‘Cannibalism’ Between Stars

Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disk forming around the star owing to conservation of angular momentum. The manner in which the material is transported through the disk onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.

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It turned out that stars may not accumulate their final mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.

One possible mechanism that can explain these brightening events was put forward 10 years ago by Eduard Vorobyov, now working at the Astrophysical Department of the Vienna University, in collaboration with Shantanu Basu from the University of Western Ontario, Canada.

According to their theory, stellar brightening can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Like the process of throwing logs into a fireplace, these episodes of clump consumption release excess energy which causes the young star to brighten by a factor of hundreds to thousands. During each episode, the star is consuming the equivalent of one Earth mass every ten days. After this, it may take another several thousand years before another event occurs.

Eduard Vorobyov describes the process of clump formation in circumstellar disks followed by their migration onto the star as “cannibalism on astronomical scales.” These clumps could have matured into giant planets such as Jupiter, but instead they were swallowed by the parental star. This invokes an interesting analogy with the Greek mythology, wherein Cronus, the leader of the first generation of Titans, ate up his newborn children (though failing to gobble up Zeus, who finally brought death upon his father).

With the advent of advanced observational instruments, such as SUBARU 8.2 meter optical-infrared telescope installed in Mauna Kea (Hawaii), it has become possible for the first time to test the model predictions. Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model — large-scale arms and arcs surrounding four young stars undergoing luminous outbursts, including the prototype FU Orionis star itself. The results of this study were accepted for publication in Science Advances — a peer-review, open-access journal belonging to the Science publishing group.

“This is a major step towards our understanding of how stars and planets form and evolve,” says Vorobyov, “If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own Sun might have experienced several such episodes, implying that the giant planets of the Solar system may in fact be lucky survivors of the Sun’s tempestuous past.”

More Evidence Affirm Battros Equation – Mantle Plumes

An article appearing in last week’s issue of the journal ‘Science’ sheds new light on the role mantle plumes have a direct causal effect on climate. New research shows the release of hot molten rock (magma) known as ‘mantle plumes’, play a significant role in Earth’s climate by causing oceans to alternate between warming and cooling cycles.

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The last million years of Earth’s history has been dominated by the cyclic advance and retreat of ice sheets over large swaths of North America, with ice ages occurring every 40,000 years or so. University of Connecticut marine scientist David Lund, and his colleagues, studied hydrothermal activity along the Mid Atlantic Ridge that extends some 37,000 miles along the ocean floor, and found a link between pressure and temperature changes.

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It’s All About Cycles
New research provides evidence indicating during the period of natural cyclical cooling trends, ice sheets will grow lowering sea levels – as a result, significant pressure is reduced along on deep seamounts, which has a cooling effect to Earth’s mantle. However, during periods of natural cyclical warming trends, ice sheets melt inducing the process of ‘fluid displacement’. Sea levels begin to rise adding significant pressure to Earth’s mantle, which in-turn stimulates convection producing active mantle plumes, which is a method Earth uses to cool herself off from overheating.

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During these periods of active mantle plumes, the molten magma rising through Earth’s crust heats the oceans which of course has a direct causal effect on climate. Once Earth has found its ambient range of temperatures, she reduces the process of convection, once again reducing temperatures causing the whole cycle to repeat itself keeping in-sync with the ever-changing cycles of our galaxy Milky Way.

New Equation:
Increase Charged Particles → Decreased Magnetic Field → Increase Outer Core Convection → Increase of Mantle Plumes → Increase in Earthquake and Volcanoes → Cools Mantle and Outer Core → Return of Outer Core Convection (Mitch Battros – July 2012)

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Well documented ocean bottom core samples provide sedimentary records going back perhaps a million years providing evidence of repeated short and long-range cycles of warming and cooling trends. My research has taken me to associate these cycles beyond our Sun and into our Milky Way. Because of today’s amazing advances in outer-space technology, it is now possible to see and measure trends far beyond our solar system.

Stayed Tuned……………….

