The image shows one of the most active and turbulent regions of star birth in our galaxy, a region called Cygnus X. The choppy cloud of gas and dust lies 4,500 light-years away in the constellation Cygnus the Swan.

Image right: The Cygnus-X star-forming region is located 4,600 light-years from Earth and spans more than 600 light-years. This infrared photograph from the Spitzer Space Telescope reveals more than a thousand protostars in the earliest stages of forming. Light of 3.6 microns is color-coded blue: 4.5-micron light is blue-green; 8.0-micron light is green; and 24-micron light is red.

Cygnus X, which spans an area of the sky larger than 100 full moons, is home to thousands of massive stars, and many more stars around the size of our sun or smaller. Spitzer has captured an infrared view of the entire region, which is bubbling with star formation.

“Spitzer captured the range of activities happening in this violent cloud of stellar birth,” said Joe Hora of the Harvard-Smithsonian Center for Astrophysics, who is the principal investigator of the research. “We see bubbles carved out from massive stars, pillars of new stars, dark filaments lined with stellar embryos and more.”

The majority of stars are thought to form in huge star-forming regions like Cygnus X. Over time, the stars dissipate and migrate away from each other. It’s possible that our sun was once packed tightly together with other, more massive stars in a similarly chaotic, though less extreme, region.

The turbulent star-forming clouds are marked with bubbles, or cavities, which are carved out by radiation and winds from the most massive of stars. Those massive stars tear the cloud material to shreds, terminating the formation of some stars, while triggering the birth of others.

“One of the questions we want to answer is how such a violent process can lead to both the death and birth of new stars,” said Sean Carey, a team member from NASA’s Spitzer Science Center at the California Institute of Technology.

Infrared data from Spitzer is helping to answer questions like these by giving astronomers a window into the dustier parts of the complex. Infrared light travels through dust, whereas visible light is blocked. For example, embryonic stars blanketed by dust pop out in the Spitzer observations. In some cases the young stars are embedded in finger-shaped pillars of dust. In other cases, these stars can be seen lining very dark, snake-like filaments of thick dust.

Related posts:

1. The Spitzer Photo Atlas of Galactic “Train Wrecks”
2. Astronomers take the first clear look inside a turbulent stellar nursery
3. Hunting for the Milky Way’s heaviest stars

“The goal of Kepler is to find Earth-sized planets in the habitable zone. Proving the existence of Earth-sized exoplanets is a major step toward achieving that goal,” said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics.

The paper describing the finding will be published in the journal Nature.

The two planets, dubbed Kepler-20e and 20f, are the smallest planets found to date. They have diameters of 6,900 miles and 8,200 miles – equivalent to 0.87 times Earth (slightly smaller than Venus) and 1.03 times Earth. These worlds are expected to have rocky compositions, so their masses should be less than 1.7 and 3 times Earth’s.

Image left: Kepler-20f orbits its star every 19.6 days at a distance of 10.3 million miles. Although its average temperature could be as high as 800 degrees F, it might have been able to retain a water atmosphere as it migrated closer to the star after it formed. (Artist’s rendering courtesy NASA/JPL-Caltech/T. Pyle)

Both worlds circle Kepler-20: a G-type star slightly cooler than the Sun and located 950 light-years from Earth. (It would take the space shuttle 36 million years to travel to Kepler-20.)

Kepler-20e orbits every 6.1 days at a distance of 4.7 million miles. Kepler-20f orbits every 19.6 days at a distance of 10.3 million miles. Due to their tight orbits, they are heated to temperatures of 1,400 degrees Fahrenheit and 800 degrees F.

An unusual solar system

In addition to the two Earth-sized worlds, the Kepler-20 system contains three larger planets. All five have orbits closer than Mercury in our solar system.

They also show an unexpected arrangement. In our solar system small, rocky worlds orbit close to the Sun and large, gas giant worlds orbit farther out. In contrast, the planets of Kepler-20 are organized in alternating size: big, little, big, little, big.

