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

TL;DR

This study analyzes two EA-type binary stars in omega Centauri, determining their physical parameters, evolutionary status, and suggesting their formation history within the cluster.

Contribution

First analysis of light curves for V211 and NV358 using the WD code, revealing their nature and evolutionary implications within omega Centauri.

Findings

V211 is a blue straggler formed by mass transfer.

NV358 is a young, second-generation binary.

Both are confirmed cluster members with detailed physical parameters.

Abstract

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.