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A Violent Wind Blown From The Heart Of A Galaxy Tells The Tale Of A Merger

An international team led by a researcher from Hiroshima University has succeeded in revealing the detailed structure of a massive ionized gas outflow streaming from the starburst galaxy NGC 6240. The team used the Suprime-Cam mounted on the 8.2-meter Subaru Telescope on Maunakea in Hawaii.

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The ionized gas the astronomers observed extends across 300,000 light-years and is carried out of the galaxy by a powerful superwind. That wind is driven by intense star-forming activity at the galactic center. The light-collecting power and high spatial resolution of Subaru Telescope made it possible to study, for the first time, the complex structure of one of the largest known superwinds being driven by starbirth — and star death.

The term “starburst” indicates large-scale intensive star-forming activity, making a “starburst galaxy” one where starbirth is occurring on a grand scale. The star formation rate (SFR) of our Milky Way Galaxy is approximately one solar mass per year. By contrast, the SFRs of starburst galaxies reach ten, or even a hundred to a thousand solar masses per year.

Starburst activity is a very important part of galaxy evolution. When a starburst occurs, the intense episode star formation rapidly consumes the galaxy’s interstellar gas. In addition, ultraviolet light from newborn massive stars as well as gas heating and ram pressure from supernova explosions blows much of a galaxy’s gas away into intergalactic space. This galactic-scale energetic wind is called a “galactic wind” or “superwind.” Its action forces interstellar gas out of the galaxy very efficiently, which accelerates the galaxy’s gas-loss rate. It also chokes off star formation.

The metal-rich gas expelled from the galaxy’s disk pollutes its halo as well as intergalactic space. Consequently, starburst and starburst-driven superwind significantly affect the evolution of the galaxy and the gas outside of that galaxy.

One of the mechanisms that seems to induce large-scale starburst activity is galaxy collision and merger. When two gas-rich giant spiral galaxies merge, the gravitational perturbation induced by the merging process disturbs the orbits of stars. At the same time, the gas in the galaxy disks loses its angular momentum via viscous process associated with gas mixture, and falls into the gravitational center of the merger. This creates a vast concentration of gas, which begins to coalesce, creating a starburst knot. The starburst also creates a huge amount of dust which emits strong infrared radiation as it absorbs ultraviolet light from the newly born massive stars.

NGC 6240 is a starburst galaxy fairly close to the Milky Way, at a distance of about 350 million light-years. Its SFR is estimated to be 25-80 times that of our galaxy. It has a peculiar, disturbed morphology which indicates that two spiral galaxies are merging. Due to the giant starburst at its heart as a result of the merger, NGC 6240 is very bright in infrared light being emitted from heated dust. The total infrared luminosity reaches almost a trillion times of that the Sun’s.

NGC 6240 is an important object to investigate in order to understand the physical and evolutional relationship among the processes of galaxy merger, the action of a starburst, and the phenomenon of an active galactic nucleus. Hence, it is one of the most-studied starburst galaxies in the nearby universe within 500 million light-years of the Sun.

The research team wanted a wide-field of NGC 6240. The Suprime-Cam optical camera was used on Subaru Telescope to zero in on the detailed structure of the starburst-driven superwind. In addition, the team searched for important clues to understanding the starburst history of NGC 6240. They observed the galaxy using a special band-pass filter that selectively transmits the light around an emission line produced by ionized hydrogen (called the H-alpha emission line). It allowed them to study the structure of the ionized gas associated with the superwind.

Their unprecedented deep observation (long-exposure images) revealed a complex giant ionized gas nebula (called an “H-alpha nebula”) surrounding NGC 6240. This nebula extends out about 300,000 light-years and contains complicated structures of filaments, loops, and blobs. Astronomers knew that such a large ionized gas nebula surrounds NGC 6240, but the depth of the observation significantly surpassed any previous studies and first allowed the Hiroshima team to study the some of the faintest, most detailed structure of the nebula. Large “broken bubbles” were detected in the northwestern and southeastern parts of the galaxy. These features are the evidence of a past energetic bipolar-shaped superwind that blew along the minor axis of the main galaxy disk (orthogonal to the main galactic disk).

