A group of Australian astronomers have found that some black
holes are bright pink!
Black holes have captured the imagination of the public over the years
with some popular depictions in science fiction movies. They have such
intense gravity fields that they even suck in light. This is why they appear
black but Dr Paul Francis, a lecturer at the Australian National University,
together with Dr Rachel Webster and Dr Michael Drinkwater, from the
University of Melbourne's School of Physics have discovered that some
black holes are pink in colour.
The "Pink holes" were discovered using telescopes at Parkes and
Coonabarabran in the western plains of NSW between 1994 and 1998.
The work will be presented at the "Fresh Science" Conference in
Melbourne.
"These pink things were quite easy to find" said Dr Francis. "The hard
bit was proving that they are black holes. These black holes are more
than a billion light-years away, and are more than one hundred thousand
times fainter than the human eye can see. It took the combined power of four of Australia's best telescopes to identify what they were."
How could a black hole be pink? "We really don't have the foggiest idea"
said Dr Francis. "We're pretty certain that it isn't the black holes
themselves that are pink, the pink light is actually coming from gas just
outside the black hole. We think that these black holes live in the middle
of galaxies, and they are devouring anything that comes near them.
Possibly as the mangled remains of space matter, stars and gas clouds
swirl down the throat of the black holes, they emit an intense pink light."
It is well known that massive black holes devour stars and gas. Black
holes like this are called quasars, and were first discovered in the
1960s."Until now", Dr Francis said, "only blue quasars had been seen,
and it was believed that the debris swirling around black holes should
emit only blue light, not pink."
So what is different about these pink quasars? "We're don't really know"
said Dr Francis. "But we are beginning to suspect that the debris swirling
around the black holes is acting as a vast natural radio transmitter,
broadcasting intense pink light to the universe."
For further information contact Niall Byrne, Media Liaison, at
ScienceNOW! In Melbourne on 0417 131 977, email niall@byc.com.au,
or Dr Paul Francis, (02) 6249-2824 (w), (02) 6257-9263 (h) Photos and
background information will be available on the website from the day
of presentation on www.asnevents.net.au/sciencenow
Senin, 15 Juni 2009
Lunar Data Supports Idea That Collision Split Earth, Moon 21.14
Analysis of data from NASA's Lunar Prospector spacecraft has
confirmed that the Moon has a small core, supporting the theory
that the bulk of the Moon was ripped away from the early Earth when
an object the size of Mars collided with the Earth.
Scientists presented this result and other findings today in a series
of papers at the 30th Lunar and Planetary Science Conference in
Houston, TX. Their data show that the lunar core contains less than
four percent of the Moon's total mass, with the probable value being
two percent or slightly less. This is very small when compared with
the Earth, whose iron core contains approximately 30 percent of the
planet's mass.
"This is a critical finding in helping scientists determine how the Earth
and Moon formed," said Dr. Alan Binder of the Lunar Research Institute,
Tucson, AZ, principal investigator for Lunar Prospector.
Similarities in the mineral composition of the Earth and the Moon
indicate that they share a common origin. However, if they had simply
formed form the same cloud of rocks and dust, the Moon would have a
core similar in proportion to the Earth's. A third theory suggests that the
moon was captured fully intact by the Earth's gravity.
Based on information first gathered during the Apollo era, scientists
suggested that the Moon was formed when a Mars-sized body hit the
Earth during its earliest history. "This impact occurred after the Earth's
iron core had formed, ejecting rocky, iron-poor material from the outer
shell into orbit," Binder explained. "It was this material that collected to
form the Moon.
"Further analysis of Lunar Prospector data to refine the exact size
of the lunar core and the amounts of elements like gold, platinum and
iridium in lunar rocks -- all of which are concentrated with metallic iron
-- is required," Binder added. "This will do much to pin down for good if
the 'giant impact' model of the formation of the Moon is correct, or if the
Moon formed in a different manner."
The current data come from gravity measurements conducted by Dr. Alex
Konopliv of NASA's Jet Propulsion Laboratory, Pasadena, CA. His results indicate that the Moon's core radius is between 140 and 280 miles (220 and 450 kilometers). This result is consistent with independent magnetic data, evaluated by Dr. Lon Hood of the University of Arizona, Tucson, which suggest that the core radius is between 180 and 260 miles (300 and 425 km).
In other results from Lunar Prospector, Dr. Robert Lin of the University of California at Berkeley, Dr. Mario Acuna of NASA's Goddard Space Flight Center, Greenbelt, MD, and Hood also found that a broad section of the southern far-side of the Moon has large localized magnetic fields in its crust. These fields occur opposite the large Crisium, Serenitatis and Imbrium basins -- three of the "seas" that cover much of the Moon's near side. This result supports earlier evidence linking strong magnetized concentrations on one side of the Moon with young, large impact basins
on the other side.
