SCIENCE IN THE NEWS DAILY
Could a Super-Earth Plus Triple Stars Equal Life?
from Time
The search for exoplanets, or worlds orbiting other stars, is evolving so fast that discoveries that seemed exotic just a few months ago have become commonplace. Multiple-planet solar systems? Astronomers expected to find just a handful; now we know of more than 200. Planets orbiting double or even triple stars? It was big news when just one was announced back in September; we've already got several more examples in hand. In short, the unexpected is something planet hunters have learned to expect--and in most cases, these surprises have tended to expand the possibilities for finding worlds where life might thrive.
It's just happened again: Astronomers from the Carnegie Institution of Washington and the University of California, Santa Cruz, writing in the Astrophysical Journal Letters, have announced the discovery of yet another new world that defies everyone's expectations. Not only does the new planet orbit one of the suns in a triple-star system--rare enough in itself--but the stars in this system have surprisingly low levels of the heavy elements planets are made from. Theory suggests that such stars shouldn't form planets in the first place, so if this isn't a fluke, there may be many more planets in the Milky Way than anyone thought.
That's not all: The new planet, called GJ667Cc, is just 4.5 times Earth's mass. That's big enough to qualify it for the astronomical label "super-Earth" but still quite small by exoplanet standards. Indeed, it's so small that GJ667Cc is thought to be made of earthlike rock rather than gas--even if those rocks had to coalesce from a smaller supply of raw material circling the parent sun. Beyond that, it orbits in its star's habitable zone: If there's water there, that water could be in life-friendly liquid form.
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