Hubble Observations Provide Insight into Planet Birth

Hubble Observations Provide Insight into Planet Birth
http://hubblesite.org/newscenter/archive/releases/2007/02/full/
http://hubblesite.org/newscenter/archive/releases/2007/02/image/a/

New observations from NASA's Hubble Space Telescope have begun to
fill gaps in the early stages of planet birth.

Hubble observed a "blizzard" of particles in a disk around a young
star revealing the process by which planets grow from tiny dust
grains. The particles are as fluffy as snowflakes and are roughly ten
times larger than typical interstellar dust grains. They were
detected in a disk encircling the 12-million-year-old star AU
Microscopii. The star is 32 light-years away in the southern
constellation of Microscopium, the Microscope.

The particles' fluffiness suggests that they were shed by much
larger, but unseen snowball-sized objects that had gently collided
with each other. These unseen objects are believed to reside in a
region dubbed the "birth ring," first hypothesized in 2005 by
Berkeley astronomers Linda Strubbe and Eugene Chiang. The ring is
between 3.7 billion and 4.6 billion miles from the star. As the
larger objects bump into each other, they release fluffy particles
that are propelled outward by the intense pressure from starlight.

"We have seen many seeds of planets and we have seen many planets,
but how they go from one to the other is a mystery," said astronomer
James Graham of the University of California at Berkeley and leader
of the Hubble observations. "These observations begin to help us fill
in that gap."

Graham and his colleagues, who include Paul Kalas of the University
of California at Berkeley and Brenda Matthews of the Herzberg
Institute of Astrophysics in Victoria, B.C., presented their results
today (Jan. 7) at the American Astronomical Association meeting in
Seattle, Wash.

The astronomers used the Advanced Camera for Survey's coronagraph and
polarizing filters to analyze the starlight reflecting off the debris
disk. The coronagraph blocked out the bright light from the star so
astronomers saw only the reflected light from the nearly edge-on
debris disk.

See: http://hubblesite.org/newscenter/archive/releases/2007/02/full/
.

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