Watery "Super Earth" spotted 40 light years from us

[Niels Bohr 72]

The latest exoplanet find is hot and heavy, but probably has liquid water, and resides close enough to Earth that we're likely to be able to characterize its atmosphere using existing observatories.

By John Timmer | Last updated December 16, 2009 7:22 PM

Our collection of exoplanets continues to expand and, in recent years, some dedicated hardware like CoRoT and Kepler have joined the search in space. But the latest discovery comes from some pretty mundane hardware—a collection of 40cm telescopes—and has some very compelling properties: a super earth that's likely to harbor liquid water, and orbits a star that's close enough to allow current observatories to image its atmosphere.

The results come courtesy of the MEarth project (a description is available via the arXiv), which is based on Mount Hopkins in Arizona. Instead of exotic, high-end optics, MEarth relies on eight 0.4m telescopes that can be pointed independently. The project works because the hardware is pointed at a very carefully chosen collection of stars: about 2,000 nearby M-dwarfs, which, as the name implies, are relatively small stars. That means that even a moderate-sized planet orbiting one will occlude a significant fraction of its surface during transit. The MEarth scopes are able to spot anything that blocks more than a half of a percent of the light as it transits in front of its host star.

Based on the first paper to come out of the project, everything worked precisely as planned. Every 1.58 days, the light from the M-dwarf GJ 1214 displayed a dip in its luminosity of about 1.3 percent. The team apparently alerted the HARPS project, which detects exoplanets by looking for red and blue shifts that their gravitational pull creates in the light from their host stars.

The HARPS instrument was able to confirm the presence of a planet and, based on how it tugged the host star around, estimated its mass: 6.55 times that of the Earth. We've also got a good sense of the radius of GJ 1214, which allows us to estimate the planet's radius, based on how much of the star's light it's occluding. Combine that radius (2.7 Earth radii) with the mass, and you have a rough estimate of the planet's density. It turns out to be less than half as dense as Earth.

There are a number of ways this could come about, but the two most likely ones are a rocky core surrounded by hydrogen gas, or planet with roughly equal amounts of rocky material and water. The scientists involved lean heavily towards the latter explanation, since it's highly unlikely that there would be much free hydrogen floating around the inner part of a planetary disk that's rich enough in iron and rocky material to produce a solid core. So, the conclusion is that GJ 1214b probably has a thin shell of hydrogen and helium for an atmosphere, and then a massive ocean above a silicate and iron core.

Depending on how reflective the planet's atmosphere is, it may have temperatures as high as 555K, or as low as 393K—the latter figure is only 20°C; above the boiling point of water. That's far and away the coolest planet we've yet spotted, and a far cry from the only other super earth we know much about, which is hot enough that its atmosphere probably contains vaporized titanium oxides. Given the gravitational differences with Earth, which will cause pressure to build up rapidly, and it's apparent that at least some of the water will almost certainly be liquid.

Because of the proximity of GJ 1214b to its host star, some of this ocean will almost certainly boil into the atmosphere (which an accompanying perspective compares to a sauna), where it will be split by UV radiation into hydrogen and oxygen. The calculated radius of the planet is a bit thicker than the one predicted by planetary models, which provides a further indication that an atmosphere is present. The planet is hot enough, however, that some fraction of those gasses will inevitably escape its pull. All indications are that the host star is old, though, so it appears that GJ 1214b is at a stable, or at least long-lived, point in its evolution.

Assuming that the planet has an atmosphere dominated by hydrogen, the authors calculate that 0.16 percent of the light from GJ 1214 will pass through the atmosphere during transit events. As such, GJ 1214b may provide one of the best opportunities we have to study the contents of an exoplanet's atmosphere in the near future.

Nature, 2009. DOI: 10.1038/nature08679

[alienlovechild 75]

I'm waiting for the day when there's a planet found that is very likely to have life on it. Even if we can't get there for a long time it's nice to speculate about the new world.

[scandal 951]

Very cool stuff.

The OP article didn't mention how close this system is to our own solar system, only that it was "nearby".

