Universe Today

February 28, 2013December 23, 2015 by Nancy Atkinson

Surprising Third Radiation Belt Found Around Earth

Two giant swaths of radiation, known as the Van Allen Belts, surrounding Earth were discovered in 1958. In 2012, observations from the Van Allen Probes showed that a third belt can sometimes appear. The radiation is shown here in yellow, with green representing the spaces between the belts. Credit: NASA/Van Allen Probes/Goddard Space Flight Center

In September of 2012, scientists with the newly launched Van Allen Probes got permission to turn on one of their instruments after only three days in space instead of waiting for weeks, as planned. They wanted to turn on the Relativistic Electron Proton Telescope (REPT) so that its observations would overlap with another mission called SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer), that was soon going to de-orbit and re-enter Earth’s atmosphere.

Now, they are very glad they did, as something happened that no one had ever seen before. A previously unknown third radiation belt formed in the Van Allen Radiation Belts that encircle Earth. The scientist watched – in disbelief – while their data showed the extra belt forming, then suddenly disappear, like it had been cut away with a knife. They have not yet seen a recurrence of a third belt.

“First we thought our instruments weren’t working correctly,” said Dan Baker, a member of the Van Allen Probes team from the University of Colorado at Boulder, “but we quickly realized we were seeing a real phenomenon.”

What happened is that shortly before REPT was turned on, solar activity on the Sun had sent energy toward Earth that caused the radiation belts to swell. The energetic particles then settled into a new configuration, showing an extra, third belt extending out into space.

“By the fifth day REPT was on, we could plot out our observations and watch the formation of a third radiation belt,” says Shri Kanekal, the deputy mission scientist for the mission. “The third belt persisted beautifully, day after day, week after week, for four weeks.”

This graph shows energetic electron data gathered by the Relativistic Electron-Proton Telescope (REPT) instruments, on the twin Van Allen Probes satellites in eccentric orbits around the Earth, from Sept. 1, 2012 to Oct. 4, 2012 (horizontal axis). It shows three discrete energy channels (measured in megaelectron volts, or MeV). The third belt region (in yellow) and second slot (in green) are highlighted, and exist up until a coronal mass ejection (CME) destroys them on Oct. 1. The vertical axis in each is L*, effectively the distance in Earth radii at which a magnetic field line crosses the magnetic equatorial plane. Credit: LASP

Since their discovery in 1958, we’ve known that the Van Allen radiation belt is composed of two donut-shaped layers of energetic charged particles around the planet Earth, held in place by its magnetic field.

The scientists are now incorporating what they saw into new models of the radiation belts – a region that can sometimes swell dramatically in response to incoming energy from the Sun, impacting satellites and spacecraft or pose potential threats to human space flight.

The belts are normally between 200 to 60,000 kilometers above Earth; the new ring was much further out.

Launched on August 30, 2012 as the Radiation Belt Storm Probes mission, the twin probes were renamed in honor of the belts’ discoverer, astrophysicist James Van Allen. Observations of the belts have shown they are dynamic and mysterious. However, this type of dynamic three-belt structure was never seen, or even considered, theoretically.

A coronal mass ejection (CME) from the Sun on August 31, 2012, the event that caused a third ring to form in the Van Allen radiation belts. Credit: NASA

The Energetic Particle, Composition, and Thermal Plasma (ECT) suite of instruments on board the probes were designed to help understand how populations of electrons moving at nearly the speed of light and penetrating ions in space form or change in response to variable inputs of energy from the Sun.

Already, what the team has learned is re-writing the textbooks of what is known about the Van Allen belts.

“These events we’ve recorded are extraordinary and are already allowing us to refine and confirm our theories of belt dynamics in a way that will lead to predictability of their behavior,” said astrophysicst Harlan Spence, principal investigator for the ECT, “which is important for understanding space weather and ultimately for the safety of astronauts and spacecraft that operate within such a hazardous region of geospace.”

