[vsnet-id 280] Re: CU Vul and CS4490

[Taichi Kato <tkato>]

Re: [vsnet-id 279] CU Vul and CS4490

>      Hoffmeister's chart is on MVS 266, and I have re-verified Timo's
> identification of CU Vul.

    Okay, the identification of CU Vul is now clear (was the BD identification
provided by Hoffmeister?)  [And I wish Timo and you could post these
established identifications to vsnet-id, using the format previously
used by me and Timo, and Yoshida-san.]

> Note that there is JHK and other photometry
> for CU Vul by Noguchi et al. (1981 PASJ 33,373).  They give J=4.86 and
> K=2.94 for C* 2798 (first Stephenson catalogue number), which they
> explicitly link to CU Vul.

    I am curious how Noguchi et al. identified this bright object with
the Stephenson C-star, which is apprently a few arcmin off.  It may have
been possible they simply measured the brightest red object near the
location of the cataloged C-star [did they consult the original catalog
source?]  If the explicit identification with CU Vul was provided, they
may have checked the original discovery reference on CU Vul; otherwise
this identification may have been purely on positional proximity, which
may not be sufficiently reliable.

> These are about five magnitudes brighter than the 2MASS object Kato-san
> found nearby.
>      Scanning the Noguchi et al. list quickly suggests cool carbon stars
> such as V Hya, T Lyr, V Aql, etc. have J-K colors of 1.5 to 2.  Giants
> near K5/M0 have J-K near 1.0, and of course stars near A0 have colors near
> zero.  Thus for the latter ordinary stars, J-K is roughly the same scale 
> as V-R in the visible.

    The 2MASS star near the cataloged position to GCCS 4490 is one of the
reddest stars in this field.  This star has a J-K color of 1.3, which is
intermediate between normal M-stars and C-stars.  USNO b-r = +4.6,
V-J = +4.8.

Regards,
Taichi Kato

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