The Wild West Days of a Solar System
FAST is a free review of mainstream French press on issues of science and technology. It appears twice weekly.
FAST is published by the Science and Technology Office of the Embassy of France to the United States, and by its CNRS Washington office.
Paris – September 13, 2001 – Issue #278
If the first few hundred million years in the life of a solar system were
set to music, it turns out that the clash of metallic rock might be more
appropriate than say a waltz by Strauss. Contrary to the stately Newtonian
image often summoned to describe how orbiting clouds of dust congeal into
planets, observations of a younger neighbor recently led a French/American
team to conclude that the process looks more like a demolition derby, with
comets and asteroids instead of cars. Astrophysicians from the Paris
Astrophysics Institute (IAP – CNRS), the Astrophysics Laboratory of
Marseille, and Johns Hopkins University pointed the French-American-Canadian
satellite telescope FUSE at the well-known southern hemisphere star Beta
Pictoris in order to get a better idea of what surrounds it. FUSE is
designed to perform high-resolution spectroscopy in the ultraviolet range;
the surprising picture it gave of Beta Pictoris is that the orbiting bands
of matter contain no molecular hydrogen (H2) despite the presence of carbon
monoxide (already detected by The Hubble). Since the universe is largely
hydrogen, and carbon monoxide on the other hand rarely shows up in space
without H2 nearby, the research team concluded that the carbon must be
coming from the passage of millions of comets. As the comets approach the
star, they emit carbon monoxide which in frozen form constitutes a large
part of themselves (but not hydrogen, which cannot be trapped this way).
This explanation accounts not only for the unexpected CO reading but also
substantiates the theory that the early life of a solar system includes a
few hundred million years of violent housecleaning as asteroids disappear in
collisions with each other, tiny planets crash into big ones, and comets by
the millions evaporate. Only then does the stately whirl of planets in their
course begin. Beta Pictoris may well be in the throes of just such an active
phase of planetary system construction. Further indication that something’s
going on around Beta has been provided by the same group, using FUSE to
detect the presence of oxygen five times ionized. The latter is typical of
very hot environments such as the corona of a mature star, but Beta is too
young to have a corona, at least according to orthodox standards. Observing
all the activity around Beta may yield insights into the early days of our
sun and its evolving system. (Agence France Presse, August 16)
FAST is produced and written by Timothy Carlson.
