[meteorite-list] OT: New Smallest, Possibly Earth-like, Extra-Solar Planet Announced

[Sterling K. Webb]

Hi, All,

    The "Marcy Team," with 106 detections of extra-solar planets to its
credit, announced today number 107, the discovery of the smallest yet
detected (by about half the previous detection),  It's only 7.5 (+/-
1.5) Earth masses.  It orbits Gliese 876, an M-class dwarf about
one-third the mass of our Sun and only 15 light years away.  We're
practically neighbors...

    The planet is close enough to its star to be pretty warm (200 to 400
degrees C).  In theory, it could be a hot mini-Uranus, but Marcy seems
to think it's a rocky terrestrial world since it would be hard to hang
onto all that gas at 200 degrees C or more.  If confirmed, it would be
the first detection of an Earth-like world outside the Solar System.

    Gliese 876 had already been discovered to have, not one, but two
Super Jupiters orbiting further out than the new discovery.  If the new
planet is a rocky terrestrial world, it seems to me to be more likely to
be a "Super Venus" than a "Super Earth"!

    The kind of star these planets orbit, M-class, are the most abundant
class of stars, far more numerous than the larger K-class and the even
larger G-class (that's us!).  M class stars are all over the place.  We
have more M class neighboring stars (within 10-20 light years) than all
the other kinds put together.  If M class stars can have terrestrial
planets close enough to be warm, then we may be sailing along in a cloud
of Earths!

    Here's the National Science Foundation press release:
<http://www.nsf.gov/news/news_summ.jsp?cntn_id=104243&org=NSF&from=news>

    And a somewhat less technical one:
<http://skyandtelescope.com/news/article_1530_1.asp>


Sterling K. Webb