Variability of Magnetic Hot Stars from the TESS Observations

Abstract

Magnetic hot stars refer to stars that have effective temperatures approximately in the range from 7000–50,000 K, and with large-scale globally organized magnetic fields. These magnetic fields exhibit strengths ranging from tens of Gauss to tens of kilo-Gauss. They are key in understanding the effects caused by magnetic fields in the stellar evolution. However, there are only three magnetic hot stars studied via a combination of spectropolarimetric and asteroseismic modeling. Combined with Transiting Exoplanet Survey Satellite sectors 1–56 data sets, we provided a photometric variability and stochastic low-frequency (SLF) variability study of 118 magnetic hot stars. Nine new rotating variable stars are identified. Using the Bayesian Markov Chain Monte Carlo framework, we fitted the morphologies of SLF variability for magnetic hot stars. Our analysis reveals that the magnetic hot stars in our sample have γ < 5.5 with the vast majority having 1 ≤ γ ≤ 3. The ν _char is primarily in the ranges of 0 day ^−1 < ν _char < 6.3 day ^−1 . The amplitude of SLF variability, log α _0 , shows a dominant distribution ranging from 0.8–3. No significant correlations are observed between the luminosity and fitting parameters, suggesting no clear dependence of SLF variability on stellar mass for our sample of magnetic hot stars with masses between approximately 1.5 M _⊙ < M < 20 M _⊙ . We found a significant negative correlation between the B _p and ν _char . This suppression effect of magnetic fields on ν _char may be a result of their inhibition of macroturbulence.

Keywords

• Magnetic fields
• Early-type variable stars
• Early-type stars
• Asteroseismology