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.
Wednesday, January 9, 2013
Peanut allergy: New methods to treat allergy to peanuts
Peanut Therapy Shows Promise in Treating Peanut Allergy
NIH-Funded Clinical Study is One of the First to Evaluate Sublingual Immunotherapy as a Peanut Allergy Treatment
A new study supported by the National Institutes of Health (NIH) suggests that sublingual immunotherapy (SLIT) can reduce the allergic response to peanut in adolescents and adults. SLIT is a treatment approach in which, under medical supervision, people place a small amount of allergen under the tongue to decrease their sensitivity to the allergen. This is one of the first randomized, placebo-controlled studies to test the efficacy and safety of SLIT to treat peanut allergy and is one of several federally funded trials investigating immune-based approaches to preventing and treating food allergy. The results appear online in the January issue of the Journal of Allergy and Clinical Immunology.
The study enrolled 40 people aged 12 to 37 years with peanut allergy who were on a peanut-free diet. After an initial food challenge to measure how much peanut powder they could eat without having an allergic reaction, participants received 44 weeks of daily therapy, followed by a second food challenge. Fourteen of the 20 participants (70 percent) given peanut SLIT were able to consume at least 10 times more peanut powder than they could at the beginning of the study, compared with only 3 of the 20 participants (15 percent) given placebo. After 68 weeks on peanut SLIT, on average, participants could consume significantly more peanut powder without having an allergic reaction. Study investigators also observed that SLIT caused only minor side effects, such as itching in the mouth, suggesting that daily therapy is safe.
Although more work is needed, the investigators hope that SLIT could one day help protect people with peanut allergy from experiencing severe allergic reactions in cases of accidental exposure. The researchers caution that people should not try peanut SLIT on their own because any form of immunotherapy carries a significant risk for allergic reactions. The therapy should be administered only under the guidance of trained clinicians.
The multicenter study was supported by the NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and conducted by the Consortium of Food Allergy Research (CoFAR) at clinical sites in Baltimore; Chapel Hill, N.C.; Denver; Little Rock, Ark.; and New York City. CoFAR investigators David Fleischer, M.D., associate professor of pediatrics in the Division of Pediatric Allergy and Immunology at National Jewish Health in Denver, and A. Wesley Burks, M.D., chair of the Department of Pediatrics at the University of North Carolina, Chapel Hill, led the trial.
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."
Subscribe to:
Posts (Atom)