The Advanced Spectral Library (ASTRAL): Reference Spectra for Evolved M-Stars. (arXiv:1811.11865v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Carpenter_K/0/1/0/all/0/1">Kenneth G. Carpenter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nielsen_K/0/1/0/all/0/1">Krister E. Nielsen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kober_G/0/1/0/all/0/1">Gladys V. Kober</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ayres_T/0/1/0/all/0/1">Thomas R. Ayres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wahlgren_G/0/1/0/all/0/1">Glenn M. Wahlgren</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rau_G/0/1/0/all/0/1">Gioia Rau</a>
The HST Treasury Program “Advanced Spectral Library Project: Cool Stars” was
designed to collect representative, high quality ultraviolet spectra of eight
evolved F-M type cool stars. The Space Telescope Imaging Spectrograph (STIS)
echelle spectra of these objects enable investigations of a broad range of
topics including stellar and interstellar astrophysics. This paper provides a
guide to the spectra of the two evolved M-stars, the M2Iab supergiant Alpha Ori
and the M3.4 giant Gamma Cru, with comparisons to the prototypical K1.5 giant
Alpha Boo. It includes identifications of the significant atomic and molecular
emission and absorption features and discusses the character of the
photospheric and chromospheric continua and line spectra. The fluorescent
processes responsible for a large portion of the emission line spectrum, the
characteristics of the stellar winds, and the available diagnostics for hot and
cool plasmas are also summarized. This analysis will facilitate the future
study of the spectra, outer atmospheres, and winds, not only of these objects,
but for numerous other cool, low-gravity stars for years to come.
The HST Treasury Program “Advanced Spectral Library Project: Cool Stars” was
designed to collect representative, high quality ultraviolet spectra of eight
evolved F-M type cool stars. The Space Telescope Imaging Spectrograph (STIS)
echelle spectra of these objects enable investigations of a broad range of
topics including stellar and interstellar astrophysics. This paper provides a
guide to the spectra of the two evolved M-stars, the M2Iab supergiant Alpha Ori
and the M3.4 giant Gamma Cru, with comparisons to the prototypical K1.5 giant
Alpha Boo. It includes identifications of the significant atomic and molecular
emission and absorption features and discusses the character of the
photospheric and chromospheric continua and line spectra. The fluorescent
processes responsible for a large portion of the emission line spectrum, the
characteristics of the stellar winds, and the available diagnostics for hot and
cool plasmas are also summarized. This analysis will facilitate the future
study of the spectra, outer atmospheres, and winds, not only of these objects,
but for numerous other cool, low-gravity stars for years to come.
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