[vsnet-be 65] Omega Canis Majoris

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

I keep observing the GCAS variable omega CMa and my observations indicate it
is brightening in a delta Sco's way since March 2001.
Its mean brightness has risen from 4.1 to 3.9 and I have found maxima spaced
by 195, 85, 35 and 17 days in my data for individual cycles since 1997
(although the star is well-observed only since the year 2000).
Studies of this star indicates that there is a 34.675 days period (Harmanec,
1998) that could be explained as a beat period of two short cycles
identified from the radial velocities (but almost invisible in light terms
[Balona et al., 1999]): 1.372 and 1.345 days.
(Harmanec). However, Balona identifies a satellite period of 1.45 days.
The 35 day period may be also intrinsic. And omega CMa could even be a 34.7
day binary in an eccentric orbit.
Anyway, this brightening reminds me of delta Sco and this last statement in
Balona's abstract is very interesting:

"The amplitudes are larger in seasons when the mean brightness is higher"

Isn't this similar to what is happening to delta Sco?
The 76 days cycle was not present in light until now that the star is
bright.

This is my visual maximum epoch for omega CMa:

JD 2452014 + 34.675 d. (17.33??) x E
It is currently at its brightest state in years around 3.83.

Cheers,
Sebastian.


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