Environments of evolved massive stars: evidence for episodic mass ejections

0582414 - ASÚ 2024 RIV GB eng C - Conference Paper (international conference)
Kraus, Michaela - Cidale, L.S. - Arias, M.L. - Torres, A.F. - Kolka, I. - Maravelias, G. - Nickeler, Dieter Horst - Glatzel, W. - Liimets, Tiina
Environments of evolved massive stars: evidence for episodic mass ejections.
The Origin of Outflows in Evolved Stars. Cambridge: Cambridge University Press, 2023, s. 51-56. Symposium of the International Astronomical Union, 366. ISBN 9781108490795. ISSN 1743-9213. E-ISSN 1743-9221.
[Symposium of the International Astronomical Union /366./. virtual (BE), 01.11.2021-06.11.2021]
R&D Projects: GA ČR(CZ) GA20-00150S
EU Projects: European Commission(XE) 823734 - POEMS
Institutional support: RVO:67985815
Keywords : supergiants * circumstellar matter * mass loss stars
OECD category: Astronomy (including astrophysics,space science)

The post-main sequence evolutionary path of massive stars comprises various transition phases, in which the stars shed large amounts of material into their environments. Our studies focus on two of them: B[e] supergiants and yellow hypergiants, for which we investigate the structure and dynamics within their environments. We find that each B[e] supergiant is surrounded by a unique set of rings or arc-like structures. These structures are either stable over time or they display high variability, including expansion and dilution. In contrast, yellow hypergiants are embedded in multiple shells of gas and dust. These objects are famous for their outburst activity. Moreover, the dynamics in their extended atmospheres imply an enhanced pulsation activity prior to outburst. The physical mechanism(s) leading to episodic mass ejections in these two types of stars is still uncertain. We propose that strange-mode instabilities, excited in the inflated envelopes of these objects, play a significant role.
Permanent Link: https://hdl.handle.net/11104/0350482