A hot and
aging star exhibits something never seen before. Sounds like a lurid Hollywood tale, but the discovery is a cosmic one.
Astronomers
have found a white dwarf star with a surface temperature of 359,500 degrees
Fahrenheit (200,000 Celsius). It's so hot that "its photosphere exhibits emission lines in the ultraviolet
spectrum, a phenomenon that has never been seen before," the researchers
said in a statement today.
Ultraviolet
light, part of the same electromagnetic
spectrum that includes radio waves, visible light and X-rays, is invisible
to the human eye.
Stars
of intermediate mass, around one to eight times the heft of the sun, terminate
their life as an Earth-sized
white dwarfs after the exhaustion of their nuclear fuel. During the
transition from a nuclear-burning star to the white dwarf stage, a star becomes
very hot.
The
white dwarf, named KPD 0005+5106, is among the hottest
stars ever known. Catching one so hot is a low-probability affair, because
they don't stay that hot for long.
Our
sun is about 10,000 degrees Fahrenheit. Scientists have previously theorized
that surfaces of the hottest stars could be up to 215,000 degrees F (120,000
degrees Celsius). For short times, when stars much more massive than the sun
explode, the inside temperature could reach as high as 10 billion degrees F.
The
finding, from observations by NASA's space-based Far-Ultraviolet Spectroscopic
Explorer (FUSE), will be detailed in the journal Astronomy &
Astrophysics.
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