NEW CHANDRA MOVIE FEATURES NEUTRON STAR ACTION
WASHINGTON -- Unlike with some blockbuster films, the sequel to a
movie from NASA's Chandra X-ray Observatory is better than the first.
This latest movie features a deeper look at a fast moving jet of
particles produced by a rapidly rotating neutron star, and may
provide new insight into the nature of some of the densest matter in
the universe.
The hero of this Chandra movie is the Vela pulsar, a neutron star that
was formed when a massive star collapsed. The Vela pulsar is about
1,000 light-years from Earth, about 12 miles in diameter, and makes a
complete rotation in 89 milliseconds, faster than a helicopter rotor.
As the pulsar whips around, it spews out a jet of charged particles
that race along the pulsar's rotation axis at about 70 percent of the
speed of light. The new Chandra data, which were obtained from June
to September 2010, suggest the pulsar may be slowly wobbling, or
precessing, as it spins. The period of the precession, which is
analogous to the slow wobble of a spinning top, is estimated to be
about 120 days.
"We think the Vela pulsar is like a rotating garden sprinkler --
except with the water blasting out at over half the speed of light,"
said Martin Durant of the University of Toronto in Canada, who is the
first author of the paper describing these results.
One possible cause of precession for a spinning neutron star is it has
become slightly distorted and is no longer a perfect sphere. This
distortion might be caused by the combined action of the fast
rotation and "glitches," sudden increases of the pulsar's rotational
speed due to the interaction of the superfluid core of the neutron
star with its crust.
"The deviation from a perfect sphere may only be equivalent to about
one part in 100 million," said co-author Oleg Kargaltsev of The
George Washington University in Washington, who presented these
results Monday at the 221st American Astronomical Society meeting in
Long Beach, Calif. "Neutron stars are so dense that even a tiny
distortion like this would have a big effect."
If the evidence for precession of the Vela pulsar is confirmed, it
would be the first time a neutron star has been found to be this way.
The shape and the motion of the Vela jet look strikingly like a
rotating helix, a shape that is naturally explained by precession.
Another possibility is the strong magnetic fields around the pulsar
are influencing the shape of the jet. For example, if the jet
develops a small bend caused, by precession, the magnetic field's
lines on the inside of the bend will become more closely spaced. This
pushes particles toward the outside of the bend, increasing the
effect.
"It's like having an unsecured fire hose and a flow of water at high
pressure," said co-author George Pavlov, principal investigator of
the Chandra proposal at Pennsylvania State University in University
Park. "All you need is a small bend in the hose and violent motion
can result."
This is the second Chandra movie of the Vela pulsar. The original was
released in 2003 by Pavlov and co-authors. The first Vela movie
contained shorter, unevenly spaced observations so that the changes
in the jet were less pronounced and the researchers did not argue
that precession was occurring. However, based on the same data,
Avinash Deshpande of Arecibo Observatory in Puerto Rico and the Raman
Research Institute in Bangalore, India, and the late Venkatraman
Radhakrishnan, argued in a 2007 paper the Vela pulsar might be
precessing.
Astronomers have returned to observing Vela because it offers an
excellent chance to study how a pulsar and its jet work. The 0.7
light-year-long jet in Vela is similar to those produced by accreting
supermassive black holes in other galaxies, but on a much smaller
scale. Because Vela's jet changes dramatically over a period of
months and is relatively close, it can be studied in great detail
unlike jets from black holes that change over much longer timescales.
If precession is confirmed and the Vela pulsar is indeed a distorted
neutron star, it should be a persistent source of gravitational
waves, and would be a prime target for the next generation of
gravitational wave detectors designed to test Einstein's theory of
general relativity.
A paper describing these results will be published in Thursday's The
Astrophysical Journal. Other co-authors of the paper were Julia
Kropotina and Kseniya Levenfish from St. Petersburg State
Polytechnical University in St. Petersburg, Russia.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the
Chandra program for NASA's Science Mission Directorate in Washington.
The Smithsonian Astrophysical Observatory controls Chandra's science
and flight operations from Cambridge, Mass.
Showing posts with label Astrophysics. Show all posts
Showing posts with label Astrophysics. Show all posts
Wednesday, January 9, 2013
461 new planet candidates found in the universe, totaling potential planets to 2740 orbiting 2036 stars
NASA'S KEPLER MISSION DISCOVERS 461 NEW PLANET CANDIDATES
WASHINGTON -- NASA's Kepler mission Monday announced the discovery of
461 new planet candidates. Four of the potential new planets are less
than twice the size of Earth and orbit in their sun's "habitable
zone," the region in the planetary system where liquid water might
exist on the surface of a planet.
Based on observations conducted from May 2009 to March 2011, the
findings show a steady increase in the number of smaller-size planet
candidates and the number of stars with more than one candidate.
"There is no better way to kickoff the start of the Kepler extended
mission than to discover more possible outposts on the frontier of
potentially life bearing worlds," said Christopher Burke, Kepler
scientist at the SETI Institute in Mountain View, Calif., who is
leading the analysis.
Since the last Kepler catalog was released in February 2012, the
number of candidates discovered in the Kepler data has increased by
20 percent and now totals 2,740 potential planets orbiting 2,036
stars. The most dramatic increases are seen in the number of
Earth-size and super Earth-size candidates discovered, which grew by
43 and 21 percent respectively.
The new data increases the number of stars discovered to have more
than one planet candidate from 365 to 467. Today, 43 percent of
Kepler's planet candidates are observed to have neighbor planets.
"The large number of multi-candidate systems being found by Kepler
implies that a substantial fraction of exoplanets reside in flat
multi-planet systems," said Jack Lissauer, planetary scientist at
NASA's Ames Research Center in Moffett Field, Calif. "This is
consistent with what we know about our own planetary neighborhood."
The Kepler space telescope identifies planet candidates by repeatedly
measuring the change in brightness of more than 150,000 stars in
search of planets that pass in front, or "transit," their host star.
At least three transits are required to verify a signal as a
potential planet.
Scientists analyzed more than 13,000 transit-like signals to eliminate
known spacecraft instrumentation and astrophysical false positives,
phenomena that masquerade as planetary candidates, to identify the
potential new planets.
Candidates require additional follow-up observations and analyses to
be confirmed as planets. At the beginning of 2012, 33 candidates in
the Kepler data had been confirmed as planets. Today, there are 105.
"The analysis of increasingly longer time periods of Kepler data
uncovers smaller planets in longer period orbits-- orbital periods
similar to Earth's," said Steve Howell, Kepler mission project
scientist at Ames. "It is no longer a question of will we find a true
Earth analogue, but a question of when."
The complete list of Kepler planet candidates is available in an
interactive table at the NASA Exoplanet Archive. The archive is
funded by NASA's Exoplanet Exploration Program to collect and make
public data to support the search for and characterization of
exoplanets and their host stars.
Ames manages Kepler's ground system development, mission operations
and science data analysis. NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, Calif., managed Kepler mission development. Ball Aerospace
and Technologies Corp. in Boulder, Colo., developed the Kepler flight
system and supports mission operations with JPL at the Laboratory for
Atmospheric and Space Physics at the University of Colorado in
Boulder.
The Space Telescope Science Institute in Baltimore archives, hosts and
distributes the Kepler science data. Kepler is NASA's 10th Discovery
Mission and is funded by NASA's Science Mission Directorate at the
agency's headquarters in Washington.
JPL manages NASA's Exoplanet Exploration Program. The NASA Exoplanet
Archive is hosted at the Infrared Processing and Analysis Center at
the California Institute of Technology.
WASHINGTON -- NASA's Kepler mission Monday announced the discovery of
461 new planet candidates. Four of the potential new planets are less
than twice the size of Earth and orbit in their sun's "habitable
zone," the region in the planetary system where liquid water might
exist on the surface of a planet.
Based on observations conducted from May 2009 to March 2011, the
findings show a steady increase in the number of smaller-size planet
candidates and the number of stars with more than one candidate.
"There is no better way to kickoff the start of the Kepler extended
mission than to discover more possible outposts on the frontier of
potentially life bearing worlds," said Christopher Burke, Kepler
scientist at the SETI Institute in Mountain View, Calif., who is
leading the analysis.
