lunedì 18 febbraio 2013

Scientists sense breakthroughs in dark-matter mystery.

Image released on June 22, 2011 combines visible light exposures of galaxy cluster Abell 2744 taken by the NASA/European Southern Observatory (ESO) Hubble Space Telescope and the ESO's Very Large Telescope, with X-ray data from NASA's Chandra X-ray Observatory and a mathematical reconstruction of the location of dark matter.
For decades, the strange substance called dark matter has teased physicists, challenging conventional notions of the cosmos.
Today, though, scientists believe that with the help of multi-billion-dollar tools, they are closer than ever to piercing the mystery—and the first clues may be unveiled just weeks from now. "We are so excited because we believe we are on the threshold of a major discovery," said Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago, at an annual conference of the American Association for the Advancement of Science (AAAS). Dark matter throws down the gauntlet to the so-called Standard Model of physics. Elegant and useful for identifying the stable of particles and forces that regulate our daily life, the Standard Model only tells part of the cosmic story. For one thing, it does not explain gravity, although we know how to measure gravity and exploit it for our needs. And the Standard Model has been found to account for only around four or five percent of the stuff in the Universe. The rest is dark matter, making up 23 percent, and dark energy, an enigmatic force that appears to drive the expansion of the Universe, which accounts for around 72 or 73 percent. "On the cosmology side we now understand that this mysterious dark matter holds together our galaxy and the rest of the Universe," said Turner. "And the tantalizing thing on the cosmology side is that we have an airtight case that the dark matter is made of something new... there is no particle in the Standard Model that can account for dark matter." The dark matter theory was born 80 years ago when Swiss astrophysicist Fritz Zwicky discovered that there was not enough mass in observable stars or galaxies to allow the force of gravity to hold them together. According to some theorists, dark matter is fleetingly formed by exotic particles called WIMPs (Weakly Interacting Massive Particles) that, as their name implies, have only weak interactions with the visible matter identified under the Standard Model.
But, again, this could only be part of the picture. "The real question is why dark matter has six times the energy that is in ordinary matter," said Lisa Randall of Harvard University. "It could be 10 trillions times bigger... This is an intriguing sign that there is maybe some other interaction we can detect." High-powered instruments track cosmic particles To track these phantom particles, physicists rely on several methods and tools. One is the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station (ISS), which captures gamma rays coming from collisions of dark matter particles. The first results will be published in two to three weeks, according to Samuel Ting, a Nobel laureate and professor at the Massachusetts Institute of Technology (MIT) who is the mastermind of the two-billion-dollar project. Ting declined to give details, only suggesting that these highly anticipated results would give humans a better idea about the nature of dark matter. Another tool used by the scientists is the South Pole Neutrino Observatory, which tracks subatomic particles known as neutrinos, which, according to physicists, are created when dark matter passes through the Sun and interacts with protons. Another big weapon is the Large Hadron Collider (LHC) near Geneva, the biggest particle smasher in the world. Its power, they insist, could allow them to break-up electrons, quarks or neutrinos to uncover dark matter. Last July, LHC physicists announced they had discovered a particle believed to be the Higgs boson, which confers mass. The Higgs was the key missing piece in the Standard Model. "The dark matter particles are very heavy. It is one of the reasons we have made the LHC, not only to look for the Higgs boson," said Maria Spiropulu, professor of physics at the California Institute of Technology (Caltech).

domenica 17 gennaio 2010

Chemical Composition of Red Giant Star With More Carbon Than Oxygen in Its Atmosphere.

