[vsnet-obs 1723] Re: KM Lac & FY Vul

[tkato@kusastro.kyoto-u.ac.jp]

L. T. Jensen wrote:

> Identication problems.
> All my observations of the star marked on Downes&Shara as KM Lac are in
> the range 14.5 - 14.8.
> All my observations of the star marked on Downes&Shara as FY Vul are in
> the range 13.8 - 14.2.
> 
> Naturally identification problems are the most probable explanation for the 
> observations.
> But what is the probability that we are in fact seeing standstills of KM Lac 
> and FY Vul ?
> Have spectroscopical observations showed that the stars are not CV's ?

   There is at least one spectroscopy of FY Vul in Downes et al. (1995,
Astron. J. in press).  According to Richter (1961), FY Vul was originally
classified as a dwarf nova with an outburst cycle length of 30-50 days.
The Z Cam classification was given by Meinunger (1965).  Downes et al.
confirmed a CV spectrum of likely dwarf nova class.  I suspect FY Vul to
be a system resembling CM Del, which shows only weak (but seemingly periodic)
outbursts.

   As far as I know, there is no published spectrum of KM Lac.  My exami-
nation of the discovery paper seems to confirm the identification by
Downes & Shara (1993).  The discoverer gave the following outbursts dates and
magnitudes.  Has the system changed its properties dramatically, or was there
any problem in the original chart?

     JD         mpg
   2430256     14.8
     32766     14.8
     33156     14.9
     33276     15.0
     33442     14.8
     33975     14.8

Regards,
Taichi Kato

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