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What's Cool about Hot Stars? Infrared Observations of White Dwarfs and Related Objects


Speaker:Dr. D.W. Hoard
Affiliation:Research Scientist, Science User Support Team Spitzer Science Center, California Institute of Technology
Date:February 11, 2009 (Wed)
Time:3:00-4:00 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract:

White dwarf stars are the most common endpoint for stellar evolution in our Galaxy. As such, they play an important role in our understanding of both the history and the future of the Galactic stellar population. Historically, white dwarfs have been discovered primarily because they are typically hot, blue objects. They have been thoroughly studied at optical, ultraviolet, and X-ray wavelengths. In the last 10-15 years, however, ground- and space-based capabilities for obtaining observations in the infrared have improved dramatically. It has become clear that investigating white dwarfs at longer wavelengths will reveal a wealth of previously unknown characteristics and astrophysical processes. I will present a review of my recent infrared observations and discoveries about white dwarfs, white dwarf precursors, and binary systems containing a white dwarf and a low mass stellar (or substellar) companion. Highlights include the discovery of many more white dwarfs with close (unresolved from the ground) low mass companions than previously known, and the presence of circumbinary and/or circumstellar dust in interacting binary stars containing a white dwarf. These data were obtained primarily from the Two Micron All Sky Survey, the Hubble Space Telescope, and the Spitzer Space Telescope, as well as dedicated ground-based observations at a number of observatories.

Coffee and tea will be served 20 minutes prior to the seminar.