More
Stars, Big and Small, for the Holidays
by Dr.
Robert Piccioni
Dec 16, 2011
Just in time for
the holiday season, astronomers have announced the discovery of new
stars—trillions of little red elves and one giant Santa.
The new Santa is over 250 times more massive than our Sun, and ten
million times brighter. R136a1 lies in the Large Magellanic Cloud, a
satellite galaxy of our Milky Way, and has over twice the mass of the
prior record holder. Unlike humans, stars are born heavy, this one at
over 300 solar masses, progressively shed weight throughout their
lives. The real heavyweights die in spectacular explosions called
supernovae. In the illustration below from the European Space Agency,
the yellow star represents our Sun and R136a1 is the mammoth blue star.
That’s one super-sized HO, HO, HO.
At the opposite end of the stellar spectrum are red dwarfs; one is
illustrated above. Red dwarfs are just barely massive enough to sustain
nature’s ultimate fire—nuclear fusion, the process that powers all
stars. These stars often have only one-tenth of our Sun’s mass and emit
thousands of times less energy. Because they are so dim, counting them
is a real challenge. New results from Yale indicate that red dwarfs are
far more common in elliptical galaxies than in spiral galaxies like
ours—perhaps 30 times more common. This means prior estimates, which
were based on the numbers seen in the Milky Way, were far too low.
While these data are not yet confirmed, adding so many more red dwarfs
would triple the total number of stars in the observable universe (to
30,000 billion, billion). The number of stars “dwarfs” the number of
grains of sand on all the beaches on Earth (“only” 10 billion, billion).
Some astrobiologists believe the vast number of red dwarf stars may
harbor a vast number of habitable planets. In fact, the exoplanet (a
planet outside our solar system) that seems most likely to be habitable
orbits the red dwarf star Gilese 581, 20 light-years from Earth.
Exoplanet “g” is in the habitable zone (where water can be liquid) and
has a nearly circular orbit; it’s “year” is 37 of our days, and it
orbits 7 times closer to its star than does Earth. At that close range,
“g” is likely to be tidally locked, meaning that one side of the planet
always faces its star while the other side is in perpetual darkness
(our Moon is tidally locked relative to Earth). This may result in one
side of the planet being too hot for life while the other is too cold,
although there may be a sweet spot in the Twilight Zone. Red dwarfs
also have occasional dramatic changes in energy output, further
challenging nearby life.
Much to ponder as we anticipate more exciting discoveries in 2011.
With all the new
stars to add to your holiday cheer,
we
wish you the very best for a great New Year!
Best Regards,
Robert
Dr Robert Piccioni,
Author of "Everyone's
Guide to Atoms, Einstein, and the Universe"
and "Can Life Be Merely An Accident?"
www.guidetothecosmos.com
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