At a press briefing today, the team was asked why this third ring had never been observed before.

“We’ve never had the capability before to see something like this, said Nicky Fox, Van Allen Probes deputy project scientist. “The fact that we had such an amazing discovery within days of turning them on shows we still have mysteries to discover and explain. What the Van Allen Probes have shown is that the advances in technology and detection made by NASA have already had an almost immediate impact on basic science.”

Baker added, “As the philosopher Yogi Bera once said, you can observe a lot just by looking. This shows that when you open new eyes on the Universe you can invariably find new things.”

The team will be seeking to understand what the third ring mean for astronauts and satellites, even though the new ring is farther out, the regions in Earth orbit are magnetically connected to the new region that formed.

“Knowing more about this and understanding more about the belt is important for having better models and being able to predict the lifetimes of spacecraft,” said Fox.

“The rings, satellites, the space station are all affected by space weather,” said Mona Kessel, Van Allen Probes program scientist. “We don’t completely understand what we’ve seen, but we are modeling it and trying to piece this all together, so stay tuned.”

The team has published a paper in the journal Science.

For more info: NASA, University of New Hampshire

February 28, 2013August 27, 2021 by Nancy Atkinson

Cosmic Rays and Exploding Stars

Scientists have known about cosmic rays for a century. But these high-energy subatomic particles, which stream through space at nearly the speed of light and crash into the Earth’s upper atmosphere, have been mostly a mystery. The primary reason: researchers have been unable to tell where they come from, or how they’re born. But new research has shed new light on the origins of cosmic rays: supernovae. (Read our article about this discovery).

Today, Thursday, Feb. 28,at 20:00-20:30 UTC (12:00-12:30 p.m. PST, 3:00 pm EST) Dr. Stefan Funk of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) will answer questions from the web. He led the research team that was able to track gamma rays — the most energetic form of electromagnetic radiation, or light — back to the remnants of supernova explosions, using the Fermi Gamma Ray Telescope. The finding offers the first astrophysical evidence for how cosmic rays are produced, as well as where they are generated: in the shock waves that emanate from an exploded star.
Continue reading “Cosmic Rays and Exploding Stars”

February 28, 2013December 23, 2015 by Nancy Atkinson

First Direct Observation of a Nearby Protoplanet

This image from the NACO system on ESO’s Very Large Telescope shows a candidate protoplanet in the disc of gas and dust around the young star HD100546. Credit: ESO.

Astronomers have taken what is likely the first-ever direct image of a planet that is still undergoing its formation, embedded in its “womb” of gas and dust. The protoplanet, about the size of Jupiter, is in the disc surrounding a young star, HD 100546, located 335 light-years from Earth.

If this discovery is confirmed, astronomers say this it will greatly improve our understanding of how planets form and allow astronomers to test the current theories against an observable target.

“So far, planet formation has mostly been a topic tackled by computer simulations,” said Sascha Quanz, from ETH Zurich in Switzerland, who led an international team using the Very Large Telescope to make the observations. “If our discovery is indeed a forming planet, then for the first time scientists will be able to study the planet formation process and the interaction of a forming planet and its natal environment empirically at a very early stage.”

The protoplanet appears as a faint blob in the circumstellar disc of HD 100546, a well-studied star, and astronomers have already discovered other protoplanets orbiting this star. In 2003, astronomers used a technique called “nulling interferometry” to reveal not only the planetary disk, but also discovered a gap in the disk, where a Jupiter-like planet is probably forming about six times farther form the star than Earth is from the Sun. This newly found planet candidate is located in the outer regions of the system, about ten times further out.

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The team used the VLT along with a near-infrared coronograph in an adaptive optics instrument called NACO, which enabled them to suppresses the bright light of the star, combined with pioneering data analysis techniques.