The attached figure represents the temporary hydrodynamic development (projection in the X-Y plan) of the binary system made up of a helium white dwarf and the core of a red giant, from the zero instant until their complete fusion, in a time of about 6,400 seconds. Every box has an estimated size of about the radius of the Sun. The colours are proportional to the logarithm of density (black is less dense, white is denser). (Credit: Image courtesy of University of Granada)
Source: ScienceDaily
ScienceDaily (Jan. 14, 2010) — What are the peculiar type-R stars made? Where does the carbon present in their shell come from? These are the questions to be solved by a research work conducted by scientists of the department of Theoretical and Cosmos Physics of the University of Granada (Spain), where they have analysed the chemical composition and the evolutionary state of spectral type R carbon stars to try to explain the origin of the carbon enrichment present in its atmosphere.
Up to now, there had hardly been performed chemical analysis for this type of start. Type-R stars are peculiar red giant stars, as they show a higher presence of carbon than oxygen in their atmosphere (the usual composition in the Universe is exactly the opposite). They can be classified in hot-R starts and cold-R stars, depending on their effective temperature.
In the case of R-cold stars, this is the first chemical analysis of these characteristics carried out worldwide, whereas for R-hot stars, the existing chemical analyses were very old (more than 25 years) and with a lower spectral resolution than that of the UGR study.
The research has been conducted by Olga Zamora Sánchez and supervised by professors Carlos Abia and Inmaculada Domínguez. The scientists of the University of Granada have also studied the essential observational features of type-R stars (distribution in the Milky Way, kinematics, luminosity, etc.) .

A 23-star sample:
This research work has determined the chemical composition of a 23 type-R star sample (both hot and cold), using spectrums in the optics with high-spectral resolution, in order to obtain information about the origin of this type of stars. To this end, the scientists performed observations with a 2.2-metre in diameter telescope placed in Calar Alto (Almeria), and carried out a chemical analysis of elements such as carbon, oxygen, nitrogen, lithium and other heavy metals, such as technetium, strontium, barium or lanthanum.
Thus, the scientists have concluded that R-cold stars are identical to type-N stars (or normal carbon stars) originated in the AGB phase, whereas R-hot stars are different. About 40% of the R-hot stars of the sample were erroneously classified up now, and therefore the portion of these stars with regard to red giant stars could be considerably reduced regarding previous estimations thanks to this work.

The most comprehensive analysis:
The analysis of the University of Granada is the most complete conducted worldwide up to now (from an observational and theoretical approach) about type-R spectral stars. Besides, the scientists have carried out a numeric simulation for the first time of the most favourable scene for the formation of a R-hot star: the fusion of a helium white dwarf with a red giant. In the end, this scene has turned out to be unviable, and therefore the explanation of the origin of R-hot stars keeps representing a challenge for present star and nucleosynthesis development models.
Although the UGR scientists warn that this type of study has not immediate applications, the information obtained could be very valuable in the future as carbon, as everybody knows, is very important for the possible development of life in the Universe. Therefore, they say, explaining the origin of this element in the stars will be useful to study the production of one of the basic ingredients of life that we know.
The results of this research work will be sent for its publication in the near future in the journal Astronomy & Astrophysics.
Story Source:
Adapted from materials provided by
University of Granada.

HIFI Resumes Quest for Water in Universe.

In the daily communications with Herschel/HIFI strange readings had been received. HIFI was in a state that was not described in the manuals. (Credit: Image courtesy of SRON Netherlands Institute for Space Research)
Source: ScienceDaily
ScienceDaily (Jan. 15, 2010) — The back up system of HIFI, the state of the art Dutch space instrument on ESA's Herschel space telescope, has been switched on successfully. Due to an unexpected voltage peak in the electronic system HIFI has been inactive for more than 160 days, but on Thursday evening 14 January Mission Control in Darmstadt confirmed that HIFI is now fully capable of performing groundbreaking observations in space again.
The coming three years HIFI, built under the supervision of SRON Netherlands Institute for Space Research, will investigate the physics and chemistry of interstellar clouds of gas and dust. The infrared spectrometer will chart the amount of carbon and water in these gas clouds, which is expected to shed new light on the birth and early development of stars and planets.
Finally, after months of tension and hard work, the engineers and researchers of SRON, the HIFI partners and the European Space Agency (ESA) could breathe freely again that Thursday evening. After some minor last obstacles had been overcome -- it took an extra day warming up the back-up Local Oscillator Control Unit (the module in which the malfunction took place) to a degree that would ensure that the switch on would bear no risks whatsoever -- HIFI is now in full swing again. Just like most space instruments HIFI has a back up system in case of a failure in the electronic system, and all tests have shown convincingly that the control units of the back up system function perfectly. Moreover, the sensors of HIFI perform on the same high level as in the beginning of August 2009, when the infrared spectrometer astonished the scientific community with the first, crystal clear observations of ionized carbon, the most challenging aspect of the measurement programme.

