The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa

Roberta M. Humphreys, L. M. Ziurys, J. J. Bernal, Michael S. Gordon, L. Andrew Helton, Kazunori Ishibashi, Terry J. Jones, A. M.S. Richards, Wouter Vlemmings

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Hubble Space Telescope/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 hundreds of au from the star. The K i lines are 10-20 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.

Original languageEnglish (US)
Article numberL26
JournalAstrophysical Journal Letters
Volume874
Issue number2
DOIs
StatePublished - Apr 1 2019

Keywords

  • Circumstellar matter
  • ISM: molecules
  • Stars: individual (VY Canis Majoris)
  • Stars: mass-loss
  • Stars: massive
  • Stars: winds, outflows
  • line: identification

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Humphreys, R. M., Ziurys, L. M., Bernal, J. J., Gordon, M. S., Helton, L. A., Ishibashi, K., Jones, T. J., Richards, A. M. S., & Vlemmings, W. (2019). The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa. Astrophysical Journal Letters, 874(2), [L26]. https://doi.org/10.3847/2041-8213/ab11e5