HD 188101: A Spotted B Star with Abundance Anomalies

TL;DR

This study characterizes the fundamental parameters and chemical peculiarities of the B9 star HD 188101, revealing overabundances of certain elements and variability in spectral lines, indicating its classification as a He-weak SiTiSr star.

Contribution

First detailed spectroscopic and photometric analysis of HD 188101, identifying its chemical peculiarities and variability, and classifying it as a He-weak SiTiSr star.

Findings

Overabundances of Si, Ti, and Sr relative to solar.

Detected spectral line variability with phase.

Classified as a chemically peculiar He-weak SiTiSr star.

Abstract

Based on spectroscopic and photometric observations, we have determined the fundamental parameters of the poorly studied star HD 188101 with a weak magnetic field. Its effective temperature $T_{\rm eff} = 14200 \pm 990$ K and surface gravity log g = 3.70 $\pm$ 0.16 are typical for main-sequence B9 stars. The He, C, O, Mg, Si, Ti, and Sr abundances have been determined by taking into account the departures from local thermodynamic equilibrium. Overabundances of Si, Ti, and Sr relative to their solar abundances have been revealed. The He abundance is lower than the solar one, but the difference is within the error limits. In addition to the photometric variability known from Kepler data, we have found changes in absorption for He I, Mg II, Si II, Si III, Ti II, and Fe II lines, with different He I and Mg II lines giving different abundances for the same phase of observations. The star HD 188101 is shown to belong to the group of chemically peculiar He-weak SiTiSr stars.