Wednesday, 18 January 2012
Jupiter Probe Snaps Picture of Earth & Moon at 6 Million Miles
NASA's Wise Mission Discovers Coolest Class of Stars
Scientists using data from NASA's Wide-field Infrared Survey Explorer (WISE) have discovered the coldest class of star-like bodies, with temperatures as cool as the human body.
Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success. When viewed with a visible-light telescope, they are nearly impossible to see. WISE's infrared vision allowed the telescope to finally spot the faint glow of six Y dwarfs relatively close to our sun, within a distance of about 40 light-years.
"WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. "They are 5,000 times brighter at the longer infrared wavelengths WISE observed from space than those observable from the ground."
The Y's are the coldest members of the brown dwarf family. Brown dwarfs are sometimes referred to as "failed" stars. They are too low in mass to fuse atoms at their cores and thus don't burn with the fires that keep stars like our sun shining steadily for billions of years. Instead, these objects cool and fade with time, until what little light they do emit is at infrared wavelengths.
Astronomers study brown dwarfs to better understand how stars form, and to understand the atmospheres of planets beyond our solar system. The atmospheres of brown dwarfs are similar to those of gas-giant planets like Jupiter, but they are easier to observe because they are alone in space, away from the blinding light of a parent star.
So far, WISE data have revealed 100 new brown dwarfs. More discoveries are expected as scientists continue to examine the enormous quantity of data from WISE. The telescope performed the most advanced survey of the sky at infrared wavelengths to date, from Jan. 2010 to Feb. 2011, scanning the entire sky about 1.5 times.
Of the 100 brown dwarfs, six are classified as cool Y's. One of the Y dwarfs, called WISE 1828+2650, is the record holder for the coldest brown dwarf, with an estimated atmospheric temperature cooler than room temperature, or less than about 80 degrees Fahrenheit (25 degrees Celsius).
"The brown dwarfs we were turning up before this discovery were more like the temperature of your oven," said Davy Kirkpatrick, a WISE science team member at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, Calif. "With the discovery of Y dwarfs, we've moved out of the kitchen and into the cooler parts of the house."
Kirkpatrick is lead author of a paper appearing in the Astrophysical Journal Supplement Series, describing the 100 confirmed brown dwarfs. Michael Cushing, a WISE team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif., is lead author of a paper describing the Y dwarfs in the Astrophysical Journal.
The Y dwarfs are in our sun's neighborhood, from approximately nine to 40 light-years away. The Y dwarf approximately nine light-years away, WISE 1541-2250, may become the seventh closest star system, bumping Ross 154 back to eighth. By comparison, the star closest to our solar system, Proxima Centauri, is about four light-years away.
"Finding brown dwarfs near our sun is like discovering there's a hidden house on your block that you didn't know about," Cushing said. "It's thrilling to me to know we've got neighbors out there yet to be discovered. With WISE, we may even find a brown dwarf closer to us than our closest known star."
Once the WISE team identified brown dwarf candidates, they turned to NASA's Spitzer Space Telescope to narrow their list. To definitively confirm them, the WISE team used some of the most powerful telescopes on Earth to split apart the objects' light and look for telltale molecular signatures of water, methane and possibly ammonia. For the very coldest of the new Y dwarfs, the team used NASA's Hubble Space Telescope. The Y dwarfs were identified based on a change in these spectral features compared to other brown dwarfs, indicating they have a lower atmospheric temperature.
Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success. When viewed with a visible-light telescope, they are nearly impossible to see. WISE's infrared vision allowed the telescope to finally spot the faint glow of six Y dwarfs relatively close to our sun, within a distance of about 40 light-years.
"WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. "They are 5,000 times brighter at the longer infrared wavelengths WISE observed from space than those observable from the ground."
The Y's are the coldest members of the brown dwarf family. Brown dwarfs are sometimes referred to as "failed" stars. They are too low in mass to fuse atoms at their cores and thus don't burn with the fires that keep stars like our sun shining steadily for billions of years. Instead, these objects cool and fade with time, until what little light they do emit is at infrared wavelengths.
Astronomers study brown dwarfs to better understand how stars form, and to understand the atmospheres of planets beyond our solar system. The atmospheres of brown dwarfs are similar to those of gas-giant planets like Jupiter, but they are easier to observe because they are alone in space, away from the blinding light of a parent star.
So far, WISE data have revealed 100 new brown dwarfs. More discoveries are expected as scientists continue to examine the enormous quantity of data from WISE. The telescope performed the most advanced survey of the sky at infrared wavelengths to date, from Jan. 2010 to Feb. 2011, scanning the entire sky about 1.5 times.
