Hans.Moravec@cmu-ri-rover.arpa@sri-unix.UUCP (06/14/84)
n085 1719 12 Jun 84
BC-PLANETS
By WALTER SULLIVAN
c.1984 N.Y. Times News Service
BALTIMORE - Newly analyzed infrared emissions indicate that as many
as 40 relatively close stars are enveloped in clouds that it is
thought will ultimately condense and form planets.
The findings were reported Tuesday by Dr. Hartmut H. Aumann of the
Jet Propulsion Laboratory in Pasadena, Calif., at a meeting of the
American Astronomical Society.
Using a catalogue of 2,000 stars within 80 light-years of Earth, he
studied the data recorded last year by the Infrared Astronomical
Satellite, or IRAS, in search of more stars that, like Vega and
Fomalhaut, might show evidence of such clouds glowing at infrared
wavelengths.
The 40 stars he so identified constitute an estimated 10 to 20
percent of the 2,000 cataloged stars that are relatively similar to
the sun in terms of luminosity, mass and lifetime.
Last year, IRAS found Vega and Fomalhaut to be surrounded by
material similar to that from which it is assumed planets are formed.
However, those two stars are relatively hot, luminous, large and
young, with a projected lifetime of only a few million years.
The 40 stars that Aumann said ''are being orbited by solid
material'' are smaller but with lifetimes of billions of years, which
is long enough for higher forms of life to evolve.
The observations call to mind the infrared emissions predicted for
the so-called Dyson civilizations according to a theory that proposed
a completely different source for such emissions.
In 1960, Freeman Dyson of the Institute for Advanced Study at
Princeton, N.J., suggested that a highly advanced civilization,
driven by population pressure, would intentionally dismantle planets
in orbit around its parent star and re-assemble them into a cloud of
artificial, eventually inhabitable planets.
These planets would then capture all, or most, of the star's
radiated energy. The star would be largely hidden from distant
observers, but such a cloud of planets would glow at the infrared
wavelengths typical of low-temperature material. It was the infrared
glow that prompted discussion of the Dyson theory.
No one at Tuesday's meeting was arguing that the nearby stars were,
in fact, such civilizations, but Frank D. Drake, of Cornell
University, said such a possibility could not be ruled out. It was
Drake who in 1959 first turned a radio telescope toward two nearby
stars in search of artificial signals from space. One of the two
stars, Epsilon Eridani, is among the 40 now identified as strong
emitters of infrared radiation.
Aumann said the infrared emissions were too strong to have emanated
from Dyson-type planets, but Drake disagreed. He said a ''smart''
civilization would build its planets farther from the parent star
than Earth's orbit is from the Sun but would keep one side
continuously facing the star, allowing for a mild climate on that
side. The cold backside, he said, would emit radiation much like that
recorded by IRAS.
The optimistic mood of a decade ago among searchers for life on
other worlds has given way, however, to a suspicion that if
technological civilizations exist, they are more distant than the
nearest stars.
Among other IRAS observations reported on Tuesday was the finding
that some galaxies scattered throughout the universe are being
powered by an enormous and baffling energy source. The galaxies are
so dim optically that the existence of many of them was unknown until
powerful telescopes were turned to those directions where IRAS had
detected pointlike sources of emission.
When photographed optically, many of these galaxies are seen to be
greatly distorted or to be in such close contact with another galaxy
as to suggest that they are, or have been, in collisions. One
suggestion is that such collisions of galactic clouds produce bursts
of star formation perhaps at rates higher than one per day, producing
the enormous infrared emissions.
The ''star burst'' hypothesis and other explanations, however, have
been challenged on some ground. As Dr. Frank J. Low of the University
of Arizona, put it: ''We are on the trail of something very
fundamental, but we don't know what it is.''
nyt-06-12-84 2014edt
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