Posted on by Tammy Plotner

Carbon “Super Earths” – Diamond Planets

Iron, carbon, and oxygen subjected to intense temperatures and pressures form a pocket of iron oxide (bottom, center) and a darker pocket of diamond (bottom, right). Electron micrograph courtesy of Ohio State University

[/caption]During a laboratory experiment at Ohio State University, researchers were simulating the pressures and conditions necessary to form diamonds in the Earth’s mantle when they came across a surprise… A carbon “Super Earth” could exist. While endeavoring to understand how carbon might behave in other solar systems, they wondered if planets high in this element could be pressurized to the point of producing this valuable gemstone. Their findings point to the possibility that the Milky Way could indeed be home to stars where planets might consist of up to 50% diamond.

The research team is headed by Wendy Panero, associate professor in the School of Earth Sciences at Ohio State, and doctoral student Cayman Unterborn. As part of their investigation they incorporated their findings from earlier experiments into a computer modeling simulation. This was then used to create scenarios where planets existed with a higher carbon content than Earth..

The result: “It’s possible for planets that are as big as fifteen times the mass of the Earth to be half made of diamond,” Unterborn said. He presented the study Tuesday at the American Geophysical Union meeting in San Francisco.

“Our results are striking, in that they suggest carbon-rich planets can form with a core and a mantle, just as Earth did,” Panero added. “However, the cores would likely be very carbon-rich – much like steel – and the mantle would also be dominated by carbon, much in the form of diamond.”

At the center of our planet is an assumed molten iron core, overlaid with a mantle of silica-based minerals. This basic building block of Earth is what condensed from the materials in our solar cloud. In an alternate situation, a planet could form in a carbon-rich environment, thereby having a different planet structure – and a different potential for life. (Fortunately for us, our molten interior provides geothermal energy!) On a diamond planet, the heat would dissipate quickly – leading to a frozen core. On this basis, a diamond planet would have no geothermal resources, lack plate tectonics and wouldn’t be able to support either an atmosphere or a magnetic field.

“We think a diamond planet must be a very cold, dark place,” Panero said.

How did they come up with their findings? Panero and former graduate student Jason Kabbes took a miniature sample of iron, carbon, and oxygen and subjected it to pressures of 65 gigapascals and temperatures of 2,400 Kelvin (close to 9.5 million pounds per square inch and 3,800 degrees Fahrenheit – conditions similar to the Earth’s deep interior). As they observed the experiment microscopically, they saw oxygen bonding with iron to create rust… but what was left turned to pure carbon and eventually formed diamond. This led them to wonder about planetary formation implications.

“To date, more than five hundred planets have been discovered outside of our solar system, yet we know very little about their internal compositions,” said Unterborn, who is an astronomer by training.

“We’re looking at how volatile elements like hydrogen and carbon interact inside the Earth, because when they bond with oxygen, you get atmospheres, you get oceans – you get life,” Panero said. “The ultimate goal is to compile a suite of conditions that are necessary for an ocean to form on a planet.”

But don’t confuse their findings with recent, unrelated studies which involves the remnants of an expired star from a binary system. The OSU team’s finding simply suggest this type of planet could form in our galaxy, but how many or where they might be is still very open to interpretation. It’s a question that’s being investigated by Unterborn and Ohio State astronomer Jennifer Johnson.

Because diamonds are forever…

Original Story Source: Ohio State Research News.

Posted on by Tammy Plotner

Incredible Spinning Star Rotates At A Million Miles Per Hour!

This is an artist's concept of the fastest rotating star found to date. The massive, bright young star, called VFTS 102, rotates at a million miles per hour, or 100 times faster than our Sun does. Centrifugal forces from this dizzying spin rate have flattened the star into an oblate shape and spun off a disk of hot plasma, seen edge on in this view from a hypothetical planet. The star may have "spun up" by accreting material from a binary companion star. The rapidly evolving companion later exploded as a supernova. The whirling star lies 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of our Milky Way. Credit: NASA, ESA, and G. Bacon (STScI)

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Located in the Large Magellanic Cloud, a star named VFTS 102 is spinning its heart out… Literally. Rotating at a mind-numbing speed of a million miles per hour (1.6 million kph), this hot blue giant has reached the edge where centrifugal forces could tear it apart. It’s the fastest ever recorded – 300 times faster than our Sun – and may have been split off from a double star system during a violent explosion.

