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Session: Stars, Planets and the Interstellar Medium

Name: Dr. Konstantina Anastasopoulou (INAF - Palermo)
Coauthors: No coauthors were included.
Type: Oral
Title: The EWOCS view of the unique population of Wolf-Rayet stars in Westerlund 1
Abstract:

Wolf-Rayet (WR) stars are the latest stage in the evolution of very massive stars, before they finally explode as supernovae (SN) or possibly gamma-ray bursts. They exhibit dense and powerful stellar winds, that along with their ultimate death as core-collapse SN, dominate the feedback to the local interstellar medium in star-forming galaxies. Studying in more detail the properties of the short-lived WR phase, will advance our understanding on star-formation processes and will test stellar evolutionary predictions. The best laboratory to study the WR phase, is the massive star cluster Westerlund 1. It is the closest massive star cluster to the Sun, and it contains an impressive large sample of coeval massive stars including one of the largest population (24) of WR stars. With a very deep Chandra survey (1Ms; as part of the Extended Westerlund One Chandra Survey; EWOCS) we are able to unravel the X-ray properties of the entire WR population, extract spectral information for more 2/3 of them, and retrieve insights on their X-ray production mechanism. We discuss these results in the context of different spectral subtypes of WR stars, as well as binarity, since several of them show signs of colliding-wind X-ray binaries.