Since the last Kepler catalog was released in February 2012, the
number of candidates discovered in the Kepler data has increased by
20 percent and now totals 2,740 potential planets orbiting 2,036
stars. The most dramatic increases are seen in the number of
Earth-size and super Earth-size candidates discovered, which grew by
43 and 21 percent respectively.
The new data increases the number of stars discovered to have more
than one planet candidate from 365 to 467. Today, 43 percent of
Kepler's planet candidates are observed to have neighbor planets.
"The large number of multi-candidate systems being found by Kepler
implies that a substantial fraction of exoplanets reside in flat
multi-planet systems," said Jack Lissauer, planetary scientist at
NASA's Ames Research Center in Moffett Field, Calif. "This is
consistent with what we know about our own planetary neighborhood."
The Kepler space telescope identifies planet candidates by repeatedly
measuring the change in brightness of more than 150,000 stars in
search of planets that pass in front, or "transit," their host star.
At least three transits are required to verify a signal as a
potential planet.
Scientists analyzed more than 13,000 transit-like signals to eliminate
known spacecraft instrumentation and astrophysical false positives,
phenomena that masquerade as planetary candidates, to identify the
potential new planets.
Candidates require additional follow-up observations and analyses to
be confirmed as planets. At the beginning of 2012, 33 candidates in
the Kepler data had been confirmed as planets. Today, there are 105.
"The analysis of increasingly longer time periods of Kepler data
uncovers smaller planets in longer period orbits-- orbital periods
similar to Earth's," said Steve Howell, Kepler mission project
scientist at Ames. "It is no longer a question of will we find a true
Earth analogue, but a question of when."
The complete list of Kepler planet candidates is available in an
interactive table at the NASA Exoplanet Archive. The archive is
funded by NASA's Exoplanet Exploration Program to collect and make
public data to support the search for and characterization of
exoplanets and their host stars.
Ames manages Kepler's ground system development, mission operations
and science data analysis. NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, Calif., managed Kepler mission development. Ball Aerospace
and Technologies Corp. in Boulder, Colo., developed the Kepler flight
system and supports mission operations with JPL at the Laboratory for
Atmospheric and Space Physics at the University of Colorado in
Boulder.
The Space Telescope Science Institute in Baltimore archives, hosts and
distributes the Kepler science data. Kepler is NASA's 10th Discovery
Mission and is funded by NASA's Science Mission Directorate at the
agency's headquarters in Washington.
JPL manages NASA's Exoplanet Exploration Program. The NASA Exoplanet
Archive is hosted at the Infrared Processing and Analysis Center at
the California Institute of Technology.
Tracing history of a black hole 11 billion years ago: Scientists find the source of ancient outburst in the farther space
GALAXY'S GAMMA-RAY FLARES ERUPTED FAR FROM ITS BLACK HOLE
WASHINGTON -- In 2011, a months-long blast of energy launched by an
enormous black hole almost 11 billion years ago swept past Earth.
Using a combination of data from NASA's Fermi Gamma-ray Space
Telescope and the National Science Foundation's Very Long Baseline
Array (VLBA), the world's largest radio telescope, astronomers have
zeroed in on the source of this ancient outburst.
Theorists expect gamma-ray outbursts occur only in close proximity to
a galaxy's central black hole, the powerhouse ultimately responsible
for the activity. A few rare observations suggested this is not the
case.
The 2011 flares from a galaxy known as 4C +71.07 now give astronomers
the clearest and most distant evidence that the theory still needs
some work. The gamma-ray emission originated about 70 light-years
away from the galaxy's central black hole.
The 4C +71.07 galaxy was discovered as a source of strong radio
emission in the 1960s. NASA's Compton Gamma-Ray Observatory, which
operated in the 1990s, detected high-energy flares, but the galaxy
was quiet during Fermi's first two and a half years in orbit.
In early November 2011, at the height of the outburst, the galaxy was
more than 10,000 times brighter than the combined luminosity of all
of the stars in our Milky Way galaxy.
"This renewed activity came after a long slumber, and that's important
because it allows us to explicitly link the gamma-ray flares to the
rising emission observed by radio telescopes," said David Thompson, a
Fermi deputy project scientist at NASA's Goddard Space Flight Center
in Greenbelt, Md.
Located in the constellation Ursa Major, 4C +71.07 is so far away that
its light takes 10.6 billion years to reach Earth. Astronomers are
seeing this galaxy as it existed when the universe was less than
one-fourth of its present age.
At the galaxy's core lies a supersized black hole weighing 2.6 billion
times the sun's mass. Some of the matter falling toward the black
hole becomes accelerated outward at almost the speed of light,
creating dual particle jets blasting in opposite directions. One jet
happens to point almost directly toward Earth. This characteristic
makes 4C +71.07 a blazar, a classification that includes some of the
brightest gamma-ray sources in the sky.
Boston University astronomers Alan Marscher and Svetlana Jorstad
routinely monitor 4C +71.07 along with dozens of other blazars using
several facilities, including the VLBA.
The instrument's 10 radio telescopes span North America, from Hawaii
to St. Croix in the U.S. Virgin Islands, and possess the resolving
power of a single radio dish more than 5,300 miles across when their
signals are combined. As a result, The VLBA resolves detail about a
million times smaller than Fermi's Large Area Telescope (LAT) and
1,000 times smaller than NASA's Hubble Space Telescope.
In autumn 2011, the VLBA images revealed a bright knot that appeared
to move outward at a speed 20 times faster than light.
"Although this apparent speed was an illusion caused by actual motion
almost directly toward us at 99.87 percent the speed of light, this
knot was the key to determining the location where the gamma-rays
were produced in the black hole's jet," said Marscher, who presented
the findings Monday at the American Astronomical Society meeting in
Long Beach, Calif.
The knot passed through a bright stationary feature of the jet, which
the astronomers refer to as its radio "core," on April 9, 2011. This
occurred within days of Fermi's detection of renewed gamma-ray
flaring in the blazar. Marscher and Jorstad noted that the blazar
brightened at visible wavelengths in step with the higher-energy
emission.
During the most intense period of flaring, from October 2011 to
January 2012, the scientists found the polarization direction of the
blazar's visible light rotated in the same manner as radio emissions
from the knot. They concluded the knot was responsible for the
visible and the gamma-ray light, which varied in sync.
This association allowed the researchers to pinpoint the location of
the gamma-ray outburst to about 70 light-years from the black hole.
The astronomers think that the gamma rays were produced when electrons
moving near the speed of light within the jet collided with visible
and infrared light originating outside of the jet. Such a collision
can kick the light up to much higher energies, a process known as
inverse-Compton scattering.
The source of the lower-energy light is unclear at the moment. The
researchers speculate the source may be an outer, slow-moving sheath
that surrounds the jet. Nicholas MacDonald, a graduate student at
Boston University, is investigating how the gamma-ray brightness
should change in this scenario to compare with observations.
"The VLBA is the only instrument that can bring us images from so near
the edge of a young supermassive black hole, and Fermi's LAT is the
only instrument that can see the highest-energy light from the
galaxy's jet," said Jorstad.
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle
physics partnership. Fermi is managed by NASA's Goddard Space Flight
Center. It was developed in collaboration with the U.S. Department of
Energy, with contributions from academic institutions and partners in
France, Germany, Italy, Japan, Sweden and the United States.
WASHINGTON -- In 2011, a months-long blast of energy launched by an
enormous black hole almost 11 billion years ago swept past Earth.
Using a combination of data from NASA's Fermi Gamma-ray Space
Telescope and the National Science Foundation's Very Long Baseline
Array (VLBA), the world's largest radio telescope, astronomers have
zeroed in on the source of this ancient outburst.
Theorists expect gamma-ray outbursts occur only in close proximity to
a galaxy's central black hole, the powerhouse ultimately responsible
for the activity. A few rare observations suggested this is not the
case.
The 2011 flares from a galaxy known as 4C +71.07 now give astronomers
the clearest and most distant evidence that the theory still needs
some work. The gamma-ray emission originated about 70 light-years
away from the galaxy's central black hole.
The 4C +71.07 galaxy was discovered as a source of strong radio
emission in the 1960s. NASA's Compton Gamma-Ray Observatory, which
operated in the 1990s, detected high-energy flares, but the galaxy
was quiet during Fermi's first two and a half years in orbit.
