V838 Mon is a famous cool star which suddenly brightened in 2002 in a series of outbursts. It was first thought it was a nova, but the subsequent evolution made the community think this was in fact a merger event.
That paper is focused on what happened just a decade after outburst, and a lot happened in such a short timespan ! First, we detected a compact dusty nebula around the central star using the VLTI MIDI instrument. Second, using the AMBER instrument, we found out that the central star itself shrinked compared to previous measurements. This work is published in Astronomy and Astrophysics.
The work was mentionned here
The corresponding data is there: V838 Mon AMBER and MIDI data