Astronomers: Star collisions are rampant, catastrophic
Three frames from an animation showing a computer-modeled collision between stars
NEW YORK (CNN) -- Astronomers once thought stellar collisions
never or rarely happened. But new research has convinced many
that stellar mergers are commonplace and perhaps capable of
producing the most violent and energetic events observable in
"Most people a few years ago though that collisions didn't
happen," said physicist Mike Shara of the American Museum of
Natural History in New York, which organized the first international
conference on the topic this week.
But in the center of many galaxies, including our own, dense
swarms of stars make such events inevitable, he said.
"Suddenly we're starting to get lots of collisions. There's
probably one about every ten seconds," said Shara, curator of
the museum's astrophysics department.
Using space telescopes like the Hubble and Chandra and
powerful computer calculations, astronomers have focused on
globular clusters to study what they consider offspring of
such mergers: blue stragglers, which are bluer, hotter and
younger than their neighbors.
"They have no business being there. There's no other way to
make them, other than to collide stars," Shara said.
Three stars combine into one
Dozens of scientists from around the world presented the
latest research on star collisions at the conference.
A team of Villanova University researchers reported the
discovery of an object that most likely formed from the
merger of three stars, a binary pair and a solitary one.
Such a collision has been predicted in the past, but now the
astronomy team has "the smoking gun," Shara said:
measurements of the giant star's mass.
Stellar collisions produce a variety of results, astronomers
said. Slowly merging pairs can form giant superstars. Two
violently colliding stars may eject all their material,
Some may only draw each other into orbit. Their cores never
touch, and the result is a binary star. Others may pass by neighbors quickly, disrupting the outer envelopes or atmospheres of both stars.
'Most violent events in the universe'
Super-dense neutron stars emit powerful bursts of energy when
they crash into one another. Some of the conference
astronomers speculated that such collisions are responsible
for intense explosions of gamma rays, observed in the distant
reaches of space.
"They are the most violent energetic events in the universe,"
Shara said. "Some release a thousand times as much energy in
a few seconds as the sun would in its lifetime."
Even black hole mergers "almost certainly happen" in some
cases when galaxies run into each other, Shara said.
Scientists think such collisions cause gravitational waves
that travel through space. New instruments may
allow them to measure those ripples in the near future.
"We'll be learning about how gravity works in a very intense
environment that we could never approach on Earth," said
Vickie Kalogera of the Harvard Smithsonian Center for
Will marauding star doom the solar system?
Current research indicates that stellar collisions are quite
common in dense star clusters, where millions of stars can be
found within a space spanning less than 100 light years.
But terrestrial dwellers take heart. Such catastrophes are
infinitesimally rare in cosmic backwaters far removed from
the centers of galaxies, like a spiral arm of the Milky Way
where the sun resides. Our neighborhood star will burn out
long before another crashes into it.
"It you waited ten million times the age of the universe,
only then would you have a 50-50 chance of a collision,"
Hubble reveals violent supernova shockwave
February 17, 2000
First Chandra images show stellar explosion, X-ray jet
August 26, 1999
Stellar nursery in nearby galaxy teems with activity
September 29, 1999
Telescope finds 'power lines' in stellar remnant
September 28, 1999
Hubble sees stars in red, white and blue
July 6, 1999
American Museum of Natural History
Hubble Heritage Project
The Chandra X-ray Observatory Center
Harvard-Smithsonian Center for Astrophysics
Note: Pages will open in a new browser window
External sites are not endorsed by CNN Interactive.