Of the 100 brown dwarfs, six are classified as cool Y's. One of the Y dwarfs, called WISE 1828+2650, is the record holder for the coldest brown dwarf, with an estimated atmospheric temperature cooler than room temperature, or less than about 80 degrees Fahrenheit (25 degrees Celsius).
"The brown dwarfs we were turning up before this discovery were more like the temperature of your oven," said Davy Kirkpatrick, a WISE science team member at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, Calif. "With the discovery of Y dwarfs, we've moved out of the kitchen and into the cooler parts of the house."
Kirkpatrick is lead author of a paper appearing in the Astrophysical Journal Supplement Series, describing the 100 confirmed brown dwarfs. Michael Cushing, a WISE team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif., is lead author of a paper describing the Y dwarfs in the Astrophysical Journal.
The Y dwarfs are in our sun's neighborhood, from approximately nine to 40 light-years away. The Y dwarf approximately nine light-years away, WISE 1541-2250, may become the seventh closest star system, bumping Ross 154 back to eighth. By comparison, the star closest to our solar system, Proxima Centauri, is about four light-years away.
"Finding brown dwarfs near our sun is like discovering there's a hidden house on your block that you didn't know about," Cushing said. "It's thrilling to me to know we've got neighbors out there yet to be discovered. With WISE, we may even find a brown dwarf closer to us than our closest known star."
Once the WISE team identified brown dwarf candidates, they turned to NASA's Spitzer Space Telescope to narrow their list. To definitively confirm them, the WISE team used some of the most powerful telescopes on Earth to split apart the objects' light and look for telltale molecular signatures of water, methane and possibly ammonia. For the very coldest of the new Y dwarfs, the team used NASA's Hubble Space Telescope. The Y dwarfs were identified based on a change in these spectral features compared to other brown dwarfs, indicating they have a lower atmospheric temperature.
NASA Spacecraft Data Suggest Water Flowing on Mar
Coloring of the map is coded to concentrations of shallow subsurface water ice found by the Gamma Ray Spectrometer - Neutron Spectrometer on NASA's Mars Odyssey orbiter. Blue, at high latitudes north and south, indicates higher concentrations of water ice (deduced from detection of hydrogen); orange designates lowest concentrations. Some hydrogen, possibly in the form of bound water, is close to the surface even at middle latitudes.
The white squares in the northern hemisphere mark locations of small fresh impact craters that exposed water ice close to the surface and validated the neutron spectrometer data. Observations of these fresh craters were made by the Context Camera and the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter.
The red squares mark locations of putative deposits of chloride based on observations by the Thermal Emission Imaging System on Mars Odyssey. Such salt deposits could have resulted from evaporation of salty water.
The blue squares mark locations of a type of feature reported in August 2011 based on sequences of observations by the High Resolution Imaging Science Experiment. The observations show relatively dark features appearing and incrementally growing down slopes during warm seasons. Researchers hypothesize that these features may result from action of briny water. Other imagery related to these new findings from the Mars Reconnaissance Orbiter is at http://www.nasa.gov/mission_pages/MRO/multimedia/gallery/gallery-index.html.
Herschel Telescope Detects Oxygen Molecules in Space
The Herschel Space Observatory's large telescope and state-of-the-art infrared detectors have provided the first confirmed finding of oxygen molecules in space. The molecules were discovered in the Orion star-forming complex.
Individual atoms of oxygen are common in space, particularly around massive stars. But molecular oxygen, which makes up about 20 percent of the air we breathe, has eluded astronomers until now.
"Oxygen gas was discovered in the 1770s, but it's taken us more than 230 years to finally say with certainty that this very simple molecule exists in space," said Paul Goldsmith, NASA's Herschel project scientist at the agency's Jet Propulsion Laboratory in Pasadena, Calif. Goldsmith is lead author of a recent paper describing the findings in the Astrophysical Journal. Herschel is a European Space Agency-led mission with important NASA contributions.
Astronomers searched for the elusive molecules in space for decades using balloons, as well as ground- and space-based telescopes. The Swedish Odin telescope spotted the molecule in 2007, but the sighting could not be confirmed.
Goldsmith and his colleagues propose that oxygen is locked up in water ice that coats tiny dust grains. They think the oxygen detected by Herschel in the Orion nebula was formed after starlight warmed the icy grains, releasing water, which was converted into oxygen molecules.
"This explains where some of the oxygen might be hiding," said Goldsmith. "But we didn't find large amounts of it, and still don't understand what is so special about the spots where we find it. The universe still holds many secrets."