Thanks to ESO’s Very Large Telescope at the Paranal Observatory in Chile, an international team of astronomers studying the heaviest and brightest stars in the Tarantula Nebula made quite a discovery – a huge blue star 25 times the mass of the Sun and about one hundred thousand times brighter was cruising through space at a speed which drew their attention.

“The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had an unusual early life. We were suspicious.” explains Philip Dufton (Queen’s University Belfast, Northern Ireland, UK), lead author of the paper presenting the results.

ESO's Very Large Telescope has picked up the fastest rotating star found so far. This massive bright young star lies in our neighbouring galaxy, the Large Magellanic Cloud, about 160 000 light-years from Earth. Astronomers think that it may have had a violent past and has been ejected from a double star system by its exploding companion. Credit: ESO

What they’ve discovered could possibly be a “runaway star” – one that began life as a binary, but may have been ejected during a supernova event. Further evidence which supports their theory also exists: the presence of a pulsar and a supernova remnant nearby. But what made this crazy star spin so fast? It’s possible that if the two stars were very close that streaming gases could have started the incredible rotation. Then the more massive of the pair blew its stack – expelling the star into space. So what would be left? It’s elementary, Watson… A supernova remnant, a pulsar and a runaway!

Even though this is a rather tidy conclusion, there’s always room for doubt. As Dufton concludes, “This is a compelling story because it explains each of the unusual features that we’ve seen. This star is certainly showing us unexpected sides of the short but dramatic lives of the heaviest stars.”

Original Story Source: HubbleSite News Release and ESO News Release. For Further Reading: he VLT-FLAMES Tarantula Survey I. Introduction and observational overview.

Posted on by Tammy Plotner

Earth’s Magnetic Pole Reversal – Don’t “Flip Out”!

Schematic illustration of Earth's magnetic field. Credit/Copyright: Peter Reid

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Have you heard or read stories about how Earth will some day reverse its magnetic poles? If you have, then chances are very good you’ve also heard this perfectly normal function of our planet could spell disaster. Before you buy into another “end of the world as we know it” scenario, let’s take a look at the facts.

For the record, we know that Earth’s magnetic field has changed its polarity more than once in its lifetime. For example, if you could step back in time some 800,000 years ago with a compass in your hand, you’d see the needle pointed to south – instead of north. Why? Because a compass works on magnetic fields, its needle directs you to the magnetic pole, measured as either positive or negative. The markings on the modern compass dial would be incorrect if the polarity of Earth’s magnetic fields were reversed! Like a witch hunt, many would-be prophets say natural occurrences like this might signal doom… But could their theories be correct? Unfortunately for hyperbole, the geologic and fossil records from past reversals show the answer is “No.” We’ll still be around.

Just like the Sun reversing its magnetic poles, Earthly switches are just a part of our planet’s schedule. During about the last 20 million years of our formation, Earth has settled into a pattern of switching magnetic poles about every 200,000 to 300,000 years… with a period of twice that long since our last reversal. And, it’s not a thing that happens rapidly. Magnetic pole reversal takes up to several hundred thousands of years to complete. The fields blend together and magnetic poles pop up at odd latitudes as it happens. It’s not that scary! Scientists say that Earth has reversed its magnetic field hundreds of times over the last three billion years and have sped up slightly with time.

How do we know about the impacts of magnetic pole reversal? We take a look at the deep evidence – sediment cores taken from the ocean floor. These samples are perfect fossil records which show us what direction the magnetic field was pointed in as the underwater lava emerged. These ancient flows were magnetized in the field’s direction at the time of their creation and exist on either side of the Mid-Atlantic Rift where the North American and European continental plates are moving away from each other.

