Radio Galaxy Zoo Talk

Voorwerp next to radio galaxy?

  • WizardHowl by WizardHowl

    The host of the hourglass signal, first commented on by mdwilber, appears to have a Voorwerp -like green nebula immediately adjacent to it. It is SDSS J102733.29+544227.9 and has a photometric redshift estimate of 0.22-0.29. The galaxy itself has an extended shape but the image does not have the resolution to say conclusively if this is a disk galaxy or a lenticular elliptical - both remain possibilities. The radio emission in FIRST shows two lobes but no core and the Voorwerp candidate is broadly in the direction of the lower lobe.

    Is this a real Voorwerp, or just a visual artefact, or are further observations needed to tell?

    Posted

  • DocR by DocR scientist

    This is worth following up on. The greenish emission is not just in the southwest (lower right), but up in the northeast also. Likely some kind of interaction with the radio galaxy. Not likely an artefact -- seen in both r and g filters.

    Posted

  • zutopian by zutopian

    Another Voorwerp-like green nebula:

    http://radiotalk.galaxyzoo.org/#/boards/BRG0000005/discussions/DRG00002kc

    Posted

  • zutopian by zutopian

    Here is a greenish galaxy.:

    http://radiotalk.galaxyzoo.org/#/subjects/ARG00036bv

    http://skyserver.sdss3.org/public/en/tools/explore/summary.aspx?id=1237672837448401092

    Posted

  • ivywong by ivywong scientist, admin

    Unlike the Voorwerps, the green is probably not due to the OIII emission line given the redshift of these objects and more likely to be due to recent star formation.

    Posted

  • JeanTate by JeanTate

    SDSS J102733.29+544227.9 certainly seems to be the host:

    enter image description here

    And whatever the galaxy is, morphologically, it is not a boring elliptical! 😃

    enter image description here

    Unlike the Voorwerps, the green is probably not due to the OIII emission line given the redshift of these objects ...

    I may be wrong, but doesn't Hanny's Voorwerp appear blue in the standard SDSS Explore images, because the 500.7nm [OIII] line is in the g-band filter, which is mapped to blue in JPEGs? For a redshift of ~0.25, that line would be observed at ~630nm, which is in the r-band, and so appear green in standard SDSS images, right?

    Boilerplate: SDSS image per http://skyservice.pha.jhu.edu/DR10/ImgCutout/getjpeg.aspx, FIRST (red) contours derived from the FITS file produced using SkyView with Python code described in this RGZ Talk thread. Image center is the galaxy SDSS J102733.29+544227.9, near the ARG image (ARG0000css; J2000.0). "z_ph" is an SDSS photometric redshift of the galaxy in the center.

    Posted