Near-Infrared SOAR Photometric Observations of Post Common Envelope Binaries

TL;DR

This study presents near-infrared light curves of two post-common envelope binaries, modeling their system parameters and analyzing irradiation effects using data from the SOAR telescope.

Contribution

First near-infrared light curve modeling of PCEBs with detailed system parameter constraints and irradiation analysis.

Findings

Determined system inclinations, mass ratios, and secondary star radii.

Estimated secondary star albedos consistent across NIR bands.

Provided insights into the irradiation effects on PCEB components.

Abstract

{From a number of today known Post Common Envelopes Binaries (PCEB) only a handful has yet been observed at near-infrared (NIR) wavelengths and an even smaller number has modeled NIR light curves. At shorter wavelengths one has access to the cooler and larger components of these systems and has the chance to detect emission from its faint and heavily irradiated atmospheres. } {By modeling NIR light curves of PCEBs we intent to constrain their system parameters and study the properties of the system components.} {Here we present simultaneous NIR $JHK_s$ light curves of two PCEBs obtained with the $4m$ SOAR telescope.} {%For this work we have selected 3 systems from a previously selected sample of 8 PCEBs. KV Vel and TW Crv are long period (P$_{\rm orb} =$ 8.6h and 7.9h, respectively) PCEBs with large irradiation effects. The results of light curve fitting provided solutions with inclination $i = (47\pm5)^\circ$, mass ratio $q = 0.3\pm0.1$ and radius of the secondary $R_2/a = 0.24^{+0.05}_{-0.03}$ (where $a$ is the orbital separation) for KV Vel, and $i = (42\pm9)\degr$, $q = 0.28\pm0.04$ and $R_2/a = 0.22\pm0.01$ for TW Crv, respectively. For KV Vel, we obtain an average value for the albedo of the secondary star of $\alpha = 0.43$, consistent in the $J$, $H$ and $K_s$-bands. For TW Crv, on the other hand, we obtain values of $\alpha_{J} = (0.4\pm0.1)$ and $\alpha_{H} = (0.3\pm0.1)$ for the $J$- and $H$-bands, respectively.