Radio Galaxy Zoo Talk

ARG0001rn6 - A radio star?

  • Dolorous_Edd by Dolorous_Edd

    SDSS J170008.72+291903.7 is a star according to SDSS spectrum, but it doesn't make any sense since it is also a host of the triple

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    Spectrum is wrong or the source is behind the star?

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    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    Spectrum looks pretty darn good; first that of SDSS J170008.72+291903.7:

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    Next, K star template (from DR7 Spectral cross-correlation templates):

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    If there's a high-z object hiding behind this star, it's both very faint and has no obvious emission lines!

    VERY interesting find; well done csunjoto and Dolorous Edd! 😃

    Posted

  • Dolorous_Edd by Dolorous_Edd

    SDSS J170008.72+291903.7 is also visible in WISE 3 and WISE 4 bands

    Implications?

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    I don't know.

    If it is indeed a K3V star, it's a normal main-sequence star (like the Sun; that's what the "V" says), and so must be fairly close by (IIRC, K stars have absolute magnitudes of ~7; this star has an apparent magnitude of ~17, so it's likely ~1000 pc distant). K stars are red(ish), so they may be bright in the WISE3 band. However, to be also bright in the WISE4 band, there'd likely be lots of dust involved. Perhaps this star has not yet fully shed/shredded its dust disk? Maybe it's a quite young K star? If so, the open cluster it was likely born in should still be visible ...

    (all just speculation on my part; I think we need someone like Bill Keel/ngc3314 to weigh in ...)

    ETA: initially I had written "so it's likely ~100 pc distant"; this is incorrect (I think), it should be "so it's likely ~1000 pc distant" (corrected). 10 mags is a factor of 10,000, with inverse square that's a distance factor of 100; absolute mags are defined at 10 pc, so turning the handle ...

    Posted

  • Dolorous_Edd by Dolorous_Edd

    Another such case

    http://radiotalk.galaxyzoo.org/#/subjects/ARG000348j

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    SDSS J082656.63+093336.7

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    Note: slight ( ~1-2" ) offset between center of a star and center of radio emission

    Maybe a background source after all

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    Cool! 😃 One case is - often - just a coincidence; two? Not so much ...

    Won't be easy to follow up, to see how many others there are like this, but maybe my Collection STAR but likely a QSO but don't know it might help? There are surely more than the 76 in it, as I have not always collected these objects when I came across them while classifying ...

    Posted