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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-8474
DTSTART:20231109T213000Z
DTEND:20231109T223000Z
DTSTAMP:20260414T045328Z
LAST-MODIFIED:20231023T132502Z
LOCATION:4421 Sterling Hall
SUMMARY:Using polluted white dwarf stars to learn about exoplanetary s
 ystems now\, and in the future\, Astronomy Colloquium\, Amy Steele\, Y
 erkes Observatory
DESCRIPTION:There is evidence that most stars have circumstellar mater
 ial that originates from the asteroids and comets of their planetary s
 ystems. What are the compositions of these small rocky objects around 
 other stars? One way to answer this question is to use the ~30% of whi
 te dwarf stars that have unexpected heavy elements polluting their pho
 tospheres. This pollution of the normally pristine white dwarf sometim
 es arises from the accretion of small planetary system objects (planet
 esimals) that end up within the white dwarf’s tidal radius or Roche 
 limit. These planetesimals sublimate---forming a gas disk---and accret
 e onto the white dwarf surface\, revealing themselves through emission
  and absorption features from constituent elements. In this talk\, I g
 ive a broad overview of polluted white dwarfs and describe what we hav
 e learned from them thus far. I also highlight my database of models c
 reated with the radiative transfer code\, CLOUDY\, for these types of 
 systems. These models provide a key to quickly understand the instanta
 neous composition and other properties of the material flowing from th
 ese (exo)planetesimals\, and will eventually make this type of modelin
 g more accessible in the future.
URL:https://www.physics.wisc.edu/events/?id=8474
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