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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2245
DTSTART:20110922T203000Z
DTEND:20110922T220000Z
DTSTAMP:20260311T034142Z
LAST-MODIFIED:20110913T203542Z
LOCATION:4421 Sterling Hall
SUMMARY:Tails of Stellar Mass Loss: The HI 21-cm Line as a Probe of th
 e Late Stages of Stellar Evolution\, Astronomy Colloquium\, Lynn Matth
 ews\, MIT Haystack Observatory
DESCRIPTION:As they near the end of their lives\, low-to-intermediate 
 mass stars undergo copious mass-loss\, leading to the formation of ext
 ensive circumstellar envelopes (CSEs) up to a parsec or more across. T
 hese envelopes are a primary source of dust and heavy element enrichme
 nt in the Galaxy\, affect the structure of the interstellar medium on 
 small scales\, and are precursors to the formation of planetary nebula
 e. I will present results from a program aimed at improving our unders
 tanding of the evolutionary histories of mass-losing giants through a 
 previously little-used probe of circumstellar material: the HI 21-cm l
 ine of neutral hydrogen. Because HI is not destroyed by the interstell
 ar radiation field\, it can trace CSEs to significant distances from t
 he star\, thereby probing mass-loss over very extended timescales (>10
 0\,000 years). HI also supplies unique kinematic information on the in
 teraction between CSEs and their environments. Our results to date inc
 lude the discovery of extended tails\, bow shocks\, and other structur
 es associated with well-known evolved stars as well as new constraints
  on mass-loss timescales. We have recently expanded our HI studies to 
 Cepheid variables\, and I will also report on implications for mass-lo
 ss on the Cepheid instability strip as a means of resolving the long-s
 tanding "Cepheid mass discrepancy".
URL:https://www.physics.wisc.edu/events/?id=2245
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