The current theory of planet formation is based mostly on observations of our own solar system. Since 1995, when the first exoplanet around a Sun-like star was discovered, several hundred planetary systems have been found, opening up new opportunities for scientists studying planetary formation. But until now, none have been “caught in the act” in the process of being formed, while still embedded in the disc of material around their young parent star.

This composite image shows a view from the NASA/ESA Hubble Space Telescope (left) and from the NACO system on ESO’s Very Large Telescope (right) of the gas and dust around the young star HD 100546. The Hubble visible-light image shows the outer disc of gas and dust around the star. The new infrared VLT picture of a small part of the disc shows a candidate protoplanet. Both pictures were taken with a special coronagraph that suppresses the light from the brilliant star. The position of the star is marked with a red cross in both panels. Credit: ESO/NASA/ESA/Ardila et al.

But in studying the disc around HD 100546, astronomers have spotted several features that support the current theory that giant planets grow by capturing some of the gas and dust that remains after the formation of a star. They have seen structures in the dusty circumstellar disc, which could be caused by interactions between the planet and the disc, as well as indications that the surroundings of the protoplanet are being heated up by the formation process.

The astronomers are doing follow-up observations to confirm the discovery, as it is possible that the detected signal could have come from an unrelated background source, or it could possibly be a fully formed planet which was ejected from its original orbit closer to the star. But the researchers say the most likely explanation is that this is actually the first protplanet that has been directly imaged.

Source: ESO

February 28, 2013December 23, 2015 by Bob King

Comet PANSTARRS Cranks up the Volume

The comet photographed with a 300mm lens. Both the main dust tail and the shorter, fainter Type III dust tail are seen. Credit: Michael Mattiazzo

Brand new photos from amateur astronomers Michael Mattiazzo and Jim Gifford, both of Australia show the current view of Comet C/2011 L4 PANSTARRS down under, and gives sky watchers in the northern hemisphere hope for great views of in little more than a week. The comet has been brightening steadily and now shines around magnitude 2.6, just a little fainter than the stars of the Big Dipper. More images below:

Comet L4 PANSTARRS on February 28 through an 11-inch telescope. Credit: Michael Mattiazzo — Comet L4 PANSTARRS from Castlemaine, Victoria, Australia on February 28 through an 11-inch telescope. Click for more photos. Credit: Michael Mattiazzo

On February 28, Mattiazzo spotted the comet and a small portion of its dust tail in evening twilight 6 degrees above the western horizon. Using large binoculars he could trace the tail to 1.5 degrees or three lunar diameters. PANSTARRS also has a second fainter dust tail, called a Type III tail, composed of heavier dust particles, dimly visible in the photo below alongside the brighter Type II tail.

Comet L4 PANSTARRS low in the western sky over Western Australia Feb. 27, 2013. Details: 400mm lens — Comet L4 PANSTARRS low in the western sky over Bridgetown, Western Australia Feb. 27, 2013. Click for more photos. Details: 400mm lens, 4-second exposure at ISO 5000. Credit: Jim Gifford

A third ion tail, while not currently visible with the naked eye, shows up well in photographs. Dust tails form when the heat of the sun vaporizes dust-laden ices in the comet’s nucleus; solar photons – literally light itself – gently pushes the dust away from the comet’s head into a long, beautiful tail. Gases like carbon monoxide and cyanogen, which are normally neutral, get their energy levels pumped up by the sun’s ultraviolet light, shed their outer electrons and become “ionized.” The same UV light causes the gases to fluoresce a pale blue.

Additional info: Comet PanSTARRS: How to See it in March 2013

Comets often develop two tails as they near the sun - a curved dust tail and straight, ion tail. Credit: NASA — Comets often develop two tails as they near the sun – a curved dust tail and straight, ion tail. Dust tails reflect sunlight and appear yellowish. Ion tails glow blue when comet gases are ionized by UV light from the sun and re-emit it as blue. Credit: NASA

Dust tails generally follow the comet’s curving orbit and assume the shape of a gently-curved arc; ion tails are straight as a stick and point directly away from the sun. Once carbon monoxide molecules have been ionized, they’re susceptible to the magnetic force that flows from the sun as part of the solar wind. The wind with its entrained solar magnetism sweeps by the comet at some 300 miles per second (500 km/sec.) and blows the ion tail straight back exactly opposite the Sun.

