Further observations of the 10830-A helium line in stars and their significance as a measure of stellar activity

Abstract

view Abstract Citations (85) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Further observations of the lambda 10830 helium line in stars and their significance as a measure of stellar activity. Zirin, H. Abstract Measurements of the 10830-A He line in 198 stars are given along with data on other features in that spectral range. Nearly 80 per cent of all G and K stars show some 10830-A absorption or emission; of these, half are variable and one-quarter show emission. The results of Vaughan and Zirin (1968) are confirmed that the 10830-A line is not found in M stars, is weak in F stars, and is particularly strong in close binaries. The line is found in emission in extremely late M and S stars along with P-gamma, but the latter is not in emission in the G and K stars with 10830-A emissions. Variable He emission along with Ti I emission is found in the RV Tauri variables R Sct and U Mon. In R Aqr, the Fe XIII coronal line at 10747 A is found in emission along with a line at 11012 A, which may be singlet He or La II, as well as the 10830-A and P-gamma lines. There is possibly a five-year period in the appearance of 10830-A emission in theta Her. The nature of coronae or hot chromospheres in the various stars is extensively discussed without definite conclusion, except that the 10830-A intensity must be more or less proportional to the energy deposited in the chromosphere-corona by nonthermal processes. Publication: The Astrophysical Journal Pub Date: September 1976 DOI: 10.1086/154621 Bibcode: 1976ApJ...208..414Z Keywords: Emission Spectra; Helium; Late Stars; Stellar Spectra; Astronomical Catalogs; Chromosphere; Coronas; F Stars; K Lines; K Stars; Statistical Analysis; Variable Stars; Astrophysics full text sources ADS | data products SIMBAD (189)