The research team performed detailed data analysis and found that NGC 6240 has experienced violent starbursts at least three times in the past and each starburst drove an energetic superwind. Those superwinds form complex structure in the H-alpha nebula. The oldest starburst started about 80 million years ago. Astronomers think that the galaxy merger process of NGC 6240 began about a billion years ago, so this work suggests that the later stages of the merger are what excited the gigantic starbursts and subsequent superwinds. These results contribute new information to the studies of galaxy evolution and its relation to galaxy-galaxy mergers.

Rare Sub-Antarctic Volcano Eruption Captured

Scientists have caught a rare glimpse of ice and fire, witnessing an eruption of the Big Ben volcano, situated on the remote Australian territory of Heard Island in the sub-Antarctic.

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While Big Ben is known to have erupted at least three other times since 2000, catching the volcano massif in the act is extremely unlikely, given how truly removed Heard Island is. Lying some 4,099 kilometres (2,547 miles) southwest of Perth in Western Australia, and almost as far to the southeast of Madagascar, the island ranks among the most remote places on Earth – and researchers haven’t set foot on it in almost 30 years.

Which makes it all the more serendipitous that scientists on board Australia’s CSIRO research vessel, Investigator, on a voyage to the Kerguelen Plateau happened to observe the eruption, in addition to seeing volcanic activity at the neighbouring McDonald Islands – Australia’s only other active volcano.

“Seeing vapour emanating from both of Australia’s active volcanoes and witnessing an eruption at Mawson Peak have been an amazing coda to this week’s submarine research,” said the voyage’s chief scientist, Mike Coffin of the Institute of Marine and Antarctic Studies. “We have 10 excited geoscientists aboard Investigator, and our enthusiasm has spread to our 50 shipmates.”

Seeing Big Ben’s summit – the 2,745-metre (9,000 foot) tall Mawson Peak – in the act of erupting was particularly surprising to those on board, as inclement weather in the area (signs of which you can see in these photos) meant it was highly probable that the elevated peak wouldn’t be visible at all.

“I’m doing my PhD on Heard Island volcanism, and to see lava emanating from Mawson Peak and flowing down the flank of Big Ben over a glacier has been incredible,” said Jodi Fox, a student researcher at the University of Tasmania. “Given persistent cloud cover and generally foul weather, I didn’t think we’d even see Mawson Peak on this voyage.”

Using shipboard sonar systems, the researchers are imaging the seafloor and water column in the area looking for underwater plumes that could represent hydrothermal systems associated with active underwater volcanoes. Although less than halfway through their 58-day trip, the scientists have identified over 50 such potential plumes already.

But, despite the progress made so far, it’s pretty clear what the most memorable highlight of the voyage is likely to be.

“Seeing land after being at sea for a couple of weeks is exciting, but to see dynamic Earth processes such as volcanoes erupting is an added bonus,” said Coffin.

NASA’s Juno Spacecraft Burns for Jupiter

NASA’s solar-powered Juno spacecraft successfully executed a maneuver to adjust its flight path today, Feb. 3. The maneuver refined the spacecraft’s trajectory, helping set the stage for Juno’s arrival at the solar system’s largest planetary inhabitant five months and a day from now.

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“This is the first of two trajectory adjustments that fine tune Juno’s orbit around the sun, perfecting our rendezvous with Jupiter on July 4th at 8:18 p.m. PDT [11:18 p.m. EDT],” said Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio.

The maneuver began at 10:38 a.m. PST (1:38 p.m. EST). ). The Juno spacecraft’s thrusters consumed about 1.3 pounds (0.6 kilograms) of fuel during the burn, and changed the spacecraft’s speed by 1 foot (0.31 meters), per second. At the time of the maneuver, Juno was about 51 million miles (82 million kilometers) from Jupiter and approximately 425 million miles (684 million kilometers) from Earth. The next trajectory correction maneuver is scheduled for May 31.

Juno was launched on Aug. 5, 2011. The spacecraft will orbit the Jovian world 33 times, skimming to within 3,100 miles (5,000 kilometers) above the planet’s cloud tops every 14 days. During the flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its aurorae to learn more about the planet’s origins, structure, atmosphere and magnetosphere.

