Abstract
Among the known Ap stars, HD101065 is probably one of the most interesting objects, demonstrating very rich spectra of rare-earth elements (REE). Strongly peculiar photometric parameters of this star that can not be fully reproduced by any modern theoretical calculations, even those accounting for realistic chemistry of its atmosphere. In this study we investigate a role of missing REE line opacity and construct a self-consistent atmospheric model based on accurate abundance and chemical stratification analysis. We employed the LLmodels stellar model atmosphere code together with DDAFit and SynthMag software packages to derive homogeneous and stratified abundances for 52 chemical elements and to construct a self-consistent model of HD101065 atmosphere. The opacity in REE lines is accounted for in details, by using up-to-date extensive theoretical calculations. We show that REE elements play a key role in the radiative energy balance in the atmosphere of HD101065, leading to the strong suppression of the Balmer jump and energy redistribution very different from that of normal stars. Introducing new line lists of REEs allowed us to reproduce, for the first time, spectral energy distribution of HD101065 and achieve a better agreement between the unusually small observed Str\"omgren c1 index and the model predictions. Using combined photometric and spectroscopic approaches and based on the iterative procedure of abundance and stratification analysis we find effective temperature of HD101065 to be Teff=6400K.
Highlights
Since its discovery by Przybylski in 1961 (Przybylski 1961) and named later after him, the Przybylski’s star (HD 101065, hereafter PS) remains one of the most intriguing objects among chemically peculiar (CP) stars
In this study we investigate a role of missing rareearth elements (REE) line opacity and construct a self-consistent atmospheric model based on accurate abundance and chemical stratification analysis
Once the stratification was introduced in the model atmosphere, the fit to the hydrogen Hα line and the observed photometric parameters required decreasing of Teff of the star down to approximately 6400 K
Summary
Since its discovery by Przybylski in 1961 (Przybylski 1961) and named later after him, the Przybylski’s star (HD 101065, hereafter PS) remains one of the most intriguing objects among chemically peculiar (CP) stars These objects are usually characterized by abundance anomalies in their atmospheres and by non-uniform horizontal and vertical distributions of chemical elements and/or surface magnetic fields of different intensities. From many observed characteristics PS is a typical representative of the coolest part of rapidly oscillating A-type (roAp) stars It pulsates with the typical roAp period, ≈12 min (Kurtz & Wegner 1979), and it was the first roAp star discovered. Przybylski was the first to note a low Fe abundance and a strong overabundance of some rareearth (REE) elements (Przybylski 1966) These features were confirmed in many subsequent spectroscopic studies of this star
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