Image right: The Kepler-20 planetary system contains five planets that alternate in size: large, small, large, small, large (as shown in this artist’s rendering). All five orbit their star closer than the planet Mercury in our solar system. (Image by David A. Aguilar)

“We were surprised to find this system of flip-flopping planets,” said co-author David Charbonneau of the CfA. “It’s very different than our solar system.”

The three largest planets are designated Kepler-20b, 20c, and 20d. They have diameters of 15,000, 24,600, and 22,000 miles and orbit once every 3.7, 10.9, and 77.6 days, respectively. Kepler-20b has 8.7 times the mass of Earth; Kepler-20c has 16.1 times Earth’s mass. Kepler-20d weighs less than 20 times Earth.

The planets of Kepler-20 could not have formed in their current locations. Instead, they must have formed farther from their star and then migrated inward, probably through interactions with the disk of material from which they all formed. This allowed the worlds to maintain their regular spacing despite alternating sizes.

Confirming tiny worlds

Kepler identifies “objects of interest” by looking for stars that dim slightly, which can occur when a planet crosses the star’s face. To confirm a transiting planet, astronomers look for the star to wobble as it is gravitationally tugged by its orbiting companion (a method known as radial velocity).

Image left: Kepler-20e is the smallest planet found to date orbiting a Sun-like star. It circles its star every 6.1 days at a distance of 4.7 million miles. At that distance, its temperature is expected to be about 1,400 degrees F. (Artist’s rendering courtesy NASA/JPL-Caltech/T. Pyle)

The radial velocity signal for planets weighing one to a few Earth masses is too small to detect with current technology. Therefore, other techniques must be used to validate that an object of interest is truly a planet.

A variety of situations could mimic the dimming from a transiting planet. For example, an eclipsing binary-star system whose light blends with the star Kepler-20 would create a similar signal. To rule out such imposters, the team simulated millions of possible scenarios with Blender – custom software developed by Fressin and Willie Torres of CfA. They concluded that the odds are strongly in favor of Kepler-20e and 20f being planets.

Fressin and Torres also used Blender to confirm the existence of Kepler-22b, a planet in the habitable zone of its star that was announced by NASA earlier this month. However, that world was much larger than Earth.

“These new planets are significantly smaller than any planet found up till now orbiting a Sun-like star,” added Fressin.

NASA Ames Research Center is responsible for the ground system development, mission operations and science data analysis. NASA’s Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system, and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Related posts:

1. From Star Wars to science fact: Tatooine-like planet discovered
2. Darkest known exoplanet, a Jupiter-sized gas giant, discovered
3. Six orbiting planets sets record for Sun-like stars say Kepler, Smithsonian astronmers

Image right: The black hole in Cygnus X-1 is located near large active regions of star formation in the Milky Way. The black hole pulls material from a massive, blue companion star toward it. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being redirected away from the black hole in the form of powerful jets. (Image NASA/CXC/M. Weiss)

Over three decades ago, Stephen Hawking placed — and eventually lost – a bet against the existence of a black hole in Cygnus X-1. Today, astronomers are confident the Cygnus X-1 system contains a black hole, and with these latest studies they have remarkably precise values of its mass, spin, and distance from Earth. With these key pieces of information, the history of the black hole has been reconstructed.

Image left: A team of scientists has combined data from radio, optical, and X-ray telescopes including Chandra to determine the black hole’s spin, mass, and distance more precisely than ever before. With these key pieces of information, the history of the black hole has been reconstructed. This is an X-ray image of Cygnus X-1 from the Chandra X-ray Observatory.(Image courtesty NASA/CXC)

“This new information gives us strong clues about how the black hole was born, what it weighed and how fast it was spinning,” said author Mark Reid of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. “This is exciting because not much is known about the birth of black holes.”

Reid led one of three papers — all appearing in the November 10th issue of The Astrophysical Journal – describing these new results on Cygnus X-1. The other papers were led by Jerome Orosz from San Diego State University and Lijun Gou, also from CfA.

