Photometric and spectroscopic studies of the long period low mass ratio deep contact binary KN Per

TL;DR

This study combines photometric and spectroscopic analyses to characterize the long period, low mass ratio deep contact binary KN Per, revealing its physical parameters, evolutionary state, and stability through detailed observational and analytical methods.

Contribution

It provides the first comprehensive photometric and spectroscopic analysis of KN Per, including period change, chromospheric activity, and evolutionary status, expanding understanding of low mass ratio contact binaries.

Findings

KN Per is an A-type low mass ratio deep contact binary with q=0.236.

The orbital period of KN Per is increasing at a rate of 5.12×10^{-7} days/year.

KN Per is currently a stable contact binary system.

Abstract

The photometric analysis and spectroscopic study of the long period low mass ratio deep contact binary KN Per were executed. The light curves of BV(RI)$_c$-band were from the Ningbo Bureau of Education and Xinjiang Observatory Telescope (NEXT) at the Xingming Observatory. Through the analysis of Wilson-Devinney (W-D) program, KN Per was found as an A-type low mass ratio deep contact binary (q=0.236, f=53.4\%). A cool spot applied on the primary component was introduced to explain the unequal maxima of the light curve. Based on the O-C analysis, we found that the rate of the increasing orbital period is $\dot{P}$ = 5.12 $\pm$ (0.30) $\times$ 10$^{-7}$ d/yr, meaning the mass transfer from the secondary component to the primary one. By analyzing the spectroscopic data, we detected chromospheric activity emission line indicators, which is corresponding to the light-curve analysis. 71 long period (P $>$ 0.5 days) contact binaries including our target were collected. The evolutionary states of all collected stars were investigated by the illustrations of mass-radius, mass-luminosity, and log M$_{T}$ - log J$_{o}$. The relations of some physical parameters were also determined. With the instability parameters of KN Per, we determined that it is a stable contact binary system at present.