Issue |
A&A
Volume 384, Number 3, March IV 2002
|
|
---|---|---|
Page(s) | 908 - 911 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20020108 | |
Published online | 15 March 2002 |
On the orbital period changes of two W-type overcontact binaries: RW Comae Berenices and CE Leonis
Yunnan Observatory, Chinese Academy of Sciences, PO Box 110, 650011 Kunming, PR China National Astronomical Observatories, Chinese Academy of Science (NAOCAS) United Laboratory of Optical Astronomy, Chinese Academy of Science (ULOAC)
Corresponding author: qsb@netease.com
Received:
14
May
2001
Accepted:
30
November
2001
O–C diagrams of two very short-period W-type overcontact binaries,
RW Com and CE Leo, are formed by considering the general trends
of their O–C curves and the natures of the period changes are analyzed.
For RW Com, its period shows a secular decrease with a
rate of days/year. Weak evidence indicates
that a small-amplitude oscillation is superimposed on the secular decrease.
For CE Leo its period is increasing at rate of
days/year. The masses of the primary
components of the two W UMa stars are nearly the same and the main
difference between the two systems is that they have a different mass
ratio (
for RW Com and 0.50 for CE Leo respectively). The different
type of period changes may be the result of
their different mass ratio. These findings are in agreement with Qian's ([CITE])
conclusion that W-type stars with high-mass ratio (
) usually
show a increasing period, while the periods of low-mass ratio
systems (
) are decreasing. The period oscillation of RW Com
may be caused either by the presence of an unseen third body or by
magnetic activity cycles. The secular period changes of the two binary stars
can be explained by the combination of the thermal relaxation oscillation
(TRO) and the variable angular momentum loss (AML) via the change of
depth of overcontact.
Key words: stars: binaries: close / stars: individual: RW Com / stars: individual: CE Leo / stars: evolution
© ESO, 2002
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