1303.0602 (Li K. et al.)

Two particular EA-type binaries in the globular cluster omega Centauri    [PDF]

Li K., Qian, S. -B

We analyzed the B and V light curves of two EA-type binaries V211 and NV358 using the WD code for the first time. Our analysis shows that V211 is a typical Algol-type binary and NV358 is a well detached binary system. As the two binaries are definite proper motion members of omega Centauri, we estimated their physical parameters, obtaining $M_1=1.13\pm0.03M_\odot,$ $R_1=0.98\pm0.01R_\odot$ and $M_2=0.33\pm0.01M_\odot,$ $R_2=0.92\pm0.01R_\odot$ for V211; $M_1=1.30\pm0.05M_\odot,$ $R_1=1.03\pm0.01R_\odot$ and $M_2=0.58\pm0.02M_\odot,$ $R_2=0.78\pm0.01R_\odot$ for NV358. On the color-magnitude diagram of $\omega$ Centauri, V211 is located in the faint blue straggler region and its primary component is more massive than a star at the main-sequence turnoff. Therefore, V211 is a blue straggler and should be formed by mass transfer from the secondary component to the primary. The age of NV358 is less than 1.93 Gyr, indicating that it is much younger than first-generation stars in omega Centauri. As NV364 in omega Centauri, NV358 should be a second-generation binary.

View original: http://arxiv.org/abs/1303.0602