Cygnus X-1 is a so-called stellar-mass black hole, a class of black holes that comes from the collapse of a massive star. The black hole is in close orbit with a massive, blue companion star.

Using X-ray data from Chandra, the Rossi X-ray Timing Explorer, and the Advanced Satellite for Cosmology and Astrophysics, a team of scientists was able to determine the spin of Cygnus X-1 with unprecedented accuracy, showing that the black hole is spinning at very close to its maximum rate. Its event horizon — the point of no return for material falling towards a black hole — is spinning around more than 800 times a second.

An independent study that compared the evolutionary history of the companion star with theoretical models indicates that the black hole was born some 6 million years ago. In this relatively short time (in astronomical terms), the black hole could not have pulled in enough gas to ramp up its spin very much. The implication is that Cygnus X-1 was likely born spinning very quickly.

Using optical observations of the companion star and its motion around its unseen companion, the team made the most precise determination ever for the mass of Cygnus X-1, of 14.8 times the mass of the Sun. It was likely to have been almost this massive at birth, because of lack of time for it to grow appreciably.

“We now know that Cygnus X-1 is one of the most massive stellar black holes in the Galaxy,” said Orosz. “And, it’s spinning as fast as any black hole we’ve ever seen.”

Knowledge of the mass, spin and charge gives a complete description of a black hole, according to the so-called “No Hair” theorem. This theory postulates that all other information aside from these parameters is lost for eternity behind the event horizon. The charge for an astronomical black hole is expected to be almost zero, so only the mass and spin are needed.

“It is amazing to me that we have a complete description of this asteroid-sized object that is thousands of light years away,” said Gou. “This means astronomers have a more complete understanding of this black hole than any other in our Galaxy.”

The team also announced that they have made the most accurate distance estimate yet of Cygnus X-1 using the National Radio Observatory’s Very Long Baseline Array (VLBA). The new distance is about 6,070 light years from Earth. This accurate distance was a crucial ingredient for making the precise mass and spin determinations.

The radio observations also measured the motion of Cygnus X-1 through space, and this was combined with its measured velocity to give the three-dimensional velocity and position of the black hole.

This work showed that Cygnus X-1 is moving very slowly with respect to the Milky Way, implying it did not receive a large “kick” at birth. This supports an earlier conjecture that Cygnus X-1 was not born in a supernova, but instead may have resulted from the dark collapse of a progenitor star without an explosion. The progenitor of Cygnus X-1 was likely an extremely massive star, which initially had a mass greater than about 100 times the sun before losing it in a vigorous stellar wind.

In 1974, soon after Cygnus X-1 became a good candidate for a black hole, Stephen Hawking placed a bet with fellow astrophysicist Kip Thorne, a professor of theoretical physics at the California Institute of Technology, that Cygnus X-1 did not contain a black hole. This was treated as an insurance policy by Hawking, who had done a lot of work on black holes and general relativity.

By 1990, however, much more work on Cygnus X-1 had strengthened the evidence for it being a black hole. With the help of family, nurses, and friends, Hawking broke into Thorne’s office, found the framed bet, and conceded.

“For forty years, Cygnus X-1 has been the iconic example of a black hole. However, despite Hawking’s concession, I have never been completely convinced that it really does contain a black hole — until now,” said Thorne. “The data and modeling described in these three papers at last provide a completely definitive description of this binary system.”

Related posts:

1. Chandra X-ray Observatory finds youngest nearby black hole
2. Astronomers seek monster black hole gorging on a buffet of stars
3. Chandra X-Ray Observatory finds massive black holes common in early universe

“Looking for alien cities would be a long shot, but wouldn’t require extra resources. And if we succeed, it would change our perception of our place in the universe,” said Loeb.

Image right: If an alien civilization builds brightly-lit cities like those shown in this artist’s conception, future generations of telescopes might allow us to detect them. This would offer a new method of searching for extraterrestrial intelligence elsewhere in our Galaxy. (Illustration by David A. Aguilar)

As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.