In early November 2011, at the height of the outburst, the galaxy was
more than 10,000 times brighter than the combined luminosity of all
of the stars in our Milky Way galaxy.
"This renewed activity came after a long slumber, and that's important
because it allows us to explicitly link the gamma-ray flares to the
rising emission observed by radio telescopes," said David Thompson, a
Fermi deputy project scientist at NASA's Goddard Space Flight Center
in Greenbelt, Md.
Located in the constellation Ursa Major, 4C +71.07 is so far away that
its light takes 10.6 billion years to reach Earth. Astronomers are
seeing this galaxy as it existed when the universe was less than
one-fourth of its present age.
At the galaxy's core lies a supersized black hole weighing 2.6 billion
times the sun's mass. Some of the matter falling toward the black
hole becomes accelerated outward at almost the speed of light,
creating dual particle jets blasting in opposite directions. One jet
happens to point almost directly toward Earth. This characteristic
makes 4C +71.07 a blazar, a classification that includes some of the
brightest gamma-ray sources in the sky.
Boston University astronomers Alan Marscher and Svetlana Jorstad
routinely monitor 4C +71.07 along with dozens of other blazars using
several facilities, including the VLBA.
The instrument's 10 radio telescopes span North America, from Hawaii
to St. Croix in the U.S. Virgin Islands, and possess the resolving
power of a single radio dish more than 5,300 miles across when their
signals are combined. As a result, The VLBA resolves detail about a
million times smaller than Fermi's Large Area Telescope (LAT) and
1,000 times smaller than NASA's Hubble Space Telescope.
In autumn 2011, the VLBA images revealed a bright knot that appeared
to move outward at a speed 20 times faster than light.
"Although this apparent speed was an illusion caused by actual motion
almost directly toward us at 99.87 percent the speed of light, this
knot was the key to determining the location where the gamma-rays
were produced in the black hole's jet," said Marscher, who presented
the findings Monday at the American Astronomical Society meeting in
Long Beach, Calif.
The knot passed through a bright stationary feature of the jet, which
the astronomers refer to as its radio "core," on April 9, 2011. This
occurred within days of Fermi's detection of renewed gamma-ray
flaring in the blazar. Marscher and Jorstad noted that the blazar
brightened at visible wavelengths in step with the higher-energy
emission.
During the most intense period of flaring, from October 2011 to
January 2012, the scientists found the polarization direction of the
blazar's visible light rotated in the same manner as radio emissions
from the knot. They concluded the knot was responsible for the
visible and the gamma-ray light, which varied in sync.
This association allowed the researchers to pinpoint the location of
the gamma-ray outburst to about 70 light-years from the black hole.
The astronomers think that the gamma rays were produced when electrons
moving near the speed of light within the jet collided with visible
and infrared light originating outside of the jet. Such a collision
can kick the light up to much higher energies, a process known as
inverse-Compton scattering.
The source of the lower-energy light is unclear at the moment. The
researchers speculate the source may be an outer, slow-moving sheath
that surrounds the jet. Nicholas MacDonald, a graduate student at
Boston University, is investigating how the gamma-ray brightness
should change in this scenario to compare with observations.
"The VLBA is the only instrument that can bring us images from so near
the edge of a young supermassive black hole, and Fermi's LAT is the
only instrument that can see the highest-energy light from the
galaxy's jet," said Jorstad.
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle
physics partnership. Fermi is managed by NASA's Goddard Space Flight
Center. It was developed in collaboration with the U.S. Department of
Energy, with contributions from academic institutions and partners in
France, Germany, Italy, Japan, Sweden and the United States.
Crackers in the deep space: Starbursts in the Milky Way
SOFIA SPOTS RECENT STARBURSTS IN THE MILKY WAY GALAXY'S CENTER
WASHINGTON -- Researchers using the Stratospheric Observatory for
Infrared Astronomy (SOFIA) have captured new images of a ring of gas
and dust seven light-years in diameter surrounding the supermassive
black hole at the center of the Milky Way, and of a neighboring
cluster of extremely luminous young stars embedded in dust cocoons.
The images of our galaxy's circumlunar ring (CNR) and its neighboring
quintuplet cluster (QC) are the subjects of two posters presented
this week during the American Astronomical Society's meeting in Long
Beach, Calif. Ryan Lau of Cornell University and his collaborators
studied the CNR. Matt Hankins of the University of Central Arkansas
in Conway is lead author of the other paper, regarding the QC.
SOFIA is a highly modified Boeing 747SP aircraft carrying a telescope
with an effective diameter of 100 inches (2.54 meters) to altitudes
as high as 45,000 feet (13.7 kilometers).
The images were obtained during SOFIA flights in 2011 with the Faint
Object Infrared Camera for the SOFIA Telescope (FORCAST) instrument
built by a team with principal investigator Terry Herter of Cornell.
FORCAST offered astronomers the ability to see the CNR and QC regions
and other exotic cosmic features whose light is obscured by water
vapor in Earth's atmosphere and interstellar dust clouds in the
mid-plane of the Milky Way. Neither ground-based observatories on
tall mountain peaks nor NASA's orbiting Hubble and Spitzer space
telescopes can see them.
WASHINGTON -- Researchers using the Stratospheric Observatory for
Infrared Astronomy (SOFIA) have captured new images of a ring of gas
and dust seven light-years in diameter surrounding the supermassive
black hole at the center of the Milky Way, and of a neighboring
cluster of extremely luminous young stars embedded in dust cocoons.
The images of our galaxy's circumlunar ring (CNR) and its neighboring
quintuplet cluster (QC) are the subjects of two posters presented
this week during the American Astronomical Society's meeting in Long
Beach, Calif. Ryan Lau of Cornell University and his collaborators
studied the CNR. Matt Hankins of the University of Central Arkansas
in Conway is lead author of the other paper, regarding the QC.
SOFIA is a highly modified Boeing 747SP aircraft carrying a telescope
with an effective diameter of 100 inches (2.54 meters) to altitudes
as high as 45,000 feet (13.7 kilometers).
The images were obtained during SOFIA flights in 2011 with the Faint
Object Infrared Camera for the SOFIA Telescope (FORCAST) instrument
built by a team with principal investigator Terry Herter of Cornell.
FORCAST offered astronomers the ability to see the CNR and QC regions
and other exotic cosmic features whose light is obscured by water
vapor in Earth's atmosphere and interstellar dust clouds in the
mid-plane of the Milky Way. Neither ground-based observatories on
tall mountain peaks nor NASA's orbiting Hubble and Spitzer space
telescopes can see them.
Weather mapping of the worlds unknown: Man gets insight of the stormy atmosphere of a brown dwarf
NASA TELESCOPES SEE WEATHER PATTERNS IN BROWN DWARF
WASHINGTON -- Astronomers using NASA's Spitzer and Hubble space
telescopes have probed the stormy atmosphere of a brown dwarf,
creating the most detailed "weather map" yet for this class of cool,
star-like orbs. The forecast shows wind-driven, planet-sized clouds
enshrouding these strange worlds.
Brown dwarfs form out of condensing gas, as stars do, but lack the
mass to fuse hydrogen atoms and produce energy. Instead, these
objects, which some call failed stars, are more similar to gas
planets with their complex, varied atmospheres. The new research is a
stepping stone toward a better understanding not only of brown
dwarfs, but also of the atmospheres of planets beyond our solar
system.
"With Hubble and Spitzer, we were able to look at different
atmospheric layers of a brown dwarf, similar to the way doctors use
medical imaging techniques to study the different tissues in your
body," said Daniel Apai, the principal investigator of the research
at the University of Arizona in Tucson, who presented the results at
the American Astronomical Society meeting Tuesday in Long Beach,
Calif.
A study describing the results, led by Esther Buenzli, also of the
University of Arizona, is published in the Astrophysical Journal
Letters.
The researchers turned Hubble and Spitzer simultaneously toward a
brown dwarf with the long name of 2MASSJ22282889-431026. They found
that its light varied in time, brightening and dimming about every 90
minutes as the body rotated. But more surprising, the team also found
the timing of this change in brightness depended on whether they
looked using different wavelengths of infrared light.