Strange readings:
The first indication that something was wrong with HIFI came from mission control in Darmstad on 3 August 2009. "Groningen, we have a problem." In the daily communications with Herschel/HIFI strange readings had been received. HIFI was in a state that was not described in the manuals. After months of intensive investigations and deliberations only one consistent scenario for this anomaly remained. Due to an unknown cause -- possibly a cosmic ray hit in the computer memory of one of the auxiliary computers- the processor of the Local Oscillator Control Unit (LCU) detected an error, rebooted and lost communication with the instrument's main computer. In this process after a little over a second inadvertently the standby switch was activated. This standby switch has been designed to protect the LCU against power drops on the main power line from the satellite, but now fully powered sent a voltage peak through the system. This peak was fatal for one of the diodes in one of the LCU DC/DC convertors.
The past months scientist from ESA, SRON and the HIFI partners have worked intensively to first determine the nature of the problem, and then on the necessary changes in the software to monitor the integrity of the computer memory and to prevent the malfunction from happening again. The first task in this process was to disable the standby switch that normally protects the Local Oscillator Control Unit (LCU) against sudden power drops. Normally it protects the precious Local Oscillator chains but now it got activated at the wrong moment. It was also necessary to subdue or eliminate any remaining voltage peaks in the system. The team achieved this by cutting back in all relay switching activities. Finally a software change ensured that communications with the LCUwill not be disturbed again."

Complex technological puzzle:
HIFI Project leader Peter Roelfsema: "It turned out to be a very complex technological puzzle that we had to solve based on limited information and under a great deal of pressure. But for all researchers involved, quickly finding an answer to this question was a matter of professional pride. We had to -- and would -- crack the problem with HIFI as soon as humanly possible, but we also had to take the time to be thourough. Scientists all over the world were waiting on the observations from HIFI. There are no certainties in space research; instruments that have to do precision work in the hostile environment of space will always be vulnerable. But we are confident that HIFI can now carry out all scientific observations."
The scientific observations focus on the quest for ionized carbon and water in the Universe. Principal investigator Frank Helmich says: "Ionized Carbon is important to astronomers because it is a good idicator for the warming up and cooling down of the gas from which stars and planets take shape. Therefore with HIFI we get a better idea of how the 'thermostat' of the Universe works. Water is probably the lubricant of the proces which gives birth to stars and planets. The molecule takes care of cooling extremely hot gases -- just like ionized carbon -- which enables them to concentrate to new suns. And HIFI also charts the atmospheres of planets and comets in our solar system. All in all we count on a rich scientific output again. This is really thanks to the great efforts made by all of the researchers at ESA, SRON and the HIFI partners, who have worked together as a single team. The motivation to crack this problem came from the depths of the professional pride of the staff themselves. While I hadn't expected anything else, I'm really very proud of this."
Story Source:
Adapted from materials provided by
SRON Netherlands Institute for Space Research.

As the Crust Turns: Cassini Data Show Enceladus in Motion.

