On the origin of orbital period change in WY Cancri: a genuine angular momentum loss?

Abstract

WY Cancri is a short-period ($P$=0.829 d) eclipsing RS Canum Venaticorum stars, and both components are late-type stars. Recently, observations provided by photometric observations and light time minima show that the orbital period of WY Cancri is experiencing a secular decrease at a rate of $\mathrm{d}P/\mathrm{d}t=-1.2\times 10^{-7}\mathrm{dy}{\mathrm{r}}^{-1}$. In this Letter, we attempt to investigate if the period change of WY Cancri can originate from the angular momentum loss. In calculation, we assume that this source has a high wind loss rate of $\sim 10^{-10}{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$. To account for the observation, magnetic braking demands a strong surface magnetic field of $\gtrsim 10000$ G like Ap/Bp stars. Furthermore, if this source may be surrounded by a circumbinary disk, and 6% of the wind loss feeds the disk, tidal torque between the disk and the binary can offer the observed angular momentum loss rate. Such a strong magnetic field or an extremely high wind input fraction seem to be highly unlikely.

4 pages, 2 figures, accepted for publication in PASJ

References in corpus (4)

• Powerful Winds from Low-Mass Stars: V374 Peg
• Magnetic field topology of the RS CVn star II Pegasi
• Orbital Evolution of Algol Binaries with a Circumbinary Disk
• Can angular momentum loss cause the period change of NN Ser?

Cited by in corpus (2)

• Rapid orbital decay in detached binaries: evidence for circumbinary disks
• Case AD, AR, and AS binary evolution and their possible connections with W UMa binaries