Analysis of eight magnetic chemically peculiar stars with rotational modulation

Abstract

Since the end of 2018, the Transiting Exoplanet Survey Satellite (TESS) has provided stellar photometry to the astronomical community. We have used TESS data to study rotational modulation in the light curves of a sample of chemically peculiar stars with measured large-scale magnetic fields (mCP stars). In general, mCP stars show inhomogeneous distributions of elements in their atmospheres that lead to spectroscopic (line profile) and photometric (light curve) variations commensurate with the rotational period. We analyzed the available TESS data from 50 sectors for eight targets after post-processing them in order to minimize systematic instrumental trends. Analysis of the light curves allowed us to determine rotational periods for all eight of our targets. For each star, we provide a phase diagram calculated using the derived period from the light curves and from the available measurements of the disk-averaged longitudinal magnetic field 〈Bz〉. In most cases, the phased light curve and 〈Bz〉 measurements show consistent variability. Using our rotation periods, and global stellar parameters derived from fitting Balmer line profiles, and from Geneva and Strömgren-Crawford photometry, we determined the equatorial rotational velocities and calculated the respective critical rotational fractions veq/vcrit. We have shown from our sample that the critical rotational fraction decreases with stellar age, at a rate consistent with the magnetic braking observed in the larger population of mCP stars.

BCD Spectrophotometry and Rotation of Active B-Type Stars: Theory and Observations

“…Thanks to the TESS and BRITE space missions, it was also possible to find many magnetic hot stars, including pulsating ones. Using TESS data, the MOBSTER collaboration has shown that the rotational ratio V/V c decreases with stellar age, consistently with the magnetic braking observed in a population of magnetic chemically peculiar stars [598]. A number of known magnetic B-type stars were also observed by BRITE and BRITEpol, and the results were commented by Shultz et al [599].…”

Magnetism in High-Mass Stars

“…In subsequent years, the discovery of chemicallypeculiar Ap/Bp stars grew further, e.g., [29,30]. It remains a very rich field of study, with increasingly more sophisticated techniques to infer surface spots and abundance patterns, e.g., [31][32][33][34][35]. There is a demonstrable link between the magnetic characteristics of magnetised pre-main sequence Herbig Ae/Be stars and main sequence Ap/Bp stars [36][37][38][39], suggesting that the observed magnetic fields of main sequence stars are already developed in the pre-main sequence phase.…”

Detection of Pulsation and Additional Components in Eclipsing Binary RS Sct

“…Period04 was used to find possible oscillation frequencies of the residuals. This program is commonly utilized to find frequencies in pulsating stars (Chen et al 2023;Kobzar et al 2023;Pothuneni et al 2023;Ulas & Ulusoy 2023). We calculate the frequency spectrum from 0 to 100 day −1 .…”