快猫短视频

FIREWORKS fans take note: astronomers have spied a pair of aged stars locked
in a dance of death that will lead inevitably to a spectacular supernova. And
you鈥檒l only have to wait 200 million years to see it.

Astrophysicists have been struggling to explain the enormous stellar
explosions known as type Ia supernovae. Type II supernovae, which are dimmer,
appear to be huge young stars giving their all in cataclysmic bursts. Yet type
Ia supernovae often appear in galaxies that haven鈥檛 produced new stars for
billions of years.

Theorists think the key ingredient of a type Ia supernova is a white dwarf,
the burned-out remnant of a star a few times more massive than the Sun. In one
model, a white dwarf gobbles up a normal hydrogen star. In another, two white
dwarves consume each other. 鈥淲e do not know with any certainty which is the
better model,鈥� says Mario Livio of the Space Telescope Science Institute in
Baltimore, Maryland.

Now astronomers Pierre Maxted, Tom Marsh and Rachel North of the University
of Southampton have found a pair of stars that come close to fitting the second
model. Known as KPD1930+2752, the pair consists of a white dwarf and a subdwarf
B star鈥攁 cousin of the white dwarf made of helium. When the stars merge,
the helium gathering on the surface of the white dwarf will go up in a huge
thermonuclear explosion, Maxted says.