A Photometric and Spectroscopic investigation of 11 TESS eclipsing contact binaries

Abstract

By cross-matching the eclipsing binary catalog provided by Prsa et al. (2022) with LAMOST medium resolution spectra, we obtained 11 targets. Combining light and radial velocity curves analysis, we have derived accurate physical parameters for these 11 targets. The results indicate that there are 3 deep contact binaries, 3 moderate ones, and 5 shallow ones. Among them, 3 targets exhibit the O'Connell effect, which is attributed to the presence of star-spot on the component's surface. One target is a low-mass ratio deep contact binary and may be contact binary merging candidates. The evolutionary status of these 11 targets was studied using the mass-luminosity and mass-radius relation diagrams. Based on the O-C (Observed minus Calculated) analysis of 10 targets, we found that the orbital periods of 5 contact binaries show a long-term decreasing trend, likely due to the combined effects of mass transfer between the two components and loss of angular momentum. Meanwhile, the orbital periods of the other 4 stars are continuously increasing, which is attributed to mass transfer. Besides, the O-C curves of 3 targets show clear periodic changes, which might result from the Applegate mechanism or the light travel time effect.

Figures (4)

• Figure 1: These figures display the theoretical light curves and radial velocity curves for 11 targets. In the light curve fitting diagrams, the gray dots represent the observed data, and the red lines indicate the fitted theoretical curve. In the radial velocity diagrams, blue dots and lines denotes the more massive primary component, while red ones signifies the less massive secondary component.
• Figure 2: The O-C values and fitting curves of 10 targets.
• Figure 3: The M-L and M-R relations for 11 contact binaries.
• Figure 4: The relation between $M_{T}$ and $J_{\text{orb}}$. Triangles and black dots represent detached binary stars and contact binary stars from 2006MNRAS.373.1483E, green dots denote our target contact binary stars, the red dots indicate deep low-mass ratio contact binary stars, and the dashed line represents the boundary between detached binary stars and contact binary stars from 2006MNRAS.373.1483E.