Suns Of All Ages Possess Comets, Maybe Planets (Forwarded)

Harvard-Smithsonian Center for Astrophysics
Cambridge, Massachusetts

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For Release: 9:20 a.m. EST, Monday, January 5, 2004

Release No.: 04-01

Suns Of All Ages Possess Comets, Maybe Planets

Atlanta, GA -- In early 2003, Comet Kudo-Fujikawa (C/2002 X5) zipped past
the Sun at a distance half that of Mercury's orbit. Astronomers Matthew
Povich and John Raymond (Harvard-Smithsonian Center for Astrophysics) and
colleagues studied Kudo-Fujikawa during its close passage. Today at the
203rd meeting of the American Astronomical Society in Atlanta, they
announced that they observed the comet puffing out huge amounts of
carbon, one of the key elements for life. The comet also emitted large
amounts of water vapor as the Sun's heat baked its outer surface.

When combined with previous observations suggesting the presence of
evaporating comets near young stars like Beta Pictoris and old stars like
CW Leonis, these data show that stars of all ages vaporize comets that
swing too close. Those observations also show that planetary systems like
our own, complete with a collection of comets, likely are common
throughout space.

"Now we can draw parallels between a comet close to home and cometary
activity surrounding the star Beta Pictoris, which just might have
newborn planets orbiting it. If comets are not unique to our Sun, then
might not the same be true for Earth-like planets?" says Povich.

SOHO Sees Carbon

The team's observations, reported in the December 12, 2003, issue of the
journal Science, were made with the Ultraviolet Coronagraph Spectrometer
(UVCS) instrument on board NASA's Solar and Heliospheric Observatory
(SOHO) spacecraft.

UVCS can only study a small slice of the sky at one time. By holding the
spectrograph slit steady and allowing the comet to drift past, the team
was able to assemble the slices into a full, two-dimensional picture of
the comet.

The UVCS data revealed a dramatic tail of carbon ions streaming away from
the comet, generated by evaporating dust. The instrument also captured a
spectacular 'disconnection event,' in which a piece of the ion tail broke
off and drifted away from the comet. Such events are relatively common,
occurring when the comet passes through a region of space where the Sun's
magnetic field switches direction.

Cometary Building Blocks

More remarkable than the morphology of the carbon ion tail was its size.
A single snapshot of Kudo-Fujikawa on one day showed that its ion tail
contained at least 200 million pounds of doubly ionized carbon. The tail
likely held more than 1.5 billion pounds of carbon in all forms.

"That's a massive amount of carbon, weighing as much as five
supertankers," says Raymond.

Povich adds, "Now, consider that astronomers see evidence for comets like
this around newly formed stars like Beta Pictoris. If such stars have
comets, then perhaps they have planets, too. And if extrasolar comets are
similar to comets in our solar system, then the building blocks for life
may be quite common."

Understanding Our Origins

In 2001, researcher Gary Melnick (CfA) and colleagues found evidence for
comets in a very different system surrounding the aging red giant star CW
Leonis. The Submillimeter Wave Astronomy Satellite (SWAS) detected huge
clouds of water vapor released by a Kuiper Belt-like swarm of comets
which are evaporating under the giant's relentless heat.

"Taken together, the observations of comets around young stars like Beta
Pictoris, middle-aged stars like our Sun, and old stars like CW Leonis
strengthen the connection between our solar system and extrasolar
planetary systems. By studying our own neighborhood, we hope to learn not
only about our origins, but about what we might find out there orbiting
other stars," says Raymond.

Other co-authors on the Science paper reporting these findings are
Geraint Jones (JPL), Michael Uzzo and Yuan-Kuen Ko (CfA), Paul Feldman
(Johns Hopkins), Peter Smith and Brian Marsden (CfA), and Thomas Woods
(University of Colorado).

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.

Note to Editors:

An image to accompany this release is online at:
http://cfa-www.harvard.edu/press/pr0401image.html