Results of efforts to map the composition of the lunar crust have surpassed the expectations of the spectrometer team, led by Dr. William Feldman of the Department of Energy's Los Alamos National Laboratory in New Mexico. Data obtained are so good that the distribution of thorium has been mapped with a resolution of 36 miles (60 kilometers). At this amount of detail, scientists can detect individual deposits rich in thorium and related elements. Their current observations suggest that thorium was excavated by impacts of asteroids and comets, and then distributed around craters, rather than being deposited by volcanic activity.
Lunar Prospector conducted its primary mapping mission at an altitude
of 63 miles (100 kilometers) for almost one year after its arrival in lunar
orbit on Jan. 11, 1998. In December and January, the spacecraft's altitude was lowered to approximately 15 miles by 23 miles (24 kilometers by 37 kilometers). Analyses of data from the lower-altitude observations are expected to further improve scientific understanding of the origin, evolution and physical resources of the Moon.
The $63 million mission is managed by NASA's Ames Research Center, Moffett Field, CA, and was developed under NASA's Discovery Program
of lower-cost, highly focused small scientific spacecraft.
Further information about Lunar Prospector, its science data return,
and relevant charts and graphics can be found on the project website
at: http://lunar.arc.nasa.gov
confirmed that the Moon has a small core, supporting the theory
that the bulk of the Moon was ripped away from the early Earth when
an object the size of Mars collided with the Earth.
Scientists presented this result and other findings today in a series
of papers at the 30th Lunar and Planetary Science Conference in
Houston, TX. Their data show that the lunar core contains less than
four percent of the Moon's total mass, with the probable value being
two percent or slightly less. This is very small when compared with
the Earth, whose iron core contains approximately 30 percent of the
planet's mass.
"This is a critical finding in helping scientists determine how the Earth
and Moon formed," said Dr. Alan Binder of the Lunar Research Institute,
Tucson, AZ, principal investigator for Lunar Prospector.
Similarities in the mineral composition of the Earth and the Moon
indicate that they share a common origin. However, if they had simply
formed form the same cloud of rocks and dust, the Moon would have a
core similar in proportion to the Earth's. A third theory suggests that the
moon was captured fully intact by the Earth's gravity.
Based on information first gathered during the Apollo era, scientists
suggested that the Moon was formed when a Mars-sized body hit the
Earth during its earliest history. "This impact occurred after the Earth's
iron core had formed, ejecting rocky, iron-poor material from the outer
shell into orbit," Binder explained. "It was this material that collected to
form the Moon.
"Further analysis of Lunar Prospector data to refine the exact size
of the lunar core and the amounts of elements like gold, platinum and
iridium in lunar rocks -- all of which are concentrated with metallic iron
-- is required," Binder added. "This will do much to pin down for good if
the 'giant impact' model of the formation of the Moon is correct, or if the
Moon formed in a different manner."
The current data come from gravity measurements conducted by Dr. Alex
Konopliv of NASA's Jet Propulsion Laboratory, Pasadena, CA. His results indicate that the Moon's core radius is between 140 and 280 miles (220 and 450 kilometers). This result is consistent with independent magnetic data, evaluated by Dr. Lon Hood of the University of Arizona, Tucson, which suggest that the core radius is between 180 and 260 miles (300 and 425 km).
In other results from Lunar Prospector, Dr. Robert Lin of the University of California at Berkeley, Dr. Mario Acuna of NASA's Goddard Space Flight Center, Greenbelt, MD, and Hood also found that a broad section of the southern far-side of the Moon has large localized magnetic fields in its crust. These fields occur opposite the large Crisium, Serenitatis and Imbrium basins -- three of the "seas" that cover much of the Moon's near side. This result supports earlier evidence linking strong magnetized concentrations on one side of the Moon with young, large impact basins
on the other side.
Results of efforts to map the composition of the lunar crust have surpassed the expectations of the spectrometer team, led by Dr. William Feldman of the Department of Energy's Los Alamos National Laboratory in New Mexico. Data obtained are so good that the distribution of thorium has been mapped with a resolution of 36 miles (60 kilometers). At this amount of detail, scientists can detect individual deposits rich in thorium and related elements. Their current observations suggest that thorium was excavated by impacts of asteroids and comets, and then distributed around craters, rather than being deposited by volcanic activity.
