Pulsation properties in hot B subdwarf star TIC 293165262 from TESS photometry

Abstract

Pulsation frequencies offer a unique opportunity to probe the interior of hot B subdwarf (sdB) stars. In this study, we present the results by analysing the pulsation properties of the sdB star TIC 293165262 using the TESS 21-sector photometry in Cycles 1, 3 and 5. Fifteen significant frequencies were detected within the frequency range of <500 \(\mu \)Hz, all of which were identified as low-frequency g-mode oscillations. By analysing the two resolved incomplete multiplets with spacings of \(\sim \) 0.056 and \(\sim \) 0.099 \(\mu \)Hz, we derived a rotational period of \(99.8\pm 1.8\) days, indicating that TIC 293165262 is a relatively slow rotating single sdB star. The period spacings of \(\ell =1\) and \(\ell =2\) sequences were determined as 264 and 154 s, respectively, which resulted in a mode discriminant of seven \(\ell =1\) modes, three \(\ell =2\) modes and two satisfied the both. During the five observational segments, the frequency and amplitude variations of six significant pulsations were clearly observed, revealing nonlinear weak mode interactions. These linear and nonlinear properties of pulsations in TIC 293165262 highlighted the continuous provision of high-quality photometry for pulsating sdB stars by the TESS mission.