[vsnet-chat 2582] FK Pup - another very red variable

[Mati Morel <morel@ozemail.com.au>]

        With the recent attention which has been given to two large
amplitude red
variables in Puppis (NSV 4189; CGCS 1825 (Paul Camilleri's star), I am
throwing in
another very red star - FK Puppis. This is a carbon star, sp. C6-,3e (N). It has
a range of 12.0 - 15.3p, and is marked on VSS, RASNZ chart 85 (Jan. 1966),
as being
about 1' N of SAO 198860 (8.6v). I have long been intrigued by this chart
and the
implication (on chart 85) that FK Pup is a minor variable, and not suitable for 
visual observation (cf Publ. 20, Var. Star Section RASNZ, 1995 November). This
grading will, I believe, be soon revised.
        After careful examination, I find that the position of FK Pup relative
to SAO 198860 (above) is in error. In fact FK Pup _IS_  SAO 198860, and
there is no
other star in the near vicinity. Also, FK Pup becomes rather bright visually
- H/T
data reports 8.64V, B-V +3.69. It may become even brighter than 8.6, if we
accept
the GCVS figure of 12.0p as being reliable. I think the mistake probably
arose in
the preparation of chart 85, when different catalogues were consulted - SAO
198860
is given a spectral type of F5, while FK Pup is definitely a carbon star. It was
doubtless assumed that there are two stars in close proximity. This has
turned out
to be wrong - the SAO spectral type is grossly in error.
        I checked the field quickly a few nights ago to confirm this - there
was 
only one star at this spot, and it was well down in the 10's visually.
        A new chart is in preparation, and FK Pup should be an easy object
to follow.
        I suspect it may have been neglected for a long time, even though it
is a
fairly easy target, allowing of course for its extreme redness.

DATA: FK Pup = SAO 198860 = CoD-35 4257 = GSC 7133.4076 = IRAS 08073-3608.
      Not in HD cat.  Spect. type = C6-,3e(N).
      (J2000) : 8h9m10.9s -36 17'7.8"

Addendum: This is the second instance within 9 months, where I have found a
_carbon_
star in the SAO catalogue with an F_ spectrum. The first one was SAO 251015
(F0) 
= CGCS 1705 = EsB 312 =CoD-62 466.  Is there something about a Carbon star
spectrum
which, under certain circumstances, can be mistaken for an F ?  

Regards,
/Mati

  /=====================================\
  |  MOREL ASTROGRAPHICS                |
  |  Stellar Data & Information Centre  |
  |  c/o M. Morel                       |
  |  6 Blakewell Road,                  |
  |  Thornton  NSW 2322  AUSTRALIA      |
  |  Tel./fax: (02) 4966 2078                                   |
  |  151d38'33" E, 32d46'47"S           |
  |  e-mail: morel@ozemail.com.au       |
  \=====================================/

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp