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!
Regards,
Robert
www.guidetothecosmos.com
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