Medium-resolution spectroscopy reveals cooling ejecta and a contracting red giant photosphere in V838 Monocerotis, indicating ongoing changes.
We report medium-resolution 0.85–2.45 μm spectroscopy obtained in 2015 and 2022 and high-resolution 2.27–2.39 μm and 4.59–4.77 μm spectroscopy obtained in 2015 of V838 Monocerotis (V838 Mon), along with modelling of the 0.85–2.45 μm spectrum. V838 Mon underwent a series of eruptions and extreme brightenings in 2002, which are thought to have occurred 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 200 km s−1.
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Geballe et al. (2025) studied this question.
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