“The last time that Earth’s poles flipped in a major reversal was about 780,000 years ago, in what scientists call the Brunhes-Matuyama reversal. The fossil record shows no drastic changes in plant or animal life.” says NASA’s Patrick Lynch. ” Deep ocean sediment cores from this period also indicate no changes in glacial activity, based on the amount of oxygen isotopes in the cores. This is also proof that a polarity reversal would not affect the rotation axis of Earth, as the planet’s rotation axis tilt has a significant effect on climate and glaciation and any change would be evident in the glacial record.”

A schematic diagram of Earth's interior and the movement of magnetic north from 1900 to 1996. The outer core is the source of the geomagnetic field. Graphic Credit: Dixon Rohr
Unlike a hard-wired magnet, Earth’s polarity isn’t constant – it moves around a bit. The reason we have a magnetic field is our solid iron core surrounding by hot, fluid metal. According to computer modeling, this flow creates electric currents which spawn the magnetic fields. While it’s not possible at this point in time to measure the outer core of our planet directly, we can guess at its movement by the changes in the magnetic field. One such change has occurred for almost 200 years now… Our northern pole has been shifting even more northward. Since it was first located, the pole has shifted its place by more than 600 miles (1,100 km)! What’s more, it’s speeding up. It would seem that it’s moving almost 40 miles per year now, instead of the 10 miles per year as recorded in the early 20th century.

Don’t be fooled by those saying a magnetic pole reversal would leave us temporarily without a magnetic field, either. This is simply isn’t going to happen and we’re not going to be exposed to harmful solar activity. While our magnetic field goes through weaker and stronger phases, there is simply no evidence to be found anywhere that it has ever disappeared completely. Even if it were weakened, our atmosphere would protect us against incoming particles and we’d have more auroral displays at lower latitudes!

So, go ahead… Sleep at night. Earthly magnetic pole reversal is a normal function of our planet and when it does happen its effects will be spread out over hundreds of thousands of years – not flipped like a pancake.

Original Story Source: NASA Earth News. For Further Reading: Earth’s Inconstant Magnetic Field..

Posted on by Tammy Plotner

Mars Express Reveals Possible Martian Glaciers

Phlegra Montes is a range of gently curving mountains and ridges on Mars. They extend from the northeastern portion of the Elysium volcanic province to the northern lowlands. The High-Resolution Stereo Camera on ESA’s Mars Express collected the data for these images on 1 June 2011 during orbit 9465. This perspective view has been calculated from the Digital Terrain Model derived from the stereo channels. Credits: ESA/DLR/FU Berlin (G. Neukum)

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When it comes to exploring Mars, one of the greatest needs future astronauts will face is water. Why? Simple enough. Transporting water would take a huge amount of fuel. Now the Mars Express has imaged an area on the red planet which may yield large quantities of sub-surface ice. Its name is Phlegra Montes…

Extending from the northeastern portion of the Elysium volcanic province to the northern lowlands, spanning latitudes from roughly 30°N to 50°N, the Phlegra Montes are a gently rolling series of hills that have been probed by radar. It is surmised these low mountain ranges are not volcanic in origin, but created through tectonic forces and may conceal a copious supply of frozen water.

Thanks to high resolution stereo imaging from ESA’s Mars Express orbiter, we’re able to detect a feature called ‘lobate debris aprons’. They appear to surround almost every mountain in the Phelegra’s and it’s a normal feature for mountains found around these latitudes. Earlier studies of the debris aprons show the material has slid down the mountain slopes with time – a feature shared with Earth’s glaciers. Because of this similarity, scientists surmise this region may be a type of Martian glacier. It’s a guess that’s also been confirmed by radar on NASA’s Mars Reconnaissance Orbiter.

