Galaxy Zoo Talk

Those round galaxy / stars that we wonder about in CANDELS

  • Budgieye by Budgieye moderator

    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

    Here are some round objects classified as galaxies in CANDELS

    The ones classified as galaxies all seem to be from the speckled images.

    enter image description here compact photoz 0.84

    http://talk.galaxyzoo.org/#/subjects/AGZ000880o posted by AmySambrook

    EIS J033249.21-274933.4 03h32m49.2s -27d49m33s G >30000 0.844000 PHOT 23.8R

    CANDELS 2-epoch

    enter image description here compact photoz=0.44

    http://talk.galaxyzoo.org/#/subjects/AGZ000878p posted by Auriam

    COMBO-17 37699 03h32m48.2s -27d45m53s G >30000 0.446000 PHOT 22.1R 0.003

    CANDELS 2-epoch

    enter image description here photoz 0.071

    http://talk.galaxyzoo.org/?_ga=1.221223262.711441289.1371287491#/subjects/AGZ00086d9 posted by dddusty

    COMBO-17 31997 03h32m47.2s -27d48m39s G 21285 0.071000 PHOT 21.9R 0.005 11

    Survey: CANDELS 2-epoch Hubble ID: GDS_10942

    Posted

  • Budgieye by Budgieye moderator

    Star or compact galaxy. NED says star, but call it compact anyway? They look the same to me in images.

    enter image description here compact z=0 star?

    http://talk.galaxyzoo.org/#/subjects/AGZ00087n5 posted by Auriam

    Survey: CANDELS 2-epoch Hubble ID: GDS_6879

    EIS J033222.81-275053.4 03h32m22.8s -27d50m53s * 0 0.000000 20.3R

    enter image description here compact z=0 star?

    http://talk.galaxyzoo.org/#/subjects/AGZ00086e4 posted by tropicaljake

    COMBO-17 31995 03h32m30.0s -27d48m39s * 0 0.000000 21.2R 0.004

    enter image description here compact z=0

    http://talk.galaxyzoo.org/#/subjects/AGZ00086zi posted by leonie van vliet

    EIS J033210.49-274641.0 03h32m10.5s -27d46m41s * 0 0.000000 20.6R 0.008

    Posted

  • Budgieye by Budgieye moderator

    Star or round galaxy? If background is speckled, it is a galaxy. If background is black, it is classed as a star. Is this real, or due to observation by different instruments? This is based on a sample of 6.

    I am starting to think that they are all stars.

    Posted

  • Budgieye by Budgieye moderator

    Images of quasars and the surrounding galaxy from publication, with our very own Brooke Simmons as second author. The quasars have refraction spikes.

    enter image description here

    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)

    Posted

  • vrooje by vrooje admin, scientist

    I'd guess at least a majority of these are stars, and others may be distant quasars or other (less luminous) AGN. The quasars in the paper mentioned above are some of the most luminous objects in the Universe, so it's unsurprising that they all have strong diffraction spikes visible above the noise. Most stars/AGN are fainter so the spikes are either not as prominent or aren't visible. If you were to image a star and then turn its brightness up and up, it would start to show those little dots arranged around the main compact source (as above), and then diffraction spikes come next. Also, in our CANDELS images, the bluish core is a signature of an unresolved source -- how strong that is depends more on the color of the star/AGN and less on the total luminosity.

    Posted

  • Budgieye by Budgieye moderator

    Thank you Dr Simmons. I had noticed that some of these compact sources had little blue cores, and I had wondered if that was significant.

    Posted