Monday, February 6, 2012

GJ 667Cc: Heavier than Earth, Maybe About as Warm

"Newfound Alien Planet is Best Candidate Yet to Support Life, Scientists Say"
Denise Chow, Space.com (February 2, 2012)

"A potentially habitable alien planet - one that scientists say is the best candidate yet to harbor water, and possibly even life, on its surface - has been found around a nearby star.

"The planet is located in the habitable zone of its host star, which is a narrow circumstellar region where temperatures are neither too hot nor too cold for liquid water to exist on the planet's surface.

" 'It's the Holy Grail of exoplanet research to find a planet around a star orbiting at the right distance so it's not too close where it would lose all its water and boil away, and not too far where it would all freeze,' Steven Vogt, an astronomer at the University of California, Santa Cruz, told SPACE.com. 'It's right smack in the habitable zone - there's no question or discussion about it. It's not on the edge, it's right in there.'..."


(Carnegie Institution for Science, via Space.com, used w/o permission)

The planet's sun, GJ 667C, is so close that light only takes 22 years to make the trip to Earth's neighborhood. By galactic standards, GJ 667C is about as close as it gets. By comparison, the closest star, Proxima Centauri, is a little over four years away as the light beam travels.

Using technology we've got, or are developing, we could send a probe to GJ 667C that wouldn't take more than several centuries to get there. Getting funding for that sort of a project is another matter. Humanity doesn't often make plans that span centuries, and that's another topic.

Vogt? the Name Sounds Familiar

"...Vogt is one of the authors of the new study, which was led by Guillem Anglada-Escudé and Paul Butler of the Carnegie Institution for Science, a private, nonprofit research organization based in Washington, D.C...."

Steven Vogt's been in the news before, and the Lemming will get back to that.

Warm Enough, But - - -

"...'This planet is the new best candidate to support liquid water and, perhaps, life as we know it,' Anglada-Escudé said in a statement.
An alien super-Earth


"The researchers estimate that the planet, called GJ 667Cc, is at least 4.5 times as massive as Earth, which makes it a so-called super-Earth. It takes roughly 28 days to make one orbital lap around its parent star, which is located a mere 22 light-years away from Earth, in the constellation Scorpius (the Scorpion).

" 'This is basically our next-door neighbor,' Vogt said. 'It's very nearby. There are only about 100 stars closer to us than this one.'

"Interestingly enough, the host star, GJ 667C, is a member of a triple-star system. GJ 667C is an M-class dwarf star that is about a third of the mass of the sun, and while it is faint, it can be seen by ground-based telescopes, Vogt said. [Gallery: The Strangest Alien Planets]...

"...The discovery of a planet around GJ 667C came as a surprise to the astronomers, because the entire star system has a different chemical makeup than our sun. The system has much lower abundances of heavy elements (elements heavier than hydrogen and helium), such as iron, carbon and silicon.

" 'It's pretty deficient in metals,' Vogt said. 'These are the materials out of which planets form - the grains of stuff that coalesce to eventually make up planets - so we shouldn't have really expected this star to be a likely case for harboring planets.'

"The fortuitous discovery could mean that potentially habitable alien worlds could exist in a greater variety of environments than was previously thought possible, the researchers said...."

The GJ 667 star system being metal-deficient probably means that planets around GJ 667C will be, too: assuming that current ideas about how planets form are anywhere near accurate. What Vogt said about planets is a bit intriguing, because Jupiter is mostly hydrogen: gaseous, liquid, and metallic. There's helium, too, and almost certainly a rocky core. ("The Outer Planets: What Are They, and Where Are They?," Laboratory for Atmospheric and Space Physics, University of Colorado)

If GJ 677Cc is mostly hydrogen and helium, it could be a very interesting place. But as a place to live? Maybe not so much. Life, the sort we know about, needs hydrogen. But it also needs lots of other elements, too: and in fairly high concentrations. Which is why we're not looking for life on, or in, Jupiter. ("The Habitability of Jupiter," NASA Astrobiology Institute)

If GJ 677Cc has liquid water in large amounts, one of the big questions will be "how?" There's hydrogen in water, of which the GJ 677 system has copious supplies. Water also contains oxygen, an element that's a "metal" in this context: heavier than hydrogen or helium.

Still: an Earth-size (almost) planet; nearby (sort of); at just the right distance from its star? That's big news.

Steven Vogt: Planet Hunter

If the name Steve Vogt sounds familiar, you may have been following astronomy news. His name came up in 2010:That time, the subject was planets circling Gliese 581. Steve Vogt was excited about the data he'd collected. He'd also been, quite sensibly, sharing what he'd found with other scientists.

Then there was the fellow who said that he'd intercepted a signal from near Gliese 581: and that's another topic.
Related posts, at

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2 comments:

Brigid said...

Extra letter: "Still: and Earth-size (almost) planet"

The Friendly Neighborhood Proofreader

Brian Gill said...

Brigid,

Oops. My fingers got creative again. Thanks!

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