With PANSTARRS sprouting tails right and left and peak brightness predictions still around magnitude 1 or 2, get ready for this herald of the new season.

Here’s bascially a naked-eye view of PANSTARRS, taken by Dave Curtis on February 22, 2013 from Dunedin, New Zealand. “The comet was just visible with the naked eye in the twilight,” Dave said. It was taken with a Canon 5D3 and a 70-200mm lens at 70mm:

Comet PanSTARRS on feb. 22, 2013 from Dunedin, New Zealand. Credit: Dave Curtis.

February 28, 2013December 23, 2015 by Elizabeth Howell

The Men Who Didn’t Go to the Moon

Elliott See (left) and Charlie Bassett, who were slated to fly aboard the Gemini 9 mission. Credit: NASA

On this day (Feb. 28) in 1966, the Gemini 9 prime crew was in a T-38 airplane making a final approach to a McDonnell Aircraft plant in St. Louis, Missouri. Amid deteriorating weather conditions, Elliot See tried to make a landing. His airplane collided with the factory building in which his spacecraft was under construction. The plane crashed, killing both See and his crewmate Charlie Bassett.

The accident sent shockwaves through the small astronaut corps, and also necessitated some hasty reassignments. The Gemini 9 backup crew of Tom Stafford and Eugene Cernan immediately became the prime crew and launched into space on May 17, 1966 on a mission that included a challenging spacewalk for Cernan.

But according to Deke Slayton, who was responsible for crew selections at the time, the deaths of See and Bassett even affected the Moon missions of Apollo.

“I … had a lot of plans for Charlie Bassett — after GT-9 [Gemini 9] he would have moved on to command module pilot for Frank Borman’s Apollo crew. Elliott was going to be backup commander for GT-12,” wrote Slayton in his memoir Deke!, which he created with help from Twilight Zone writer (and multiple book author) Michael Cassutt.

In Slayton’s mind, the loss of this one crew affected assignments all the way to the first crew who landed on the Moon: Neil Armstrong and Buzz Aldrin on Apollo 11. (Michael Collins was also on the mission, but remained in orbit in the command module.)

Buzz Aldrin on the Moon for Apollo 11. Credit: NASA

“All the backups were changed, and Jim Lovell and Buzz Aldrin wound up being pointed at GT-12,” Slayton wrote. “Without flying GT-12, it was very unlikely that Buzz would have been in any position to be lunar module pilot on the first landing attempt.”

It’s possible this crash could even have affected Apollo 13, which happened four years later.

Jim Lovell flew on Apollo 8 as the command module pilot. While Slayton didn’t state it, Lovell’s experience on that mission likely led to his appointment as commander for Apollo 14. Fate then shifted him forward a flight to the ill-fated Apollo 13, which was crippled by an oxygen tank explosion, after the original commander of that flight, Al Shepard, required a little more time for training.

As for See and Bassett, their remains were buried at Arlington National Cemetery, which is also home to many other fallen crews. Several crew members from Apollo 1, the Challenger disaster and the Columbia disaster have been laid to rest there.

February 28, 2013December 23, 2015 by Jason Major

A New Look at Saturn’s Northern Hexagon

Raw Cassini image captured on 26 Feb. 2013 (NASA/JPL/SSI)

Freshly delivered from Cassini’s wide-angle camera, this raw image gives us another look at Saturn’s north pole and the curious hexagon-shaped jet stream that encircles it, as well as the spiraling vortex of clouds at its center.

Back in November we got our first good look at Saturn’s north pole in years, now that Cassini’s orbit is once again taking it high over the ringplane. With spring progressing on Saturn’s northern hemisphere the upper latitudes are getting more and more sunlight — which stirs up storm activity in its atmosphere.