These variations are the result of different layers or patches of
material swirling around the brown dwarf in windy storms as large as
Earth itself. Spitzer and Hubble see different atmospheric layers
because certain infrared wavelengths are blocked by vapors of water
and methane high up, while other infrared wavelengths emerge from
much deeper layers.
"Unlike the water clouds of Earth or the ammonia clouds of Jupiter,
clouds on brown dwarfs are composed of hot grains of sand, liquid
drops of iron, and other exotic compounds," said Mark Marley,
research scientist at NASA's Ames Research Center in Moffett Field,
Calif., and co-author of the paper. "So this large atmospheric
disturbance found by Spitzer and Hubble gives a new meaning to the
concept of extreme weather."
According to Buenzli, this is the first time researchers can probe
variability at several different altitudes at the same time in the
atmosphere of a brown dwarf. "Although brown dwarfs are cool relative
to other stars, they are actually hot by earthly standards. This
particular object is about 1,100 to 1,300 degrees Fahrenheit (600 to
700 degrees Celsius)," Buenzli said.
"What we see here is evidence for massive, organized cloud systems,
perhaps akin to giant versions of the Great Red Spot on Jupiter,"
said Adam Showman, a theorist at the University of Arizona involved
in the research. "These out-of-sync light variations provide a
fingerprint of how the brown dwarf's weather systems stack up
vertically. The data suggest regions on the brown dwarf where the
weather is cloudy and rich in silicate vapor deep in the atmosphere
coincide with balmier, drier conditions at higher altitudes -- and
vice versa."
Researchers plan to look at the atmospheres of dozens of additional
nearby brown dwarfs using both Spitzer and Hubble.
"From studies such as this we will learn much about this important
class of objects, whose mass falls between that of stars and
Jupiter-sized planets." said Glenn Wahlgren, Spitzer Program
scientist at NASA Headquarters in Washington. "This technique will
see extensive use when we are able to image individual exoplanets."
WASHINGTON -- Astronomers using NASA's Spitzer and Hubble space
telescopes have probed the stormy atmosphere of a brown dwarf,
creating the most detailed "weather map" yet for this class of cool,
star-like orbs. The forecast shows wind-driven, planet-sized clouds
enshrouding these strange worlds.
Brown dwarfs form out of condensing gas, as stars do, but lack the
mass to fuse hydrogen atoms and produce energy. Instead, these
objects, which some call failed stars, are more similar to gas
planets with their complex, varied atmospheres. The new research is a
stepping stone toward a better understanding not only of brown
dwarfs, but also of the atmospheres of planets beyond our solar
system.
"With Hubble and Spitzer, we were able to look at different
atmospheric layers of a brown dwarf, similar to the way doctors use
medical imaging techniques to study the different tissues in your
body," said Daniel Apai, the principal investigator of the research
at the University of Arizona in Tucson, who presented the results at
the American Astronomical Society meeting Tuesday in Long Beach,
Calif.
A study describing the results, led by Esther Buenzli, also of the
University of Arizona, is published in the Astrophysical Journal
Letters.
The researchers turned Hubble and Spitzer simultaneously toward a
brown dwarf with the long name of 2MASSJ22282889-431026. They found
that its light varied in time, brightening and dimming about every 90
minutes as the body rotated. But more surprising, the team also found
the timing of this change in brightness depended on whether they
looked using different wavelengths of infrared light.
These variations are the result of different layers or patches of
material swirling around the brown dwarf in windy storms as large as
Earth itself. Spitzer and Hubble see different atmospheric layers
because certain infrared wavelengths are blocked by vapors of water
and methane high up, while other infrared wavelengths emerge from
much deeper layers.
"Unlike the water clouds of Earth or the ammonia clouds of Jupiter,
clouds on brown dwarfs are composed of hot grains of sand, liquid
drops of iron, and other exotic compounds," said Mark Marley,
research scientist at NASA's Ames Research Center in Moffett Field,
Calif., and co-author of the paper. "So this large atmospheric
disturbance found by Spitzer and Hubble gives a new meaning to the
concept of extreme weather."
According to Buenzli, this is the first time researchers can probe
variability at several different altitudes at the same time in the
atmosphere of a brown dwarf. "Although brown dwarfs are cool relative
to other stars, they are actually hot by earthly standards. This
particular object is about 1,100 to 1,300 degrees Fahrenheit (600 to
700 degrees Celsius)," Buenzli said.
"What we see here is evidence for massive, organized cloud systems,
perhaps akin to giant versions of the Great Red Spot on Jupiter,"
said Adam Showman, a theorist at the University of Arizona involved
in the research. "These out-of-sync light variations provide a
fingerprint of how the brown dwarf's weather systems stack up
vertically. The data suggest regions on the brown dwarf where the
weather is cloudy and rich in silicate vapor deep in the atmosphere
coincide with balmier, drier conditions at higher altitudes -- and
vice versa."
Researchers plan to look at the atmospheres of dozens of additional
nearby brown dwarfs using both Spitzer and Hubble.
"From studies such as this we will learn much about this important
class of objects, whose mass falls between that of stars and
Jupiter-sized planets." said Glenn Wahlgren, Spitzer Program
scientist at NASA Headquarters in Washington. "This technique will
see extensive use when we are able to image individual exoplanets."
Star Fomalhaut has a mysterious planet circling it
NASA'S HUBBLE REVEALS ROGUE PLANETARY ORBIT FOR FOMALHAUT
WASHINGTON -- Newly released NASA Hubble Space Telescope images of a
vast debris disk encircling the nearby star Fomalhaut and a
mysterious planet circling it may provide forensic evidence of a
titanic planetary disruption in the system.
Astronomers are surprised to find the debris belt is wider than
previously known, spanning a section of space from 14 to nearly 20
billion miles from the star. Even more surprisingly, the latest
Hubble images have allowed a team of astronomers to calculate the
planet follows an unusual elliptical orbit that carries it on a
potentially destructive path through the vast dust ring.
The planet, called Fomalhaut b, swings as close to its star as 4.6
billion miles, and the outermost point of its orbit is 27 billion
miles away from the star. The orbit was recalculated from the newest
Hubble observation made last year.
"We are shocked. This is not what we expected," said Paul Kalas of the
University of California at Berkeley and the SETI Institute in
Mountain View, Calif.
The Fomalhaut team led by Kalas considers this circumstantial evidence
there may be other planet-like bodies in the system that
gravitationally disturbed Fomalhaut b to place it in such a highly
eccentric orbit. The team presented its finding Tuesday at the 221st
meeting of the American Astronomical Society in Long Beach, Calif.
Among several scenarios to explain Fomalhaut b's 2,000-year-long orbit
is the hypothesis that an as yet undiscovered planet gravitationally
ejected Fomalhaut b from a position closer to the star, and sent it
flying in an orbit that extends beyond the dust belt.
"Hot Jupiters get tossed through scattering events, where one planet
goes in and one gets thrown out," said co-investigator Mark Clampin
of NASA's Goddard Space Flight Center in Greenbelt, Md. "This could
be the planet that gets thrown out."
Hubble also found the dust and ice belt encircling the star Fomalhaut
has an apparent gap slicing across the belt. This might have been
carved by another undetected planet. Hubble's exquisite view of the
dust belt shows irregularities that strongly motivate a search for
other planets in the system.
If its orbit lies in the same plane with the dust belt, then Fomalhaut
b will intersect the belt around 2032 on the outbound leg of its
orbit. During the crossing, icy and rocky debris in the belt could
crash into the planet's atmosphere and create the type of cosmic
fireworks seen when Comet Shoemaker-Levy 9 crashed into Jupiter. Most
of the fireworks from collisions will be seen in infrared light.
However, if Fomalhaut b is not co-planar with the belt, the only
thing to be seen will be a gradual dimming of Fomalhaut b as it
travels farther from the star.
Kalas hypothesized that Fomalhaut b's extreme orbit is a major clue in
explaining why the planet is unusually bright in visible light, but
very dim in infrared light. It is possible the planet's optical
brightness originates from a ring or shroud of dust around the
planet, which reflects starlight. The dust would be rapidly produced
by satellites orbiting the planet, which would suffer extreme erosion
by impacts and gravitational stirring when Fomalhaut b enters into
the planetary system after a millennium of deep freeze beyond the
main belt. An analogy can be found by looking at Saturn, which has a
tenuous, but very large dust ring produced when meteoroids hit the
outer moon Phoebe.