Here's a Scientific American article about this system - GJ 1214. It's about 42 light years from us - astonishingly close by!

http://www.scientificamerican.com/article....arth-exoplanets

At a distance of 42 light years, one could conceivably monitor for SETI transmissions from that specific direction, and even aim a transmission that way in the hope of a 'hit'. A signal turnaround time could be in the vicinity of an Earth century, allowing time for an inbound signal to be detected and technology constructed to return the message.

As to the likelihood of life, if the lower bound of the temperature range is accurate (393K, or 120C), it's quite possible to have organic life. Earth certainly has life with far more extreme temperature/pressure conditions in the deep sea vents.

[HAL 9000 96]

42 light years? That's almost 13 parsecs. Even though Han Solo was wrong to use a unit of distance in place of speed, all we'd need is the Millenium Falcon and getting there would be almost like doing the Kessel Run.

[NickD 202]

42 light years? That's almost 13 parsecs. Even though Han Solo was wrong to use a unit of distance in place of speed, all we'd need is the Millenium Falcon and getting there would be almost like doing the Kessel Run.

That trip to our potentially nearest habitable planet is beginning to sound easier than renting a car in Bogota and driving to Caracas. Sorry for injecting earthly type problems.

[HAL 9000 96]

42 light years? That's almost 13 parsecs. Even though Han Solo was wrong to use a unit of distance in place of speed, all we'd need is the Millenium Falcon and getting there would be almost like doing the Kessel Run.

That trip to our potentially nearest habitable planet is beginning to sound easier than renting a car in Bogota and driving to Caracas. Sorry for injecting earthly type problems.

Earthly indeed. Why on Earth you'd want to drive that route, however... would make the monopolized airfare seem like a cakewalk.

[NickD 202]

42 light years? That's almost 13 parsecs. Even though Han Solo was wrong to use a unit of distance in place of speed, all we'd need is the Millenium Falcon and getting there would be almost like doing the Kessel Run.

That trip to our potentially nearest habitable planet is beginning to sound easier than renting a car in Bogota and driving to Caracas. Sorry for injecting earthly type problems.

Earthly indeed. Why on Earth you'd want to drive that route, however... would make the monopolized airfare seem like a cakewalk.

Was just curious, would take about 33 hours of constant driving with some possible interference from guerrillas and could run into a landslide. Does sound cool and adventuresome, but wife said no way. Also asked about visiting my brother-in-law's farm, gather it's about 300 Km north of Bogota, but her sister said I may be uncomfortable with the mosquitoes. Not sure about malaria in that next of the woods, but we sure have mosquitoes in Canada north of us, and zillions of them, night or day.

[HAL 9000 96]

42 light years? That's almost 13 parsecs. Even though Han Solo was wrong to use a unit of distance in place of speed, all we'd need is the Millenium Falcon and getting there would be almost like doing the Kessel Run.

That trip to our potentially nearest habitable planet is beginning to sound easier than renting a car in Bogota and driving to Caracas. Sorry for injecting earthly type problems.

Earthly indeed. Why on Earth you'd want to drive that route, however... would make the monopolized airfare seem like a cakewalk.

Was just curious, would take about 33 hours of constant driving with some possible interference from guerrillas and could run into a landslide. Does sound cool and adventuresome, but wife said no way. Also asked about visiting my brother-in-law's farm, gather it's about 300 Km north of Bogota, but her sister said I may be uncomfortable with the mosquitoes. Not sure about malaria in that next of the woods, but we sure have mosquitoes in Canada north of us, and zillions of them, night or day.

Well not until you go into the state of Norte de Santander (on the border) would you have to particularly worry about any armed men stopping you. The other kind of robbery you have to watch out for are the ridiculously expensive tolls for such horrible roadways.

[Hilarious Clinton 452]

I'm waiting for the day when there's a planet found that is very likely to have life on it. Even if we can't get there for a long time it's nice to speculate about the new world.

word

[Marina-Del 10]

But from the article it does sound possible that life is on this planet. Just not life exactly like we have here....

