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

## TL;DR

This study uses HST/STIS spectra to reveal that the innermost ejecta of VY CMa contain strong atomic and molecular emissions originating close to the star, challenging previous assumptions about their formation in a dusty shell.

## Contribution

It demonstrates that the strong K I and molecular emissions originate in small clumps near the star, not in a distant circumstellar shell, providing new insights into the star's immediate environment.

## Key findings

- K I emission is 10-20 times stronger in ejecta than on the star.
- VO is confirmed as a circumstellar molecule.
- Ejecta have a nearly clear line of sight to the star's radiation.

## Abstract

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.