Radio Galaxy Zoo Talk

ARG00009go - radio active star?

  • JeanTate by JeanTate

    The bright IR source slightly offset from the head of this #tadpole radio source is SDSS J143440.82+564554.6, a ~16 mag star of spectroscopic class K3, also a USNO object with zero pm.

    enter image description here

    Is it possible that the star is radio active?

    Posted

  • akapinska by akapinska scientist

    Yes, stellar radio sources can be observed, perfect example would be for instance pulsars (neutron stars). But in general radio stars are fairly rare; well as compared to radio galaxies and AGN which dominate the radio maps at these frequencies and sensitivities! 😃

    If you want to know more about physics then have a look at this lecture: http://www.annualreviews.org/doi/pdf/10.1146/annurev.astro.40.060401.093806

    I'm not expert in stars so can't comment on this one, but I think I would expect rather compact emission from stars with the FIRST survey. Anyway, stellar experts from our team should jump in here 😃

    Posted

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

    Thanks.

    I know the Sun is radio active, especially when flares go off, and as it's a fairly normal G dwarf, I'd expect a good fraction of main sequence stars are similarly active. But the Sun's intrinsic radio brightness is, well, rather wimpy, right? If it were, what, a few dozen pc away, FIRST wouldn't see it, even if an X-class flare were aimed straight at it, right?

    What I was wondering is whether a K3 star* with zero pm could possibly be the source of FIRSTJ143441.0+564603 ... the zero pm suggests that it's not close, so more likely a giant (or supergiant) than a main sequence star (I realize that it's far more likely that the radio source is a distant AGN plus jet/lobe, especially if the offset is real/the FIRST astrometry is ±~1")

    *there's no doubt that the SDSS spectrum is of a K3 star!

    Posted

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

    If you want to know more about physics then have a look at this lecture: http://www.annualreviews.org/doi/pdf/10.1146/annurev.astro.40.060401.093806

    I've no doubt that document is well worth reading.

    Unfortunately, it's not readily accessible:

    Purchase access to this review article using a credit card or an Annual Reviews access token.

    (Grants access for 24 hours after purchase - registration required)
    Review Price: $32.00(USD)

    $32 just to be able to read it for only 24 hours ... well, it's surely not that good.

    Many individuals can gain access to the full-text through their institution's site license. Before purchasing this article or a subscription, we encourage you to check your library's holdings.

    OK, but I'm just an ordinary zooite; I have no 'institution' (I guess they mean university, right?), so there's nothing for me to check.

    Now what?

    Posted

  • akapinska by akapinska scientist

    It's archived here http://arxiv.org/abs/astro-ph/0206436 to get around the pay-wall.
    I must have put the link from my office earlier where we have access to online journals 😉

    Besides, with regards to the radio emission from stars - completely forgotten to mention the obvious supernovae!

    Posted

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

    Thanks.

    Figure 1 seems to summarize the situation re normal stars (i.e. not pulsars or SNe). If I am reading it right, at least one K 'single star' supergiant has been observed (the red circle top middle), and quite a few K giants (though most are in 'RS CVn' or Algol binaries. Further, the K supergiant is among the most intrinsically luminous (log(L) ~18).

    However, it seems that no observed (normal) radio star has a huge radio plume ...

    Posted