New Planets Discovered!
As Earthlings, we’re so used to thinking about planets being
in simple orbits around a single star. But the Sun likely didn’t begin its life
alone. It formed as part of a cluster of stars, all feeding from the same well
of gas. Could star cluster also host planets? Or do they have to wait for the
little guys until the stars evolve and move further apart?
We Are Not Alone!
Well, astronomers have actually just found planets — yes,
two planets — orbiting Sun-like stars in a cluster 3,000 light-years from
Earth. These are the third and fourth star cluster planets yet discovered, but
the first found “transiting” or passing across the face of their stars as seen
from Earth. (The others were found through detecting gravitational wobbles in
the star.)This is no small feat for a planet to survive. In a telescope, a star
cluster might look pretty benign, but up close it’s pretty darn harsh.
A press release about
the discovery used a lot of words like “strong radiation”, “harsh stellar
winds” and “stripping planet-forming materials” in a description of what NGC
6811 would feel like.
“Old clusters represent a stellar environment much different
than the birthplace of the Sun and other planet-hosting field stars,” stated
lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics.
“We thought maybe planets couldn’t easily form and survive
in the stressful environments of dense clusters, in part because for a long
time we couldn’t find them.”
The find, as you would expect, comes from the prolific
planet-hunting NASA Kepler spacecraft that is now battling problems with
pointing in the right direction. Although the telescope is in the penalty box,
there still are reams of data waiting to be analyzed and released.
The planets are known as Kepler-66b and Kepler-67b, and are
both approaching the size of Neptune (which is four times the size of Earth).
Their parent cluster, NGC 6811, is one billion years old. Astronomers are still
puzzled as to how these little worlds survived for so long.
“Highly energetic phenomena including explosions, outflows
and winds often associated with massive stars would have been common in the
young cluster,” stated the journal paper in Nature.
“The degree to which the formation and evolution of planets
is influenced by a such a dense and dynamically and radiatively hostile
environment is not well understood, either observationally or theoretically.”
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