The team has also considered a different scenario where a hypothetical
second dwarf planet suffered a catastrophic collision with Fomalhaut
b. The collision scenario would explain why the star Fomalhaut has a
narrow outer belt linked to an extreme planet. But in this case the
belt is young, less than 10,000 years old, and it is difficult to
produce energetic collisions far from the star in such young systems.
Fomalhaut is a special system because it looks like scientists may
have a snapshot of what our solar system was doing 4 billion years
ago. The planetary architecture is being redrawn, the comet belts are
evolving, and planets may be gaining and losing their moons.
Astronomers will continue monitoring Fomalhaut b for decades to come
because they may have a chance to observe a planet entering an icy
debris belt that is like the Kuiper Belt at the fringe of our own
solar system.
WASHINGTON -- Newly released NASA Hubble Space Telescope images of a
vast debris disk encircling the nearby star Fomalhaut and a
mysterious planet circling it may provide forensic evidence of a
titanic planetary disruption in the system.
Astronomers are surprised to find the debris belt is wider than
previously known, spanning a section of space from 14 to nearly 20
billion miles from the star. Even more surprisingly, the latest
Hubble images have allowed a team of astronomers to calculate the
planet follows an unusual elliptical orbit that carries it on a
potentially destructive path through the vast dust ring.
The planet, called Fomalhaut b, swings as close to its star as 4.6
billion miles, and the outermost point of its orbit is 27 billion
miles away from the star. The orbit was recalculated from the newest
Hubble observation made last year.
"We are shocked. This is not what we expected," said Paul Kalas of the
University of California at Berkeley and the SETI Institute in
Mountain View, Calif.
The Fomalhaut team led by Kalas considers this circumstantial evidence
there may be other planet-like bodies in the system that
gravitationally disturbed Fomalhaut b to place it in such a highly
eccentric orbit. The team presented its finding Tuesday at the 221st
meeting of the American Astronomical Society in Long Beach, Calif.
Among several scenarios to explain Fomalhaut b's 2,000-year-long orbit
is the hypothesis that an as yet undiscovered planet gravitationally
ejected Fomalhaut b from a position closer to the star, and sent it
flying in an orbit that extends beyond the dust belt.
"Hot Jupiters get tossed through scattering events, where one planet
goes in and one gets thrown out," said co-investigator Mark Clampin
of NASA's Goddard Space Flight Center in Greenbelt, Md. "This could
be the planet that gets thrown out."
Hubble also found the dust and ice belt encircling the star Fomalhaut
has an apparent gap slicing across the belt. This might have been
carved by another undetected planet. Hubble's exquisite view of the
dust belt shows irregularities that strongly motivate a search for
other planets in the system.
If its orbit lies in the same plane with the dust belt, then Fomalhaut
b will intersect the belt around 2032 on the outbound leg of its
orbit. During the crossing, icy and rocky debris in the belt could
crash into the planet's atmosphere and create the type of cosmic
fireworks seen when Comet Shoemaker-Levy 9 crashed into Jupiter. Most
of the fireworks from collisions will be seen in infrared light.
However, if Fomalhaut b is not co-planar with the belt, the only
thing to be seen will be a gradual dimming of Fomalhaut b as it
travels farther from the star.
Kalas hypothesized that Fomalhaut b's extreme orbit is a major clue in
explaining why the planet is unusually bright in visible light, but
very dim in infrared light. It is possible the planet's optical
brightness originates from a ring or shroud of dust around the
planet, which reflects starlight. The dust would be rapidly produced
by satellites orbiting the planet, which would suffer extreme erosion
by impacts and gravitational stirring when Fomalhaut b enters into
the planetary system after a millennium of deep freeze beyond the
main belt. An analogy can be found by looking at Saturn, which has a
tenuous, but very large dust ring produced when meteoroids hit the
outer moon Phoebe.
The team has also considered a different scenario where a hypothetical
second dwarf planet suffered a catastrophic collision with Fomalhaut
b. The collision scenario would explain why the star Fomalhaut has a
narrow outer belt linked to an extreme planet. But in this case the
belt is young, less than 10,000 years old, and it is difficult to
produce energetic collisions far from the star in such young systems.
Fomalhaut is a special system because it looks like scientists may
have a snapshot of what our solar system was doing 4 billion years
ago. The planetary architecture is being redrawn, the comet belts are
evolving, and planets may be gaining and losing their moons.
Astronomers will continue monitoring Fomalhaut b for decades to come
because they may have a chance to observe a planet entering an icy
debris belt that is like the Kuiper Belt at the fringe of our own
solar system.
Sunday, October 21, 2012
Astronomers uncover a surprising trend in galaxy evolution
WASHINGTON -- A comprehensive study of hundreds of galaxies observed
by the Keck telescopes in Hawaii and NASA's Hubble Space Telescope
has revealed an unexpected pattern of change that extends back 8
billion years, or more than half the age of the universe.
"Astronomers thought disk galaxies in the nearby universe had settled
into their present form by about 8 billion years ago, with little
additional development since," said Susan Kassin, an astronomer at
NASA's Goddard Space Flight Center in Greenbelt, Md., and the study's
lead researcher. "The trend we've observed instead shows the
opposite, that galaxies were steadily changing over this time
period."
Today, star-forming galaxies take the form of orderly disk-shaped
systems, such as the Andromeda Galaxy or the Milky Way, where
rotation dominates over other internal motions. The most distant blue
galaxies in the study tend to be very different, exhibiting
disorganized motions in multiple directions. There is a steady shift
toward greater organization to the present time as the disorganized
motions dissipate and rotation speeds increase. These galaxies are
gradually settling into well-behaved disks.
Blue galaxies -- their color indicates stars are forming within them -- show less disorganized motions and ever-faster rotation speeds the closer they are observed to the present. This trend holds true for galaxies of all masses, but the most massive systems always show the highest level of organization.
Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way.
"Previous studies removed galaxies that did not look like the
well-ordered rotating disks now common in the universe today," said
co-author Benjamin Weiner, an astronomer at the University of Arizona
in Tucson. "By neglecting them, these studies examined only those
rare galaxies in the distant universe that are well-behaved and
concluded that galaxies didn't change."
Rather than limit their sample to certain galaxy types, the
researchers instead looked at all galaxies with emission lines bright
enough to be used for determining internal motions. Emission lines
are the discrete wavelengths of radiation characteristically emitted
by the gas within a galaxy. They are revealed when a galaxy's light
is separated into its component colors. These emission lines also
carry information about the galaxy's internal motions and distance.
The team studied a sample of 544 blue galaxies from the Deep
Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, a project
that employs Hubble and the twin 10-meter telescopes at the W. M.
Keck Observatory in Hawaii. Located between 2 billion and 8 billion
light-years away, the galaxies have stellar masses ranging from about
0.3 percent to 100 percent of the mass of our home galaxy.
A paper describing these findings will be published Oct. 20 in The
Astrophysical Journal.
The Milky Way galaxy must have gone through the same rough-and-tumble
evolution as the galaxies in the DEEP2 sample, and gradually settled
into its present state as the sun and solar system were being formed.
In the past 8 billion years, the number of mergers between galaxies
large and small has decreased sharply. So has the overall rate of
star formation and disruptions of supernova explosions associated
with star formation. Scientists speculate these factors may play a
role in creating the evolutionary trend they observe.
Now that astronomers see this pattern, they can adjust computer
simulations of galaxy evolution until these models are able to
replicate the observed trend. This will guide scientists to the
physical processes most responsible for it.
The DEEP2 survey is led by Lick Observatory at the University of
California at Santa Cruz in collaboration with the University of
California at Berkeley, the University of Hawaii at Manoa, Johns
Hopkins University in Baltimore, Md., the University of Chicago and
the California Institute of Technology in Pasadena.
The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space
Flight Center in Greenbelt, Md., manages the telescope. The Space
Telescope Science Institute (STScI) in Baltimore, Md., conducts
Hubble science operations. STScI is operated by the Association of
Universities for Research in Astronomy, Inc. in Washington.
by the Keck telescopes in Hawaii and NASA's Hubble Space Telescope
has revealed an unexpected pattern of change that extends back 8
billion years, or more than half the age of the universe.
