Infrared Spectroscopy of V838 Monocerotis in 2015 and 2022

TL;DR

This paper presents infrared spectroscopic observations of V838 Monocerotis from 2015 and 2022, revealing ongoing contraction and dispersal of ejecta from a stellar merger event, with detailed spectral modeling.

Contribution

It provides new infrared spectra and modeling of V838 Monocerotis, showing the continued evolution of its photosphere and ejecta post-merger.

Findings

Disturbed red giant photosphere contracting

Ejecta cooling and dispersing at up to 200 km/s

Spectral evolution consistent with ongoing post-merger changes

Abstract

We report medium-resolution $0.85-2.45\,\mu$m spectroscopy obtained in 2015 and 2022 and high resolution $2.27-2.39\,\mu$m and $4.59-4.77\,\mu$m spectroscopy obtained in 2015 of V838 Monocerotis, along with modeling of the $0.85-2.45\,\mu$ spectrum. V838 Mon underwent a series of eruptions and extreme brightenings in 2002, which are thought to have occured as a result of a stellar merger. The new spectra and modelling of them reveal a disturbed red giant photosphere that is probably continuing to contract and ejecta that are cooling and continuing to disperse at velocities up to 200kms$^{-1}$.