On Oct. 5, 2008, just after coming within 25 kilometers (15.6 miles) of the surface of Enceladus, NASA's Cassini captured this stunning mosaic as the spacecraft sped away from this geologically active moon of Saturn. (Credit: NASA/JPL/Space Science Institute)
Source: ScienceDaily
ScienceDaily (Jan. 15, 2010) — Blobs of warm ice that periodically rise to the surface and churn the icy crust on Saturn's moon Enceladus explain the quirky heat behavior and intriguing surface of the moon's south polar region, according to a new paper using data from NASA's Cassini spacecraft.
"Cassini appears to have caught Enceladus in the middle of a burp," said Francis Nimmo, a planetary scientist at the University of California Santa Cruz and a co-author of the new paper in Nature Geoscience. "These tumultuous periods are rare and Cassini happens to have been watching the moon during one of these special epochs."
The south polar region captivates scientists because it hosts the fissures known as "tiger stripes" that spray water vapor and other particles out from the moon. While the latest paper, released on Jan. 10, doesn't link the churning and resurfacing directly to the formation of fissures and jets, it does fill in some of the blanks in the region's history.
"This episodic model helps to solve one of the most perplexing mysteries of Enceladus," said Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., of the research done by his colleagues. "Why is the south polar surface so young? How could this amount of heat be pumped out at the moon's south pole? This idea assembles the pieces of the puzzle."
About four years ago, Cassini's composite infrared spectrometer instrument detected a heat flow in the south polar region of at least 6 gigawatts, the equivalent of at least a dozen electric power plants. This is at least three times as much heat as an average region of Earth of similar area would produce, despite Enceladus' small size. The region was also later found by Cassini's ion and neutral mass spectrometer instrument to be swiftly expelling argon, which comes from rocks decaying radioactively and has a well-known rate of decay.
Calculations told scientists it would be impossible for Enceladus to have continually produced heat and gas at this rate. Tidal movement -- the pull and push from Saturn as Enceladus moves around the planet -- cannot explain the release of so much energy.
The surface ages of different regions of Enceladus also show great diversity. Heavily cratered plains in the northern part of the moon appear to be as old as 4.2 billion years, while a region near the equator known as Sarandib Planitia is between 170 million and 3.7 billion years old. The south polar area, however, appears to be less than 100 million years old, possibly as young as 500,000 years.
Craig O'Neill of Macquarie University in Sydney, Australia, and Nimmo, who was partially funded by the NASA Outer Planets Research program, adapted a model that O'Neill had developed for the convection of Earth's crust. For Enceladus, which has a surface completely covered in cold ice that is fractured by the tug of Saturn's gravitational pull, the scientists stiffened up the crust. They picked a strength somewhere between that of the malleable tectonic plates on Earth and the rigid plates of Venus, which are so strong, it appears they never get sucked down into the interior.
Their model showed that heat building up from the interior of Enceladus could be released in episodic bubbles of warm, light ice rising to the surface, akin to the rising blobs of heated wax in a lava lamp. The rise of the warm bubbles would send cold, heavier ice down into the interior. (Warm is, of course, relative. Nimmo said the bubbles are probably just below freezing, which is 273 degrees Kelvin or 32 degrees Farenheit, whereas the surface is a frigid 80 degrees Kelvin or -316 degrees Farenheit.)
The model fits the activity on Enceladus when the churning and resurfacing periods are assumed to last about 10 million years, and the quiet periods, when the surface ice is undisturbed, last about 100 million to two billion years. Their model suggests the active periods have occurred only 1 to 10 percent of the time that Enceladus has existed and have recycled 10 to 40 percent of the surface. The active area around Enceladus's south pole is about 10 percent of its surface.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.
Story Source:
Adapted from materials provided by
NASA/Jet Propulsion Laboratory.

venerdì 15 gennaio 2010

Sky Map: Solar Scientists Use 'Magnetic Mirror Effect' to Reproduce IBEX Observation.

