Archive for August, 2013

Magnetic Star Reveals Its Hidden Power

August 14, 2013 Leave a comment

Artist's impression. Credit: ESA/ATG Medialab

Artist’s impression. Credit: ESA/ATG Medialab

A team of astronomers including two researchers from UCL’s Mullard Space Science Laboratory has made the first ever measurement of the magnetic field at a specific spot on the surface of a magnetar. Magnetars are a type of neutron star, the dense and compact core of a giant star which has blasted away its outer layers in a supernova explosion.

Magnetars have among the strongest magnetic fields in the Universe. Until now, only their large scale magnetic field had been measured. However, using a new technique and observations of a magnetar in X-rays, the astronomers have now revealed a strong, localised surface magnetic field on one.

Magnetars are very puzzling neutron stars. Astronomers discovered them through their unusual behaviour when observed in X-ray wavelengths, including sudden outbursts of radiation and occasional giant flares. These peculiar features of magnetars are caused by the evolution, dissipation and decay of their super-strong magnetic fields, which are hundreds or thousands of times more intense than those of the more common type of neutron stars, the radio pulsars.

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Newly Found Pulsar Helps Astronomers Explore Milky Way’s Mysterious Core

August 14, 2013 Leave a comment

Artist's conception. Credit: Bill Saxton, NRAO/AUI/NSF

Artist’s conception. Credit: Bill Saxton, NRAO/AUI/NSF

Astronomers have made an important measurement of the magnetic field emanating from a swirling disk of material surrounding the black hole at the center of our Milky Way Galaxy. The measurement, made by observing a recently-discovered pulsar, is providing them with a powerful new tool for studying the mysterious region at the core of our home galaxy.

The Milky Way’s central black hole is some four million times more massive than the Sun. Black holes, concentrations of mass so dense that not even light can escape them, can pull in material from their surroundings. That material usually forms a swirling disk around the black hole, with material falling from the outer portion of the disk inward until it is sucked into the black hole itself.

Such disks concentrate not only the matter pulled into them but also the magnetic fields associated with that matter, forming a giant, twisting magnetic field that is thought to propel some of the matter back outward along its poles in superfast “jets.”

The region near the black hole is obscured from visible-light observations by gas and dust, and is an exotic, extreme environment still little-understood by astronomers. The magnetic field in the central portion of the region is an important component that affects other phenomena.

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Precisely Measuring Velocity Of Supernova Shockwave

August 13, 2013 1 comment

©Keio University / NAOJ

©Keio University / NAOJ

A research team led by Tomoro Sashida and Tomoharu Oka (Keio University) has succeeded in precisely measuring the expansion velocity of a shockwave of the supernova remnant W44. The remnant is located in the constellation of Aquila, approximately 10,000 light-years away from our solar system. The team observed the high-temperature and high-density molecular gas in the millimeter/submillimeter wave ranges. The analysis shows that the expansion velocity of the W44 shockwave is 12.9±0.2 km/sec. In addition, it became clear that the supernova explosion released kinetic energy of (1-3)×1050 erg into the interstellar medium. The energy emitted from the Sun is approximately 3.6 × 1033 ergs/sec. Can you image how enormous amount of energy is released from the supernova explosion? Furthermore, other molecular gas with an extremely high velocity of higher than 100 km/sec was also detected. The origin of this super-high-velocity molecular gas remains unclear at the present time.

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Early Solar System Garnet-Like Mineral Named For Livermore Cosmochemist

August 13, 2013 Leave a comment

Photos by Julie Korhummel/LLNL

Photo by Julie Korhummel/LLNL

A recently discovered mineral appears to be clear but may have a tinge of light blue. No matter its color, you won’t be able to make earrings from it.

For one, you can’t see the material with the naked eye. Hutcheonite, recently named after Lawrence Livermore meteorite researcher Ian Hutcheon, can be seen only with high powered scanning electron microscopes.

Known also by its chemical makeup, Ca3Ti2SiAl2O12, hutcheonite was discovered in a refractory inclusion in the Allende meteorite by Sasha Krot (University of Hawaii) and Chi Ma (Caltech) and named in honor of Hutcheon, who has made numerous contributions to the study of meteorites and what they can tell us about the evolution of the early solar system.

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On The Trail Of Dark Energy: Physicists Propose Higgs Boson ‘Portal’

August 12, 2013 Leave a comment

One of the biggest mysteries in contemporary particle physics and cosmology is why dark energy, which is observed to dominate energy density of the universe, has a remarkably small (but not zero) value. This value is so small, it is perhaps 120 orders of magnitude less than would be expected based on fundamental physics.

Resolving this problem, often called the cosmological constant problem, has so far eluded theorists.

Now, two physicists – Lawrence Krauss of Arizona State University and James Dent of the University of Louisiana-Lafayette – suggest that the recently discovered Higgs boson could provide a possible “portal” to physics that could help explain some of the attributes of the enigmatic dark energy, and help resolve the cosmological constant problem.

