The New Ephemeris and Light Curve Analysis of V870 Ara by the Ground-Based and TESS Data

Atila Poro,Mark G Blackford,Fatemeh Davoudi,Elnaz Bozorgzadeh,Amirreza Mohandes,Mohammad Madani,Samaneh Rezaei

doi:10.1515/astro-2021-0004

Abstract

Abstract New CCD photometric observations and their investigation of the W UMa-type binary, V870 Ara, are presented. Light curves of the system were taken through BVIfilters from the Congarinni Observatory in Australia. The new ephemeris is calculated based on seven new determined minimum times, together with the TESS data and others compiled from the literature. Photometric solutions determined by the Wilson-Devinney (W-D) code are combined with the Monte Carlo simulation to determine the adjustable parameters’ uncertainties. These solutions suggest that V870 Ara is a contact binary system with a mass ratio of 0.082, a fillout factor of 96±4 percent, and an inclination of 73.60±0.64 degrees. The absolute parameters of V870 Ara were determined by combining the Gaia EDR3 parallax and photometric elements.

Highlights

The contact binary system V870 Ara is located in the southern constellation Ara and has a magnitude of V = 8.96 and an orbital period of 0.399722 day (Eker et al 2009; Szalai et al 2007)
The new ephemeris is calculated based on seven new determined minimum times, together with the Transiting Exoplanet Survey Satellite (TESS) data and others compiled from the literature
To extract the minimum times and their uncertainties, we employed the Monte Carlo Markov Chain (MCMC) approach through fitting the models to the light curves based on Gaussian distributions (Poro et al 2020)

Summary

Introduction

V870 Ara is one of the systems discovered by the Hipparcos space-based telescope. Selam (2004) analyzed the light curve of this system for the first time, calculated a mass ratio of q = 0.25, and put this variable star in the W-subtypes of the W UMa contact binary type. Szalai et al (2007) and Pribulla and Rucinski (2014) studied the period change of five systems, including the V870 Ara, to identify the third body, and they could not find signs of multiplicity in the V870 Ara. Ulaş et al (2012) classified the V870 Ara as a late-type contact binary system, whereas Hu et al (2018) classified it as a deep-contact binary system. The multi-color CCD light curves in B, V, and I bands, along with photometric data obtained from the TESS space telescope, are presented.

Observation and Data Reduction

New Ephemeris

Binary Parameter Analysis

Summary and Conclusion