"What is the most widely accepted theory on how photosynthesis evolved from non-photosynthesis based life?"
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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
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in WebEx. Questions can be posted in the WebEx chat area to be
answered at the end of the talk.December 21, 2007
The Director’s Seminar series features talks from scientists who are invited by the NAI Director to present their research results to the community. A primary goal of the seminars is to encourage interdisciplinary collaboration across NAI teams and within the astrobiology community at large.
Team Overview Seminars describe the work of the fourteen NAI teams and NAI Central. They offer an opportunity to find out more about the science, E/PO and other activities being performed by the NAI teams and the NAI Central office.
The Forum for Astrobiology Research (FAR) provides an opportunity for graduate students to present their research results and to meet as a student community for networking and mutual support.
The University of Washington seminar series is hosted by the NAI Virtual Planetary Lab (VPL) team from the UW campus in Seattle.