Lunar Prospector conducted its primary mapping mission at an altitude
of 63 miles (100 kilometers) for almost one year after its arrival in lunar
orbit on Jan. 11, 1998. In December and January, the spacecraft's altitude was lowered to approximately 15 miles by 23 miles (24 kilometers by 37 kilometers). Analyses of data from the lower-altitude observations are expected to further improve scientific understanding of the origin, evolution and physical resources of the Moon.
The $63 million mission is managed by NASA's Ames Research Center, Moffett Field, CA, and was developed under NASA's Discovery Program
of lower-cost, highly focused small scientific spacecraft.
Further information about Lunar Prospector, its science data return,
and relevant charts and graphics can be found on the project website
at: http://lunar.arc.nasa.gov
The Cosmic Light No One Can Explain A puzzling body stumps astronomy's best minds 21.12
BY LEON JAROFF
It isn't visible to the naked eye, and when viewed through a large telescope
it looks very much like any of the ordinary cosmic bodies in its celestial
neighborhood. But this pinpoint of light is anything but ordinary. Spotted
more than three years ago, it seemed at first to be a garden-variety
star--but it wasn't. It might have turned out to be an unremarkable galaxy
or quasar--but it didn't. Frustrated in their attempts to learn its nature,
and even its distance from Earth, astronomers have begun to refer to the
mystery object as, well, the "mystery object."
Just what the enigmatic body is has been the subject of much buzz in
the astronomical community--and deservedly so. Astronomer S. George
Djorgovski and his team at the California Institute of Technology first
spotted the object in color photographs taken for an ongoing digitized
survey of the northern skies. In one of the images, they noticed what
seemed to be an oddly colored star in the constellation Serpens (the
snake).
Intrigued, the Caltech team turned a larger telescope on the object to
analyze its light. They were confident that the resulting spectrum, not
unlike the band of colors that appears when sunlight is passed through a
prism, would tell them a lot. "Once you have a star's spectrum," says
Djorgovski, "you can determine its temperature, its heavy elements and
how fast it's moving with respect to Earth."
Ordinarily, astronomers can take the measure of a star within hours after
obtaining its spectrum. But when the Caltech astronomers got their first
look at this object's spectrum, displayed in the form of an EKG-like graph
on a computer screen, they were shocked. "Our mouths fell open," says
Djorgovski. "I suspect that what we said was not printable. But the gist of
it was, 'What the heck is this?'"
What stunned the scientists was where the peaks and dips of the graph
fell. A trained astronomer can read a star's spectrum the way a forensic
scientist reads a fingerprint, spotting almost at a glance the presence of
an element like magnesium or carbon. But on this spectrum, something was drastically amiss. "It looks like somebody crumpled the spectrum,"
says Djorgovski. "It's not that we see things that we know about but are in
the wrong place. It's simply that we don't know what they are."
The spectrum has two large peaks that may or may not mark an ample
presence of an as yet unidentified element, and many small dips that
probably represent segments of the spectrum where light has been
absorbed by other elements--perhaps those in the object's outer
atmosphere or in gas clouds between the object and Earth. Bewildered,
the Caltech team looked for other answers. Maybe the object was a
supernova, an exploding star, which often projects what Djorgovski calls
a "weird-looking" spectrum. But the team observed the target a number
of times over several months and noted no change. That ruled out a supernova's light, which gradually fades after the initial explosion.
Some of the astronomers then suggested that the spectrum resembled
those of a particular category of quasars--fantastically bright and distant
objects powered by black holes. Only one or two of them, known as iron
broad-absorption quasars, have spectrums that bear a passing
resemblance to that of the Caltech object. Could it be that a plethora of
iron ions in the mystery object is distorting its spectrum?
"My personal guess," says Djorgovski. "is that we're dealing with a very
special, sub-sub-sub-category of quasar. There may be only one of them."
Or, he muses, his team may be looking at a quasar through a "very
special" line of sight, a line that passes through a strange cloud of gas
that accounts for its curious absorptions. But, he stresses, "I wouldn't
stake any money on either of these possibilities."
The Caltech team was reluctant to publish a report that would merely say,
in Djorgovski's words, "Gee, look what we've found," without offering a
viable explanation. So after three years of examining and re-examining the
spectrum and vainly searching through scientific literature, the team at last
decided to go semipublic.
At the meeting of the American Astronomical Society in Chicago this
spring, they showed their prize spectrum to other scientists and asked for
their opinion. No one had seen anything like it, and few would hazard a
guess about what message it might convey. Stymied at every turn,
Djorgovski is pinning his hopes on investigating the object's invisible
infrared emissions, which have wavelengths slightly longer than the red
light at one end of the visible spectrum. Within the next few weeks,
astronomers at the Keck Observatory in Hawaii will train a telescope
equipped with an experimental infrared spectrograph on the quarry. What
it captures could be revealing. "Our hope," says Djorgovski, "is that by
seeing the longer wavelengths on the spectrum, we might actually notice
a pattern that is familiar."
