from the NY times, astronomy

Interesting..... (enough so that I'm sending this without making you
jump
through the hoop of going to NYT and getting an ID and password etc. -
pain
in the butt, that is) - I figure an infringement I make by posting this
here
is made up for by their intrusive questioning and mandatory fields in
the
account registration. 
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SAN DIEGO, Jan. 9 - Astronomers have discovered two more planetary
systems
in the universe, and they appear to bear little or no resemblance to
each
other or to the solar system.
In one of the systems, a Sun-like star is accompanied by a massive
planet
and an even larger object 17 times as massive as Jupiter. If this
whopper is
a planet, it is the largest ever detected, defying current theory.
Scientists suspect that it could be a dim failed star or a type of
astronomical object that has never been observed before.
In the other system, two planets of more normal size are orbiting a
small
star. But their orbits are anything but normal. The pair of planets are
locked in resonant orbits, moving in synchrony around the star with
orbital
periods of 61 and 30 days; the inner planet goes around twice for each
orbit
of the outer one.
"They are unique and frightening," the discovery team's leader, Dr.
Geoffrey
W. Marcy of the University of California at Berkeley, said of the
newfound
planetary systems. "We thought we understood the mass ranges of planets
of
other stars. We thought we understood the full diversity of planets."
The two systems are indeed unlike anything observed before, and this
makes
astronomers wonder, What is a typical congregation of planets orbiting a
central star? Are the Sun and its planets the oddball system? Are there
more
kinds of planets in the heavens than scientists have dreamed of?
In announcing the findings here today at a meeting of the American
Astronomical Society, Dr. Marcy confessed that in particular the system
with
the unusually enormous planet - the one with 17 times the mass of
Jupiter,
largest companion of the Sun - called into question the very meaning of
the
term "planet."
Another team member, Dr. R. Paul Butler of the Carnegie Institution of
Washington, said: "This massive planetary object defies our expectations
for
the largest planets. But it's right there next to another planet. We
never
expected nature would make such gargantuan planets, and indeed maybe
they
aren't planets at all."
Dr. Marcy, Dr. Butler and an associate, Dr. Debra Fischer of Berkeley,
sidestepped interpretations of the formation and evolution of such
bizarre
planetary families.
"I can't wait until the theorists explain these things to us," Dr.
Butler
remarked at a news conference.
Dr. Douglas N. C. Lin, a theorist of planetary systems at the University
of
California at Santa Cruz, who is not a team member, seemed ready to
accept
the challenge. "I'm so excited by these observations," Dr. Lin said.
The discovery compounded the perplexity and confusion raised by earlier
detection of planets beyond the Sun's family, beginning in 1995. Of more
than 1,000 stars observed, over 50, all relatively nearby Earth, have so
far
been found to be accompanied by single planets. 
The first multiplanet system to have been discovered - and until now the
only one - was found two years ago, and its three Jupiter-class planets
are
orbiting much closer to their star, Upsilon Andromedae, than Jupiter is
to
the Sun.
The most recent observations, in research financed by the National
Aeronautics and Space Administration and the National Science
Foundation,
were made at the Keck telescope atop Mauna Kea in Hawaii and at the Lick
Observatory near San Jose, Calif. The objects could not be seen in the
telescopes, but the effects of their gravitational pull could be
detected in
the distinct wobbles of their stars. Astronomers tracked these
perturbations
for at least two years before determining that they signaled the
presence of
the two planetary systems. 
(Page 2 of 2) 
Around the Sun-like star HD 168443, which is 123 light-years away in the
constellation Serpens, the astronomers detected one planet orbiting at a
distance comparable to that from the Sun to a point between Mercury and
Venus. Its mass is estimated to be more than seven times Jupiter's,
which is
toward the high end of the sizes of previously detected planets outside
our
solar system.
Farther out, at a distance equivalent to that from the Sun to the
asteroid
belt between Mars and Jupiter, the astronomers found what they call "the
mystery object," the object with 17 times Jupiter's mass.
>From previous research, Dr. Marcy and Dr. Butler had concluded that
planet
mass could not exceed about 13 times that of Jupiter. So what was this
they
had detected?
If it is considered a planet, astronomers said, then there is much about
planetary formation that scientists have yet to learn. Or it could be a
brown dwarf, a starlike object that failed to achieve a mass sufficient
to
ignite nuclear fusion and thus shine like a true star.
Besides size, the main difference between a brown dwarf and a planet is
their formation. A brown dwarf, like a star, is formed by the
gravitational
collapse of a cloud of gas. A planet is created by the accretion of a
core
and gases from the disk of gas and dust surrounding a new star.
Dr. Lin, the theorist, said that at present it was "not possible to rule
out
one versus the other" explanation for the mystery object. But he
suggested
that gravitational instabilities might have made it difficult for a
brown
dwarf to emerge as close to a true star as in this case.
No one ruled out the possibility that the object was neither a brown
dwarf
nor a planet but instead something new to astronomy.
The other discovery was made around Gliese 876, a red dwarf star only
one-third the mass of the Sun. No planets had previously been found
around
so small a star.
The star is only 15 light-years away, in the constellation Aquarius. Its
two
planets are of modest size; one is about half the mass of Jupiter, the
other
nearly twice Jupiter's.
But their fascination is the gravitational lock step of their orbits.
Astronomers had known for more than two years that there was something
there
tugging on the star, but the observations were puzzling.
"We were fooled," said another team member, Dr. Steven Vogt, an
astronomer
at Santa Cruz. "The synchrony allowed one planet - the smaller, inner
planet
- to hide in the wobble of the other."
Orbiting objects linked in this way are not unheard of. Three of
Jupiter's
large satellites - Io, Europa and Ganymede - travel in such a
configuration,
as do some of the small satellites of Saturn.
Dr. Hal Levison, a planetary scientist at the Southwest Research
Institute
in Boulder, Colo., noted that in recent computer simulations of
extra-solar
planetary motions, "25 percent of the cases produced planets in
near-resonant orbits."

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Thomas R. S. Barclay
Voice: (613) 722-3232 ext 349
e-mail: tomb@bitheads.com

2001: To the New Millenium! The next thousand years
are MINE. 
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