Individual atoms of oxygen are common in space, particularly around massive stars. But molecular oxygen, which makes up about 20 percent of the air we breathe, has eluded astronomers until now.
"Oxygen gas was discovered in the 1770s, but it's taken us more than 230 years to finally say with certainty that this very simple molecule exists in space," said Paul Goldsmith, NASA's Herschel project scientist at the agency's Jet Propulsion Laboratory in Pasadena, Calif. Goldsmith is lead author of a recent paper describing the findings in the Astrophysical Journal. Herschel is a European Space Agency-led mission with important NASA contributions.
Astronomers searched for the elusive molecules in space for decades using balloons, as well as ground- and space-based telescopes. The Swedish Odin telescope spotted the molecule in 2007, but the sighting could not be confirmed.
Goldsmith and his colleagues propose that oxygen is locked up in water ice that coats tiny dust grains. They think the oxygen detected by Herschel in the Orion nebula was formed after starlight warmed the icy grains, releasing water, which was converted into oxygen molecules.
"This explains where some of the oxygen might be hiding," said Goldsmith. "But we didn't find large amounts of it, and still don't understand what is so special about the spots where we find it. The universe still holds many secrets."
NASA and Chevron Partner to Benefit the Energy Industry
NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Chevron Corporation in San Ramon, Calif., have announced a partnership to develop a range of advanced technologies that can be used in harsh environments, both on Earth and in space.
"We are proud that the same pool of talent that sends rovers to Mars, explores our universe and studies Earth's environment will help contribute advanced technology towards our energy future here on Earth," said JPL Director Charles Elachi.
Elachi and Paul Siegele, president of Chevron Energy Technology Company, met at JPL to kick off a partnership for Advanced Energy Technology Development. Under this partnership, JPL will assist in the demonstration, development and commercial deployment of a range of technologies that benefit from JPL's unique heritage in space exploration. These technologies include: valves to selectively control oil and gas flow from different geological formations in a well; single-phase pumping motors for continuous operation at the bottom of deep wells; sensors and electronics for downhole deployment; and integrated management systems for monitoring temperature, pressure and flow rates in deep wells and assessing the health of drilling operations.
This new collaboration will benefit NASA by further advancing technologies that could one day be used for exploring other planets, and will also promote commercialization of technologies developed for space exploration. The partnership will help Chevron develop its energy resources to enable a better energy future for all of us.
"NASA and JPL are highly acclaimed national treasures, and Chevron is proud to collaborate with them to unlock new energy potential," said John McDonald, Chevron's corporate vice president and chief technology officer. "This alliance is an opportunity to bridge public- and private-sector technology and research to discover oil and natural gas volumes that are found in deep remote reservoirs. In many ways, the research is akin to deep space exploration, making the missions of our two organizations highly complementary."
As NASA's lead center for robotic exploration of the solar system, JPL has a wide-ranging charter that also includes active programs in Earth science, astronomy and physics, and technology development. The demands of space missions provide the impetus to JPL scientists and engineers to push the boundaries of design and technology to achieve smaller size, better performance, and less power consumption in a cost-constrained environment. Many technologies developed at JPL, from hardware and software to materials, have direct applications right here on Earth.
"We are proud that the same pool of talent that sends rovers to Mars, explores our universe and studies Earth's environment will help contribute advanced technology towards our energy future here on Earth," said JPL Director Charles Elachi.
Elachi and Paul Siegele, president of Chevron Energy Technology Company, met at JPL to kick off a partnership for Advanced Energy Technology Development. Under this partnership, JPL will assist in the demonstration, development and commercial deployment of a range of technologies that benefit from JPL's unique heritage in space exploration. These technologies include: valves to selectively control oil and gas flow from different geological formations in a well; single-phase pumping motors for continuous operation at the bottom of deep wells; sensors and electronics for downhole deployment; and integrated management systems for monitoring temperature, pressure and flow rates in deep wells and assessing the health of drilling operations.
This new collaboration will benefit NASA by further advancing technologies that could one day be used for exploring other planets, and will also promote commercialization of technologies developed for space exploration. The partnership will help Chevron develop its energy resources to enable a better energy future for all of us.
"NASA and JPL are highly acclaimed national treasures, and Chevron is proud to collaborate with them to unlock new energy potential," said John McDonald, Chevron's corporate vice president and chief technology officer. "This alliance is an opportunity to bridge public- and private-sector technology and research to discover oil and natural gas volumes that are found in deep remote reservoirs. In many ways, the research is akin to deep space exploration, making the missions of our two organizations highly complementary."