Phlegra Montes is a range of gently curving mountains and ridges on Mars. Flow patterns attributable to water are widely visible across the image. Linear flow patterns can be seen inside the valley (Box 1). Nearly every mountain is surrounded by an apron of rocky debris (Box 2). Over time, this debris appears to have moved down the mountainside and looks similar to the debris found covering glaciers here on Earth. Lobe-shaped structures seen inside impact craters in the region (Box 3) are known as concentric crater fill and are perhaps another indication of subsurface water ice. The High-Resolution Stereo Camera on ESA’s Mars Express collected the data for these images on 1 June 2011 during orbit 9465. Credits: ESA/DLR/FU Berlin (G. Neukum)

According to the radar data, the lobate debris aprons could indeed signal the presence of ice – perhaps only 20 meters below the surface. To further confirm their findings, nearby impact craters also show signs of recent glaciation. It would appear that ridges formed inside these ancient holes from snowfall, and then slid down the slopes. With time, it compacted to form a glacier structure… and even more glacier flow patterns are visible in the valleys.

How did this come to be? A one time, Mars’ polar axis was quite different than it is today. As it changed, it created different climatic conditions and mid-latitude glaciers may have developed at different times over the last several hundred million years. While you might be tired of hearing about water on Mars, the findings are very exciting for the future of exploration. It means the door is open…

And one day we just might go through it!

Original Story Source: ESA News.

Posted on by Tammy Plotner

Supernova Candidate Stars May Signal “Impending Doom”

This Large Binocular Telescope image below of the Whirlpool Galaxy, otherwise known as M51, is part of a new galaxy survey by Ohio State University, where astronomers are searching for signs that stars are about to go supernova. The insets show one particular binary star system before (left) and after (right) one of its stars went supernova. Image by Dorota Szczygiel, courtesy of Ohio State University.

[/caption] This past year has given both backyard and professional astronomers a rare treat – a very visible supernova event. Hosted in the Whirlpool Galaxy (M51), these stellar death throes may have been clued to us by a rather ordinary binary star system. In a recent study done by researchers at Ohio State University, a galaxy survey may have captured evidence of a “stellar signal” just before it went supernova!

Employing the Large Binocular Telescope located in Arizona, the OSU team was undertaking a survey of 25 galaxies for stars that changed their magnitude in usual ways. Their goal was to find a star just before it ended its life – a three-year undertaking. As luck would have it, a binary star system located in M51 produced just the results they were looking for. One star dropped amplitude just a short period of time before the other exploded. While the probability factor of them getting the exact star might be slim, chances are still good they caught its brighter partner. Despite that, principal investigator Christopher Kochanek, professor of astronomy at Ohio State and the Ohio Eminent Scholar in Observational Cosmology, remains optimistic as their results prove a theory.

“Our underlying goal is to look for any kind of signature behavior that will enable us to identify stars before they explode,” he said. “It’s a speculative goal at this point, but at least now we know that it’s possible.”

“Maybe stars give off a clear signal of impending doom, maybe they don’t,” said study co-author Krzystof Stanek, professor of astronomy at Ohio State, “But we’ll learn something new about dying stars no matter the outcome.”

Postdoctoral researcher Dorota Szczygiel, the leader of the supernova study tells us why the galaxy survey remains paramount.

“The odds are extremely low that we would just happen to be observing a star for several years before it went supernova. We would have to be extremely lucky,” she said. “With this galaxy survey, we’re making our own luck. We’re studying all the variable stars in 25 galaxies, so that when one of them happens go supernova, we’ve already compiled data on it.”

On May 31, 2011, the whole astronomy world was abuzz when SN2011dh gave both amateurs and professionals a real thrill as an easily observable event. As luck would have it, it was a binary star system being studied by the OSU team, and consisted of both a blue and red star. At this point, the astronomers surmise the red star was the one that dimmed significantly over the three-year period while the blue one blew its top. When reviewing the LBT data, the Ohio team found that when compared with Hubble images, the red star dimmed at about 10% over the final three-year period at an estimated 3% per previous years. As a curiosity, the researchers surmise the red star may have actually survived the supernova event.

“After the light from the explosion fades away, we should be able to see the companion that did not explode,” Szczygiel said.

As the team continues to collect valuable information, they estimate they could also detect another candidate set of stars at a rate of about one per year. There is also a strong possibility these detections could act as a type of test bed to predict future supernova events… looking for signals of impending doom. However, according to the news release, the Sun won’t be one to bother with.

“There’ll be no supernova for the Sun – it’ll just fizzle out,” Kochanek said. “But that’s okay – you don’t want to live around an exciting star.”

