-
Seminar Detail
Using White Dwarfs to Study Extrasolar Asteroids and Planets
Presenter: Michael Jura
October 24, 2005 11:00 AM Pacific
White dwarfs cooler than 20000 K have very thin atmospheres. Consequently,
in these high gravity stars, heavy elements sink and become undetectable on
a time scale of less than 1000 years. While 75% of cool white dwarfs have
calcium abundances less than 10^-6 of the Sun's, about 25% of these stars
have at least some detectable calcium. One model is that white dwarfs with
metals are accreting them from the interstellar medium. Alternatively, the
white dwarfs could be accreting from the dust produced by the disintegration
of comets and the destruction of asteroids. Accretion rates as low as 3
106 g s^-1, the rate at which dust is manufactured to produce the zodiacal
cloud in the Solar System are detectable. Infrared emission from the dust
around white dwarfs can be used to study their circumstellar matter. We
describe how the previous detection of an infrared excess around the white
dwarf G29-38 and our recent detection of an infrared excess around GD 362
can be used to investigate systems of asteroids and planets around these
stars.Participation Instructions
Sites who would like to connect via Polycom MUST notify Diane Hawks at
dhawks@mail.arc.nasa.gov at least three hours before the seminar. If you
need Polycom help during the live event, call the videoconferencing
help-desk at (650) 604-6412
The slides from the seminar can be viewed real-time using WebEx at:
https://nasa.webex.com/nasa/j.php?ED=85414242&UID=31735697
Meeting number: 921 035 642
Password: 1K*Falcon
If you've never joined a WebEx meeting before, please allow an extra 5-10
minutes to install the plug-in.
Sites without a Polycom system can hear the seminar over the telephone while
viewing the slides in WebEx. The NASA conference phone number for this is
(877) 891-6023, passcode 381880.
Alternatively, participants without a Polycom system can view the webcast
at: http://vanseg-1.arc.nasa.gov/2005/AB051024-01.ram There is a 30 second
delay for the webcast, so viewers will need to advance the slides manually
in WebEx. Questions can be posted in the WebEx chat area to be
answered at the end of the talk.December 21, 2007