Monday, May 2, 2011

55 Cancri e - A Fairly Dense, Fairly Big, Very Intriguing, Exoplanet

"Alien Planet Nearly Dense as Lead" (May 2, 2011)

"Astronomers have pinned down some details of an exotic nearby alien planet that's almost as dense as lead.

"The exoplanet, called 55 Cancri e, is 60 percent larger in diameter than Earth but eight times as massive, researchers revealed Friday (April 29). That makes the alien world the densest solid planet known -- twice as dense as Earth. [Gallery: The Strangest Alien Planets]...

"...The super-dense alien world is part of a multiplanet solar system about 40 light-years from Earth, in the constellation Cancer (The Crab). Its sunlike parent star, 55 Cancri, is bright enough to be seen from Earth by the unaided eye, researchers said.

"Since 1997, astronomers have discovered five planets circling 55 Cancri (including 55 Canrci e in 2004). All five alien worlds were detected using the so-called radial velocity -- or Doppler -- method, which looks for tiny wobbles in a star's movement caused by the gravitational tugs of orbiting planets. [A Field Guide to Alien Planets]...

"...'It's wonderful to be able to point to a naked-eye star and know the mass and radius of one of its planets, especially a distinctive one like this,' said study lead author Josh Winn of MIT....

"...'Because of the infernal heat, it's unlikely that 55 Cancri e has an atmosphere,' Winn said. 'So this is not the type of place where exobiologists would look for life.'...

"...But the appeal of 55 Cancri e is not limited to such gee-whiz factoids. Because it's so close to Earth, the planet and its solar system should inspire all sorts of future work, researchers said...."

What's puzzling - and fascinating - for the Lemming about 55 Cancri is its comparatively mild strangeness. It's not all that much bigger in diameter than Earth - 60 percent, the article said - and not all that much more massive - eight times Earth's. That's about as dense as several sorts of ordinary matter - not the ultra-condensed stuff that collapsed stars are made of.

And - 55 Cancri is not like anything we've got in the Solar system. Not quite, anyway.

The Lemming's guess is that it'll be hard to get direct observations of what 55 Cancri is made of - that far away, it's hard to imagine a telescope getting reflection spectra from the planet's surface. (Although 'about 40 light years' is practically next door, on a galactic scale: it's still a respectable distance.)

There may be other ways to work out what the oddly-dense planet is made of. The Lemming hopes so.

Re-Thinking 'Class M Planets' - Again

Never mind the heat (up to 4,892 degrees Fahrenheit (2,700 degrees Celsius), the article says). A person standing on 55 Cancri would be held in place three times as powerfully as what we experience here on Earth.

That, in the Lemming's opinion, would be more than just uncomfortable for human beings: Arch supports alone won't help.

But it's the heat, not the gravity, that makes 55 Cancri an unlikely place to find life. Which brings the Lemming to another article:

"Alien Bacteria Could Breed in Extreme 'Hypergravity'"
Mike Wall, Space.come (April 25, 2011)

"If alien life is out there, it may be able to exploit more-extreme environments than scientists think, because huge gravitational forces don't seem to pose much of a problem for microbes.

"Several different species of bacteria can survive and reproduce in 'hypergravity' more than 400,000 times stronger than that of the Earth, a new study reports. The find suggests that alien life could take root in a wide range of conditions -- and that it could survive the high G-forces imposed by meteorite impacts and ejections, making the exchange of life between planets a distinct possibility...."

And widens the range of places to look for life in the universe. Considerably. In terms of temperature and surface gravity - some 'brown dwarfs,' objects smaller than stars but bigger than planets (for the most part), that are merely warm, might be home to critters like those hypergravity-resistant microbes.

And that's another topic.

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