"Astronomers thought disk galaxies in the nearby universe had settled
into their present form by about 8 billion years ago, with little
additional development since," said Susan Kassin, an astronomer at
NASA's Goddard Space Flight Center in Greenbelt, Md., and the study's
lead researcher. "The trend we've observed instead shows the
opposite, that galaxies were steadily changing over this time
period."
Today, star-forming galaxies take the form of orderly disk-shaped
systems, such as the Andromeda Galaxy or the Milky Way, where
rotation dominates over other internal motions. The most distant blue
galaxies in the study tend to be very different, exhibiting
disorganized motions in multiple directions. There is a steady shift
toward greater organization to the present time as the disorganized
motions dissipate and rotation speeds increase. These galaxies are
gradually settling into well-behaved disks.
Blue galaxies -- their color indicates stars are forming within them -- show less disorganized motions and ever-faster rotation speeds the closer they are observed to the present. This trend holds true for galaxies of all masses, but the most massive systems always show the highest level of organization.
Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way.
"Previous studies removed galaxies that did not look like the
well-ordered rotating disks now common in the universe today," said
co-author Benjamin Weiner, an astronomer at the University of Arizona
in Tucson. "By neglecting them, these studies examined only those
rare galaxies in the distant universe that are well-behaved and
concluded that galaxies didn't change."
Rather than limit their sample to certain galaxy types, the
researchers instead looked at all galaxies with emission lines bright
enough to be used for determining internal motions. Emission lines
are the discrete wavelengths of radiation characteristically emitted
by the gas within a galaxy. They are revealed when a galaxy's light
is separated into its component colors. These emission lines also
carry information about the galaxy's internal motions and distance.
The team studied a sample of 544 blue galaxies from the Deep
Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, a project
that employs Hubble and the twin 10-meter telescopes at the W. M.
Keck Observatory in Hawaii. Located between 2 billion and 8 billion
light-years away, the galaxies have stellar masses ranging from about
0.3 percent to 100 percent of the mass of our home galaxy.
A paper describing these findings will be published Oct. 20 in The
Astrophysical Journal.
The Milky Way galaxy must have gone through the same rough-and-tumble
evolution as the galaxies in the DEEP2 sample, and gradually settled
into its present state as the sun and solar system were being formed.
In the past 8 billion years, the number of mergers between galaxies
large and small has decreased sharply. So has the overall rate of
star formation and disruptions of supernova explosions associated
with star formation. Scientists speculate these factors may play a
role in creating the evolutionary trend they observe.
Now that astronomers see this pattern, they can adjust computer
simulations of galaxy evolution until these models are able to
replicate the observed trend. This will guide scientists to the
physical processes most responsible for it.
The DEEP2 survey is led by Lick Observatory at the University of
California at Santa Cruz in collaboration with the University of
California at Berkeley, the University of Hawaii at Manoa, Johns
Hopkins University in Baltimore, Md., the University of Chicago and
the California Institute of Technology in Pasadena.
The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space
Flight Center in Greenbelt, Md., manages the telescope. The Space
Telescope Science Institute (STScI) in Baltimore, Md., conducts
Hubble science operations. STScI is operated by the Association of
Universities for Research in Astronomy, Inc. in Washington.
Saturday, October 6, 2012
Two Black Holes Inhabit Same Star Cluster
by Ken Croswell
Black holes are antisocial: Not only do they gobble gas from the stars that orbit them, but according to theory, they also kick one another out of their homes. Now, however, astronomers say they have spotted two separate black holes that inhabit the same cluster of stars, suggesting more black holes await discovery—both in this cluster and in others, according to a report in the journal, Science.
Never before have astronomers found a black hole in a Milky Way star cluster. The star cluster in question is a so-called globular cluster, a tightly packed conglomeration containing hundreds of thousands of stars. All Milky Way globular clusters formed long ago, so their short-lived massive stars have died and become black holes. Each black hole weighs more than any of the many cluster stars that still shine and so should sink to the cluster's center. There, their large gravity ejects other black holes into the galaxy at large, leaving behind at most one black hole system.
At least, that's how the theory went. Now, astronomer Jay Strader of Michigan State University in East Lansing and colleagues report online today in Nature that they have found two separate black holes in M22, a globular cluster 10,000 light-years from Earth in the constellation Sagittarius. Observations with the Very Large Array near Socorro, New Mexico, revealed two objects whose radio spectra resemble those of other black hole systems located outside of star clusters.
The discovery came as a surprise. "We were pretty excited," says astronomer and team member Thomas Maccarone of the University of Southampton in the United Kingdom. "But we wanted to be cautious and make sure that we could rule out all the other possibilities." For example, the scientists say that white dwarfs or neutron stars wouldn't emit so many radio waves.
"It's a pretty significant discovery," says Stefan Umbreit, an astrophysicist at Northwestern University in Evanston, Illinois, who was not part of the team. "This is an indication that the [black hole] ejection process is not as efficient as we thought."
However, astronomer Shrinivas Kulkarni of the California Institute of Technology in Pasadena is skeptical—and even willing to bet $100 that neither object is a black hole. "Great results need great proof," he says. "This doesn't convince me." Given M22's plethora of stars, Kulkarni says the cluster could easily have some odd star that mimics a black hole system's peculiar radio spectrum.
If the discoveries hold up, though, they represent two firsts. They're the first black holes ever found in a Milky Way star cluster. They're also the first stellar-mass black holes discovered by means of radio waves. Other stellar-mass black holes—such as the one in Cygnus X-1, the first black hole found—came to attention because hot gas swirling into the black holes emits x-rays.
In fact, Strader's team detected no x-rays from the black hole systems, indicating they give off far more radio waves than x-rays. Strader says that's a characteristic of black holes that are 10 times to 20 times as massive as the sun, on the heavy side for stellar-mass black holes, making them comparable to the black hole in Cygnus X-1, which is 15 solar masses. Furthermore, both of M22's black holes lie within just a couple of light-years of the cluster's center, a location consistent with high masses, because heavy objects should sink into the cluster's core. But Kulkarni counters that such massive objects should sink even closer to the center and says the lack of x-rays means they aren't black holes at all.
If the objects are black holes, however, each presumably has a star that orbits it and dumps material onto it in order to generate the observed radio waves. In one case, observations with the Hubble Space Telescope reveal that the putative black hole lies near a red dwarf, a star much smaller, cooler, and fainter than the sun. In the other case, the companion may be an orange dwarf, whose properties lie between those of a red dwarf and the sun. But the astronomers aren't sure, and they hope to use Hubble to make additional observations.
The discovery suggests that M22 hosts yet more black holes, because black holes without stellar partners wouldn't emit radio waves. "I think it's pretty likely," Strader says. If so, black holes may not be as antisocial as thought—although you probably wouldn't want to invite them to a party.
Sunday, September 23, 2012
Stars outside the solar system too have planets, says Nasa
FIRST PLANETS FOUND AROUND SUN-LIKE STARS IN A CLUSTER
NASA-funded astronomers have, for the first time,
spotted planets orbiting sun-like stars in a crowded cluster of
stars. The findings offer the best evidence yet planets can sprout up
in dense stellar environments. Although the newfound planets are not
habitable, their skies would be starrier than what we see from Earth.
The starry-skied planets are two so-called hot Jupiters, which are
massive, gaseous orbs that are boiling hot because they orbit tightly
around their parent stars. Each hot Jupiter circles a different
sun-like star in the Beehive Cluster, also called the Praesepe, a
collection of roughly 1,000 stars that appear to be swarming around a
common center, says a Nasa statement.
The Beehive is an open cluster, or a grouping of stars born at about
the same time and out of the same giant cloud of material. As such,
the stars share a similar chemical composition. Unlike the majority
of stars, which spread out shortly after birth, these young stars
remain loosely bound together by mutual gravitational attraction.
"We are detecting more and more planets that can thrive in diverse and
extreme environments like these nearby clusters," said Mario R.
Perez, the NASA astrophysics program scientist in the Origins of
Solar Systems Program. "Our galaxy contains more than 1,000 of these
open clusters, which potentially can present the physical conditions
for harboring many more of these giant planets."