Original Story Source: Ohio State Research News.

Posted on by Tammy Plotner

Ancient Zircons Help Reveal Early Earth Atmosphere

Image courtesy of NASA

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Roughly 2.4 billion years ago, Earth’s atmosphere underwent a huge change known as the “Great Oxidation Event”. This switch from an oxygen-poor to an oxygen-rich environment may be accountable for giving rise to life. However, scientists are extremely curious about what our atmosphere may have been like not long after our planet formed. Now researchers from the New York Center for Astrobiology at Rensselaer Polytechnic Institute are using some of the oldest minerals known to exist to help understand what may have occurred some five million years after Earth arose.

For the most part, scientists have theorized that early-Earth atmosphere was dominated by noxious methane, carbon monoxide, hydrogen sulfide, and ammonia. This highly reduced mixture results in a limited amount of oxygen and has led to a wide variety of theories about how life may have started in such a hostile environment. However, by taking a closer look at ancient minerals for oxidation levels, scientists at Rensselaer have proved the early-Earth atmosphere wasn’t like that at all… but held copious amounts of water, carbon dioxide, and sulfur dioxide.

“We can now say with some certainty that many scientists studying the origins of life on Earth simply picked the wrong atmosphere,” said Bruce Watson, Institute Professor of Science at Rensselaer.

How can they be so sure? Their findings depend on the theory that Earth’s atmosphere was formed volcanically. Each time magma flows to the surface, it releases gases. If it doesn’t come to the top, then it interacts with the surrounding rocks where it cools and becomes a rocky deposit in its own right. These deposits – and their elemental construction – allows science to paint an accurate portrait of the conditions at the time of their formation.

“Most scientists would argue that this outgassing from magma was the main input to the atmosphere,” Watson said. “To understand the nature of the atmosphere ‘in the beginning,’ we needed to determine what gas species were in the magmas supplying the atmosphere.”

One of the most important of all magma components is zircon – a mineral nearly as old as Earth itself. By determining the oxidation levels of the magmas that formed these ancient zircons, scientists are able to deduce how much oxygen was being released into the atmosphere.

“By determining the oxidation state of the magmas that created zircon, we could then determine the types of gases that would eventually make their way into the atmosphere,” said study lead author Dustin Trail, a postdoctoral researcher in the Center for Astrobiology.

To enable their work, the team set about cooking up magma in a laboratory setting – which led to the creation of an oxidation gauge to assist them in comparing their artificial specimens against natural zircons. Their study also included a watchful eye for a rare Earth metal called cerium that can exist in two oxidation states. By exposing cerium in zircon, the team can be confident the atmosphere was more oxidized after their creation. These new findings point to an atmospheric state more like our present day conditions… setting the stage for a new starting point on which to base life’s beginnings on Earth.

“Our planet is the stage on which all of life has played out,” Watson said. “We can’t even begin to talk about life on Earth until we know what that stage is. And oxygen conditions were vitally important because of how they affect the types of organic molecules that can be formed.”

While “life as we know it” is highly dependent on oxygen, our current atmosphere probably isn’t the ideal model for spawning primordial life. It’s more likely a methane-rich atmosphere might “have much more biologic potential to jump from inorganic compounds to life-supporting amino acids and DNA.” This leaves the door wide open to alternate theories, such as panspermia. But don’t sell the team’s results short. They still reveal the beginning nature of gases here on Earth, even if they don’t solve the riddle of the Great Oxidation Event.

Original Story Source: Rensselaer Polytechnic Institute News Release.

Posted on by Tammy Plotner

New Planet Kepler-21b Confirmed From Both Space And Ground

The Kepler field as seen in the sky over Kitt Peak National Observatory. The approximate position of HD 179070 is indicated by the circle (sky imaged using a diffraction grating to show spectra of brighter stars, credit J. Glaspey; telescopes imaged separately and combined, credit P. Marenfeld)

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Are you ready to add another planet to the growing list of discoveries? Thanks to work done by Steve Howell of the NASA Ames Research Center and his research team, the Kepler Mission has scored another. Cataloged as 21-b, this “new” planet measures about one and half times the Earth’s radius and no more than 10 times the mass… but its “year” is only 2.8 days long!

