The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa. (arXiv:1903.08744v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Humphreys_R/0/1/0/all/0/1">Roberta M. Humphreys</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ziurys_L/0/1/0/all/0/1">L. M. Ziurys</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bernal_J/0/1/0/all/0/1">J. J. Bernal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gordon_M/0/1/0/all/0/1">Michael S. Gordon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Helton_L/0/1/0/all/0/1">L. Andrew Helton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ishibashi_K/0/1/0/all/0/1">Kazunori Ishibashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jones_T/0/1/0/all/0/1">Terry J. Jones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Richards_A/0/1/0/all/0/1">A. M. S. Richards</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vlemmings_W/0/1/0/all/0/1">Wouter Vlemmings</a>
HST/STIS spectra of the small clumps and filaments closest to the central
star in VY CMa reveal that the very strong K I emission and TiO and VO
molecular emission, long thought to form in a dusty circumstellar shell,
actually originate in a few small clumps 100’s of AU from the star. The K I
lines are 10 to 20 times stronger in these nearest ejecta than on the star. The
observations also confirm VO as a circumstellar molecule. In this letter we
discuss the spectra of the features, their motions and ages, and the
identification of the molecular emission. The strength of the atomic and
molecular features in the small clumps present an astrophysical problem for the
excitation process. We show that the clumps must have a nearly clear line of
sight to the star’s radiation.
HST/STIS spectra of the small clumps and filaments closest to the central
star in VY CMa reveal that the very strong K I emission and TiO and VO
molecular emission, long thought to form in a dusty circumstellar shell,
actually originate in a few small clumps 100’s of AU from the star. The K I
lines are 10 to 20 times stronger in these nearest ejecta than on the star. The
observations also confirm VO as a circumstellar molecule. In this letter we
discuss the spectra of the features, their motions and ages, and the
identification of the molecular emission. The strength of the atomic and
molecular features in the small clumps present an astrophysical problem for the
excitation process. We show that the clumps must have a nearly clear line of
sight to the star’s radiation.
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