The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa
Journal article, 2019

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.

stars: mass-loss

line: identification

ISM: molecules

stars: massive

circumstellar matter

stars: individual (VY Canis Majoris)

stars: winds, outflows


Roberta M. Humphreys

University of Minnesota

L. M. Ziurys

University of Arizona

J. J. Bernal

University of Arizona

Michael S. Gordon

NASA Ames Research Center

L. Andrew Helton

NASA Ames Research Center

Kazunori Ishibashi

Nagoya University

Terry J. Jones

University of Minnesota

A. M. S. Richards

University of Manchester

Wouter Vlemmings

Chalmers, Space, Earth and Environment, Onsala Space Observatory

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 874 2 L26

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Theoretical Chemistry


Onsala Space Observatory



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