With such a speedy orbit around its parent star, this little planet quickly drew attention to itself. Kepler 21-b’s sun is much like our own and one of the brightest in the Kepler field. Given its unique set of circumstances, it required a team of over 65 astronomers (that included David Silva, Ken Mighell and Mark Everett of NOAO) and cooperation with several ground-based telescopes including the 4 meter Mayall telescope and the WIYN telescope at Kitt Peak National Observatory to confirm its existence.

At this point, observations place this hot little planet at about 6 million kilometers away from the parent star, where it has estimated temperatures of about 1900 K, or 2960 F. While this isn’t even anywhere near a life-supporting type of planet, Kepler 21-b remains of interest because of its size. The parent star, HD 179070, is just slightly larger than the Sun and about half its age. Regardless, it can still be seen with optical aid and it is only about 352 light years away from Earth.

Kepler light curve of HD 179070 showing the eclipse of Kepler-21b. The data cover 15 months. The figure shows the binned, and phase folded-data based on 164 individual transits over-plotted by the model fit (red line).

Why are findings like these exciting? Probably because a large amount of stars show short period brightness oscillations – which means it’s difficult to detect a planetary passage from a normal light curve. In this case, it took 15 long months to build up enough information – including spectroscopic and imaging data from a number of ground based telescopes – to make a confident call on the planet’s presence.

It ain’t easy being a little planet… But they can be found!

Original Story Source: NOAO News Release.

Posted on by Tammy Plotner

“Star Wars” Laser Methods Tracks Greenhouse Gases

A green laser was used to guide the invisible infrared beam from La Palma to Tenerife as part of an experiment to test a new satellite concept for measuring atmospheric greenhouse gases and turbulence. Credits: ESA

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It may have looked like a futuristic scene from Star Wars, but ESA’s latest technique for aiding space exploration might shed some “green light” on greenhouse gases. A recent experiment involving the Spanish Canary Islands was conducted by shooting laser beams from a peak on La Palma to Tenerife. The two-week endeavor not only increased the viability of using laser pulses to track satellites, but increased our understanding of Earth’s atmosphere.

ESA runs an optical ground station in Tenerife for communications links with satellites. The facility is part of a larger astronomical installation Observatorio del Teide run by Instituto de Astrofisica de Canarias. Credit: ESA
Known as infrared differential absorption spectroscopy, the laser method is an accurate avenue to measure trace gases such as carbon dioxide and methane. It is accomplished by linking two Earth-orbiting satellites – one a transmitter and the other a receiver – and examining the atmosphere as the beam passes between the two. As satellites orbit, they both rise and set behind Earth and radio occultation occurs. It’s a time-honored way of employing microwave signals to measure Earth’s atmosphere, but new wave thinking employs shortwave infrared laser pulses. When the correct wavelength is achieved, the atmospheric molecules impact the beam and the resultant data can then be used to establish amounts of trace gases and possibly wind. By different angular repetitions, a vertical picture can be painted which stretches between the lower stratosphere to the upper troposphere.

While it all sounded good on paper – the proof of a working model is when it is tested. Enter ESA’s optical ground station on Tenerife – a facility built on a peak 2390 meters above sea level and part of a larger astronomical installation called the Observatorio del Teide run by the Instituto de Astrofisica de Canarias (IAC).With equipment placed on two islands, the Tenerife location offered the perfect setting to install receiver hardware grafted to the main telescope. The transmitter was then assigned to a nearly identical peak on La Palma. With nothing but 144 kilometers of ocean between them, the scenario was ideal for experimentation.

Over the course of fourteen days, the team of researchers from the Wegener Center of the University of Graz in Austria and the Universities of York and Manchester in the UK were poised to collect this unique data.