These two maps show the entire sky in the emission of neutral hydrogen. The energetic neutral atom (ENA) measurements by the IBEX mission (bottom image) show a ribbon feature spanning across the entire sky. A group of solar physicists led by Jacob Heerikhuisen discovered that this feature can be closely reproduced by sophisticated models (top image) after adding an unpredicted "mirror effect." The two images show modeled and observed ENAs, respectively, at comparable speeds. (Credit: Heerikhuisen et al.)
Source: ScienceDaily
ScienceDaily (Jan. 15, 2010) — Ever since NASA's Interstellar Boundary Explorer, or IBEX, mission scientists released the first comprehensive sky map of our solar system's edge in particles, solar physicists have been busy revising their models to account for the discovery of a narrow "ribbon" of bright emission that was completely unexpected and not predicted by any model at the time.
Further study by a team of scientists funded through NASA's Heliophysics Guest Investigator program has produced a revised model that explains and closely reproduces the IBEX result by incorporating a single new effect into an existing model. The new effect, put forward by the IBEX team soon after sighting of the ribbon, is that the magnetic field surrounding our solar system -- called the local galactic magnetic field -- acts like a mirror for the particles that IBEX sees.
The results appear in the January 10 issue of the Astrophysical Journal Letters. Jacob Heerikhuisen, a solar physicist at the University of Alabama in Huntsville, is the lead author of the paper. Heerikhuisen and his colleagues believe the orientation of the local galactic magnetic field is closely related to the location of the ribbon in the sky.
Charged particles "orbit" magnetic field lines. When they suddenly lose their charge, they fly off in a straight line maintaining their current direction. Only particles that orbit the magnetic mirror, where it faces us directly, can flow back toward us and are captured by IBEX.
These particles originate in our magnetized solar system, or heliosphere -- the region from the sun to where the solar wind meets the local interstellar medium (LISM). First these particles lose their charge and fly out of the heliosphere. At some distance they charge again and start "orbiting" a field line of the local interstellar magnetic field, where they get "recycled" by losing their charge again.
Solar physicists did not expect this "mirror effect," which is "somewhat analogous to exploring an unknown cave," says Arik Posner, IBEX program scientist at NASA Headquarters. "By activating IBEX, we suddenly see that the solar system has a lit candle and see its light reflected in the 'cave walls' shining back at us," says Posner. "What we find is that the 'cave wall' acts more like a faint mirror than like a normal wall," he adds.
What we saw with IBEX is that this "cave" we are exploring apparently has very straight and smooth magnetic walls, being shaped somewhat like a subway tunnel. IBEX can remotely observe the direction of the local interstellar magnetic field and may observe whether it stays the same or changes over time.
The sun's presence affects the local interstellar magnetic field, bulging the field out to form something larger that is similar to a subway station. However, the "station" itself, our heliosphere, slowly moves along the tunnel, not subway cars.
Straight magnetic field lines are only found in plasmas where the magnetic field is strong and shapes the flow of particles, such as the smooth magnetic loops observed in the sun's corona.
The IBEX results appear consistent with a recent finding by the Voyager mission that the surrounding galactic magnetic field in the LISM is much stronger than previously thought.
Assuming this "magnetic mirror effect" produces the narrow "ribbon" discovered by IBEX, then the orientation of the local galactic magnetic field is closely related to the location of the ribbon. With the help of global 3D models, this mechanism could help accurately determine the magnetic field's direction. The finding would also suggest that IBEX is detecting the particles from both inside and outside the heliopause, which is the boundary region between the outer solar system and the local interstellar medium.
"The IBEX mission has from the outset stressed both the criticality of new measurements and the collaboration between observations and theoretical research," explains Robert MacDowall, IBEX mission scientist at NASA Goddard. "The discovery by Heerikhuisen and colleagues demonstrates how successful this approach can be."
Story Source:
Adapted from materials provided by
NASA/Goddard Space Flight Center.

giovedì 14 gennaio 2010

Radio pulses from pulsar appear to move faster than light.

A diagram of a pulsar, showing its rotation axis and its magnetic axis. Image: NASA
Laboratory experiments in the last few decades have shown that some things can appear to move faster than light without contradicting Einstein's special theory of relativity, but now astrophysicists have seen real examples of superluminal speeds in the form of radio pulses from a pulsar.

Superluminal, or faster than light, speeds are associated with anomalous dispersion, which is a process in which the refractive index of a medium increases with the wavelength of light passing through it. If a light pulse (consisting of a group of at different wavelengths) passes through such a medium, the group velocity of the pulse can increase to a velocity greater than any of the waves within the pulse, but the energy of the pulse still travels at the speed of light, which means information is transmitted in accordance with Einstein's theory.
Astrophysicists, led by Frederick Jenet of the University of Texas at Brownsville, have been monitoring a
, PSR B1937+21, which is about 10,000 light years from Earth. They used the Arecibo Observatory in Puerto Rico to obtain radio data over three days at 1420.4 MHz with a bandwidth of 1.5 MHz. They found that pulses closer to the center arrived earlier than the normal timing, which suggests they had travelled faster than the speed of light.
A pulsar is a neutron star that is spinning rapidly and emitting a rotating beam of radio radiation as it spins, which is observed on Earth at regular intervals rather like light from a lighthouse. The pulses of radiation can be affected by several factors as they travel through the interstellar medium (ISM). Their polarization can be rotated if they pass through a magnetic field, for example, and they can be scattered if they encounter
, and can be absorbed by neutral hydrogen in the ISM. Jenet and his colleagues think anomalous dispersion also affects the pulses.
According to Jenet and colleagues, the pulses from the pulsar traveled through a cloud of neutral hydrogen, which has a resonance of 1420.4 MHz -- the exact center of the bandwidth studied. Passing through the cloud caused anomalous dispersion that resulted in a superluminal group velocity, and pulses with frequencies closest to the resonance frequency arrived earlier than other pulses.
The scientists believe the pulses appear to travel faster than light because of an "interplay between the time scales present in the pulse and the time scales present in the medium." The faster-than-light pulses do not violate Einstein's theory because technically the pulse carries no information. The effect has been known in laboratory experiments, but these observations were the first in an astrophysical context.
The findings, to be published in the Astrophysical Journal, could help astronomers gain a more complete understanding of the composition of space in the regions between stars, and in particular the properties of neutral
clouds in our galaxy.
More information: A preprint of the article is available at .

