Optical and near-infrared observations of the Fried Egg Nebula; Multiple shell ejections on a 100 yr timescale from a massive yellow hypergiant

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Speaker :  
Dr. Evgenia Koumpia (Univ. of Leeds, UK)
Location :  
Online seminar
Date :  

Time : 

Abstract :

The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss rate and geometry. The geometry of the mass-loss process can be inferred from the shape of the circumstellar material, having a significant influence on the evolution of massive stars (25 and 40 Msun), i.e., type II SN progenitors. In this context, yellow hypergiants (YHGs) offer an excellent opportunity to study mass-loss events.

I will present the analysis of a large set of optical and near-infrared data in spectroscopic, photometric, spectropolarimetric, and interferometric (GRAVITY/VLTI) modes, towards the IRAS 17163-3907 and its associated Fried Egg Nebula. This talk will cover the first reconstructed images of IRAS 17163−3907 around the 2-micron emission tracing milli-arcsecond scales, but also how our 2D radiative transfer modelling led to the discovery of a third hot inner shell with a maximum dynamical age of only 30 yr. We find three observed distinct mass-loss episodes which are characterised by different mass-loss rates and can inform theories of mass-loss mechanisms, which is a topic still under debate both in theory and observations. These will be discussed in the context of photospheric pulsations and wind bi-stability mechanisms.