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Today at the American Astronomical Society conference in Boston, the Kepler team announced the confirmation of a new rocky planet in orbit around Kepler-10. Dubbed Kepler-10c, this planet is described as a “scorched, molten Earth.”
2.2 times the radius of Earth, Kepler-10c orbits its star every 45 days. Both it and its smaller, previously-discovered sibling 10b are located too close to their star for liquid water to exist.
Kepler-10c was validated using a new computer simulation technique called “Blender” as well as additional infrared data from NASA’s Spitzer Space Telescope. This method can be used to locate Earth-sized planets within Kepler’s field of view and could also potentially help find Earth-sized planets within other stars’ habitable zones.
This is the first time the team feels sure that it has exhaustively ruled out alternative explanations for dips in the brightness of a star… basically, they are 99.998% sure that Kepler-10c exists.
The Kepler-10 star system is located about 560 light-years away near the Cygnus and Lyra constellations.
Read the release on the Nature.com blog.
Image credit: NASA/Ames/JPL-Caltech
I opt to rename this planet, Krispy-10c.
I vote for Krispy-10c, as well!
How do you know it’s rocky? All we know so far is that the mass is less than 20 Earth-masses, and the radius is just over twice that of Earth. It could just as easily be (and probably is, based on what we’ve seen of these kinds of planets from Kepler-11) a mini-Neptune.
I would imagine that a 2.2 Earth-radius ball of rock would require enough mass to raise it above that detection limit.
A Gas Giant (or in this case a “Hot Jupiter”) couldn’t exist at that size. The gravity would be too weak to hold onto all the gas.
If you’re talking about gravity, then you’re discussing mass. Even the 2.3 Earth-mass planet Kepler-11 f has a radius that requires it to have an extended gaseous envelope, essentially a mini-Neptune or a mini-Gas giant. Kepler-10 c has a mass less than 20 Earth-masses, so there is nothing that requires Kepler-10 c to be terrestrial.
Mass and radius can determine the type of body in question. The higher the mass and smaller the radius, the more likely it is terrestrial in nature. Imagine Venus with double the atmosphere.
Perhaps we could call it a Veneptune!
lol
The detection technique used by Kepler is only dependant on the radius of the planet, not the mass. If enough light from the star is blocked, the planet can be detected.
That being said, in many cases a heavier planet also have a larger radius, atleast if the density is the same. And thats how we can say that this is most certainly a rocky planet.
20Me / 2.2^3 = 1.88 times more dense than earth, or almost as dense on the average as lead. And with that closeness to the star, there is no room for any massive atmosphere.
The problem is that we don’t know the mass. All we know is that it is < 20 M_e.
"And with that closeness to the star, there is no room for any massive atmosphere."
You're no doubt aware of a large population of planets that have a massive atmosphere who are, in fact, much closer to their stars?
The problem is that we don’t know the mass. All we know is that it is < 20 M_e.
"And with that closeness to the star, there is no room for any massive atmosphere."
You're no doubt aware of a large population of planets that have a massive atmosphere who are, in fact, much closer to their stars?
Yes, you have a point. It might theoretically be a large sized low mass planet with lower than water density. Such a low mass swollen ‘hot neptune’ type of planet would however not be able to hang on to the atmosphere for any longer period of time. Short lived transitional planet ? Dont think so, perhaps not impossible, but hardly believable.
Indeed i am aware of such planets, and they are as you say ‘Massive’ and would fall into that 20Me category (or larger) and thus with that small radious would even more surely be rocky planets. The planets that you do mention are all about Jupiter massed swollen gasgiants with radious 2-3 Rjupiter, not 2.2Rearth
It is the small radius that surely detects it as a rocky planet.
You overestimate how much energy this planet gets. It’s genuinely not much, and no — I’m talking about planets that have massive envelopes that are *much* less than 20 Earth-masses. See the Kepler-11 system.
I’m taking this directly from the Kepler-10c paper.
“A massive 20 M_e core should have attained a H/He envelope, and it would appear to be stable at Kepler-10c’s relatively modest irradiation level, which would lead to a planetary radius dramatically larger than 2.3 R_e. This would tend to favour a scenario where Kepler-10 c is more akin to Gliese 1214 b and Kepler-11 b and Kepler 11f, which are all below 7 M_e, and enriched in volatiles.”
The problem is that we don’t know the mass. All we know is that it is < 20 M_e.
"And with that closeness to the star, there is no room for any massive atmosphere."
You're no doubt aware of a large population of planets that have a massive atmosphere who are, in fact, much closer to their stars?
I’m not sure what you want to argue here. We don’t “know” it is rocky, the press release describes it as “expected” and the article correctly refer to that as a description.
All of these things are a likelihood game, and the question to ask is not what the (known) likelihood is but how constrained it is. Sometimes the constraint puts at as solid as any other observation. The new validation process, which btw is awesome if they can pull it off on transit data alone, seems to belong to the later set.
Why look 560 light-years away? Why not 10 or 20? Surely there are candidate star systems closer for scrutiny. Or is it no easier to use the above techniques at 10 l.y that it is at 500 l.y?
Hey hack: It seems as though you may not be aware that Kepler’s view is fixed on a very small section of the sky. If there were a closer star within that field of view, then it would be a candidate.
Thanks. Next time I’ll post after I’ve woken up 🙂
You and me both, my friend.
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Can human live on that planet?
Also, given what we know about exoplanets so far, the planet probably doesn’t have a solid surface.
If you consider the density and the size together; it is safe to assume that the body is primarily rocky. Molten perhaps, but solid as the the first 4 terrestrial planets of our own system.
Problem is that we don’t know the density. All we know about the planet is its radius. For planets that have radii similar to it, from what we’ve observed so far, a gaseous envelope is present.
Problem is that we don’t know the density. All we know about the planet is its radius. For planets that have radii similar to it, from what we’ve observed so far, a gaseous envelope is present.
article says : ” located too close to their star for liquid water to exist”. So the answer is no.
As exciting as this news is I dont understand why we are concentrating on and stars more than 50 LY away. These are worlds we will never be able to visit anytime soon. Lets look at the closest star and keep going from there. I know that seems simple but its really the most realstic approach.