In their paper, “Higgs Seesaw Mechanism as a Source for Dark Energy,” Krauss and Dent explore how a possible small coupling between the Higgs particle, and possible new particles likely to be associated with what is conventionally called the Grand Unified Scale – a scale perhaps 16 orders of magnitude smaller than the size of a proton, at which the three known non-gravitational forces in nature might converge into a single theory – could result in the existence of another background field in nature in addition to the Higgs field, which would contribute an energy density to empty space of precisely the correct scale to correspond to the observed energy density.

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Astronomers Celebrate “Celestail Pollution” From Perseid Meteor Shower

Credit: Gemini Observatory/AURA

Credit: Gemini Observatory/AURA

This weekend, as millions of people gaze up at the stars and wait for Perseid meteors to streak across the sky, one would hardly think that these awe-inspiring “shooting stars” are also a source of atmospheric pollution.

However, meteors, like those from this month’s Perseid meteor shower, burn up high in the Earth’s atmosphere leaving behind gases. “It’s a form of natural pollution,” says Gemini Observatory’s Chad Trujillo who heads up the facility’s state-of-the-art Adaptive Optics (AO) program.

“One of the gases left behind by meteors is sodium, which collects in a layer about 60 miles (90 kilometers) above the Earth,” says Trujillo (see animation). “The reason astronomers are so fond of this particular pollution layer is because we can make it glow by using a sodium laser to excite this sodium and produce temporary, artificial stars wherever we like. Believe it or not,” jokes Trujillo, “there aren’t enough stars in the sky for astronomers!”

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Hubble Finds Source Of Magellanic Stream

Astronomers using NASA’s Hubble Space Telescope have solved a 40-year mystery on the origin of the Magellanic Stream, a long ribbon of gas stretching nearly halfway around our Milky Way galaxy.

The Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way, are at the head of the gaseous stream. Since the stream’s discovery by radio telescopes in the early 1970s, astronomers have wondered whether the gas comes from one or both of the satellite galaxies. Now, new Hubble observations reveal that most of the gas was stripped from the Small Magellanic Cloud about 2 billion years ago, and a second region of the stream originated more recently from the Large Magellanic Cloud.

“What’s interesting is that all the other nearby satellite galaxies of the Milky Way have lost their gas,” Andrew J. Fox (of the Space Telescope Science Institute in Baltimore, Md). said. “The Magellanic Clouds have been able to retain their gas and are still forming stars because they’re more massive than the other satellites. However, as they’re now approaching the Milky Way, they’re feeling its gravity more and also encountering its halo of hot gas, which puts pressure on them.”

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Constructing A 3D Map Of The Large-Scale Structure Of The Universe

An international team led by astronomers from Kyoto University, the University of Tokyo and the University of Oxford has released its first version of a 3D map of the Universe from its FastSound project, which is surveying galaxies in the Universe over nine billion light years away. Using the Subaru Telescope’s new Fiber Multi-Object Spectrograph, the team’s 3D map includes 1,100 galaxies and shows the large-scale structure of the Universe nine billion years ago.

The FastSound project, one of Subaru Telescope’s Strategic Programs, began its observations in March 2012 and will continue them into the spring of 2014. Although surveys with 3D maps of the Universe have been conducted on the nearby Universe (e.g., the Sloan Digital Sky Survey with coverage up to five billion light years away), the FastSound project distinguishes itself by developing a 3D map of the far-distant Universe, covering the largest volume of the Universe farther than ten billion light years away (in comoving distance).

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Gemini Observatory Press Release/Image Release

Credit: Gemini Observatory/AURA

Credit: Gemini Observatory/AURA

Gemini Observatory’s latest tool for astronomers, a second-generation infrared instrument called FLAMINGOS-2, has “traveled a long road” to begin science observations for the Gemini scientific community. Recent images taken by FLAMINGOS-2 during its last commissioning phase dramatically illustrate that the instrument was worth the wait for astronomers around the world who are anxious to begin using it.

“It’s already one of our most requested instruments at the Gemini telescopes,” remarks Nancy Levenson, Gemini’s Deputy Director and Head of Science. “We see a long and productive life ahead for FLAMINGOS-2 once astronomers really start using it later this year.”

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Quasar Observed In 6 Separate Light Reflections

Quasars are active black holes – primarily from the early universe. Using a special method where you observe light that has been bent by gravity on its way through the universe, a group of physics students from the Niels Bohr Institute have observed a quasar whose light has been deflected and reflected in six separate images. This is the first time a quasar has been observed with so many light reflections. The results are published in the scientific journal, Astrophysical Journal.

“We had three hours to observe and already after one hour we had the first spectrum. It was a new experience for us, but we could see immediately that it was a quasar. A typical characteristic of a quasar is that the light has broad emission lines from gas close to the black hole. We were very excited and moved on to the other ‘candidates’ from observation and later that night we found yet another light reflection of the quasar,” explains Thejs Brinckmann, one of the astrophysics students working on the project. The other students in the group were Mikkel Kristensen, Mikkel Lindholmer and Anders Nielsen.

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