Galaxy Zoo Talk

Two galaxies and something bright

  • st_isidore by st_isidore

    What's going on in this one?

    Posted

  • Budgieye by Budgieye moderator

    There is no sign of interaction between the two galaxies.

    The photoZ s are different, the spiral is closer.

    spiral photoZ 0.0970 http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237666273664827408

    bright object is an overlap star in our galaxy , though there might be a galaxy behind it.

    enter image description here

    edge-on photoZ 0.116 http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237666273664827407

    Posted

  • JeanTate by JeanTate in response to Budgieye's comment.

    spiral photoZ 0.0970

    The DR8 pipeline gives 0.097061±0.026006, i.e. between 0.071 and 0.123 (1 sigma, presumably)

    edge-on photoZ 0.116

    Likewise, 0.116162±0.018842, i.e. between 0.097 and 0.135 (ditto).

    Given the uncertainties in the photoZ's, I don't think it's possible to say which is closer.

    bright object is an overlap star in our galaxy , though there might be a galaxy behind it.

    The SDSS pipeline thinks there is a galaxy, SDSS J012207.45+225551.3, and gives its photoZ as 0.142377±0.08267 (i.e. between 0.060 and 0.225; 1 sigma).

    There's another galaxy of similar appearance, top-right, SDSS J012208.15+225620.3; its photoZ is 0.089272±0.017104 (i.e. between 0.072 and 0.106).

    The four photoZ's are consistent with the four galaxies having the same redshift, and so it's possible they make up a fairly tight group. The barred spiral is 'red', as are the other three (as far as one can tell); perhaps star-formation has all-but ceased in all four galaxies? If so, that may be due to depletion of cold (molecular) gas, as a result of earlier interactions.

    It's a pity there are no spectra.

    Posted

  • zutopian by zutopian in response to JeanTate's comment.

    It's a pity there are no spectra.

    Well, there are no spectra for these galaxies in DR8, but there is a spectrum available for one of the galaxies in DR10.:
    The spectroscopic redshift of the spiral (red square on below image) is z=0.071 .

    enter image description here
    http://skyserver.sdss3.org/dr10/en/tools/explore/summary.aspx?id=0x112d12eb20460010&spec=0x4fec6396fd080000&apid=

    Posted

  • Budgieye by Budgieye moderator

    Thank you JeanTate

    and Zutopian thanks for finding out that dr10 has more information.

    So spiral galaxy has PhotoZ 0.097±0.026, so maybe 0.071 and the Z is 0.071. Not a bad guess by the PhotoZ

    Posted