Re: GSC 540-84

[Patrick Wils <patrickwils@yahoo.com>]

Also, the period (0.29 days) is long for a delta Scuti.  
The light curve changes observed by Michael, take place on a time scale
of a week, which is in the range of the Blazhko periods observed in the
MACHO first overtone RR Lyrae stars (RRc).

Patrick

--- "Shawn Dvorak (Rolling Hills Obs)" <rollinghillsobs@cfl.rr.com>
wrote:
> The range is 0.4 mag which, if I'm not mistaken, is fairly large for
> a delta
> Scuti.  V-Ic from TASS is 0.34 and B-V from Tycho is 0.16.
> 
> Shawn
> 
> 
> ----- Original Message ----- 
> From: "Arne Henden" <aah@nofs.navy.mil>
> To: "Michael Koppelman" <lolife@bitstream.net>
> Cc: "Tass" <tass@listserv.wwa.com>
> Sent: Monday, August 04, 2003 6:58 PM
> Subject: Re: GSC 540-84
> 
> 
> > I find it hard to believe that you would have double min/max
> > with a pulsating star; if eclipsing binary, then I find the
> > bump at maximum hard to believe if it occurs on both eclipses.
> >    More likely is that this is a delta Scuti variable with
> > more than one period, so you are getting amplitude modulation
> > of the light curve.  Similar to the Blazhko effect for RR Lyrs.
> > I don't know the color of your variable to see whether it is
> > an RR Lyr or delta Scuti, though the effect is the same.
> > However, Blazhko is usually a long-period modulation and takes
> > many fundamental-period cycles before you can see the effects;
> > delta Scuti periods can modulate the light curve quicker.
> > Bottom line:  not all pulsators are as easy to study as eclipsing
> > binary systems.  Look at the MACHO papers on variable stars; they
> > are the Bible with regard to statistical studies of specific
> > classes.  Just look for Doug Welch's name through ADS.
> > Arne
> >
> > Michael Koppelman wrote:
> > > I actually got a nice steady night last night:
> > >
> > > http://www.lolife.com/astronomy/gsc540-84/gsc540-84_20030804.jpg
> > >
> > > My comp star 1-sigma was 0.004! That's pretty good for me. The
> size of
> > > the dots is the size of the error bars.
> > >
> > > I'm still a little confused on this one. Using Patrick's period,
> which
> > > was confirmed by Chris Lloyd we get this:
> > >
> > > http://www.lolife.com/astronomy/gsc540-84/gsc540-84_phase.jpg
> > >
> > > Using double that period we get this:
> > >
> > > http://www.lolife.com/astronomy/gsc540-84/gsc540-84_dbl_phase.jpg
> > >
> > > The data from 07/29/03 seems discrepant at the start and end of
> the
> > > night if the period is not doubled. If the period is doubled it
> seems
> > > like the end of that night of 7/29 has problems. If you assume
> that no
> > > data has problems, something weird is going on.
> > >
> > > Michael Koppelman
> > >
> > >
> > >
> > >
> >
> >
> >
> 
> 


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