As NASA's lead center for robotic exploration of the solar system, JPL has a wide-ranging charter that also includes active programs in Earth science, astronomy and physics, and technology development. The demands of space missions provide the impetus to JPL scientists and engineers to push the boundaries of design and technology to achieve smaller size, better performance, and less power consumption in a cost-constrained environment. Many technologies developed at JPL, from hardware and software to materials, have direct applications right here on Earth.
Astronomers Find Largest, Most Distant Reservoir of Water
Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe. The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away.
"The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times." Bradford leads one of the teams that made the discovery. His team's research is partially funded by NASA and appears in the Astrophysical Journal Letters.
A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.
Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way's water is frozen in ice.
Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles). Its presence indicates that the quasar is bathing the gas in X-rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards. Although the gas is at a chilly minus 63 degrees Fahrenheit (minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.
Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.
Bradford's team made their observations starting in 2008, using an instrument called "Z-Spec" at the California Institute of Technology's Submillimeter Observatory, a 33-foot (10-meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.
The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team serendipitously detected water in APM 8279+5255, observing one spectral signature. Bradford's team was able to get more information about the water, including its enormous mass, because they detected several spectral signatures of the water.
"The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times." Bradford leads one of the teams that made the discovery. His team's research is partially funded by NASA and appears in the Astrophysical Journal Letters.
A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.
Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way's water is frozen in ice.
Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles). Its presence indicates that the quasar is bathing the gas in X-rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards. Although the gas is at a chilly minus 63 degrees Fahrenheit (minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.
Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.
Bradford's team made their observations starting in 2008, using an instrument called "Z-Spec" at the California Institute of Technology's Submillimeter Observatory, a 33-foot (10-meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.
The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team serendipitously detected water in APM 8279+5255, observing one spectral signature. Bradford's team was able to get more information about the water, including its enormous mass, because they detected several spectral signatures of the water.
Twisted Tale of our Galaxy's Ring
"We have looked at this region at the center of the Milky Way many times before in the infrared," said Alberto Noriega-Crespo of NASA's Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. "But when we looked at the high-resolution images using Herschel's sub-millimeter wavelengths, the presence of a ring is quite clear." Noriega-Crespo is co-author of a new paper on the ring published in a recent issue of Astrophysical Journal Letters.
The Herschel Space Observatory is a European Space Agency-led mission with important NASA contributions. It sees infrared and sub-millimeter light, which can readily penetrate through the dust hovering between the bustling center of our galaxy and us. Herschel's detectors are also suited to see the coldest stuff in our galaxy.
When astronomers turned the giant telescope to look at the center of our galaxy, it captured unprecedented views of its inner ring -- a dense tube of cold gas mixed with dust, where new stars are forming.
Astronomers were shocked by what they saw -- the ring, which is in the plane of our galaxy, looked more like an infinity symbol with two lobes pointing to the side. In fact, they later determined the ring was torqued in the middle, so it only appears to have two lobes. To picture the structure, imagine holding a stiff, elliptical band and twisting the ends in opposite directions, so that one side comes up a bit.
"This is what is so exciting about launching a new space telescope like Herschel," said Sergio Molinari of the Institute of Space Physics in Rome, Italy, lead author of the new paper. "We have a new and exciting mystery on our hands, right at the center of our own galaxy."
Observations with the ground-based Nobeyama Radio Observatory in Japan complemented the Herschel results by determining the velocity of the denser gas in the ring. The radio results demonstrate that the ring is moving together as a unit, at the same speed relative to the rest of the galaxy.
The ring lies at the center of our Milky Way's bar -- a bar-shaped region of stars at the center of its spidery spiral arms. This bar is actually inside an even larger ring. Other galaxies have similar bars and rings. A classic example of a ring inside a bar is in the galaxy NGC 1097, imaged here by NASA's Spitzer Space Telescope. The ring glows brightly in the center of the galaxy's large bar structure. It is not known if that ring has a kink or not.
The details of how bars and rings form in spiral galaxies are not well understood, but computer simulations demonstrate how gravitational interactions can produce the structures. Some theories hold that bars arise out of gravitational interactions between galaxies. For example, the bar at the center of our Milky Way might have been influenced by our largest neighbor galaxy, Andromeda.
The twist in the ring is not the only mystery to come out of the new Herschel observations. Astronomers say that the center of the torqued portion of the ring is not where the center of the galaxy is thought to be, but slightly offset. The center of our galaxy is considered to be around "Sagittarius A*," where a massive black hole lies. According to Noriega-Crespo, it's not clear why the center of the ring doesn't match up with the assumed center of our galaxy. "There's still so much about our galaxy to discover," he said
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