Chromospheric emission lines in the red spectrum of AD Leonis. I - The nonflare spectrum

Abstract

view Abstract Citations (34) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Chromospheric emission lines in the red spectrum of AD Leonis. I. The nonflare spectrum. Giampapa, M. S. ; Linsky, J. L. ; Schneeberger, T. J. ; Worden, S. P. Abstract High-resolution red (5300-7300 A) spectra of the flare star AD Leonis were obtained with the Kitt Peak 4 m echelle spectrograph system at a spectral resolution of 0.22 A at Ha. A series of time-trailed plates with 5 hours integration in total were averaged together to obtain a representation of the star's nonflaring spectrum with high signal-to-noise ratio. The He i A5876 triplet line and A6678 singlet line appear in emission with measured equivalent widths of 0.312 + 0.016 A and 0.058 + 0.029 A, respectively. The corresponding triplet-to-singlet line flux ratio is 3.7, close to the ratio of the level statistical weights. We argue that the He i lines are not produced by recombination and cascade following photoionization by A < 504 A coronal photons, but are instead collisionally excited. We suggest that these lines are formed in a geometrically thin chromospheric layer at 20,000-50,000 K with a column density of nel 6 x 1018 . The sodium D emission lines (A5890, AS 896) are found to be stellar in origin, with measured FWHM of 0.7 A for both lines, and the Ha line has a FWHM of 1.4 A. No other chromospheric emission lines were found in this spectral region. Subject headings: stars: chromospheres - stars: emission-line - stars: flare - stars: individual Publication: The Astrophysical Journal Pub Date: November 1978 DOI: 10.1086/156594 Bibcode: 1978ApJ...226..144G Keywords: Chromosphere; Emission Spectra; Flare Stars; Light (Visible Radiation); Line Spectra; Stellar Spectra; D Lines; Dwarf Stars; H Alpha Line; Helium; M Stars; Stellar Atmospheres; Astronomy; Chromospheres:Flare Stars; Emission Lines:Flare Stars full text sources ADS | data products SIMBAD (5)