That insight might merely confirm that the Caltech astronomers have
found an oddball quasar. Or it could herald the discovery of an entirely
new and remarkable celestial object. (*)
It isn't visible to the naked eye, and when viewed through a large telescope
it looks very much like any of the ordinary cosmic bodies in its celestial
neighborhood. But this pinpoint of light is anything but ordinary. Spotted
more than three years ago, it seemed at first to be a garden-variety
star--but it wasn't. It might have turned out to be an unremarkable galaxy
or quasar--but it didn't. Frustrated in their attempts to learn its nature,
and even its distance from Earth, astronomers have begun to refer to the
mystery object as, well, the "mystery object."
Just what the enigmatic body is has been the subject of much buzz in
the astronomical community--and deservedly so. Astronomer S. George
Djorgovski and his team at the California Institute of Technology first
spotted the object in color photographs taken for an ongoing digitized
survey of the northern skies. In one of the images, they noticed what
seemed to be an oddly colored star in the constellation Serpens (the
snake).
Intrigued, the Caltech team turned a larger telescope on the object to
analyze its light. They were confident that the resulting spectrum, not
unlike the band of colors that appears when sunlight is passed through a
prism, would tell them a lot. "Once you have a star's spectrum," says
Djorgovski, "you can determine its temperature, its heavy elements and
how fast it's moving with respect to Earth."
Ordinarily, astronomers can take the measure of a star within hours after
obtaining its spectrum. But when the Caltech astronomers got their first
look at this object's spectrum, displayed in the form of an EKG-like graph
on a computer screen, they were shocked. "Our mouths fell open," says
Djorgovski. "I suspect that what we said was not printable. But the gist of
it was, 'What the heck is this?'"
What stunned the scientists was where the peaks and dips of the graph
fell. A trained astronomer can read a star's spectrum the way a forensic
scientist reads a fingerprint, spotting almost at a glance the presence of
an element like magnesium or carbon. But on this spectrum, something was drastically amiss. "It looks like somebody crumpled the spectrum,"
says Djorgovski. "It's not that we see things that we know about but are in
the wrong place. It's simply that we don't know what they are."
The spectrum has two large peaks that may or may not mark an ample
presence of an as yet unidentified element, and many small dips that
probably represent segments of the spectrum where light has been
absorbed by other elements--perhaps those in the object's outer
atmosphere or in gas clouds between the object and Earth. Bewildered,
the Caltech team looked for other answers. Maybe the object was a
supernova, an exploding star, which often projects what Djorgovski calls
a "weird-looking" spectrum. But the team observed the target a number
of times over several months and noted no change. That ruled out a supernova's light, which gradually fades after the initial explosion.
Some of the astronomers then suggested that the spectrum resembled
those of a particular category of quasars--fantastically bright and distant
objects powered by black holes. Only one or two of them, known as iron
broad-absorption quasars, have spectrums that bear a passing
resemblance to that of the Caltech object. Could it be that a plethora of
iron ions in the mystery object is distorting its spectrum?
"My personal guess," says Djorgovski. "is that we're dealing with a very
special, sub-sub-sub-category of quasar. There may be only one of them."
Or, he muses, his team may be looking at a quasar through a "very
special" line of sight, a line that passes through a strange cloud of gas
that accounts for its curious absorptions. But, he stresses, "I wouldn't
stake any money on either of these possibilities."
The Caltech team was reluctant to publish a report that would merely say,
in Djorgovski's words, "Gee, look what we've found," without offering a
viable explanation. So after three years of examining and re-examining the
spectrum and vainly searching through scientific literature, the team at last
decided to go semipublic.
At the meeting of the American Astronomical Society in Chicago this
spring, they showed their prize spectrum to other scientists and asked for
their opinion. No one had seen anything like it, and few would hazard a
guess about what message it might convey. Stymied at every turn,
Djorgovski is pinning his hopes on investigating the object's invisible
infrared emissions, which have wavelengths slightly longer than the red
light at one end of the visible spectrum. Within the next few weeks,
astronomers at the Keck Observatory in Hawaii will train a telescope
equipped with an experimental infrared spectrograph on the quarry. What
it captures could be revealing. "Our hope," says Djorgovski, "is that by
seeing the longer wavelengths on the spectrum, we might actually notice
a pattern that is familiar."
That insight might merely confirm that the Caltech astronomers have
found an oddball quasar. Or it could herald the discovery of an entirely
new and remarkable celestial object. (*)
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