Death Cry of Matter, Unexplained Gravity, and New Bunny :o]
Black Hole Caught Eating Matter
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For the first time ever, astrophysicists may have captured the dying
wail of material tumbling at more than 6 million miles per hour into the
maul of a galaxy-eating black hole.
"This is the first indication that we have of matter actually falling
into a black hole," says Richard Mushotzky, one of the researchers
involved in the discovery at NASA's Goddard Space Flight Center in
Maryland.
Their findings will be published in the upcoming issue of Astrophysical
Journal Letters.
Previously, scientists had detected X-ray signals from heated material
spiraling around several black holes, but they hadn't managed to catch
the X-ray scream of material closer in -- actually free-falling out of
our universe.
To catch the death cry, the researchers used the Japanese/U.S. Advanced
Satellite for Cosmology and Astrophysics to stare an unprecedented five
hours at the black hole at the center of galaxy NGC-3516, says
Mushotzky.
Their patience won them a subtle and unique X-ray signal from
superheated iron atoms the moment before they disappeared into the
mysterious interior of the black hole.
"We think our data is the first that can be interpreted this way," says
Mushotzky.
As material is gathered by a black hole's intense gravity, it forms a
spiraling disk about the black hole's "equator." The material in such an
"accretion" disks can whirl around at speeds of up to one third of the
speed of light, says University of Pennsylvania astrophysicist Neil
Brandt.
That sort of speed warms up things beyond "red" or "white" hot -- all
the way to X-ray hot. Astronomers find black holes by searching the
heavens for this X-ray "shine" of accretion disks.
The new X-ray signature appears to come from two to three times nearer
the "surface" of the black hole than ever before detected, Brandt says.
It's possibly right from the edge of oblivion.
"Once you go past that edge," says Brandt, "that's the end."
There's no telling for sure what happens next, Brandt says. Nothing
escapes a black hole, including clues to their workings.
A much better look at the edge of black holes ought to come sometime
next year after the launching of new U.S., European and Japanese X-ray
observing satellites equipped for this kind of research, Brandt says.
By Larry O'Hanlon, Discovery News Brief
Eclipse Experiment Shows Results
================================
During the solar eclipse Aug. 11, researchers at 20 universities in
Europe and the United States participated in a NASA experiment designed
to confirm 45-year-old data suggesting that slight, unexplained gravity
shifts occur during the celestial phenomenon.
"The early results are intriguing," says David Noever, a researcher at
NASA's Marshall Space Flight Science Center who came up with the plan to
gather simultaneous data from around the world.
"But we have huge reams of data that will take several weeks sort out,"
he adds.
In 1954 and 1959, a French physicist and Nobel laureate named Maurice
Allais claimed to have detected tiny changes in Earth's gravity during a
total solar eclipse.
Noever says that the idea that gravity would change during a total
eclipse, but not during a new moon, when the Earth is in almost the same
alignment with the moon and sun, seemed "nonsensical" to physicists.
Many dismissed Allais' claims when they were published in 1959, although
three subsequent measurements in the 1970s and '80s seemed to confirm
eclipse-associated anomalies, according to Noever.
Allais made his observations using a Foucault pendulum. The device
demonstrates the rotation of the Earth by tracing a progressive series
of geometric curves as it swings in a circular path -- something like
the patterns made by a Spirograph.
In the Aug. 11 experiment, observers combined Foucault pendulums with
much more sensitive devices called "superconducting gravimeters" to
simultaneously measure gravity both inside and outside the path of the
eclipse.
"In addition to encouraging measurements within the totality, we had
very interesting readings from gravimeters located on the opposite side
of the planet," says Noever.
He declined to describe the results specifically until they can be
verified and submitted to a peer-reviewed scientific journal -- which he
says the team plans to do "within the next few weeks."
Allais, 88, is understandably excited about the first attempt to verify
his claims using simultaneous global measurements.
"He FedExed us a 750-page manuscript of his explanation of the
phenomenon and invited us to Paris to discuss the results," says Noever.
"Given the sensitivity of their measuring apparatus and the fact that
the observations were coordinated with so many other teams, if they say
they've measured an effect it is probably really there," says Jules
Mollere, a physicist at Henderson State University. "The hard part will
be coming up with a good mechanism to explain it."
By Michael Ray Taylor, Discovery News Brief
New Rabbit Discovered
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A new species of rabbit with distinctive stripes, a red behind and short
ears has been discovered by a British biologist in a meat market in the
Annamite Mountains of Laos and Vietnam.
The banded bunny was unknown to science until Rob Timmins of Cambridge
University spotted it.
Timmins, Alison Surridge and colleagues at the University of East Anglia
report the identification of the rabbit in the current issue of Nature.
Scientists have never encountered the rabbit alive, but one was caught
on film by a camera rigged to photograph passing animals in a nature
reserve across the border in Vietnam in 1998. "It seems to be very shy,
very elusive,"' Timmins says. It is not known how many rabbits there
are.
Distant relatives of the striped lagomorph include the European rabbit
of "Watership Down" fame, mountain hares and the mouse hare, or pika.
Its closest cousin is a critically endangered species living on the
island of Sumatra, 1000 miles south. Only one Sumatran rabbit has been
seen since 1916, although a few stuffed specimens reside in museums.
The Cambridge team analyzed the lagomorph's DNA and found that although
the two rabbits look similar, their DNA does not match exactly. By
working backwards on one gene, they unearthed a possible common ancestor
that lived eight million years ago.
"Since that time the sea level between Sumatra and the mainland have
fluctuated and the forest habitat expanded and contracted," explains
Surridge. "Eventually the two isolated species we see, or rather don't
see, today evolved."
"The discovery underscores the region's significance as a preserve of
biodiversity that may date back millions of years," says Mary Dawson of
the Carnegie Museum of Natural History. "It's a sad commentary that it
was found in a meat market."
Four other large mammals have been discovered in Vietnam and the
surrounding countries in the last decade as biologists have started
exploring a little-studied area.
Says Dawson, "Perhaps this discovery can be used as a strong incentive
to protect this rapidly disappearing ecosystem before something as
wonderful as a colorful, striped rabbit is doomed to extinction at the
hands of market hunters."
By David Bradley, Discovery News Brief
Copyright 1999 Discovery Communications Inc. |