How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.

As the planet orbits, it goes through phases similar to those of the Moon.

When it’s in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the day side. So the total flux from a planet with city lighting will vary in a way that is measurably different from a planet that has no artificial lights.

Spotting this tiny signal would require future generations of telescopes.

However, the technique could be tested closer to home, using objects at the edge of our solar system.

Loeb and Turner calculate that today’s best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt – the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now. By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.

“It’s very unlikely that there are alien cities on the edge of our solar system, but the principle of science is to find a method to check,” Turner said. “Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate.”

As our technology has moved from radio and TV broadcasts to cable and fiber optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilizations, then artificial lights might be the best way to spot them from afar.

Loeb and Turner’s work has been submitted to the journal Astrobiology and is available at arxiv.org.

Related posts:

1. New supernova remnant lights up!
2. Can we spot volcanoes on alien worlds? Astronomers say yes
3. Kepler spacecraft used by Smithsonian astronomers to find other earths

Water is an essential ingredient for life. Scientists have found thousands of Earth-oceans’ worth of it within the planet-forming disk surrounding the star TW Hydrae. TW Hydrae is 176 light years away in the constellation Hydra and is the closest solar-system-to-be.

Image right: An illustration depicting the sprawling cloud of cold water vapor that astronomers have detected around the burgeoning solar system at the nearby star TW Hydrae. The cold water vapor could could eventually deliver oceans to dry planets that are forming in the system. (Credit: NASA/JPL-Caltech/T. Pyle SSC/Caltech)

The findings published in the Oct. 21 edition of Science were co-authored by Gary Melnick of the Harvard-Smithsonian Center for Astrophysics, University of Michigan astronomy professor Ted Bergin and their colleagues from the California Institute of Technology, the University of Amsterdam, Johns Hopkins University, the European Southern Observatory, NASA Jet Propulsion Lab and the Max-Planck-Institut für Extraterrestrische Physik.

The researchers used the Heterodyne Instrument for the Far-Infrared (HIFI) on the orbiting Hershel Space Observatory to detect the chemical signature of water.

“This tells us that the key materials that life needs are present in a system before planets are born,” said Bergin, a HIFI co-investigator. “We expected this to be the case, but now we know it is because have directly detected it. We can see it.”

Scientists had previously found warm water vapor in planet-forming disks close to the central star. But until now, evidence for vast quantities of water extending into the cooler, far reaches of disks where comets and giant planets take shape had not emerged. The more water available in disks for icy comets to form, the greater the chances that large amounts will eventually reach new planets through impacts.

“The detection of water sticking to dust grains throughout the planet-forming disk would be similar to events in our own solar system’s evolution, where over millions of years, these dust grains would then coalesce to form comets. These would be a prime delivery mechanism for water on planetary bodies,” said principal investigator Michiel Hogerheijde of Leiden University in the Netherlands.

Other recent findings from HIFI support the theory that comets delivered a significant portion of Earth’s oceans. Researchers found that the ice on a comet called Hartley 2 has the same chemical composition as our oceans.

HIFI is helping astronomers gain a better understanding of how water comes to terrestrial planets—Earth and beyond. If TW Hydrae and its icy disk are representative of many other young star systems, as researchers think they are, then the process for creating planets around numerous stars with abundant water throughout the universe appears to be in place, NASA officials say.

Herschel, a European Space Agency mission with NASA participation, is an orbiting telescope that allows astronomers to observe at the far-infrared wavelengths where organic molecules and water emit their chemical signatures.–Source: University of Michigan

Related posts:

1. Planets form around many star types, but intelligent life is probably rare
2. Astronomers appraise the amount of water in the Orion Nebula
3. Two Earth-sized planets discovered orbiting a distant Sun-like star

“After completing this study, we know less about dark matter than we did before,” said lead author Matt Walker, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics.

