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By Mike Wehner, BGR
We usually think of planets as having a certain level of permanence
but for worlds that reside within very close proximity of a star
existence can be fleeting. One particular type of exoplanet that
astronomers are trying to learn more about are the so-called “hot
Neptunes,” which are superheated giants that are incredibly rare.
Now, researchers using the Hubble Space Telescope have pinpointed
what they believe to be a planet just on the cusp of being considered a
“hot Neptune,” and it’s so close to its star that the planet is
actually evaporating right before our eyes.
The exoplanet, called GJ 3470b, is located near what researchers call
the “Hot Neptune Desert” around its host star. Scientists believe that
there’s a lack of such planets because they are completely destroyed
over time due to their close relationship with the stars they orbit, and
GJ 3470b might be the next to go.
One
of GJ 3470b’s fellow planets is GJ 436b, which astronomers believe is
losing its atmosphere as its star strips it away. Scientists think that
436b will survive the ordeal without being completely destroyed, but
3470b is in a much tougher spot. 3470b is being stripped of mass 100
times faster than 436b, and it’s possible that the planet will be
completely vaporized.
“I think this is the first case where this
is so dramatic in terms of planetary evolution,” Vincent Bourrier of the
University of Geneva and co-author of the work, said in a statement.
“It’s one of the most extreme examples of a planet undergoing a major
mass-loss over its lifetime. This sizable mass loss has major
consequences for its evolution, and it impacts our understanding of the
origin and fate of the population of exoplanets close to their stars.”
So
how close is too close when it comes to planets and their stars? The
closest planet to our own Sun, the scorching-hot Mercury, has made a go
of it for a long time, but 3470b is much closer to its star. In fact,
both 436b and 3470b are just one-tenth the distance from their star than
Mercury is from the Sun.
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