Galaxy Zoo Talk

Cometary galaxy

  • zookeeper by zookeeper admin, scientist

    This is a fun object; it's easier to see if you Zoom out.

    There's a faint body of gas with large, blue, star forming regions at either end, although one is much larger than the other. So the real question is why all the star formation is at one end of the galaxy. It's tempting to argue that it must be an environmental effect - maybe a bowshock because this thing is ploughing through some denser medium.

    But if you zoom out again then you find nothing around, certainly no dense cluster that might have hot gas amongst the galaxies to cause this kind of effect.

    I therefore suspect that this is just a reflection of the fact that star formation is random - triggering star formation is a complicated process, and it's subject to a feedback loop. So perhaps this end of the galaxy happened to produce a massive star which went supernova, and then that caused more star formation. Would be interesting to look at exactly how blue this is...

    Posted

  • Budgieye by Budgieye moderator

    Hubble image and spectrum available.

    from Ultracompact Blue Dwarf Galaxies: Hubble Space Telescope Imaging and Stellar Population Analysis http://iopscience.iop.org/0004-637X/651/2/861/fulltext/

    Hubble image http://iopscience.iop.org/0004-637X/651/2/861/fulltext/ image is bottom left.

    SDSS J0248-0817.β€”This object qualifies as a "cometary" type of BCD, with a large starburst region at its northern edge and a relatively low surface brightness component (approximately 20.5 mag arcsec-2 in F814W) of redder stars extending to the south. Only the starburst region was detected and cataloged in the SDSS object database, leading to our identification of it as a UCBD candidate. While it is not strictly a UCBD under our criterion of a physical size less than 1 kpc, its small size and morphology in the SDSS images was sufficiently striking to warrant inclusion in the sample. The starburst region has a complex structure, consisting of two central loose clusters of stars with surrounding associations and individual OB stars. Two shelllike structures are seen at the northern edge of the starburst region, with recently formed stars on their edges. This may be an example of supernovae-induced star formation

    enter image description here

    enter image description here

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  • Capella05 by Capella05 moderator

    Thanks Chris and Budgie!

    Interesting reading πŸ˜ƒ

    Posted

  • Budgieye by Budgieye moderator

    This blue pea was noticed 6 times in Galaxy Zoo, but no conclusions made. Access to Hubble would have helped. πŸ˜ƒ Initially, SDSS had the redshift as 3.8 but it was revised. http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237652900229414954

    http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587727179004510258

    http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237652900229414954

    Posted