Second Smallest Exoplanet Spotted: Discovery Highlights New Potential for Eventually Finding Earth-Mass Planets.

Astronomers have detected an extrasolar planet with a mass just four times that of Earth. (Credit: L. Calcada, ESO)
Source: ScienceDaily
ScienceDaily (Jan. 14, 2010) — Astronomers from the California Institute of Technology (Caltech) and other institutions, using the highly sensitive 10-meter Keck I telescope atop Hawaii's Mauna Kea, have detected an extrasolar planet with a mass just four times that of Earth. The planet, which orbits its parent star HD156668 about once every four days, is the second-smallest world among the more than 400 exoplanets (planets located outside our solar system) that have been found to date. It is located approximately 80 light-years from Earth in the direction of the constellation Hercules.
The find, made possible through NASA's Eta-Earth Survey for Low-Mass Planets was announced at the 215th American Astronomical Society meeting held January 4-7, 2010, in Washington, D.C.
Dubbed HD 156668b, the planet -- a so-called "super Earth" that would glow with blast-furnace-like temperatures -- offers a tantalizing hint of discoveries yet to come. Astronomers hope those discoveries will include Earth-size planets located in the "habitable zone," the area roughly the distance from the earth to the sun, and thus potentially favorable to life.
HD 156668b was discovered with the radial velocity or wobble method, which relies on Keck's High Resolution Echelle Spectrometer (HIRES) to spread light collected from the telescope into its component wavelengths or colors, producing a spectrum. As the planet orbits the star, it causes the star to move back and forth along our line of sight, which causes the starlight to become redder and then bluer in a periodic fashion.
The color shifts give astronomers the mass of the planet and the characteristics of its orbit, such as how much time it takes to orbit the star. The majority of the exoplanets discovered have been found in this way.
The discovery of low-mass planets like HD 156668b has become possible due to the development of techniques to watch stars wobble with increasing clarity, and of software that can pluck the signals of increasingly smaller planets from amid the 'noise' made by their pulsating, wobbling parent stars.
"If the stars themselves have imperfections and are unstable, their wobbling would cause jumps in velocity that could mimic or hide the existence of a planet," says John A. Johnson, assistant professor of astronomy at Caltech and codiscoverer of the new planet along with Andrew Howard and Geoff Marcy of the University of California at Berkeley, Debra Fischer of Yale University, Jason Wright of Penn State University, and the members of the California Planet Survey collaboration.
"We have been doing simulations to understand the astrophysics of these imperfections, and how to distinguish them from the signals from a planet," says Johnson. "We hope to use these simulations to design even better observing strategies and data-analysis techniques."
The discovery of a planet that is comparable in size to Earth and found within the habitable zone, however, "will require a great deal of work," he says. "If we could build the best possible radial-velocity instrument tomorrow, we might have answers in three years, and a solid census of Earthlike planets within a decade. We'll need gigantic leaps in sensitivity to get there, and we're hot on the trail."
Johnson is also currently building a new camera for the 60-inch telescope at Caltech's Palomar Observatory. The camera will allow astronomers to search for the passages -- or transits -- of low-mass planets like HD156668 across the faces of their stars.
"If we catch the planet in transit, we can measure the planet's radius and density, and therefore address the question of whether the planet has a composition more like Earth, with a solid surface and thin atmosphere, or is a miniature version of Neptune, with a heavy gaseous atmosphere," he says.
The Keck I telescope is part of the Keck Observatory, a joint effort of Caltech and the University of California.
For more information about extrasolar planet discoveries, visit
Story Source:
Adapted from materials provided by
California Institute of Technology.