TY - JOUR

T1 - The nature of the photometric variability of HgMn stars

T2 - a test of simulated light curves of phi Phe against the TESS data

AU - Prvak, Milan

AU - Krticka, Jiri

AU - Korhonen, Heidi

PY - 2020/2

Y1 - 2020/2

N2 - 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 phi Phe 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 phi 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 phi Phe correspond roughly to the variability of the star observed with the Transiting Exoplanet Survey Satellite (TESS).

AB - 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 phi Phe 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 phi 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 phi Phe correspond roughly to the variability of the star observed with the Transiting Exoplanet Survey Satellite (TESS).

KW - radiative transfer

KW - stars: atmospheres

KW - stars: chemically peculiar

KW - stars: early-type

KW - stars: individual: phi Phe

KW - stars: variables: general

U2 - 10.1093/mnras/stz3564

DO - 10.1093/mnras/stz3564

M3 - Journal article

VL - 492

SP - 1834

EP - 1840

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 2

ER -