The bright tops of upper-level storm clouds speckle Saturn’s skies, and a large circular cyclone can be seen near the north pole, within the darker region contained by the hexagonal jet stream. This could be a long-lived storm, as it also seems to be in the images captured on November 27.

About 25,000 km (15,500 miles) across, Saturn’s hexagon is wide enough to fit nearly four Earths inside!

The Saturn hexagon as seen by Voyager 1 in 1980 (NASA)

The hexagon was originally discovered in images taken by the Voyager spacecraft in the early 1980s. It encircles Saturn at about 77 degrees north latitude and is estimated to whip around the planet at speeds of 354 km/h (220 mph.)

Watch a video of the hexagon in motion here.

The rings can be seen in the background fading into the shadow cast by the planet itself. A slight bit of ringshine brightens Saturn’s nighttime limb.

Cassini was approximately 579,653 kilometers (360,180 miles) from Saturn when the raw image above (W00079643) was taken.

Image credit: NASA/JPL/Space Science Institute

February 27, 2013December 23, 2015 by Tammy Plotner

Greek Observatory Probes Ancient Star

An image of the enclosure of the new 2.3-m Aristarchos telescope, sited at Helmos Observatory. Credit: P. Boumis, National Observatory of Athens.

Some 2,500 years ago, a Greek astronomer named Aristarchus certainly made some very correct assumptions when he postulated the Sun to be at the center of our known Universe and that the Earth revolved around it. Through this, he also knew that the stars were incredibly far away and now his namesake telescope, the new 2.3 meter Aristarchos, is taking that distant look from the Helmos Observatory, high atop the Peloponnese Mountains in Greece. Its purpose is to determine the distance and evolution of a mysterious star system – one which is encased in an ethereal nebula.

While looking at the demise of a possible binary star system, researchers Panos Boumis of the National Observatory of Athens and John Meaburn of the University of Manchester, set out to photograph this enigmatic study with the narrowband imaging camera onboard the Aristarchos telescope. Their target designation is planetary nebula KjPn8, and it was originally discovered during the 1950’s Palomar Sky Survey. What makes it out of the ordinary is two huge lobes, measuring a quarter of a degree across, which surround the system. This artifact was researched by Mexican astronomers at the San Pedro Martir Observatory some four decades after its revelation, but it wasn’t until the year 2000 that the Hubble Space Telescope uncovered its central star.

An image of the giant lobes of the planetary nebula KjPn 8 in the light of the emission lines of hydrogen and singly ionised nitrogen, obtained with the narrowband camera on the new 2.3-m Aristarchos telescope. Detailed measurements of the lobes have allowed the determination of their expansion velocity, distance and ages. The results indicate their origin in a remarkable eruptive binary system. Credit: P. Boumis / J. Meaburn

Dr. Boumis and Prof. Meaburn began to study this ancient cosmic artifact, concentrating on measuring the expansion with utmost accuracy. Through their work, they were unable to uncover the system’s distance and trace the history of the lobes through time. What they discovered was KjPn8 is roughly 6,000 light years away and the lobes of material have three epochs: 3200, 7200 and 50,000 years. According to the research team: “The inner lobe of material is expanding at 334 km per second, suggesting it originates in an Intermediate Luminosity Optical Transient (ILOT) event. ILOTs are caused by the transfer of material from a massive star to its less massive companion, in turn creating jets that flow in different directions. We believe that the core of KjPn8 is therefore a binary system, where every so often ILOT events lead to the ejection of material at high speed.”

It is certainly a triumph for the Aristachos Telescope and the new Greek facility. Dr. Bournis is quite proud of the conclusive results gathered by telescope – especially when the object in question cries out for more research. He comments: “Greece is one of the global birthplaces of astronomy, so it is fitting that research into the wider universe continues in the 21st century. With the new telescope we expect to contribute to that global effort for many years to come.”

