Invited Presentation

Investigating the Mysterious Deaths of Ordinary Stars: ALMA leads the way

Author(s): Raghvendra Sahai

Presenter: Raghvendra Sahai (Jet Propulsion Laboratory, California Institute of Technology)

Stars with main-sequence masses in the range 1–8 solar masses live ordinary lives for 1-10 billion years, but die extraordinary deaths. First, during their death throes as red giant stars, they eject, over 10^4–10^5 years, half or more of their mass in slow (~10-20 km/s) spherical winds, and then, in a very short (a few 100–1,000 years) and poorly understood phase, they are transformed into preplanetary and planetary nebulae with a breathtaking variety of morphologies, including the frequent presence of fast (~100 km/s) collimated outflows or jets as well as dense, dusty central disk-like structures. Although it is widely believed that strong gravitational interactions with (sub)stellar companions play a key role, many questions remain. For example, the nature of the interaction and the formation of jets and disks is poorly understood, and, although UV and X-ray observations provide strong indirect evidence of close companions, direct evidence is lacking . In this talk, using recent observational studies as examples, I describe how high-sensitivity, high-angular-resolution observations with ALMA can play a pivotal role in providing the critical data needed to address these questions.