Um... what? Blue-purple galaxy
-
I have not the faintest clue what this thing is... can anyone help?
It's not a quasar- I can resolve its size quite easily.
It's not a voorwerp- it's centered on the galaxy itself!
It's not a green pea- the color is blue enough that it's brighter in the G band than any other band!The photoZ is apparently 0.041 ± 0.0327, but that doesn't seem right. The galaxy would have to be only 3,000 to 25,000 light years across, and MUCH closer than any known pea!
I've verified that it's not an exposure artifact as well. It appears unusually blue in every one of the several SDSS exposures over several years, as well as PANSTARRS & DECaLS!
Posted
-
by
Ghost_Sheep_SWR
in response to planetaryscience's comment.
No spectra, no references, no redshift (error margins on PhotoZ always fun), confirmed very blue and non-stellar (extended source).
In combination with a GALEX (UV) detection I would go for an (extreme) starburst galaxy, perhaps a Blue Compact Dwarf galaxy but theres nothing to say about it's possible size without spectrum z (or good photometric guess).
Weird find btw, how'd you find it?
Posted
-
by
planetaryscience
in response to Ghost_Sheep_SWR's comment.
I found it sticking out like a sore thumb in a field supposedly containing a Jupiter Trojan.
I've done some research of my own since posting, and apparently the color is that of OIII. OIII only has that specific color at very low distances (z less than 0.07) and rarely even looks so blue at the most distant ranges. As such, I'd highly bet its z is less than 0.05, and it's just an extremely tiny galaxy.
I don't think high star formation alone can account for the color. For instance look at BCD UGCA 281:
Sure it's blue, but not THAT kind of blue. The blue looks more like that of active merging galaxies like the ones put in the GZ index section 3.3 (examples:)
Posted
-
by
bluemagi
Hi, Don't know if this will help you but I thought I'd give it a go. There are 2 galaxies I think they could be either a Blue Compact or a Wolf-Rayet. Have a look at MRK 209 also look at SDSS Dr8 at RA:186.566 DEC:48.494. Sorry unable to post photos. bluemagi
Posted
-
by
bluemagi
I forgot also have a look at NGC 5471.
Posted
-
by
JeanTate
Somewhat larger than usual blueberry?
A blueberry is a lower-redshift green pea (GP), the [OIII] 5007 line falls in the g band filter (B) rather than the r band one (G). They're lower mass than GPs, but otherwise similar. There's a link to a paper on them somewhere ...
Posted
-
by
Budgieye
moderator
Put in Objects that need more research https://talk.galaxyzoo.org/#/boards/BGZ0000004/discussions/DGZ0000ycq
for the time being. My own vote is for a double star, one being an (ultraviolet) white dwarf, the other maybe a red star.Posted
-
by
CeciliaB
Looking at Budgieye's photo I would say that the colour is more purple than blue. That's the colour one might expect to get from a purple pea at z=0.04.
Posted
-
by
planetaryscience
in response to JeanTate's comment.
Now that looks promising. The other blueberries have a very similar color
Budgieye, Given the clear horizontal elongation, I'd say it's unlikely it's a WD binary and such- besides, the emission of such a new WD would be MUCH higher in the UV!
Posted
-
Looks more like a point source in u and z band, extended in g r i bands
Posted
-
by
Budgieye
moderator
Some discussion about blueberries in
p 7 and 8
The Green Pea Galaxies.
Started 3 years ago by Rick N.https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000zvt
Posted
-
by
bluemagi
https://arxiv.org/abs/1706.02819
Interesting article on Blueberries.Posted
-
by
Budgieye
moderator
Looks different in SDSS dr7, more like a blue pea.
http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587738947192685003
Posted