Image right: This artist’s conception shows a dwarf galaxy seen from the surface of a hypothetical exoplanet. A new study finds that the dark matter in dwarf galaxies is distributed smoothly rather than being clumped at their centers. This contradicts simulations using the standard cosmological model known as lambda-CDM. (Credit: David A. Aguilar)

The standard cosmological model describes a universe dominated by dark energy and dark matter. Most astronomers assume that dark matter consists of “cold” (i.e. slow-moving) exotic particles that clump together gravitationally. Over time these dark matter clumps grow and attract normal matter, forming the galaxies we see today.

Cosmologists use powerful computers to simulate this process. Their simulations show that dark matter should be densely packed in the centers of galaxies. Instead, new measurements of two dwarf galaxies show that they contain a smooth distribution of dark matter. This suggests that the standard cosmological model may be wrong.

“Our measurements contradict a basic prediction about the structure of cold dark matter in dwarf galaxies. Unless or until theorists can modify that prediction, cold dark matter is inconsistent with our observational data,” Walker stated.

Dwarf galaxies are composed of up to 99 percent dark matter and only one percent normal matter like stars. This disparity makes dwarf galaxies ideal targets for astronomers seeking to understand dark matter.

Walker and his co-author Jorge Penarrubia (University of Cambridge, UK) analyzed the dark matter distribution in two Milky Way neighbors: the Fornax and Sculptor dwarf galaxies. These galaxies hold one million to 10 million stars, compared to about 400 billion in our galaxy. The team measured the locations, speeds and basic chemical compositions of 1500 to 2500 stars.

“Stars in a dwarf galaxy swarm like bees in a beehive instead of moving in nice, circular orbits like a spiral galaxy,” explained Penarrubia. “That makes it much more challenging to determine the distribution of dark matter.”

Their data showed that in both cases, the dark matter is distributed uniformly over a relatively large region, several hundred light-years across. This contradicts the prediction that the density of dark matter should increase sharply toward the centers of these galaxies.

“If a dwarf galaxy were a peach, the standard cosmological model says we should find a dark matter ‘pit’ at the center. Instead, the first two dwarf galaxies we studied are like pitless peaches,” said Penarrubia.

Some have suggested that interactions between normal and dark matter could spread out the dark matter, but current simulations don’t indicate that this happens in dwarf galaxies. The new measurements imply that either normal matter affects dark matter more than expected, or dark matter isn’t “cold.”

The team hopes to determine which is true by studying more dwarf galaxies, particularly galaxies with an even higher percentage of dark matter.

The paper discussing this research was accepted for publication in The Astrophysical Journal and is available online.

Related posts:

1. Discovery triples number of stars in universe
2. Astronomers in distant future might still deduce the Big Bang origin of the Universe
3. Mystery of the quiet Sun solved

Astronomers now estimate there are roughly 19,500 — not 35,000 — mid-size near-Earth asteroids. Scientists say this improved understanding of the population may indicate that the hazard to Earth could be less than previously thought. However, the majority of these mid-size asteroids remain to be discovered. More research also is needed to determine if fewer mid-size objects (between 330 and 3,300 feet wide) also mean fewer potentially hazardous asteroids (those that come closest to Earth).

Image right: NEOWISE observations indicate that there are at least 40 percent fewer near-Earth asteroids in total that are larger than 330 feet, or 100 meters. Our solar system’s four inner planets are shown in green, and our sun is in the center. Each red dot represents one asteroid. Click to enlarge. (Image courtesy NASA/JPL-Caltech)

The results come from the most accurate census to date of near-Earth asteroids, the space rocks that orbit within 120 million miles (195 million kilometers) of the sun into Earth’s orbital vicinity. WISE observed infrared light from those in the middle to large-size category. The survey project, called NEOWISE, is the asteroid-hunting portion of the WISE mission. Study results appeard in September in the The Astrophysical Journal.

“The risk of a really large asteroid impacting the Earth before we could find and warn of it has been substantially reduced,” said Tim Spahr, the director of the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and a co-author on the study.

