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Comet
'Bites the
Dust'
Around
Dead Star
This
artist's
concept
illustrates
a comet
being torn
to shreds
around
G29-3, a
so-called
dead star,
or white
dwarf.
NASA's
Spitzer
Space
Telescope
observed a
cloud of
dust
around
this white
dwarf that
may have
been
generated
from this
type of
comet
disruption.
The
findings
suggest
that a
host of
other
comet
survivors
may still
orbit in
this
long-dead
solar
system.
This
illustration
shows a
comet in
the
process of
being
pulverized:
part of it
still
exists as
a chain of
small
clumps,
while the
rest has
already
spread out
into a
dusty
disk.
Comet
Shoemaker-Levy
9 broke
apart in a
similar
fashion
when it
plunged
into
Jupiter in
1994.
The white
dwarf
G29-38
began life
as a star
that was
about
three
times as
massive as
our sun.
Its death
involved
the same
steps that
the sun
will
ultimately
undergo
billions
of years
from now.
According
to theory,
the G29-38
star
became
brighter
and
brighter
as it
aged,
until it
grew into
a dying
star
called a
red giant,
which was
large
enough to
engulf and
evaporate
any
terrestrial
planets
that
happened
to be in
its way.
Later, the
red giant
shed its
outer
atmosphere,
leaving
behind a
shrunken
skeleton
of star,
called a
white
dwarf. If
the star
did host a
planetary
system,
outer
planets
akin to
Jupiter
and
Neptune
and a
remote
ring of
icy comets
would
remain.
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