[vsnet-chat 5279] Re: [vsnet-gcvs 204] Re: theta Apodis

["Stan Walker" <astroman@xtra.co.nz>]

Hi Peter,

Your note is interesting. If possible, could I see the theta Apodis visual
measures? I'd like to subject these to a periodogram and send the results
back to you.

As for L2 Puppis, Harry Williams has been measuring this recently. It has
just gone through an extremely faint minimum - the faintest that we have
ever recorded. I'm awaiting further data from Harry but the weather in
Auckland has been poor. My problem is a lack of BVRI filters - the set I
have delaminated - but hopefully this will be resolved shortly. The L2
measures are set out below - JDH -2400000, V, B-V, U-B.

52296.8945,6.124,1.842,.707
52307.9433,6.381,1.971,.724
52320.8844,6.475,1.845,.824
52322.9151,6.47,1.795,1.136::
52323.8674,6.46,1.754,.786
52331.8709,6.405,1.746,.838

The light curve shows that the B reaches minimum a little before the V - not
unusual.

Regards,
Stan

----- Original Message -----
From: Peter F Williams <pfwilliams@onaustralia.com.au>
To: Sebastian Otero <varsao@fullzero.com.ar>; vsnet-chat
<vsnet-chat@kusastro.kyoto-u.ac.jp>; <vsnet-gcvs@kusastro.kyoto-u.ac.jp>
Sent: Friday, March 29, 2002 1:26 PM
Subject: [vsnet-gcvs 204] Re: [vsnet-chat 5267] Re: theta Apodis


> Hi Sebastian, Stan  and All,
>
> As Stan noted, multiple cycles is probably closer to reality than a single
> mean period.
>
> The observations used in the VSS RASNZ paper are more continuous from
about
> 1993 through 1999. During this interval, the binned periods mostly ranged
> from 90-99 days upto 130-139 days, peaking in the 110-119 day range.  The
> O-C diagram shown for the mean period 115.93 days period suggests a second
> much longer cycle of period near 1855 days (about 5 years or 16 cycles)
may
> also be present but a much more extensive series of observations would be
> needed to confirm if this is correct.
>
> This also suggests the period length may currently be decreasing (as seen
> by Sebastian) towards a minimum period in the 90-99 day range (as reported
> by Stan) during the next year or two, before again increasing.  We will
> have to watch on Theta Aps over the next few years to confirm this.
>
> The O-C daigram also plots values for an alternative 118.85 day period
> which is close to the current GCVS period.  This period produces a
> continual slope towards lower right which suggest this as a mean period is
> a little too long.
>
> Sebastian also mentions L2 Pup, a star currently going through interesting
> faint stage.  Check out the long term data on this star at the AAVSO light
> curve generator.  There are still some interesting stars for the binocular
> observer.
>
> Regards
>
> Peter Williams
> Heathcote NSW
>
> ----------
> From: Sebastian Otero <varsao@fullzero.com.ar>
> To: vsnet-chat <vsnet-chat@kusastro.kyoto-u.ac.jp>;
> vsnet-gcvs@kusastro.kyoto-u.ac.jp
> Subject: [vsnet-chat 5267] Re: [vsnet-gcvs 201] Re: theta Apodis
> Date: Wednesday, 27 March 2002 4:53
>
> Dear all:
>
> Stan wrote:
>
> > 14 UBV measures tend to
> > suggest that the variation is from 5.0 to 5.8 at least. I did a
> periodogram
> > of this and found a main period of 98.8 days although the data didn't
fit
> > this all too well. I see the GCVS gave 119 days and a range of 6.4-8.6p.
>
> >We concluded that it probably had
> > two periods which beat together.
>
> And Peter wrote:
>
> > Theta Aps, appearing in Publications No24 of the VSS RASNZ (April 2000)
> > is a paper I prepared based on 553 visual observations between 1959 and
> > 1999 from the VSS data base. These indicated a mean visual range of 5.6
> to
> > 6.4 and extremes of 5.2 to 6.8.  An average period of 115.93 days was
> > found.  Derived elements for maximum are JD 2449558 +/- 115.93 days.
>
> It sounds interesting that my current deduced period (from visual
> inspection
> fo the lightcurve only) is exactly at the middle of both periods Peter and
> Stan quoted:
>
> Peter: 115.9 days
> Stan:  98.8 days
> Mine: 107 days
>
> From the recent lightcurve is obvious that the ephemeris provided by Peter
> don't fit with the observed.
> Maybe the period has been shortening (119 - 116 - 107...)
> I'll download Hipparcos data and read the papers mentioned by Brian that
> must be very interesting.
>
>
> > I'd imagine that Sebastian has measures during an interval when the beat
> > period is low, or has reinforced one or two bright maxima. I didn't see
> him
> > quote a period and haven't had time to get onto the website.
>
> However I don't find any irregularity or traces of beating between two
> periods in the shape of the lightcurve. The beating effect is tremendously
> evident in the L2 Puppis case mentiones by Stan.
> (See http://ar.geocities.com/varsao/Curva_L2_Pup.htm  ) and in other cases
> like R Doradus (http://ar.geocities.com/varsao/Curva_R_Dor.htm  ) and S
> Leporis
> (http://ar.geocities.com/varsao/Curva_S_Lep.htm  ).
>
> As mentioned in the past these red variables are very interesting and make
> up a somewhat overlooked discussion topic.
> I can't keep my eyes off of the changong period miras like BH Cru and R
Cen
> for example !!!
>
> Regards,
> Sebastian.
>
>
> ---
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