The Observatorio del Roque de los Muchachos on the island of La Palma housed the equipment to transmit the infrared signal and green guidance laser across the Atlantic Ocean to the receiving station in Tenerife. The experiment was carried out to test a new satellite mission concept for measuring concentrations of atmospheric carbon dioxide and methane. Credit: ESA
While the infrared beam wasn’t visible to the unaided eye, the green guidance laser lit up the night during its runs to record atmospheric turbulence. Gottfried Kirchengast from the Wegener Center said, “The campaign has been a crucial next step towards realising infrared-laser occultation observations from space. We are excited that this pioneering inter-island demonstration for measuring carbon dioxide and methane was successful.”

Armin Loscher from ESA’s Future Mission Division added, “It was a challenging experiment to coordinate, but a real pleasure to work with the motivated teams of renowned scientists and young academics.” The experiment was completed within ESA’s Earth Observation Support to Science Element.

Nice shootin’!

Original Story Source: ESA News Release.

Posted on by Tammy Plotner

Cygnus X – A Cosmic-ray Cocoon

Cygnus X hosts many young stellar groupings, including the OB2 and OB9 associations and the cluster NGC 6910. The combined outflows and ultraviolet radiation from the region's numerous massive stars have heated and pushed gas away from the clusters, producing cavities of hot, lower-density gas. In this 8-micron infrared image, ridges of denser gas mark the boundaries of the cavities. Bright spots within these ridges show where stars are forming today. Credit: NASA/IPAC/MSX

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Situated about 4,500 light-years away in the constellation of Cygnus is a veritable star factory called Cygnus X… one estimated to have enough “raw materials” to create as many as two million suns. Caught in the womb are stellar clusters and OB associations. Of particular interest is one labeled Cygnus OB2 which is home to 65 of the hottest, largest and meanest O-type stars known – and close to 500 B members. The O boys blast out holes in the dust clouds in intense outflows, disrupting cosmic rays. Now, a study using data from NASA’s Fermi Gamma-ray Space Telescope is showing us this disturbance can be traced back to its source.

Discovered some 60 years ago in radio frequencies, the Cygnus X region has long been of interest, but dust-veiled at optical wavelengths. By employing NASA’s Fermi Gamma-ray Space Telescope, scientists are now able to peer behind the obscuration and take a look at the heart through gamma ray observations. In regions of star formation like Cygnus X, subatomic particles are produced and these cosmic rays shoot across our galaxy at light speed. When they collide with interstellar gas, they scatter – making it impossible to trace them to their point of origin. However, this same collision produces a gamma ray source… one that can be detected and pinpointed.

“The galaxy’s best candidate sites for cosmic-ray acceleration are the rapidly expanding shells of ionized gas and magnetic field associated with supernova explosions.” says the FERMI team. “For stars, mass is destiny, and the most massive ones — known as types O and B — live fast and die young.”

Because these star types aren’t very common, regions like Cygnus X become important star laboratories. Its intense outflows and huge amount of mass fills the prescription for study. Within its hollowed-out walls, stars reside in layers of thin, hot gas enveloped in ribbons of cool, dense gas. It is this specific area in which Fermi’s LAT instrumentation excels – detecting an incredible amount of gamma rays.

“We are seeing young cosmic rays, with energies comparable to those produced by the most powerful particle accelerators on Earth. They have just started their galactic voyage, zig-zagging away from their accelerator and producing gamma rays when striking gas or starlight in the cavities,” said co-author Luigi Tibaldo, a physicist at Padova University and the Italian National Institute of Nuclear Physics.

Clocked at up to 100 billion electron volts by the LAT, these highly accelerated particles are revealing the extreme origin of gamma-ray emission. For example, visible light is only two to three electron volts! But why is Cygnus X so special? It entangles its sources in complex magnetic fields and keeps the majority of them from escaping. All thanks to those high mass stars…

“These shockwaves stir the gas and twist and tangle the magnetic field in a cosmic-scale jacuzzi so the young cosmic rays, freshly ejected from their accelerators, remain trapped in this turmoil until they can leak into quieter interstellar regions, where they can stream more freely,” said co-author Isabelle Grenier, an astrophysicist at Paris Diderot University and the Atomic Energy Commission in Saclay, France.

