The nature of the photometric variability of HgMn stars: A test of simulated light curves of ϕ Phe against the TESS data

Abstract

The inhomogeneous surface distribution of heavy elements is known to cause periodic light variability of magnetic chemically peculiar stars. It is unclear to what extent the same paradigm applies to mercury-manganese (HgMn) stars. We aim to model the photometric variability of the HgMn star ϕPhe using abundance maps obtained from high-resolution spectroscopy and to study how this variability evolves with time. We compute a grid of ATLAS12 model atmospheres and the corresponding SYNSPEC synthetic spectra. Interpolating within this grid and integrating the specific intensity over the visible stellar surface at different rotational phases, we obtain theoretical light curves of the star. We predict the variability of ϕ Phe in the ultraviolet and in the visible spectral regions with amplitude of the order of millimagnitudes, mainly caused by absorption in lines of yttrium, chromium, and titanium. We also show how this variability is affected by changes of the distribution of the heavy elements over time. The main characteristics of the predicted light variability of ϕ Phe correspond roughly to the variability of the star observed with the TESS satellite.

References in corpus (5)

• The Transiting Exoplanet Survey Satellite
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• MOBSTER - II. Identification of rotationally variable A stars observed with \emph{TESS} in Sectors 1 to 4
• Four new HgMn stars: HD 18104, HD 30085, HD 32867, HD 53588
• A Spectroscopic and Photometric Investigation of the Mercury-Manganese Star KIC 6128830

Cited by in corpus (3)

• Mysterious, Variable, and Extremely Hot: White Dwarfs Showing Ultra-High Excitation Lines I. Photometric Variability
• V772 Cas: an ellipsoidal HgMn star in an eclipsing binary
• Understanding the rotational variability of K2 targets. HgMn star KIC 250152017 and blue horizontal branch star KIC 249660366