[HAL 9000 96]

But from the article it does sound possible that life is on this planet. Just not life exactly like we have here....

Like in AVATAR maybe??

[Niels Bohr 72]

Dam. I want to see that movie!

[zqt3344 21]

Are there any hot men on it?

The latest exoplanet find is hot and heavy, but probably has liquid water, and resides close enough to Earth that we're likely to be able to characterize its atmosphere using existing observatories.

By John Timmer | Last updated December 16, 2009 7:22 PM

Our collection of exoplanets continues to expand and, in recent years, some dedicated hardware like CoRoT and Kepler have joined the search in space. But the latest discovery comes from some pretty mundane hardware—a collection of 40cm telescopes—and has some very compelling properties: a super earth that's likely to harbor liquid water, and orbits a star that's close enough to allow current observatories to image its atmosphere.

The results come courtesy of the MEarth project (a description is available via the arXiv), which is based on Mount Hopkins in Arizona. Instead of exotic, high-end optics, MEarth relies on eight 0.4m telescopes that can be pointed independently. The project works because the hardware is pointed at a very carefully chosen collection of stars: about 2,000 nearby M-dwarfs, which, as the name implies, are relatively small stars. That means that even a moderate-sized planet orbiting one will occlude a significant fraction of its surface during transit. The MEarth scopes are able to spot anything that blocks more than a half of a percent of the light as it transits in front of its host star.

Based on the first paper to come out of the project, everything worked precisely as planned. Every 1.58 days, the light from the M-dwarf GJ 1214 displayed a dip in its luminosity of about 1.3 percent. The team apparently alerted the HARPS project, which detects exoplanets by looking for red and blue shifts that their gravitational pull creates in the light from their host stars.

The HARPS instrument was able to confirm the presence of a planet and, based on how it tugged the host star around, estimated its mass: 6.55 times that of the Earth. We've also got a good sense of the radius of GJ 1214, which allows us to estimate the planet's radius, based on how much of the star's light it's occluding. Combine that radius (2.7 Earth radii) with the mass, and you have a rough estimate of the planet's density. It turns out to be less than half as dense as Earth.

There are a number of ways this could come about, but the two most likely ones are a rocky core surrounded by hydrogen gas, or planet with roughly equal amounts of rocky material and water. The scientists involved lean heavily towards the latter explanation, since it's highly unlikely that there would be much free hydrogen floating around the inner part of a planetary disk that's rich enough in iron and rocky material to produce a solid core. So, the conclusion is that GJ 1214b probably has a thin shell of hydrogen and helium for an atmosphere, and then a massive ocean above a silicate and iron core.

Depending on how reflective the planet's atmosphere is, it may have temperatures as high as 555K, or as low as 393K—the latter figure is only 20°C; above the boiling point of water. That's far and away the coolest planet we've yet spotted, and a far cry from the only other super earth we know much about, which is hot enough that its atmosphere probably contains vaporized titanium oxides. Given the gravitational differences with Earth, which will cause pressure to build up rapidly, and it's apparent that at least some of the water will almost certainly be liquid.

Because of the proximity of GJ 1214b to its host star, some of this ocean will almost certainly boil into the atmosphere (which an accompanying perspective compares to a sauna), where it will be split by UV radiation into hydrogen and oxygen. The calculated radius of the planet is a bit thicker than the one predicted by planetary models, which provides a further indication that an atmosphere is present. The planet is hot enough, however, that some fraction of those gasses will inevitably escape its pull. All indications are that the host star is old, though, so it appears that GJ 1214b is at a stable, or at least long-lived, point in its evolution.

Assuming that the planet has an atmosphere dominated by hydrogen, the authors calculate that 0.16 percent of the light from GJ 1214 will pass through the atmosphere during transit events. As such, GJ 1214b may provide one of the best opportunities we have to study the contents of an exoplanet's atmosphere in the near future.

Nature, 2009. DOI: 10.1038/nature08679

[Niels Bohr 72]

Are there any hot men on it?

[zqt3344 21]

Seriously.........

Are there any hot men on it?