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[vsnet-chat 2854] Re: HD 88392 = RST 5345 = GSC 4904-00331


  John Greaves wrote, concerning this star:

> TASS J101131.7-001758 = RST 5345 = WDS10115-0018 = HD 88392
> [9.9-10.2 V]                      [mag 10.1, 12.7, rho 2.1", theta 14deg]
>                                   [Vj 10.2 (Tyc1), Vj 10.1 (Tyc2)]
>                                   [A5/7 II (MHD Vol5 Houk+ 1999)]
>
> I do not know what the resolution of the TASS instruments used on this
> star is.  Two arcsecs' separation is small, but given nights of variable
> seeing this [probably non-physical] double could be resolved some nights
> and not others.

  The TASS Mark III cameras have pixels about 14 arcseconds across,
so this star will never be resolved (or even close to resolved)
by TASS, regardless of the weather.

  Measurements of this star in the TASS "tenxcat" catalog, available
on-line at

          http://a188-L009.rit.edu/tass/www_scripts/make_chart.html

show the following:

              Vmean  Vsig  nV       Imean  Isig  nI
           -------------------------------------------
             9.981  0.099  11      9.492  0.073  20 


  A light curve from the catalogued measurements  (which may also be 
created at the above URL) shows little evidence for anything other than 
random variation, to my eye.  The scatter in the V-band is about 2.5
times the median scatter for stars of its brightness, but the scatter
in the I-band is close to the median for I-band.


> Note TASS log this star as an eclipser, ...

  The evidence for this is at 

      http://home.fuse.net/deepsky/TASS_J101131_7-001758.htm

which does show some periodicity in both V-band and I-band.
I agree with Greaves that this may not be an eclipsing system.
A period of 0.87 days for an A-star plus companion big enough 
to cause 20% variation sounds unlikely to me.  Perhaps some sort
of pulsation is more likely, if the star really is variable?


                                                  Michael Richmond

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