The two new Beehive planets are called Pr0201b and Pr0211b. The star's
name followed by a "b" is the standard naming convention for planets.
"These are the first 'b's' in the Beehive," said Sam Quinn, a graduate
student in astronomy at Georgia State University in Atlanta and the
lead author of the paper describing the results, which was published
in the Astrophysical Journal Letters.
Quinn and his team, in collaboration with David Latham at the
Harvard-Smithsonian Center for Astrophysics, discovered the planets
by using the 1.5-meter Tillinghast telescope at the Smithsonian
Astrophysical Observatory's Fred Lawrence Whipple Observatory in
Arizona to measure the slight gravitational wobble the orbiting
planets induce upon their host stars. Previous searches of clusters
had turned up two planets around massive stars but none had been
found around stars like our sun until now.
"This has been a big puzzle for planet hunters," Quinn said. "We know
that most stars form in clustered environments like the Orion nebula,
so unless this dense environment inhibits planet formation, at least
some sun-like stars in open clusters should have planets. Now, we
finally know they are indeed there."
The results also are of interest to theorists who are trying to
understand how hot Jupiters wind up so close to their stars. Most
theories contend these blistering worlds start out much cooler and
farther from their stars before migrating inward.
"The relatively young age of the Beehive cluster makes these planets
among the youngest known," said Russel White, the principal
investigator on the NASA Origins of Solar Systems grant that funded
this study. "And that's important because it sets a constraint on how
quickly giant planets migrate inward. And knowing how quickly they
migrate is the first step to figuring out how they migrate."
The research team suspects planets were turned up in the Beehive
cluster because it is rich in metals. Stars in the Beehive have more
heavy elements such as iron than the sun has.
According to White, "Searches for planets around nearby stars suggest
that these metals act like a 'planet fertilizer,' leading to an
abundant crop of gas-giant planets. Our results suggest this may be
true in clusters as well."
Microbial life on the Mars? Nasa Mars rover Opportunity reveals geological mystery of the Red Planet
NASA MARS ROVER OPPORTUNITY REVEALS GEOLOGICAL MYSTERY
NASA's long-lived rover Opportunity has returned
an image of the Martian surface that is puzzling researchers.
Spherical objects concentrated at an outcrop Opportunity reached last
week differ in several ways from iron-rich spherules nicknamed
"blueberries" the rover found at its landing site in early 2004 and
at many other locations to date, says a NASA statement.
Opportunity is investigating an outcrop called Kirkwood in the Cape
York segment of the western rim of Endeavour Crater. The spheres
measure as much as one-eighth of an inch (3 millimeters) in diameter.
The analysis is still preliminary, but it indicates that these
spheres do not have the high iron content of Martian blueberries.
"This is one of the most extraordinary pictures from the whole
mission," said Opportunity's principal investigator, Steve Squyres of
Cornell University in Ithaca, N.Y. "Kirkwood is chock full of a dense
accumulation of these small spherical objects. Of course, we
immediately thought of the blueberries, but this is something
different. We never have seen such a dense accumulation of spherules
in a rock outcrop on Mars."
The Martian blueberries found elsewhere by Opportunity are concretions
formed by action of mineral-laden water inside rocks, evidence of a
wet environment on early Mars. Concretions result when minerals
precipitate out of water to become hard masses inside sedimentary
rocks. Many of the Kirkwood spheres are broken and eroded by the
wind. Where wind has partially etched them away, a concentric
structure is evident.
Opportunity used the microscopic imager on its arm to look closely at
Kirkwood. Researchers checked the spheres' composition by using an
instrument called the Alpha Particle X-Ray Spectrometer on
Opportunity's arm.
"They seem to be crunchy on the outside, and softer in the middle,"
Squyres said. "They are different in concentration. They are
different in structure. They are different in composition. They are
different in distribution. So, we have a wonderful geological puzzle
in front of us. We have multiple working hypotheses, and we have no
favorite hypothesis at this time. It's going to take a while to work
this out, so the thing to do now is keep an open mind and let the
rocks do the talking."
Just past Kirkwood lies another science target area for Opportunity.
The location is an extensive pale-toned outcrop in an area of Cape
York where observations from orbit have detected signs of clay
minerals. That may be the rover's next study site after Kirkwood.
Four years ago, Opportunity departed Victoria Crater, which it had
investigated for two years, to reach different types of geological
evidence at the rim of the much larger Endeavour Crater.
The rover's energy levels are favorable for the investigations. Spring
equinox comes this month to Mars' southern hemisphere, so the amount
of sunshine for solar power will continue increasing for months.
"The rover is in very good health considering its 8-1/2 years of hard
work on the surface of Mars," said Mars Exploration Rover Project
Manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena,
Calif. "Energy production levels are comparable to what they were a
full Martian year ago, and we are looking forward to productive
spring and summer seasons of exploration."
NASA launched the Mars rovers Spirit and Opportunity in the summer of
2003, and both completed their three-month prime missions in April
2004. They continued bonus, extended missions for years. Spirit
finished communicating with Earth in March 2010. The rovers have made
important discoveries about wet environments on ancient Mars that may
have been favorable for supporting microbial life.
NASA's long-lived rover Opportunity has returned
an image of the Martian surface that is puzzling researchers.
Spherical objects concentrated at an outcrop Opportunity reached last
week differ in several ways from iron-rich spherules nicknamed
"blueberries" the rover found at its landing site in early 2004 and
at many other locations to date, says a NASA statement.
Opportunity is investigating an outcrop called Kirkwood in the Cape
York segment of the western rim of Endeavour Crater. The spheres
measure as much as one-eighth of an inch (3 millimeters) in diameter.
The analysis is still preliminary, but it indicates that these
spheres do not have the high iron content of Martian blueberries.
"This is one of the most extraordinary pictures from the whole
mission," said Opportunity's principal investigator, Steve Squyres of
Cornell University in Ithaca, N.Y. "Kirkwood is chock full of a dense
accumulation of these small spherical objects. Of course, we
immediately thought of the blueberries, but this is something
different. We never have seen such a dense accumulation of spherules
in a rock outcrop on Mars."
The Martian blueberries found elsewhere by Opportunity are concretions
formed by action of mineral-laden water inside rocks, evidence of a
wet environment on early Mars. Concretions result when minerals
precipitate out of water to become hard masses inside sedimentary
rocks. Many of the Kirkwood spheres are broken and eroded by the
wind. Where wind has partially etched them away, a concentric
structure is evident.
Opportunity used the microscopic imager on its arm to look closely at
Kirkwood. Researchers checked the spheres' composition by using an
instrument called the Alpha Particle X-Ray Spectrometer on
Opportunity's arm.
"They seem to be crunchy on the outside, and softer in the middle,"
Squyres said. "They are different in concentration. They are
different in structure. They are different in composition. They are
different in distribution. So, we have a wonderful geological puzzle
in front of us. We have multiple working hypotheses, and we have no
favorite hypothesis at this time. It's going to take a while to work
this out, so the thing to do now is keep an open mind and let the
rocks do the talking."
Just past Kirkwood lies another science target area for Opportunity.
The location is an extensive pale-toned outcrop in an area of Cape
York where observations from orbit have detected signs of clay
minerals. That may be the rover's next study site after Kirkwood.
Four years ago, Opportunity departed Victoria Crater, which it had
investigated for two years, to reach different types of geological
evidence at the rim of the much larger Endeavour Crater.
The rover's energy levels are favorable for the investigations. Spring
equinox comes this month to Mars' southern hemisphere, so the amount
of sunshine for solar power will continue increasing for months.
"The rover is in very good health considering its 8-1/2 years of hard
work on the surface of Mars," said Mars Exploration Rover Project
Manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena,
Calif. "Energy production levels are comparable to what they were a
full Martian year ago, and we are looking forward to productive
spring and summer seasons of exploration."
NASA launched the Mars rovers Spirit and Opportunity in the summer of
2003, and both completed their three-month prime missions in April
2004. They continued bonus, extended missions for years. Spirit
finished communicating with Earth in March 2010. The rovers have made
important discoveries about wet environments on ancient Mars that may
have been favorable for supporting microbial life.