Image left: This chart shows how data from NASA’s Wide-field Infrared Survey Explorer, or WISE, has led to revisions in the estimated population of near-Earth asteroids. The infrared-sensing telescope performed the most accurate survey to date of a slice of this population. This allowed the science team to make new estimates of the total numbers of the objects in different size categories. NEOWISE observed more than 500 objects larger than 100-meters (330-feet) wide. (Image courtesy NASA/JPL-Caltech)

WISE scanned the entire celestial sky twice in infrared light between January 2010 and February 2011, continuously snapping pictures of everything from distant galaxies to near-Earth asteroids and comets. NEOWISE observed more than 100,000 asteroids in the main belt between Mars and Jupiter, in addition to at least 585 near Earth.

“NEOWISE allowed us to take a look at a more representative slice of the near-Earth asteroid numbers and make better estimates about the whole population,” said Amy Mainzer, lead author of the new study and principal investigator for the NEOWISE project at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “It’s like a population census, where you poll a small group of people to draw conclusions about the entire country.”

Related posts:

1. Super sensitive telescope will detect “killer” asteroids and comets on collision course with Earth
2. New research reveals our galaxy is much larger than we thought
3. Stellar eclipse gives glimpse of exoplanet: New data reveals a ‘super-Earth’ next door, astronomically speaking

Related posts:

1. Stellar eclipse gives glimpse of exoplanet: New data reveals a ‘super-Earth’ next door, astronomically speaking
2. Infrared survey reveals fewer near-Earth asteroids than previously thought
3. Swift satellite alerts astronomers to cosmic accident in constellation Draco

The same object that dazzled skygazers in 1054 C.E. continues to dazzle astronomers today by pumping out radiation at higher energies than anyone expected. Researchers have detected pulses of gamma rays with energies exceeding 100 billion electron-volts (100 GeV) — a million times more energetic than medical X-rays and 100 billion times more than visible light.

Image right: Artist’s conception of the pulsar at the center of the Crab Nebula, with a Hubble Space Telescope photo of the nebula in the background. Researchers using the Veritas telescope array have discovered pulses of high-energy gamma rays coming from this object. (Image credit David A. Aguilar/NASA/ESA)

“If you asked theorists a year ago whether we would see gamma-ray pulses this energetic, almost all of them would have said, ‘No.’ There’s just no theory that can account for what we’ve found,” said corresponding author Martin Schroedter of the Harvard-Smithsonian Center for Astrophysics (CfA).

The gamma rays come from an extreme object at the Crab Nebula’s center known as a pulsar. A pulsar is a spinning neutron star — the collapsed core of a massive star. Although only a few miles across, a neutron star is so dense that it weighs more than the Sun.

Image left: An artist’s rendering of the VERITAS array detecting gamma-ray pulses from the Crab Nebula.(Credit: José Francisco Salgado based on images by M. SubbaRao, S. Criswell, B. Humensky, and J.F. Salgado)

Rotating about 30 times a second, the Crab pulsar generates beams of radiation from its spinning magnetic field. The beams sweep around like a lighthouse beacon because they’re not aligned with the star’s rotation axis. So although the beams are steady, they’re detected on Earth as rapid pulses of radiation.

The discovery was reported by an international team of scientists in a paper in the October 7 issue of Science. Corresponding author Nepomuk Otte, a postdoctoral researcher at the University of California, Santa Cruz, said that some researchers had told him he was crazy to even look for pulsar emission in this energy realm.

“It turns out that being persistent and stubborn helps,” Otte said. “These results put new constraints on the mechanism for how the gamma-ray emission is generated.”

Some possible scenarios to explain the data have been put forward, but it will take more data, or even a next-generation observatory, to really understand the mechanisms behind these gamma-ray pulses.

