Ka Tat Wong (Uppsala University): (Sub)millimetre observations of the inner wind regions of asymptotic giant branch stars

Thursday 8 Sept 2022, 14:00 → 15:00 Europe/Stockholm

4101 (Ångströmlaboratoriet)

Title: (Sub)millimetre observations of the inner wind regions of asymptotic giant branch stars
Speaker: Ka Tat Wong
Affiliation: Uppsala University
Time: Thursday 8 September 2022, 1400 to 1500
Location: 4101Å

Abstract:

The extended atmosphere and the inner circumstellar envelope of asymptotic giant branch (AGB) stars are characterised by physical processes such as stellar pulsation, convection, and radiation pressure on newly formed dust grains. Studying these processes is important for understanding the mass loss of AGB stars, the formation and acceleration of the stellar wind, and hence the cosmic cycle of matter. With the advancement of sensitivity and angular resolution of (sub)millimetre observations with telescopes like ALMA, we can trace the wind kinematics in the innermost layers of AGB stars' envelope by imaging the emission and/or absorption from various molecular lines. Recent high-resolution ALMA observations reveal high-velocity wings in the line profiles of molecules, such as SiO, exceeding the terminal velocity of the fully accelerated wind as determined by the line width of low-excitation CO lines. I will discuss some hypotheses and recent work on this phenomenon.

 

 

 

 

UU_astro_220908.pdf