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Tartu Observatory talk

On Wednesday, May 11, I gave a talk at Tartu Observatory (Estonia), where I am spending a few weeks as a visitor.
Of course this is by no means something extraordinary. However, it is interesting that they could record the talk so it is available for others to see (or, most probable, for my own use).

So, the link is here:
Grigoris Maravelias: “The circumstellar environment of B[e] Supergiants – disks or rings?”

The circumstellar environment of B[e] Supergiants – disks or rings?

Massive stars affect strongly their environment through their intense stellar winds, which transfer momentum and energy to the interstellar medium and enrich it with chemically processed material as they evolve. This interaction becomes substantial in short-lived transition phases of massive stars (e.g. B[e] Supergiants, Luminous Blue Variables, Yellow Hypergiants) in which mass-loss is more enhanced and usually eruptive. However, these phases are not well-understood, such as the lack of B[e] Supergiants predicted from stellar evolution theory. In order to improve our knowledge for the particular class of B[e] Supergiants we have initiated a campaign to study them with high-resolution optical and near-infrared spectroscopy. This tool allow us to investigate their complex circumstellar environment, consisting of a combination of atomic, molecular and dust regions of different temperatures and densities. We use the strategic [OI] and [CaII] emission lines, and the CO bandheads to probe the structure and the kinematics of their formation regions. We find that these emission lines form either in a single or in multiple equatorial rings, a probable result of previous mass-loss events.

Initial Source: Tartu Observtory / seminars