Original Story Source: Royal Astronomical Society News Release.

February 27, 2013December 23, 2015 by Tammy Plotner

NuSTAR Puts New Spin On Supermassive Black Holes

A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech — A team of astronomers from South Africa have noticed a series of supermassive black holes in distant galaxies that are all spinning in the same direction. Credit: NASA/JPL-Caltech

Checking out the spin rate on a supermassive black hole is a great way for astronomers to test Einstein’s theory under extreme conditions – and take a close look at how intense gravity distorts the fabric of space-time. Now, imagine a monster … one that has a mass of about 2 million times that of our Sun, measures 2 million miles in diameter and rotating so fast that it’s nearly breaking the speed of light.

A fantasy? Not hardly. It’s a supermassive black hole located at the center of spiral galaxy NGC 1365 – and it is about to teach us a whole lot more about how black holes and galaxies mature.

What makes researchers so confident they have finally taken definitive calculations of such an incredible spin rate in a distant galaxy? Thanks to data taken by the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellites, the team of scientists has peered into the heart of NGC 1365 with x-ray eyes – taking note of the location of the event horizon – the edge of the spinning hole where surrounding space begins to be dragged into the mouth of the beast.

“We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole,” said the coauthor of a new study, NuSTAR principal investigator Fiona Harrison of the California Institute of Technology in Pasadena. “The radiation we see is warped and distorted by the motions of particles and the black hole’s incredibly strong gravity.”

However, the studies didn’t stop there, they advanced to the inner edge to encompass the location of the accretion disk. Here is the “Innermost Stable Circular Orbit” – the proverbial point of no return. This region is directly related to a black hole’s spin rate. Because space-time is distorted in this area, some of it can get even closer to the ISCO before being pulled in. What makes the current data so compelling is to see deeper into the black hole through a broader range of x-rays, allowing astronomers to see beyond veiling clouds of dust which only confused past readings. These new findings show us it isn’t the dust that distorts the x-rays – but the crushing gravity.

Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. Image credit: NASA/JPL-Caltech

“This is the first time anyone has accurately measured the spin of a supermassive black hole,” said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF — Arcetri Observatory.

“If I could have added one instrument to XMM-Newton, it would have been a telescope like NuSTAR,” said Norbert Schartel, XMM-Newton Project Scientist at the European Space Astronomy Center in Madrid. “The high-energy X-rays provided an essential missing puzzle piece for solving this problem.”

Even though the central black hole in NGC 1365 is a monster now, it didn’t begin as one. Like all things, including the galaxy itself, it evolved with time. Over millions of years it gained in girth as it consumed stars and gas – possibly even merging with other black holes along the way.

“The black hole’s spin is a memory, a record, of the past history of the galaxy as a whole,” explained Risaliti.

“These monsters, with masses from millions to billions of times that of the sun, are formed as small seeds in the early universe and grow by swallowing stars and gas in their host galaxies, merging with other giant black holes when galaxies collide, or both,” said the study’s lead author, Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and the Italian National Institute for Astrophysics.

This new spin on black holes has shown us that a monster can emerge from “ordered accretion” – and not simply random multiple events. The team will continue their studies to see how factors other than black hole spin changes over time and continue to observe several other supermassive black holes with NuSTAR and XMM-Newton.

“This is hugely important to the field of black hole science,” said Lou Kaluzienski, NuSTAR program scientist at NASA Headquarters in Washington, D.C. “NASA and ESA telescopes tackled this problem together. In tandem with the lower-energy X-ray observations carried out with XMM-Newton, NuSTAR’s unprecedented capabilities for measuring the higher energy X-rays provided an essential, missing puzzle piece for unraveling this problem.”

Original Story Source: JPL/NASA News Release.

