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SUMMARY:Tracing late-stage stellar evolution in the galactic bulge: A stud
 y of OH/IR stars with ALMA
DTSTART:20260505T103000Z
DTEND:20260505T113000Z
DTSTAMP:20260503T112400Z
UID:indico-event-9335@scitalks.tifr.res.in
DESCRIPTION:Speakers: Ramlal Unnikrishnan (Chalmers University of Technolo
 gy\, Sweden)\n\nLow- to intermediate-mass stars ascend the Asymptotic Gian
 t Branch (AGB) at the end of their stellar evolution. These stars are crit
 ical sites for heavy-element nucleosynthesis and dust production\, contrib
 ute to galaxy luminosities at IR wavelengths\, and ultimately evolve into 
 planetary nebulae. AGB evolution is driven by intense stellar mass loss 
 — a process that dictates the star's final fate and also dominates the c
 hemical enrichment of the interstellar medium. OH/IR stars represent a hea
 vily dust-obscured\, IR-bright phase of oxygen-rich stars in the late AGB\
 , having high mass-loss rates. In this talk\, I will present multi-wavelen
 gth observations\, led by spatially-resolved ALMA CO spectral line data\, 
 paired with SEDs and photometry\, for a sample of 77 equidistant OH/IR sta
 rs in the inner Galactic bulge. These data allow us to trace the transform
 ations occurring in the mass-loss characteristics\, circumstellar geometry
 \, and kinematics as these sources evolve up and beyond the AGB. I will de
 monstrate how this extensive sample can be separated into four distinct ev
 olutionary classes: upper AGB\, tip of the AGB\, just beyond the AGB tip\,
  and post-AGB. By detailing the observable properties that define these tr
 ansitions\, I will show that while large-scale circumstellar environments 
 remain remarkably homogeneous on the upper AGB\, they undergo rapid struct
 ural changes upon leaving it\, a finding that is currently being followed 
 up with detailed radiative transfer modelling.\n \n\nhttps://scitalks.tif
 r.res.in/event/9335/
LOCATION:AG-66
URL:https://scitalks.tifr.res.in/event/9335/
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