400Å are Hα+[N II]. The weaker peaks a little ways to the red are the [S II] doublet at 6718, 6733Å. That makes the redshift of the second system z≈0.126. I'm sure more lines could be identified, but those two sets alone are enough to establish the redshift.
Bill Keel might be interested in this one.
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Budgieye
moderator
Good thought. There might be a buried lens arc in it. I will contact a scientist.
I think that Bill Keel needs galaxies half overlapped, so he can compare the spectra in the 2 sides.
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drphilmarshall
scientist
Looks like an overlap, but if there's lensing going on then most of it will be weak (i.e., little multiple imaging). It's hard to tell how massive the foreground galaxy is, but even it was a typical massive eliiptical then the Einstein radius of around 1 arcsec would give a ring (or arc/counter-arc pair) of diameter 8 pixels - which is very close indeed to the center of the less red, whiter, main peak in the image. The secondary peak you found looks to be about 10 pixels away or more, so unlikely to be multiply-imaged. However, the outer parts of the background galaxy will be being magnified by the foreground object - which could be something to keep in mind when analyzing the two galaxies.
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Budgieye
moderator
Thank you Dr Phil 😃
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mlpeck
in response to Budgieye's comment.
The paper by Kugler et al. (2015) that Budgieye linked earlier singles this object out for discussion. They think there's evidence for lensing based on the SDSS imaging. Check out their Figure 8.
FWIW the algorithm they are testing picked up on the same Hα+[N II]+[S II] set of emission lines that I noticed.
Thanks for following up on this!
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Budgieye
moderator
Maybe the visible galaxy is not the lens
We are just looking at the top graph.
. The green line in the background is the SDSS spectrum with the gray
spectrum at the bottom being the typical noise deviation. The red
curve shows the fitted spectrum with a redshift as obtained by SDSS,
the blue curve is the overplotted spectrum with the redshift as
obtained by our regression model.SDSS i-band image of J094419.05-004051.44 (smoothed with Gaussian blur
of 3-pixel width). In the right image the asymmetric arc has been
overplotted by a green circle.http://www.aanda.org/articles/aa/full_html/2015/04/aa24801-14/aa24801-14.html#figs
left : the vague curved line, right where to look.
SDSS skyserver dr9 same scale different orientation, red curve over the galaxy
differerent orientation, I will try to rotate later
ra=146.07941066&dec=-0.68095728&scale=0.049515875&width=400&height=400&opt=&query=SDSS J094419.05-004051.4 2MASXi J0944190-004051
Maybe the lens is where the purple arrow is pointing? Or one of the other red galaxies?
SDSS used g, r and i bands to construct images. (green, red and far red light)
The unlabelled peak should be a red item on the SDSS image.
3.10 Spectra Guide : How colour is presented to you on the computer screen https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000ulp?page=3&comment_id=53fef74c25c642799800005c
DECaLS is even redder, and has more resolution, so we should be able to see it. But we can't because image is overexposed.
DECaLs Browser dr2
http://legacysurvey.org/viewer/jpeg-cutout/?ra=146.0798&dec=-0.6812&zoom=16&layer=decals-dr2
Maybe someone who knows FITS images can make us a red image?
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mlpeck
in response to Budgieye's comment.
Maybe someone who knows FITS images can make us a red image?
I had a look at the FITS images using DS9 and every available stretch, and saw nothing in any band. The "good" news, I guess, is the DECals public release images are recorded in the g, r, and z bands. The i band filter covers the wavelength range ∼7000-8000Å and if the background galaxy's light is dominated by emission it might only be bright in i since Hα+[N II] are redshifted to ∼7400Å.
I wonder why they made that choice of filters. There's a 1000Å gap between the red edge of the r filter and the blue edge of z, while g,r,i together cover the human visible wavelength range. This probably partly explains why the DECals images have a noticeably different color balance than SDSS imaging.
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Budgieye
moderator
Too bad there is no evidence for a lens arc in the red filter image. Thank you so much for trying. Maybe the red is from the slightly redness, which I can barely see, and might be my imagination.
Galaxy redshiftof 0.067 is quite exact since absorption peaks are identified.
What is red? see Galaxy Redshift Chart http://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
Hydrogen Hα peak redshift 0.127
Red OIII (red pea) at 0.9
If the red is a very distant quasar z=5 or so, it
http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?ra=146.07941312635975&dec=-0.680955274889875
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Budgieye
moderator
Maybe it is a faint voorwerpje, like the example below. The red colour comes from hydrogen being heated by UV light from the nucleus.
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