CW Cas: A solar-type contact binary system with an unseen third companion in a hierarchical quadruple system

Abstract

We present a comprehensive multiband photometric and spectroscopic study of the G-type binary CW Cas whose parameters have not been well determined. Our double-lined spectroscopic radial velocity curve of this system yields a reliable mass ratio of $q=1.88(9)$. By combining $BV{R}_c{I}_c$ bands, TESS light curves and radial velocity curves, we found that CW Cas is a W-subtype shallow contact binary with a fill-out factor of 15\%. The components have masses of $0.98(6)M_{\odot }$ and $0.52(4)M_{\odot }$, separated by $2.25(5)R_{\odot }$. A notable asymmetry in the maxima of the light curves was detected and explained by a dark spot located on the surface of at least one component. Comparison of light curves from different years revealed that these dark spot activities exhibit cyclic variations with an approximate period of 1250 days. Orbital period analysis via O-C diagram spanning 125 years shows a long-term decrease superimposed with periodic oscillation caused by the light-travel-time effect (LTTE) due to a third body. This tertiary component has an orbital period of $P_3=99.4(6)$ years and a minimal mass of $M_3=0.91(1)M_{\odot }$. The absence of detectable signatures for this massive object in either spectroscopic or photometric datasets implies it must be a compact object such as a white dwarf or neutron star. Furthermore, a visual companion was identified based on Gaia DR3 astrometric data, suggesting that CW Cas is part of a hierarchical quadruple system. As such, CW Cas represents a valuable laboratory for probing 2+1+1 hierarchical multiple system hosting compact object.

This paper have 16 pages, 8 figures and 8 tables. This paper presents an investigation of an unseen third body in the hierarchical triple system of the eclipsing close binary star CW Cas

References in corpus (29)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Transiting Exoplanet Survey Satellite
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• The Revised TESS Input Catalog and Candidate Target List
• The TESS Input Catalog and Candidate Target List
• A database of high and medium-resolution stellar spectra
• ULySS: A Full Spectrum Fitting Package
• The Xinglong 2.16-m Telescope: Current Instruments and Scientific Projects
• Physical Properties and Catalogue of EW-type Eclipsing Binaries Observed by LAMOST
• Statistics of 700 individually studied W UMa stars
• Photometric study and absolute parameters estimation of six totally eclipsing contact binaries
• Contact Binaries of the Galactic Disk: Comparison of the Baade's Window and Open Cluster Samples
• The Anticorrelated Nature of the Primary and Secondary Eclipse Timing Variations for the Kepler Contact Binaries
• Radial Velocity Studies of Close Binary Stars. XI
• The SUPERWIDE Catalog: A Catalog of 99,203 Wide Binaries Found in Gaia and Supplemented by the SUPERBLINK High Proper Motion Catalog
• Tracking the Stellar Longitudes of Starspots in Short-Period Kepler Binaries
• The ASAS-SN Catalog of Variable Stars X: Discovery of 116,000 New Variable Stars Using g-band Photometry
• A BVRcIc Survey of W Ursae Majoris Binaries
• Comparative study of TESS photometry and radial velocities on six early K-type contact binaries with similar periods around 0.268 days
• YZ Phe: an active contact binary with variation of the O'Connell effect and orbital period change
• Investigating the Efficiency of the Beijing Faint Object Spectrograph and Camera (BFOSC) of the Xinglong 2.16-m Reflector
• X-ray emission of contact binary variables within 1 kpc
• CSS_J154915.7+375506: A low-mass-ratio marginal contact binary system with a hierarchical third body
• KM UMa: An active short-period detached eclipsing binary in a hierarchical quadruple system