However, there’s more to the story. The Gamma Cygni supernova remnant is also nearby and may impact the findings as well. At this point, the Fermi team considers it may have created the initial “cocoon” which holds the cosmic rays in place, but they also concede the accelerated particles may have originated through multiple interactions with stellar winds.

“Whether the particles further gain or lose energy inside this cocoon needs to be investigated, but its existence shows that cosmic-ray history is much more eventful than a random walk away from their sources,” Tibaldo added.

Original Story Source: NASA Fermi News.

Posted on by Tammy Plotner

Positron Signaling For Dark Matter Inconclusive

The Fermi Gamma-ray Space Telescope (formerly called GLAST). Credit: NASA

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A couple of years ago, the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, PAMELA, sent us back some curious information… an overload of anti-matter in the Milky Way. Why does this member of the cosmic ray spectrum have interesting implications to the scientific community? It could mean the proof needed to confirm the existence of dark matter.

By employing the Fermi Large Area Telescope, researchers with the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University were able to verify the results of PAMELA’s findings. What’s more, by being in the high energy end of the spectrum, these abundances seem to verify current thinking on dark matter behavior and how it might produce positrons.

“There are various theories, but the basic idea is that if a dark matter particle were to meet its anti-particle, both would be annihilated. And that process of annihilation would generate new particles, including positrons.” says Stephan Funk, an assistant professor at Stanford and member of KIPAC. “When the PAMELA experiment looked at the spectrum of positrons, which means sampling positrons across a range of energy levels, it found more than would be expected from already understood astrophysics processes. The reason PAMELA generated such excitement is that it’s at least possible the excess positrons are coming from annihilation of dark matter particles.”

But there has been a glitch in what might have been a smooth solution. Current thinking has the positron signal dropping off when it reaches a specific level – a finding which wasn’t verified and led the researchers to feel the results were inconclusive. But the research just didn’t end there. The team consisting of Funk, Justin Vandenbroucke, a postdoc and Kavli Fellow and avli-supported graduate student Warit Mitthumsiri, came up with some creative solutions. While the Fermi Gamma-ray Space Telescope can’t distinguish between negatively charged electrons and positively charged positrons without a magnet – the group came up with their needs just a few hundred miles away.

Earth’s own magnetic field…

This illustration shows how the electron-positron sky appears to the Large Area Telescope. The purple region contains positrons while electrons are blocked by the Earth's bulk, the orange region contains electrons but is inaccessible to positrons, and the green region is completely out of the Earth's shadow for both positrons and electrons. Image courtesy Justin Vandenbroucke, Fermi-LAT collaboration.
That’s right. Our very own planet is capable of bending the paths of these highly charged particles. Now it was time for the research team to start a study on geophysics maps and figure out precisely how the Earth was sifting out the previously detected particles. It was a new way of filtering findings, but could it work?

“The thing that was most fun about this analysis for me is its interdisciplinary nature. We absolutely could not have made the measurement without this detailed map of the Earth’s magnetic field, which was provided by an international team of geophysicists. So to make this measurement, we had to understand the Earth’s magnetic field, which meant poring over work published for entirely different reasons by scientists in another discipline altogether.” said Vandenbroucke. “The big takeaway here is how valuable it is to measure and understand the world around us in as many ways as possible. Once you have this basic scientific knowledge, it’s often surprising how that knowledge can be useful.”

Oddly enough, they still came up with more than the expected amount of antimatter positrons as previously reported in Nature. But again, the findings didn’t show the theoretical drop-off that was to be expected if dark matter were involved. Despite these inconclusive results, it’s still a unique way of looking at difficult studies and making the most of what’s at hand.

“I find it to be fascinating to try to get the most out of an astrophysical instrument and I think we did that with this measurement. It was very satisfying that our approach, novel as it was, seemed to work so well. Also, you really have to go where the science takes you.” says Funk. “Our motivation was to confirm the PAMELA results because they are so exciting and unexpected. And as far as understanding what the Universe is actually trying to tell us here, I think it was important that PAMELA results were confirmed by a completely different instrument and technique.”

Original Story Source: Kavli Foundation News Release. For Further Reading: Measurement of separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope.