Re: Astronomers discover scaled-down Jupiter and Saturn in a faraway solar system like our own (Forwarded)

Interesting as hell, and no wonder this topic isn't getting any Usenet
action. Are we taking of thousands or possibly a million of such
potential solar systems within our Milky Way?
. - Brad Guth


Andrew Yee wrote:
Research Communications
Ohio State University

Contact:
Scott Gaudi, (614) 292-1914

Written by:
Pam Frost Gorder, (614) 292-9475

Embargoed until Thursday, February 14, 2008 at 2:00 p.m. ET, to coincide
with publication in the journal Science.

ASTRONOMERS DISCOVER SCALED-DOWN JUPITER AND SATURN IN A FARAWAY SOLAR
SYSTEM LIKE OUR OWN

COLUMBUS, Ohio -- An international team of astronomers has discovered two
planets that resemble smaller versions of Jupiter and Saturn in a solar
system nearly 5,000 light years away.

The find suggests that our galaxy hosts many planetary systems like our
own, said Scott Gaudi, assistant professor of astronomy at Ohio State
University.

He and his colleagues reported their results in the February 15 issue of
the journal Science.

The two planets were revealed when the star they orbit crossed in front of
a more distant star as seen from Earth. For a two-week period from late
March through early April of 2006, the nearer star magnified the light
shining from the farther star.

The phenomenon is called gravitational microlensing, and this was a
particularly dramatic example: the light from the more distant star was
magnified 500 times.

The Optical Gravitational Lensing Experiment (OGLE) first detected the
event, dubbed OGLE-2006-BLG-109, on March 28, 2006. The Microlensing
Follow Up Network (MicroFUN), led by Andrew Gould, professor of astronomy
at Ohio State, then joined with OGLE to organize astronomers worldwide to
gather observations of it. Andrzej Udalski, professor of astronomy at
Warsaw University Observatory, is the leader of OGLE.

Gaudi took the lead in analyzing the data as they came in. As he studied
the light signal, he saw a distortion that he thought was caused by a
Saturn-mass planet. Then, less than a day later, came an additional
distortion he wasn't expecting: a "blip" in the signal that appeared to be
caused by a second, larger planet orbiting the same star.

Over the next few months, Gaudi demonstrated that this two-planet
interpretation was correct. Then David Bennett, a research associate
professor of astrophysics and cosmology at the University of Notre Dame,
refined Gaudi's preliminary model using sophisticated software, and
revealed additional details about the system.

This is the third time a Jupiter-mass planet was found by microlensing,
Gaudi explained. In the previous two cases, additional planets would have
been very difficult to detect, had they been there.

"This is the first time we had a high-enough magnification event where we
had significant sensitivity to a second planet -- and we found one." Gaudi
said. "You could call it luck, but I think it might just mean that these
systems are common throughout our galaxy."

Astronomers have found two planets at once before, "but using other
techniques that don't pick up on solar systems like ours," he said.

The newly-discovered planets appear to be gaseous planets like Jupiter and
Saturn -- only about 80 percent as big -- and they orbit a star about half
the size of the sun. The star is dim and cold compared to ours, issuing
only five percent as much light.

Still, the new solar system appears to be a smaller analog of our own. The
larger planet is about as massive compared to its star as Jupiter is to
ours. The smaller planet shares a similar mass ratio with Saturn.

Also, the smaller planet is roughly twice as far from its star as the
larger one, just as Saturn is roughly twice as far away from the sun as
Jupiter. Although the star is much dimmer than our sun, temperatures at
both planets are likely to be similar to that of Jupiter and Saturn,
because they are closer to their star.

"The temperatures are important because these dictate the amount of
material that is available for planet formation," Gaudi said. "Most
theorists think that the biggest planet in our solar system formed at
Jupiter's location because that is the closest to the sun that ice can
form. Saturn is the next biggest because it is in the next location
further away, where there is less primordial material available to form
planets."

"Theorists have wondered whether gas giants in other solar systems would
form in the same way as ours did. This system seems to answer in the
affirmative."

The fact that astronomers found the planets during the first event that
allowed such a detection suggests that these scaled-down versions of our
solar system are very common, he added.

Previously, astronomers had found four planets using microlensing; two of
those were found by the Ohio State University-based MicroFUN group. The
latest two planets make six, and he expects that number to double over the
next year as other teams publish new findings.

"We're just getting better at what we do," Gaudi said. "We've hit our
stride with this technique."

He has also calculated that the next generation of microlensing
experiments -- using telescopes on the ground and in space -- will likely
be able to detect analogs to all of our solar system's planets, except for
the tiniest one, Mercury.

The current discovery relied on 11 different ground-based telescopes in
countries around the world, including New Zealand, Tasmania, Israel,
Chile, the Canary Islands, and the United States.

Both professional and amateur skywatchers joined in. People from three
other microlensing collaborations -- the Microlensing Observations in
Astrophysics (MOA) Collaboration, the Probing Lensing Anomalies NETwork
(PLANET), and the RoboNet Collaboration -- all contributed observations
and are co-authors of the study with MicroFUN and OGLE.

Gaudi described this microlensing event as the most complicated one ever
studied. The astronomers carefully modeled their data on computers, and
explored all possible explanations for the light signal. A year and a half
later, they were confident that they'd found two planets. In part, their
confidence came from additional observations from the W.M. Keck
Observatory in Hawaii, which they used to calculate the mass of the star.

Ohio State coauthors on the Science paper included Darren DePoy and
Richard Pogge, both professors of astronomy; and Subo Dong and Stephan
Frank, both graduate students.

Other coauthors hailed from the University of Notre Dame, Warsaw
University Observatory, Auckland Observatory, Tel-Aviv University, Farm
Cove Observatory, Mt. John Observatory, Lawrence Livermore National
Laboratory, Princeton University Observatory, Universidad de Concepci�n,
University of Cambridge, Chungbuk National University, Korea Astronomy and
Space Science Institute, Campo Catino Astronomical Observatory, Nagoya
University, Massey University, University of Auckland, University of
Canterbury, Victoria University, Konan University, Nagano National College
of Technology, University of Manchester, Tokyo Metropolitan College of
Aeronautics, University of Exeter, Universit� Pierre et Marie Curie,
Liverpool John Moores University, University of St. Andrews, University of
Tasmania, Universit� Paul Sabatier-Toulouse, Dartmouth College, and the
University of Oxford.

This work was sponsored by the National Science Foundation; NASA; the
Polish Ministry of Scientific Research and Information Technology; the SRC
Korea Science & Engineering Foundation; the Korea Astronomy & Space
Science Institute; Deutsche Forschungsgemeinschaft; the Particle Physics
and Astronomy Research Council; The European Union's Framework Programme
for Research and Technological Development; The Israel Science Foundation;
the Marsden Fund of New Zealand; the Japan Ministry of Education, Culture,
Sports, Science and Technology; and the Japan Society for the Promotion of
Science.

IMAGES:
High-resolution jpeg images of these illustrations and of Scott Gaudi and
Andrew Gould are available to accompany this story at
http://researchnews.osu.edu/archive/analogpix.htm

VIDEO:
An animation showing an artist's conception of what the new planets might
look like is available at
http://researchnews.osu.edu/archive/analogvideo.htm
.

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