February 27, 2013December 23, 2015 by Nancy Atkinson

Losing the Night: New Video Highlights Problems of Light Pollution

Air glow (along with a lightning sprite) is visible in this image from the International Space Station. Credit: NASA

Light pollution is a two-way murky street. Not only have millions of people never seen the glow of our Milky Way in the night sky because of light pollution, but also when astronauts in the International Space Station look down at Earth, they see lights almost everywhere and a faint green or yellow air-glow — caused mostly by light pollution — hovers over the planet in a majority of the images they send back from space.

“Light pollution threatens the health of every living thing on Earth,” says a new planetarium-like video from the International Dark-Sky Association in collaboration with Loch Ness Productions, a U.S.-based full-dome planetarium show production company.

“Losing the Dark” illustrates problems caused by light pollution, with particular emphasis on how it affects night-sky visibility. But the video also offers simple solutions for mitigating light pollution, and reminds everyone it is not too late to save the starry sky.

Bob Parks, IDA Executive Director said, “Everyone who views ‘Losing the Dark’ can see how easy it is to make wise choices about outdoor lighting, and that together we can work to restore the night sky to its former glory.”

The video is narrated by astronomer Carolyn Collins Petersen, (whose voice you may recognize from past 365 Days of Astronomy podcasts), and the show is also available in full-dome versions for planetariums and science centers as a public service announcement.

“Planetariums champion the night sky already,” Collins Petersen said. “They tap into public awareness, so their audiences are a prime demographic for this message. The show gives planetarium professionals another tool to help educate the public about this critical issue. The HD version extends the message to more people through presentations by educators and dark-sky advocates.”

For more information about the video, see the International Dark Skies Association website.

February 27, 2013December 23, 2015 by David Dickinson

Pulsar Jackpot Scours Old Data for New Discoveries

Space Shuttle Atlantis passes behind the Parkes radio telescope after final undocking from the International Space Station in July 2011. (Image Copyright: John Sarkissian; used with permission).

Chalk another one up for Citizen Science. Earlier this month, researchers announced the discovery of 24 new pulsars. To date, thousands of pulsars have been discovered, but what’s truly fascinating about this month’s discovery is that came from culling through old data using a new method.

A pulsar is a dense, highly magnetized, swiftly rotating remnant of a supernova explosion. Pulsars where first discovered by Jocelyn Bell Burnell and Antony Hewish in 1967. The discovery of a precisely timed radio beacon initially suggested to some that they were the product of an artificial intelligence. In fact, for a very brief time, pulsars were known as LGM’s, for “Little Green Men.” Today, we know that pulsars are the product of the natural death of massive stars.

The data set used for the discovery comes from the Parkes 64-metre radio observatory based out of New South Wales, Australia. The installation was the first to receive telemetry from the Apollo 11 astronauts on the Moon and was made famous in the movie The Dish. The Parkes Multi-Beam Pulsar Survey (PMPS) was conducted in the late 1990’s, making thousands of 35-minute recordings across the plane of the Milky Way galaxy. This survey turned up over 800 pulsars and generated 4 terabytes of data. (Just think of how large 4 terabytes was in the 90’s!)

Artist's conception of a pulsar. (Credit: NASA/GSFC). — Artist’s conception of a pulsar. (Credit: NASA/GSFC).

The nature of these discoveries presented theoretical astrophysicists with a dilemma. Namely, the number of short period and binary pulsars was lower than expected. Clearly, there were more pulsars in the data waiting to be found.

Enter Citizen Science. Using a program known as Einstein@Home, researchers were able to sift though the recordings using innovative modeling techniques to tease out 24 new pulsars from the data.

“The method… is only possible with the computing resources provided by Einstein@Home” Benjamin Knispel of the Max Planck Institute for Gravitational Physics told the MIT Technology Review in a recent interview. The study utilized over 17,000 CPU core years to complete.

Einstein@Home screenshot. (Credit: LIGO Consortium).