Juno’s name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife — the goddess Juno — was able to peer through the clouds and reveal Jupiter’s true nature.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. The California Institute of Technology in Pasadena manages JPL for NASA.

Activity On Seafloor Linked To Icy Ebb And Flow On Surface

The last million years of Earth’s history has been dominated by the cyclic advance and retreat of ice sheets over large swaths of North America, with ice ages occurring every 40,000 years or so.

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While conventional wisdom says that this icy ebb and flow is an interaction between the water and atmosphere, the cause of the rapid transition between alternating cold glacial and warmer interglacial periods has been a mystery.

Until now. An article appearing in the Jan. 28 issue of the journal Science sheds new light on the role that the Earth itself may play in this climatological ballet.

UConn marine scientist David Lund and his colleagues studied hydrothermal activity along the mid-ocean ridge system – the longest mountain range in the world, which extends some 37,000 miles along the ocean floor – and found a link between pressure and temperature changes.

Their research suggests that the release of hot molten rock, or magma, from beneath the Earth’s crust in response to changes in sea level plays a significant role in the Earth’s climate by causing oceans to alternately warm and cool. This change in temperature is attributed to the release of heat and carbon dioxide (CO2) into the deep ocean.

During cold glacial intervals, ice sheets reached as far south as Long Island and Indiana, while during warm periods, the ice rapidly retreated to Greenland.

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There is evidence that when ice sheets grow, sea level lowers and significant pressure is taken off the ocean ridges. But, as the pressure lessens, the mantle begins melting, which, in turn, warms the water and causes the ice to begin melting. Then, as the ice melts, sea levels rise, causing pressure on the mountain ranges to increase and activity within the mountain ranges to slow.

Think of the effect that applying pressure to a wound has in slowing the flow of bleeding.

The release of molten rock through volcanic vents or fissures is driven by seafloor spreading and decompression melting of the upper mantle, the partially molten layer just beneath the earth’s crust.

Well documented sedimentary records from the East Pacific Rise (EPR) – a mid-ocean ridge extending roughly from Antarctica to the Gulf of California – show evidence of increased hydrothermal activity at the ends of the last two glacial eras.

Researchers also examined core samples from the ocean floor mountain ridges and determined concentrations of major and trace elements.

The results establish the timing of hydrothermal anomalies. Says Lund, “Our results support the hypothesis that enhanced ridge magmatism [the release of molten rock through volcanic vents or fissures], hydrothermal output, and perhaps mantle CO2 flux act to reduce the size of ice sheets.”

Seismic Data Suggests Slow Slip Events May Presage Larger Earthquakes

A team of researchers, two from Tohoku University in Japan and two from the University of California in the U.S., has found evidence that suggests that a speedup in small underground deformations may occur prior to larger earthquakes, possibly providing a means for sounding a warning. In their paper published in the journal Science, the team describes how they pored over seismic data that spanned 28 years and which included approximately 6,000 seismic events, and what they found as a result—they also suggest that their findings might one day lead to a true earthquake early warning system.

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Scientists the world over have for years been searching for a way to predict when an earthquake will strike, with enough certainty to warn people in the area. To date such efforts have come up empty, though much has been learned in the process. In this new effort, the researchers report that they believe they may have found a possible indicator of an impending quake, and it is based on what are known as slips, small underground movement similar to earthquakes, but which happen so slowly that they don’t cause damage or even register on seismic monitors—the only way to detect them is to use GPS equipment.

To come to these conclusions, the researchers analyzed seismic data for Japan’s two largest islands, going back to 1984. Doing so led to the identification of 1,500 instances where there appeared to be a pattern of repetition—that allowed them to estimate the speed at which the tectonic plates below were moving. They then used statistics to correlate slippages with non-repeating measurable quakes with a magnitude of 5 or higher. Doing so revealed that there appeared to be a speedup in slippage just prior to major earthquakes. The team also looked at GPS data, which can actually be used to measure tectonic shifting, and report that it matched the rates they had calculated earlier.

The team acknowledges that much more work needs to be done before it can be confirmed that GPS monitoring devices could one day offer an early warning system, but suggest their research shows that there is the potential for such an outcome.