The Atmospheres of A-Type Subdwarfs and 95 Leonis.

Citations Over Time

Abstract

Line profiles and equivalent widths have been measured in the spectra of two subdwarfs, HD 19445 and HD 140283, classified as A4sp and A5sp, and a main-sequence A4 star, 95 Leonis. The data are analyzed by conventional curve-of-growth procedures and by the method of model atmospheres and line profiles. The point of view adopted is that the structure of the atmosphere must correctly reproduce the profiles of the hydrogen lines. It is found that for 95 Leonis Teff= 89000 K and log g 3.90 (which are normal for an A4 star), whereas for the subdwarfs Teff = 63000 K and log g 4.80. The assumption that the amount of hydrogen per gram of stellar material is the same as that in the sun is in harmony with the data; i.e., there is no evidence that the subdwarfs are deficient in hydrogen. The excitation temperatures are derived from curves of growth for Fe I, using King's laboratoryJ-values. A comparison of theoretical and observed line profiles and equivalent widths suggests that Ca is deficient in the subdwarf atmospheres. Low Fe abundances in these stars are indicated by curves of growth constructed with Greenstein's empirical line strengths for r UMa and v Sgr. The color temperatures and the Balmer discontinuities are predi6ted.

Related Papers

• → New Variable Hot Subdwarf Stars Identified from Anomalous Gaia Flux Errors, Observed by TESS, and Classified via Fourier Diagnostics(2022)20 cited
• → KIC 10449976: discovery of an extreme helium subdwarf in the Kepler field(2013)18 cited
• → Self-broadening of the hydrogen Balmerαline(2008)31 cited
• → Confirmation of monoperiodicity above 20 s for two blue large-amplitude pulsators(2020)9 cited
• → The MSST Campaign: II.Effective temperature and gravity variations in the multi-periodic pulsating subdwarf B star PG1605+072(2007)12 cited