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Астронет: Астрономическая картинка дня NGC 1818: Выбери звезду http://variable-stars.ru/db/msg/1190630/eng |
Credit & Copyright: R. Elson and R. Sword
(IoA Cambridge),
NASA
Explanation:
This is NGC 1818,
a youthful, glittering cluster
of 20,000 stars residing in the
Large
Magellanic Cloud, 180,000 light-years away.
Pick a star. Any star.
Astronomers
might pick the unassuming bluish-white one (circled) which
appears
to be a hot newly formed white dwarf star.
What makes it so interesting?
The standard astronomical wisdom
suggests that stars over 5 times as massive as the
sun rapidly exhaust
their nuclear fuel and end their lives in a spectacular
supernova explosion.
With less than this critical mass
they evolve into red giants, pass through a relatively
peaceful planetary nebula phase,
and calmly fade away as
white dwarf stars like this one.
Except that as a member of the NGC 1818 cluster,
this new white dwarf would have evolved from
a red
giant star over 7.6 times as massive as the
sun -- which should have exploded!
Its discovery
will likely force astronomers to revise the
limiting mass estimate for supernovae upward.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.