Image right: This artist’s conception shows the Crab Nebula pulsar, which astronomers discovered to be sending out pulses of gamma rays with energies exceeding 100 billion electron-volts (100 GeV). A pulsar is a spinning neutron star – the collapsed core of a massive star that exploded as a supernova. (Credit: David A. Aguilar)

The gamma-ray pulses were detected by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) — the most powerful very-high-energy gamma-ray observatory in the Northern Hemisphere. VERITAS is located at the Smithsonian’s Whipple Observatory, just south of Tucson, Ariz.

Astronomers observe very-high-energy gamma rays with ground-based Cherenkov telescopes. These gamma rays, coming from cosmic “particle accelerators,” are absorbed in Earth’s atmosphere, where they create a short-lived shower of subatomic particles. The Cherenkov telescopes detect the faint, extremely short flashes of blue light that these particles emit (named Cherenkov light) using extremely sensitive cameras. The images can be used to infer the arrival direction and initial energy of the gamma rays.

This technique is used by gamma-ray observatories throughout the world, and was pioneered under the direction of CfA’s Trevor Weekes using the 10-meter Cherenkov telescope at Whipple Observatory. The Whipple 10-meter telescope was used to detect the first Galactic and extragalactic sources of very-high-energy gamma rays.

VERITAS continues the tradition of Whipple’s 10-meter telescope. It is comprised of an array of four 12-meter-diameter Cherenkov telescopes. VERITAS began full-scale observations in September 2007. The telescopes are used to study the remnants of exploded stars, distant galaxies, powerful gamma-ray bursts, and to search for evidence of mysterious dark matter particles.

Related posts:

1. Recent eruptions in the Crab Nebula mystify astronomers
2. Telescope array finds new evidence that exploding stars are sources of cosmic rays
3. Astronomers Find Rare Supernova by New Means

Thousands of scientists from around the world competed to be the first few researchers to explore some of the darkest, coldest, farthest, and most hidden secrets of the cosmos with this new astronomical tool. One of the projects chosen for ALMA Early Science observations was that of David Wilner of the Harvard-Smithsonian Center for Astrophysics (CfA).

Image left: View from the center of the Atacama Large Millimeter/ submillimeter Array at an elevation of 16,500 feet on the Chajnantor Plain in northern Chile. Each of these radio telescopes has a dish spanning nearly 40 feet across. (Photo by Tania Burchell)

“My team hunts for the building blocks of solar systems, and ALMA is uniquely equipped to spot them,”Wilner said.

His team’s target is AU Microscopii, a star 33 light-years away that is only about 50 million years old. “We will use ALMA to image the ‘birth ring’ of planetesimals that we believe orbits this young star. Only with ALMA can we hope to discover clumps in these dusty asteroid belts, which can be the markers of unseen planets,” said Wilner.

Wilner and his team will share their data with a European team who also requested ALMA observations of this nearby, dust-ringed star.

For the start of Early Science, around one third of ALMA’s eventual 66 radio telescopes will make up the growing array. Even while still under construction, ALMA has become the best telescope of its kind — a fact that was apparently well known to the astronomers who requested to observe with it.

Considering the limited number of hours allocated to this first phase of science, ALMA could only take about a hundred projects. “We were stunned when we received over nine hundred requests from all over the world!” said Lewis Ball, ALMA Deputy Director and ALMA Chief of Staff at the National Radio Astronomy Observatory (NRAO). “No other telescope on ground or in space has ever had this magnitude of over-demand.” The successful projects were chosen based on their scientific value, their regional diversity, and also their relevance to ALMA’s major science goals.

During its Early Science observations, ALMA will continue its construction phase in the Chilean Andes, high on the remote Chajnantor Plain in the harsh Atacama Desert. By 2013, ALMA will be an up to 11-mile-wide array of 66 ultra-precision millimeter/submillimeter wave radio telescopes working together as one and built by ALMA’s multinational partners in North America, East Asia, and Europe.

Related posts:

1. Harvard-Smithsonian Center for Astrophysics to own and operate ALMA Vertex Prototype Antenna
2. Luminosity of extreme galaxy most likely driven by star formation
3. Free, online course in physics offered by the Harvard-Smithsonian Center for Astrophysics