'Exciting' find: Possible planets without orbits
NEW YORK: Are these planets without orbits? Astronomers have found 10
potential planets as massive as Jupiter wandering through a slice of the
Milky Way galaxy, following either very wide orbits or no orbit at all.
And scientists think they are more common than the stars.
These mysterious bodies, apparently gaseous balls like the largest
planets in our solar system, may help scientists understand how planets
form. They're finding evidence for a lot of pretty big planets, said
Alan Boss of the Carnegie Institution of Washington, who wasn't involved
in the research.
If they orbit stars, their sheer number suggests every star in the
galaxy has one or two of them, which is astounding because that's five
or 10 times the number of stars scientists had thought harbored such
gas-giant planets, he said. And if instead they are wandering free, that
would be really stunning because it's hard to explain how they formed,
he said. If that's the case, it would give a boost to some theories that
say planets can be thrown out of orbit during formation, said Lisa
Kaltenegger of the Harvard-Smithsonian Center for Astrophysics, another
outside expert.
Other scientists have reported free-wandering objects in star-forming
regions of the cosmos, but the newfound objects appear to be different,
said one author of the new study, physicist David Bennett of the
University of Notre Dame.
Bennett and colleagues from Japan, New Zealand and elsewhere report
the finding in Thursday's issue of the journal Nature. They didn't
observe the objects directly. Instead, they used the fact that massive
objects bend the light of distant stars with their gravity, just as a
lens does. So they looked extensively for such microlensing events. They
found 10, each caused by one of the newfound objects.
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