V4142 Sgr: a Double Periodic Variable with an accretor surrounded by the accretion-disk's atmosphere

TL;DR

This study analyzes the binary system V4142 Sgr, revealing its orbital and long cycle periods, stellar properties, and accretion disk characteristics, providing insights into its evolutionary history and accretion processes.

Contribution

It offers a detailed photometric and spectroscopic analysis of V4142 Sgr, including modeling of the light curve and comparison with evolutionary models, which is novel for this system.

Findings

Orbital period of 30.633 days

Long cycle of approximately 1201 days

Evidence of wind emission from the hotspot region

Abstract

Context: A detailed study of the close interacting binary V4142\,Sgr based on photometric and spectroscopic analysis is presented.This system belongs to the enigmatic class of Algol-like variables showing a long photometric cycle of unknown nature. Aims: Performing photometric data-mining and spectroscopic observations covering the orbital cycle, we obtain the orbital parameters and the stellar properties of the binary system, along with the physical properties of the accretion disk located around the hot star. Insights on the evolutive path of the system are obtained. Methods: The light curve was modeled through an inverse modeling method using a theoretical light curve of the binary system, considering the light curve contribution of both stars and the accretion disk of the hot star to obtain the fundamental parameters. To constrain the main stellar parameters the mass ratio was fixed, as well as the donor temperature using the obtained values from our spectroscopic analysis including deblending methods to isolate the spectral lines of the stellar components. The system parameters were compared with a grid of binary star evolutive models in order to get insights on the evolutionary history of the system. Results: The orbital period and the long cycle were re-calculated and found to be of $30.633 \pm 0.002 ~\mathrm{days}$ and $1201 \pm 14 ~\mathrm{days}$. The spectral analysis reveals H$\alpha$ double emission with a persistent $V \leq R$ asymmetry which is considered evidence of a possible wind emergin from the hotspot region...