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[vsnet-ecl 332] V1154 Tauri - HIP EA and more...
Dear friends:
I've been working on several Hipparcos EB's and I have
found one interesting case:
V1154 Tauri. It is not only an EA but also a pulsating variable with a
period near 0.599 days. Maybe an SPB star.
The range is 6.71 - 6.75 Hp, or 6.68 - 6.72 V. An interesting photometric
project.
But the main reason of this mail is to ask for
observations tonight, since according to my period an eclipse could occur on
JD 2452016.568 = April 17, 01.38 UT. (duration +- 0.3 days).
There are three secondary eclipses on Hipparcos data
(6.82 Hp) and from them I got the following elements:
JD 2448484.325 + 12.6152 d x E
The period looks very good for those eclipses, but when I use it for the
primary (6.97: Hp) there is an observation made by Hipparcos 0.05 days
before a predicted mideclipse time that shows the star at maximum...
However, before ruling out my period (something I've tried but other
possibilities are the ones that end up being ruled out by the data), I
remembered that Hipparcos 2.21 point in the delta Velorum dataset that made
us insist on a short period for the 45 day bright eclipser.
So tomorrow we have a chance to see if the star geets fainter or not.
From 6.7, the star should fall to 6.95. Small but detectable change in
light.
More data:
V1154 Tauri = HD 32641 = HIP 23699
Position: 5h 05m 37.72s +2303' 39.8" (2000.0)
It should be said that Hipparcos resolved the star as a close binary (0.4"
apart) with 6.97 and 8.45 Hp magnitudes.
It's an interesting coincidence that the brightness of the A star of this
binary is the same as the combined brightness of the system when primary
eclipse takes place (Hp= 6.97)
I say "coincidence" because if the binarity was resoved, this component can
hardly be orbiting the main star with a 12.6152 day period !!! So this star
has nothing to do with the eclipses, as in the delta Velorum's case.
If some of you can observe, I have prepared a chart and uploaded it to my
webpage:
http://ar.geocities.com/varsao/
and go to "Cartas de Variables"
Or straight to:
http://ar.geocities.com/varsao/Carta_V1154_Tau.htm
Best regards,
Sebastian.
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