What lies in the Red Planet Mars: Latest photos further deepen mystery of the Earth's neighbour
Mystery Spheres on Mars
NASA's long-lived rover Opportunity has returned an image of the Martian surface that is puzzling researchers.
Spherical objects concentrated at an outcrop called Kirkwood on the western rim of Endeavour Crater differ in several ways from iron-rich spherules nicknamed "blueberries" the rover found at its landing site in early 2004.
"This is one of the most extraordinary pictures from the whole mission," said Opportunity's principal investigator, Steve Squyres of Cornell University in Ithaca, N.Y. "Kirkwood is chock full of a dense accumulation of these small spherical objects. Of course, we immediately thought of the blueberries, but this is something different. We never have seen such a dense accumulation of spherules in a rock outcrop on Mars."
The Martian blueberries found elsewhere by Opportunity are concretions formed by action of mineral-laden water inside rocks, evidence of a wet environment on early Mars. Concretions result when minerals precipitate out of water to become hard masses inside sedimentary rocks. Many of the Kirkwood spheres are broken and eroded by the wind. Where wind has partially etched them away, a concentric structure is evident.
Opportunity used the microscopic imager on its arm to look closely at Kirkwood. Researchers checked the spheres' composition by using an instrument called the Alpha Particle X-Ray Spectrometer on Opportunity's arm.
"They seem to be crunchy on the outside, and softer in the middle," Squyres said. "They are different in concentration. They are different in structure. They are different in composition. They are different in distribution. So, we have a wonderful geological puzzle in front of us. We have multiple working hypotheses, and we have no favorite hypothesis at this time. It's going to take a while to work this out, so the thing to do now is keep an open mind and let the rocks do the talking."
Just past Kirkwood lies another science target area for Opportunity. The location is an extensive pale-toned outcrop in an area of Cape York where observations from orbit have detected signs of clay minerals. That may be the rover's next study site after Kirkwood. Four years ago, Opportunity departed Victoria Crater, which it had investigated for two years, to reach different types of geological evidence at the rim of the much larger Endeavour Crater.
The rover's energy levels are favorable for the investigations. Spring equinox comes this month to Mars' southern hemisphere, so the amount of sunshine for solar power will continue increasing for months. Indeed, Opportunity is on the verge of completing the first Martian Marthon.
"The rover is in very good health considering its 8-1/2 years of hard work on the surface of Mars," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Energy production levels are comparable to what they were a full Martian year ago, and we are looking forward to productive spring and summer seasons of exploration."
Monday, June 25, 2012
The story of voyager 1: Reaching the edge of the solar system, the first man-made object to reach such a far destination
For nearly 35 years, NASA’s Voyager 1 probe has been hurtling toward the edge of the solar system, flying through the dark void on a mission unlike anything attempted before. One day, mission controllers hope, Voyager 1 will leave the solar system behind and enter the realm of the stars—interstellar space.
That day may be upon us.
"The latest data from Voyager 1 indicate that we are clearly in a new region where things are changing quickly," says Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. This is very exciting. We are approaching the solar system's final frontier."
The “frontier” he’s referring to is the edge of the heliosphere, a great magnetic bubble that surrounds the sun and planets. The heliosphere is the sun’s own magnetic field inflated to gargantuan proportions by the solar wind. Inside lies the solar system—“home.” Outside lies interstellar space, where no spacecraft has gone before.
A telltale sign of the frontier’s approach is the number of cosmic rays hitting Voyager 1. Cosmic rays are high energy particles such as protons and helium nuclei accelerated to near-light speed by distant supernovas and black holes. The heliosphere protects the solar system from these subatomic bullets, deflecting and slowing many of them before they can reach the inner planets.
As Voyager approaches the frontier, the number of cosmic rays has gone up.
"From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering," says Stone.
"More recently, however, we have seen a very rapid escalation in that part of the energy spectrum. Beginning on May 7, 2012, the cosmic ray hits have increased five percent in a week and nine percent in a month."
The sharp increase means that Voyager 1 could be on the verge of a breakthrough 18 billion kilometers from Earth.
When Voyager 1 actually exits the heliosphere, researchers expect to see other changes as well. For one thing, energetic particles from the sun will become scarce as the spacecraft leaves the heliosphere behind. Also, the magnetic field around Voyager 1 will change direction from that of the sun’s magnetic field to that of the new and unexplored magnetism of interstellar space.
So far, neither of these things has happened. Nevertheless, the sudden increase in cosmic rays suggests it might not be long.
Meanwhile, Voyager 2 is making its own dash for the stars, but because of its slower pace lags a few billion kilometers behind Voyager 1. Both spacecraft remain in good health.
"When the Voyagers launched in 1977, the Space Age was all of 20 years old," says Stone. "Many of us on the team dreamed of reaching interstellar space, but we really had no way of knowing how long a journey it would be -- or if these two vehicles that we invested so much time and energy in would operate long enough to reach it. "
Friday, June 22, 2012
How much water does our Moon hold? 22 per cent? May be at the poles
Evidence Mounts for Ice in Shackleton Crater
According to data from NASA's Lunar Reconnaissance Orbiter (LRO), ice may make up as much as 22 percent of the surface material in Shackleton crater at the Moon's south pole.
The huge crater, named after the Antarctic explorer Ernest Shackleton, is two miles deep and more than 12 miles wide. The small tilt of the lunar spin axis means Shackleton's interior is permanently dark and very cold.. Researchers have long thought that ice might collect there.
When a team of NASA and university scientists used LRO's laser altimeter to examine the floor of Shackleton crater, they found it to be brighter than the floors of other nearby craters around the South Pole. This is consistent with the presence of small amounts of reflective ice preserved by cold and darkness. The findings are published in the journal Nature.
The huge crater, named after the Antarctic explorer Ernest Shackleton, is two miles deep and more than 12 miles wide. The small tilt of the lunar spin axis means Shackleton's interior is permanently dark and very cold.. Researchers have long thought that ice might collect there.
When a team of NASA and university scientists used LRO's laser altimeter to examine the floor of Shackleton crater, they found it to be brighter than the floors of other nearby craters around the South Pole. This is consistent with the presence of small amounts of reflective ice preserved by cold and darkness. The findings are published in the journal Nature.
In addition to the possible evidence of ice, the group's map of Shackleton revealed a remarkably preserved crater that has remained relatively unscathed since its formation more than three billion years ago. The crater's floor is itself pocked with several small craters, which may have formed as part of the collision that created Shackleton.
"The crater's interior is extremely rugged," said Maria Zuber, the team's lead investigator from the Massachusetts Institute of Technology in Cambridge in Mass. "It would not be easy to crawl around in there."
"The crater's interior is extremely rugged," said Maria Zuber, the team's lead investigator from the Massachusetts Institute of Technology in Cambridge in Mass. "It would not be easy to crawl around in there."
While the crater's floor was relatively bright, Zuber and her colleagues observed that its walls were even brighter. The finding was at first puzzling. Scientists had thought that if ice were anywhere in a crater, it would be on the floor, where no direct sunlight penetrates. The upper walls of Shackleton crater are occasionally illuminated, which could evaporate any ice that accumulates.
"The brightness measurements have been puzzling us since two summers ago," said Gregory Neumann of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper.
A theory offered by the team to explain the puzzle is that "moonquakes"-- seismic shaking brought on by meteorite impacts or gravitational tides from Earth -- may have caused Shackleton's walls to slough off older, darker soil, revealing newer, brighter soil underneath. Zuber's team's ultra-high-resolution map provides strong evidence for ice on both the crater's floor and walls.
"There may be multiple explanations for the observed brightness throughout the crater," said Zuber. "For example, newer material may be exposed along its walls, while ice may be mixed in with its floor."
A theory offered by the team to explain the puzzle is that "moonquakes"-- seismic shaking brought on by meteorite impacts or gravitational tides from Earth -- may have caused Shackleton's walls to slough off older, darker soil, revealing newer, brighter soil underneath. Zuber's team's ultra-high-resolution map provides strong evidence for ice on both the crater's floor and walls.
"There may be multiple explanations for the observed brightness throughout the crater," said Zuber. "For example, newer material may be exposed along its walls, while ice may be mixed in with its floor."
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