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posted by martyb on Tuesday June 03 2014, @08:37AM   Printer-friendly [Skip to comment(s)]
from the Super-Mega-Ultra dept.

ScienceDaily reports that Astronomers find a new type of planet: The "mega-Earth":

Astronomers announced on June 2nd that they have discovered a new type of planet a rocky world weighing 17 times as much as Earth. Theorists believed such a world couldn't form because anything so hefty would grab hydrogen gas as it grew and become a Jupiter-like gas giant. This planet, though, is all solids and much bigger than previously-discovered "super-Earths," making it a "mega-Earth."

The planet, Kepler-10c, orbits its host star every forty-five days at a quarter of the average distance between the Sun and Earth. It has a radius more than double that of Earth, but a higher density, making it the largest and most massive rocky planet discovered as of June 2014.

The story notes another aspect of Kepler-10c that complicates our understanding of planet formation:

The discovery that Kepler-10c is a mega-Earth also has profound implications for the history of the universe and the possibility of life. The Kepler-10 system is about 11 billion years old, which means it formed less than 3 billion years after the Big Bang.

The early universe contained only hydrogen and helium. Heavier elements needed to make rocky planets, like silicon and iron, had to be created in the first generations of stars. When those stars exploded, they scattered these crucial ingredients through space, which then could be incorporated into later generations of stars and planets.

This process should have taken billions of years. However, Kepler-10c shows that the universe was able to form such huge rocks even during the time when heavy elements were scarce.

So the question becomes how such a planet could have accumulated so much rocky material when so little was generally available at the time without also accumulating a large amount of gas and becoming a gas giant like Neptune and Jupiter.

See also: The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet [abstract] and full article (pdf)

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  • (Score: 1, Redundant) by crutchy on Tuesday June 03 2014, @08:48AM

    by crutchy (179) on Tuesday June 03 2014, @08:48AM (#50563) Homepage Journal

    ...goes with red mega planet, and yellow mega planet, to make the ultra mega mega planet. you have to have all three or it doesn't work, see"

  • (Score: 4, Interesting) by AnonTechie on Tuesday June 03 2014, @09:35AM

    by AnonTechie (2275) on Tuesday June 03 2014, @09:35AM (#50576) Journal

    What qualifies this planet as Mega-Earth ?? It does not have liquid water, it is too hot, it orbits too close to it's star, the planet is much larger than earth ...

    --
    Albert Einstein - "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
    • (Score: 5, Informative) by GreatAuntAnesthesia on Tuesday June 03 2014, @11:18AM

      by GreatAuntAnesthesia (3275) on Tuesday June 03 2014, @11:18AM (#50589) Journal

      It's rocky, as opposed to gassy or icy. As far as most exo-planet hunters and/ or attendant journalists are concerned, that seems to be enough to describe a world as "Earth-like".

    • (Score: 2, Informative) by laserfusion on Tuesday June 03 2014, @03:02PM

      by laserfusion (1450) on Tuesday June 03 2014, @03:02PM (#50652)

      Liquid water might exist on the surface. At 485 K surface temperature, it needs only a little higher atmospheric pressure than Earth to have liquid water. With 3x the surface gravity this is easily possible.

      But it might not be habitable for humans without protection.

  • (Score: 2, Interesting) by GreatAuntAnesthesia on Tuesday June 03 2014, @12:02PM

    by GreatAuntAnesthesia (3275) on Tuesday June 03 2014, @12:02PM (#50601) Journal
    So suppose we an FTL drive and could go visit this place. What would it be like? This world is very very hot, too hot for any interesting chemistry (ie life) to be going on. However, even if we imagine it cooled down (maybe shaded by a massive orbital solar collector) then it would still be a very inhospitable place to humans. With over 3 times Earth's surface gravity it would be near impossible to stand up or move about unassisted. You'd be more comfortable underwater, so you'd probably want to visit wearing a fluid-filled liquid-breathing [wikipedia.org] environment suit/ craft. The landscape would seem very flat compared to Earth, because the high gravity would mean that hills and mountains would have to have shallow slopes. It would be interesting to see if any complex life at all could survive there. Single-celled organisms probably wouldn't be too worried about the gravity. Most earth plants would have trouble surviving, because it would be hard work staying upright and pumping water up against that gravity. Moss and lichen would be your best contenders, and of course subaquatic plants. Anything from the animal kingdom would have to be either aquatic or very short, with a strong, dense skeleton / exoskeleton and a very well adapted respiratory system (regular earth-lungs aren't going to work very well). Some arthropods or molluscs might be OK, being close to the ground, with a high strength/mass ratio and able to breathe through their skins/ shells. Lobsters would probably be best, being both arthropods and aquatic. They aren't too fussy about what they eat either, which would be a bonus in an environment so hostile to your potential food sources. Makes me think of the game "Elite", where many planets were inhabited by various types of intelligent lobster. Maybe they were high gravity planets..?
  • (Score: 2) by M. Baranczak on Tuesday June 03 2014, @02:36PM

    by M. Baranczak (1673) on Tuesday June 03 2014, @02:36PM (#50643)

    They're looking at a tiny dot on the screen, and making calculations based on tiny variations in the dot's position and brightness. They can't even see the planet directly. Whenever we see these articles, they report a single number for the planet's size, as if they can determine it exactly. Seems to me that there should be a pretty wide margin of error.

  • (Score: 2, Interesting) by Yog-Yogguth on Tuesday June 03 2014, @03:41PM

    by Yog-Yogguth (1862) Subscriber Badge on Tuesday June 03 2014, @03:41PM (#50662) Journal

    Maybe it's hollow?

    *runs away*

    --
    Bite harder Ouroboros, bite! tails.boum.org/ linux USB CD secure desktop IRC *crypt tor (not endorsements (XKeyScore))
  • (Score: 1) by ScriptCat on Tuesday June 03 2014, @08:46PM

    by ScriptCat (4389) on Tuesday June 03 2014, @08:46PM (#50776)

    Can the humans survive on a planet with 3g of gravity?