HPM@SU-AI@sri-unix.UUCP (08/14/83)
From: Hans Moravec <HPM@SU-AI>
a059 0652 13 Aug 83
Vega's Halo Emerges As 'Super-Duper Asteroid Belt'
LOS ANGELES (AP) - The vast ring of objects around the nearby star
Vega is more likely ''a super-duper asteroid belt'' than a new solar
system, some astronomers say.
Stuart Weidenschilling, an astronomer with the Planetary Sciences
Institute of Tuscon, Ariz., said the strong infrared signal coming
from the region suggests an enormous number of small particles
radiating at the same frequency, comparable to the asteroid belt
within the Earth's solar system.
The Earth's belt consists of more than 100,000 fragments believed to
be leftovers from the formation of the solar system. They range in
size from a few inches to several hundred miles in diameter.
The 15-billion-mile shell of debris around Vega was discovered
earlier this week. The star is 150 trillion miles from Earth and the
third brightest star in our sky.
The debris has yet to be glimpsed clearly, but it appears to be ''a
super-duper asteroid belt,'' Weidenschilling said. ''If there were
just a few big planet-sized objects there, they wouldn't radiate
(infrared energy) as strongly as a large number of small objects with
a greater total surface.''
That means there may be much more material the size of buckshot,
popcorn and boulders surrounding Vega than revolve around the sun. If
there are any large bodies, they are probably few and far between.
George W. Wetherill, a geophysicist with the Carnegie Institution of
Washington, agreed.
''There's got to be a lot of small stuff, debris, around Vega,'' he
said, ''and for that very reason, I'd be reluctant to call it a
'planetary' system. In fact, you could even argue the evidence is
against calling it a 'planetary' system because it is such small
stuff.''
The scientists' comments were reported today in the Los Angeles
Times.
Wetherill and Richard Greenberg, another Planetary Sciences
Institute astronomer, are skeptical that material could ever amount to
a planetary system. They said that if it has not happened by now, it
is not likely to happen in the future.
Astronomers have been searching for decades for evidence of other
solar systems. Some argue that uncountable millions of planets must
exist in the universe and some should harbor extraterrestrial life.
None has yet been found.
But the Vega particles sparked guarded excitement that scientists
might be on the trail of one.
The particles were discovered by H.H. Aumann of the Jet Propulsion
Laboratory in Pasadena and Fred Gillett of Arizona's Kitt Peak
National Observatory, at a tracking station at Chilton, England, for a
telescope rocketed into space in January to map the heavens.
The infrared satellite measured a temperature of minus 300 degrees
Fahrenheit for the frigid matter circling Vega, in the consellation
Lyra, similar to that found within the inner rings of the planet
Saturn.
Conway Snyder of the Jet Propulsion Laboratory cautioned when the
discovery was announced that whether it represented a solar system
''was very much conjecture.'' He termed it an ''exciting'' find,
however.
Despite the doubts over whether the matter is forming planets, the
spotting of the Vega particles is a shot in the arm for cosmogony, the
science that seeks to understand how astronomical structures such as
stars and stellar systems form.
It offers scientists an example of how huge clouds of gas and dust
condense to build a central star and, perhaps, a retinue of planets.
Until now, scientists have had only one subject to study: our solar
system.
''When you only have one of something you're trying to study, no
matter what the subject is, it's hard to do much,'' said Charles
Beichman, an astronomer at the Jet Propulsion lab. ''But when you find
two, there's probably a lot more out there just waiting to be
discovered.''
ap-ny-08-13 0953EDT
***************REM@MIT-MC@sri-unix.UUCP (08/18/83)
From: Robert Elton Maas <REM @ MIT-MC> That article refers to it as a "shell", i.e. a spherical surface. The asteroid belt of our Sun is more like a ring. Was that a mistake in terminology or has the Vegan system definitely been identified as a shell instead of a ring? Perhaps the shell is really a Dyson sphere, i.e. artificial. Do the current observations refute that possibility? I would rather doubt a shell of natural particles could remain after a billion years, while a ring could. If it's really a shell that would seem to indicate somebody's artificially maintaining it.