Einstein@Home is a program uniquely adapted to accomplish this feat. Begun in 2005, Einstein@Home is a distributed computing project which utilizes computing power while machines are idling to search through downloaded data packets. Similar to the original distributed computing program SETI@Home which searches for extraterrestrial signals, Einstein@Home culls through data from the LIGO (Laser Interferometer Gravitational Wave Observatory) looking for gravity waves. In 2009, the Einstein@Home survey was expanded to include radio astronomy data from the Arecibo radio telescope and later the Parkes observatory.

Among the discoveries were some rare finds. For example, PSR J1748-3009 Has the highest known dispersion measure of any millisecond pulsar (The dispersion measure is the density of free electrons observed moving towards the viewer). Another find, J1750-2531 is thought to belong to a class of intermediate-mass binary pulsars. 6 of the 24 pulsars discovered were part of binary systems.

These discoveries also have implications for the ongoing hunt for gravity waves by such projects as LIGO. Specifically, a through census of binary pulsars in the galaxy will give scientists a model for the predicted rate of binary pulsar mergers. Unlike radio surveys, LIGO seeks to detect these events via the copious amount of gravity waves such mergers should generate. Begun in 2002, LIGO consists of two gravity wave observatories, one in Hanford Washington and one in Livingston Louisiana just outside of Baton Rouge. Each LIGO detector consists of two 2 kilometre Fabry-Pérot arms in an “L” configuration which allow for ultra-precise measurements of a 200 watt laser beam shot through them. Two detectors are required to pin-point the direction of an incoming gravity wave on the celestial sphere. You can see the orientation of the “L’s” on the display on the Einstein@Home screensaver. Two geographically separate detectors are also required to rule out local interference. A gravity wave from a galactic source would ripple straight through the Earth.

Arial view of LIGO Livingston. (Image credit: The LIGO Scientific Collaboration).

Such a movement would be tiny, on the order of 1/1,000^th the diameter of a proton, unnoticed by all except the LIGO detectors. To date, LIGO has yet to detect gravity waves, although there have been some false alarms. Scientists regularly interject test signals into the data to see if system catches them. The lack of detection of gravity waves by LIGO has put some constraints on certain events. For example, LIGO reported a non-detection of gravity waves during the February 2007 short gamma-ray burst event GRB 070201. The event arrived from the direction of the Andromeda Galaxy, and thus was thought to have been relatively nearby in the universe. Such bursts are thought to be caused by neutron star and/or black holes mergers. The lack of detection by LIGO suggests a more distant event. LIGO should be able to detect a gravitational wave event out to 70 million light years, and Advanced LIGO (AdLIGO) is set to go online in 2014 and will increase its sensitivity tenfold.

The control room at LIGO Livingston. (Photo by Author).

Knowledge of where these potential pulsar mergers are by such discoveries as the Parkes radio survey will also give LIGO researchers clues of targets to focus on. “The search for pulsars isn’t easy, especially for these “quiet” ones that aren’t doing the equivalent of “screaming” for our attention,” Says LIGO Livingston Data Analysis and EPO Scientist Amber Stuver. The LIGO consortium developed the data analysis technique used by Einstein@Home. The direct detection of gravitational waves by LIGO or AdLIGO would be an announcement perhaps on par with CERN’s discovery of the Higgs Boson last year. This would also open up a whole new field of gravitational wave astronomy and perhaps give new stimulus to the European Space Agencies’ proposed Laser Interferometer Space Antenna (LISA) space-based gravity wave detector. Congrats to the team at Parkes on their discovery… perhaps we’ll have the first gravity wave detection announcement out of LIGO as well in years to come!

-Read the original paper on the discovery of 24 new pulsars here.

-Amber Stuver blogs about Einstein@Home & the spin-off applications of gravity wave technology at Living LIGO.

-Parkes radio telescope image is copyrighted and used with the permission of CSIRO Operations Scientist John Sarkissian.

-For a fascinating read on the hunt for gravity waves, check out Gravity’s Ghost.