[vsnet-ecl 777] V1261 Orionis eclipses

["Sebastian Otero" <varsao@fullzero.com.ar>]

Dear colleagues,

V1261 Orionis is a binary system of the symbiotic class, made up of a white
dwarf and an S-type red giant.
In IBVS # 3730, Jorissen et al.(1992) say it is an eclipsing binary with a
642 days period.
The following features are described:

* Eclipses occur at phase 0.13 of the orbital cycle.
* Duration of the eclipses are less than 4% of the period.
* Amplitude of the eclipses is 0.14 mag. in y.

The observations were carried out in the framework of the LTPV project.

Adelman (1997) studied the star between 1993 and 1996 and concluded that
"the phases corresponding to eclipse and transit showed no particular
signature"
The phased lightcurve doesn't seem to be periodic.

We also have the Hipparcos epoch photometry in which there are also a lot of
dips and brightenings but with no relation with phase.

In all cases the T used was that published by Jorissen and Mayor in 1992 for
the orbital cycle (not for primary minimum)= JD 2445494.

Now I have been monitoring the star for a couple of years. The resulting
variations are in agreement with the published values (published: 6.698 -
7.037, observed: 6.67 - 7.00)
The lightcurve shows the ups and downs mentioned by Adelman but the most
interesting features are two deeper minima that are separated by ~645 days,
a figure too similar to the orbital period.
However, I can't find the same phase relation mentioned by Jorissen et al
according to the above ephemeris.
I made a phase diagram of my two eclipses and they fit with a 645 days
period.
Surprisingly, when using this new period and the old T (JD 2445494), the
eclipses appear almost at phase 0 (-0.01).

But data from Adelman, Hipparcos and LTPV don't show eclipses at these
phase, so this is not clear what happens actually.
Maybe a hot spot is there to be eclipsed sometimes but not always...?

Please, take a look at the lightcurves at:
http://ar.geocities.com/varsao/Curva_V1261_Ori.htm

Regards,
Sebastian.






---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://vsnet.grisoft.com).
Version: 6.0.423 / Virus Database: 238 - Release Date: 25/11/02

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp