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Astronomers Find a New Type of Planet: The "Mega-Earth"

posted by martyb on Tuesday June 03 2014, @08:37AM   
from the Super-Mega-Ultra dept.

Bytram writes:

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)

• Conditions on the surface Conditions on the surface (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..?

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• Elcor (Score: 0) by Anonymous Coward on Tuesday June 03 2014, @08:43PM

  by Anonymous Coward on Tuesday June 03 2014, @08:43PM (#50774)

  It's just the Elcor Homeworld!

  http://masseffect.wikia.com/wiki/Elcor [wikia.com]

  Parent