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Colloquium

Circumstellar envelopes of Oxygen-rich AGB stars

2022-08-29
  • Speaker : Do Thi Hoai (Vietnam National Space Center)
  • Date : 2022-11-02 10:30 ~ 11:30
  • Location : Online Seminar
  • Host : Nguyen Thi Phuong

Spherical symmetry breaking in the transition from Red Giant to Planetary Nebula, and the mechanism that governs it, have been a topic of intense interest for decades. Recent observations with high sensitivity and angular resolution have shown that spherical symmetry breaking was already present, in many cases, in the early AGB phase. At large distances from the star the circumstellar envelopes of AGB stars have been shown very complex with many fragments in the form of bipolar outflows, blobs, arcs and spirals. At smaller distance, the nascent winds share some features which need to pay attention including the presence of line broadening in the inner layer, the strong absorption of SiO emission over and beyond the stellar disc and the rotation within 30 au or so from the star. In this presentation, I will review the properties of their circumstellar envelopes (CSE) and their nascent winds with the aim of revealing significant similarities or differences in the hope of improving our understanding of the mechanisms at stake.