[vsnet-campaign-be 264] Re: [vsnet-be 142] Re: V1294 Aql [vsnet-campaign-be 258][vsnet-spectroscopy 37]

[Thom Gandet <tgandet@mindspring.com>]

   Other astronomical history buffs may be interested to know that
V1294 Aql (HD 184297) has an observational history somewhat similar to
that of Delta Sco.

   Before 1971, HD 184297 was used as a secondary photometric standard
by Johnson and Morgan, with V=6.82 and B-V=+0.02.  It's spectral type
was accepted to be B0.5 IV, although it was seen to have H-alpha in
emission during the Mt. Wilson emission-line star survey in the 1920s.

   In 1971, the star was used as a comparison star by the observers
at USNO/FS, who found V=7.17, B-V=+0.02.  (See Dahn and Guetter 1973,
ApJ, 179, 551.)  That's the earliest mention of variability I have in
my file.

   The Hipparcos light curve of V1294 Aql shows it was at V=6.86 in
late 1990 and then smoothly faded back to V=7.16 by early-to-mid 1993.

   Likewise, Delta Sco was used in 1914 by Joel Stebbins, as a
comparison star for his photometry of Beta Sco.

   Dahn and Guetter used Delta Sco (one of the original MK standard
stars!) and Kappa Aql to re-classify V1294 Aql.  They confirmed the
earlier classification of B0.5 IV.  They saw no emission lines in 
any of the three stars, but they noted that the lower Balmer lines
appeared significantly sharper than in the other two stars.  The 
resolution of the spectra Dahn and Guetter used would not have
revealed weak emission lines, unfortunately.

Historically yours,
Thom Gandet



Sebastian Otero wrote:
>
>  Petr Harmanec wrote:
> >      Please, note that V1294 Aql is known to be an object with
> > an inverse correlation between the brightness and emission-line strength
> > already since our 1982 study (see ADS: Horn et al. 1982 BAICz 33, 308)
> > and it had been observed as faint as 7.6m once in the past.
> 
> Petr, when did the star get that faint before?
> I haven't seen this in the literature.
> 
> Thanks,
> Sebastian.
>