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02/20/2008
Bend Light - Detect Solar System
Last Saturday on the way to the hospital to pick up one of my
wife’s CTscans, I saw a flock of robins. It was only 20 degrees
Fahrenheit and snow and ice were still on the ground. I thought
to myself those robins are either stupid or know about global
warming. Sure enough, on Monday the temperature hit 65
degrees and our snow/ice-covered driveway is totally clear and
robins were flitting about in our neighborhood. However, today
the temps are in the 20s and 30s and a substantial wind makes it
feel like anything but spring. Nevertheless, I’m trusting that
those robins will bring warm weather back again soon.
Hopefully, when spring does arrive, my wife will also be able to
flit around a least a bit without her walker, which she’s currently
using following her fall and fractured vertebra.
After all the media articles last year on Einstein in
commemoration of the hundredth anniversary of his “miracle
year”, I thought he would disappear from the radar for some
time. I was surprised when the latest issue of Discover magazine
featured several articles on the man and his work. I haven’t had
time yet to read them but another article I spotted recently relates
to one of Einstein’s major triumphs, his prediction that light
bends in response to the gravitational pull of stars or other large
bodies.
A brief news item in the February 15 Star-Ledger reported on the
discovery of a planetary system that might possibly be a kind of
scaled down version of our own solar system. The star is only
about half the size of our Sun and astronomers have discovered
two gaseous planets orbiting it. The two planets are about 80
percent the size of Jupiter and Saturn. Brian Trumbore brought
me a more detailed article by Richard Macey on the discovery in
the February 15 Sydney Morning Herald. A visit to the Ohio
State University Web site’s Research News provided added
information. The work was published in last week’s February 15
issue of Science, which just arrived as I’m proof reading this
column. Actually, I find that the inner planet is about 71 percent
as massive as Jupiter and the outer planet is 90 percent as
massive as Saturn (average 80 percent).
Two of the 70 or so astronomers involved in the discovery are
Scott Gaudi of Ohio State University and John Greenhill of the
University of Tasmania. The study involved 11 ground-based
telescopes in Tasmania and other spots such as New Zealand,
Chile, the U.S., Israel and the Canary Islands. Einstein comes
into play because this new solar system was discovered by the
technique of “gravitational microlensing”. Only four of the more
than 250 planets outside our solar system have been discovered
using microlensing. On March 28, 2006, the star in question
(5,000 light-years from earth) was discovered to passing between
us and another star in our Milky Way galaxy some 25,000 light-
years away. As Einstein predicted, the light from the more
distant star was bent as it passed around the intervening star,
which in essence behaves like a magnifying glass.
Greenhill says the effect is like a magnifying glass passing in
front of a candle. If the magnifying glass has a couple of water
spots on it, you’ll see a “glistening”. In this case, those spots are
the planets orbiting the lens, the star. Gaudi, the lead author on
the paper, was analyzing the data as it came in from all the
telescopes and saw a blip in the data that he thought heralded a
planet the size of Saturn. Less than a day later, another blip
appeared that told him there was a second planet about the size
of Jupiter orbiting our star. It took him several months of
analysis to really nail down the conclusion that these were indeed
two planets, the first time two planets were revealed by
microlensing. After that, David Bennett at Notre Dame refined
Gaudi’s calculations with more sophisticated software and
pinned down more details about the new planetary system.
This discovery of a sort of scaled down version of our own solar
system is really neat. When the researchers take into account the
size of the star and the distances of the two planets from the star,
the amount of sunlight reaching the planets is comparable to the
sunlight from our Sun reaching Jupiter and Saturn. The
calculated equilibrium temperatures on the two planets are only
about 30 percent lower than on Jupiter and Saturn.
Unfortunately, if there are any scaled down Earths in this system
we’ll not likely find them. By the time we have more powerful
telescopes on the ground and/or in space the new little solar
system would have to pass between us and another distant star, a
rather improbable event.
Finally, I must admit that I have a problem with the term
“microlensing”. It seems to me that, if anything should be called
“macrolensing” this is it. After all, the “lens” is a star! When
my care giving duties diminish, I’ll have to look into this more
closely.
Allen F. Bortrum
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