ARG00033m7 - strange blue cloud near galaxy
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by Dolorous_Edd
What is that wierd thingy around SDSS J124509.11+094606.4?
CFHT color composite image ( IGU as RGB)
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by JeanTate in response to Dolorous_Edd's comment.
Cool! 😃
My first impression is that it's the remnants of a disrupted disk, caused by interaction with the galaxy to the N, which itself shows signs of blue stuff. Star-forming regions? The fact that both nuclei are (compact) radio sources, possibly AGNs, also points to recent interaction. The N galaxy - zsp 0.047 SDSS J124509.20+094644.5 - has strong, narrow-line H-alpha, H-beta, [NII], and [SII] emission lines; [OII] and [OIII] not so much (I don't know enough about what causes one set of forbidden lines to be strong but not another to say what this signifies 😦).
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by 42jkb scientist, admin
Very cool!
Beyond my knowledge. I'll send this one to Bill.
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by NGC3314
Cool. That color almost certainly means line emission. No redshift either from SDSS DR12 or NED; the companion galaxy to the north has z=0.047, which would make sense for this one. That might be ionized by star formation spread through a disrupted disk (Jean Tate beat me to typing that) or by an AGN. I'm hoping to get an H-alpha image for that redshift with one of our remote telescopes soon, and we may have a chance to get a spectrum via colleagues at the 6-m telescope in Russia around the end of April. In the meantime - checking the GALEX archive interface shows that the spray of emission-line regions is fairly bright in both near- and far-UV filters which suggests star formation (AGN emission lines are weighted to the far-UV band). If it is star formation in a tidally distorted disk this could be relevant to whether (and when) disks re-form after major disturbances.
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by sisifolibre
Wow! Thank you for coment, this sound promising. Please keep us up to date with these new observations!
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by Dolorous_Edd
Most likely irrelevant, but I quickly looked at SDSS
And there are quite a few galaxies in the neighborhood with spectroscopic redshift of ~0.047
I marked them by red circles
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by 42jkb scientist, admin in response to Dolorous_Edd's comment.
How far away are these galaxies from the one with the blue blobs coming out of it?
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by Dolorous_Edd in response to 42jkb's comment.
I have updated the image
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by NGC3314
It's slightly hidden, but NED has added a tool to list objects within specified ranges of projected radius and redshift (among redshift-derived quantities, it's under "search for nearby objects"). That lists 11 objects with spectroscopic redshifts within 750 kpc=13 arcminutes and 500 km/s of the northern galaxy, for example. That seems sort of like a filament or sheet - if I could find a redshift-angle plot for SDSS in this area it might be clearer. The wide-angle ones I can find show a bunch of small structures around this area, closer than the Sloan Great Wall.
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by 42jkb scientist, admin
A filament? Interesting....wonder what we could say about that. Thinking....will return.
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by NGC3314
Update: I observed the pair with the SARA remote 1m telescope at Kitt Peak in a filter which includes H-alpha at the redshift of the northern companion galaxy (+/-0.01, fairly broad filter), and the blue structures are bright in that filter. This is consistent with them being a physical, interacting pair, but still not an actual redshift. I hope to get better data when the bright moon isn't up shortly, and we've suggested this as attract for spectroscopic observations at the 6-meter telescope coming up soon. (Having that filter installed was a piece of serendipity; apparently it was designed to measure CaH indices in stellar atmospheres).
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by JeanTate in response to NGC3314's comment.
Cool! 😃 Thanks for the update.
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by ivywong scientist, admin
Firstly, thanks all for getting me all excited about this blue fuzz. From my quick check, I think that the "blue fuzz" consist of extraplanar star formation due to some past interaction. The reason I think this is because the blue bits also correspond to very bright FUV emission from young O/B stars. Check out the UV colour image from GALEX (where the blue is FUV and yellow is NUV):
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by sisifolibre
Hi!. There are some new observations about this?
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