Planet Orbiting Two Suns?
5th Nov 1999
Astronomers searching the universe for its elusive dark matter may have
found the first evidence of a planet orbiting two stars. At right is
an artist's rendition of what that might look like.
Of the 20 or so planets already discovered orbiting other stars, all
are circling a single star, even if there is another star in the system.
If the new planet is verified, it could be the first one seen to orbit
both stars in a binary star system.
The new planet was uncovered while scientists were analyzing two-year-old
data of a two-star system 20,000 light years away eclipsing an even
more distant star. The alignment of the systems created what is called
a gravitational lens.
The unexpectedly complex behavior of the light from the "lensing" event
may signal the existence of a planet about three times the size of Jupiter,
or about 100 times larger than Earth, say the researchers. The findings
appear in the latest issue of the journal Nature.
Einstein predicted that gravity could effectively "bend" light, and
that if a star or other massive object was directly between Earth and
a more distant object, the light from the distant object would bend
around it and appear brighter.
The discovery of the possible new planet was made by a group of scientists
working on the Microlensing Planet Search project led by David Bennett
and Sun Hong Rhie of the University of Notre Dame.
The group specializes in searching the sky for dark massive objects
that give themselves away by bending star light.
They found evidence of the planet as they studied data from the 1997
Massive Compact Halo Objects (MACHO) project.
MACHOs are one of the candidates for "dark matter" in the universe:
the unseen mass that could make or break eternal expansion or eventual
contraction of the universe.
"Between half and two-thirds of the stars in our solar neighborhood
are known to be members of binary or multiple star systems," says Morris
Aizenman of NSF's Astronomical Sciences Division. "To find evidence
of a planet orbiting a pair of stars means there could be more planetary
systems than we previously thought."
"I think the exciting thing here is that it was found with a gravitational
lens," says University of California at Santa Cruz astronomer Douglas
Lin. The jury is still out on the new planet, however. Astronomers hope
to test out soon other theories about what could be causing the lensing
event with more telescope observations.
Mysteries, UFOs, etc.
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