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diskilt1.txt
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1996-01-12
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RELEASE DATE: May 22, 1995
PHOTO FILE NO.: STSCI-PF95-23
RELEASE DATE: May 22, 1995
CATACLYSMIC VARIABLE STAR
(ARTIST CONCEPT)
This is an illustration of a class of double star called a cataclysmic
variable. The system consists of a white dwarf star - a dense,
burned-out star that has collapsed to the size of Earth and a companion
that is a normal star, similar to but smaller than the Sun. The stars
are so close together gas flows from the normal star onto the dwarf
where it swirls into a pancake-shaped disk.
When the disk of gas periodically collapses onto the white dwarf, it
unleashes a burst of kinetic energy. Once dumped onto the dwarf's
surface, hydrogen accumulates until it undergoes thermonuclear fusion
reactions that eventually trigger the classical nova. After the
detonation the "fueling" of the white dwarf starts again.
Spectroscopic studies by Hubble Space Telescope have allowed
astronomers to measure directly the white dwarf's temperature, spin
rate and chemical composition in two such systems. Hubble has
surprised researchers by finding that the white dwarf stars at the
heart of the fireworks are cooler than expected and spin more slowly
than thought.
Credit: STScI
* * * * * * *
Image files in GIF and JPEG format may be accessed on Internet via
anonymous ftp from ftp.stsci.edu in /pubinfo:
GIF: /pubinfo/gif/DiskIllus.gif
JPEG: /pubinfo/jpeg/DiskIllus.jpg
The same images are available via World Wide Web from URL
http://www.stsci.edu/Latest.html, or via links in
http://www.stsci.edu/public.html.