Tumbling into Infinity!

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NASA Spacecraft to Visit Newly Named Asteroid

NASA’s Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) spacecraft will visit the asteroid now called Bennu, named after an important ancient Egyptian avian deity. OSIRIS-Rex is scheduled to launch in 2016, rendezvous with Bennu in 2018 and return a sample of the asteroid to Earth in 2023. 

The name for the carbon-rich asteroid, designated in the scientific community as (101955) 1999 RQ36, is the winning entry in an international student contest. Nine-year-old Michael Puzio suggested the name because he imagined the Touch-and-Go Sample Mechanism (TAGSAM) arm and solar panels on OSIRIS-REx look like the neck and wings in drawings of Bennu, which Egyptians usually depicted as a gray heron. Puzio wrote the name suits the asteroid because it means “the ascending one,” or “to shine.” 

TAGSAM will collect a sample from Bennu and store it for return to Earth. The sample could hold clues to the origin of the solar system and the source of water and organic molecules that may have contributed to the development of life on Earth. The mission will be a vital part of NASA’s plans to find, study, capture and relocate an asteroid for exploration by astronauts. NASA recently announced an asteroid initiative proposing a strategy to leverage human and robotic activities for the first human mission to an asteroid while also accelerating efforts to improve detection and characterization of asteroids. 

“There were many excellent entries that would be fitting names and provide us an opportunity to educate the world about the exciting nature of our mission,” said Dante Lauretta of the University of Arizona in Tucson, a contest judge and the principal investigator of the OSIRIS-REx mission. “The information about the composition of Bennu and the nature of its orbit will enable us to explore our past and better understand our future.” 

For more information on OSIRIS-REx, visit:  http://osiris-rex.lpl.arizona.edu/

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Dark  Matter - “The Tip of an Iceberg of Another World Unrelated to Ours

Answering the observation that the dark matter particle might not be detectable at a colloquium organized by the Kavli Institute for Cosmological Physics at the University of Chicago, Michael Turner, a theoretical cosmologist trained in both particle physics and astrophysics who coined the term “dark energy,” said that for 20 to 30 years, this idea that dark matter is part of a unified theory has been our Holy Grail and has led to the WIMP hypothesis and the belief that the dark matter particle is detectable. “But there’s a new generation of physicists that is saying, ‘Well, there’s an alternative view. Dark matter is actually just the tip of an iceberg of another world that is unrelated to our world. And I cannot even tell you about that world. There are no rules for that other world, at least that we know of yet.

“Ten years ago,” Turner says, “I don’t think you would’ve found astronomers, cosmologists, and particle physicists all agreeing that dark matter was really important. And now, they do. And all of them believe we can solve the problem soon. It’s wonderful listening to particle physicists explain the evidence for dark matter, and vice versa –astronomers explaining WIMPs as dark matter. ”

“As cosmologists,” said Rocky Kolb, who studies the application of elementary-particle physics to the very early Universe, and is the co-author with Michael Turner of The Early Universe, the standard textbook on particle physics and cosmology, “one of our jobs is to understand what the universe is made of. To a good approximation, the galaxies and other structures we see in the universe are made predominantly of dark matter. We have concluded this from a tremendous body of evidence, and now we need to discover what exactly is dark matter. The excitement now is that we are closing in on an answer, and only once in the history of humans will someone discover it. “

“Nothing in cosmology makes sense without dark matter, says Turner. “We needed it to form galaxies, stars and other structures in the Universe. And so it’s absolutely central to cosmology. We also know that none of the particles known to exist can be the dark matter particle. So it has to be a new particle of nature. Remarkably, our most conservative hypothesis right now is that the dark matter is a new form of matter – out there to be discovered and to teach us about particle physics.”

“Dark matter is absolutely central to cosmology, said Turner, “and the evidence for it comes from many different measurements: the amount of deuterium produced in the big bang, the cosmic microwave background, the formation of structure in the Universe, galaxy rotation curves, gravitational lensing, and on and on.”

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Mysterious hot spots observed in a cool red supergiant

Astronomers have released a new image of the outer atmosphere of Betelgeuse – one of the nearest red supergiants to Earth – revealing the detailed structure of the matter being thrown off the star.

The new image, taken by the e-MERLIN radio telescope array operated from the Jodrell Bank Observatory in Cheshire, also shows regions of surprisingly hot gas in the star’s outer atmosphere and a cooler arc of gas weighing almost as much as the Earth.

Betelgeuse is easily visible to the unaided eye as the bright, red star on the shoulder of Orion the Hunter. The star itself is huge – 1,000 times larger than our Sun – but at a distance of about 650 light years it still appears as a tiny dot in the sky, so special techniques combining telescopes in arrays are required to see details of the star and the region around it.

The new e-MERLIN image of Betelgeuse – published in the journal Monthly Notices of the Royal Astronomical Society, shows its atmosphere extends out to five times the size of the visual surface of the star. It reveals two hot spots within the outer atmosphere and a faint arc of cool gas even farther out beyond the radio surface of the star.

The hot spots are separated by roughly half the visual diameter of the star and have a temperature of about 4,000-5,000 Kelvin, much higher than the average temperature of the radio surface of the star (about 1,200 Kelvin) and even higher than the visual surface (3,600 Kelvin). The arc of cool gas lies almost 7.4 billion kilometres away from the star – about the same distance as the farthest Pluto gets from the Sun. It is estimated to have a mass almost two thirds that of the Earth and a temperature of about 150 Kelvin.

Lead author Dr Anita Richards, from The University of Manchester, said that it was not yet clear why the hot spots are so hot. She said: “One possibility is that shock waves, caused either by the star pulsating or by convection in its outer layers, are compressing and heating the gas. Another is that the outer atmosphere is patchy and we are seeing through to hotter regions within. The arc of cool gas is thought to be the result of a period of increased mass loss from the star at some point in the last century but its relationship to structures like the hot spots, which lie much closer in, within the star’s outer atmosphere, is unknown.”

The mechanism by which supergiant stars like Betelgeuse lose matter into space is not well understood despite its key role in the lifecycle of matter, enriching the interstellar material from which future stars and planets will form. Detailed high-resolution studies of the regions around massive stars like the ones presented here are essential to improving our understanding.

Dr Richards, who is based in Manchester’s School of Physics and Astronomy, added: “Betelgeuse produces a wind equivalent to losing the mass of the Earth every three years, enriched with the chemicals that will go into the next generation of star and planet formation. The full detail of how these cool, evolved stars launch their winds is one of the remaining big questions in stellar astronomy.

“This is the first direct image showing hot spots so far from the centre of the star. We are continuing radio and microwave observations to help decide which mechanisms are most important in driving the stellar wind and producing these hot spots. This won’t just tell us how the elements that form the building blocks of life are being returned to space, it will also help determine how long it is before Betelgeuse explodes as a supernova.”

Future observations planned with e-MERLIN and other arrays, including ALMA and VLA, will test whether the hotspots vary in concert due to pulsation, or show more complex variability due to convection. If it is possible to measure a rotation speed this will identify in which layer of the star they originate.

The new Betelgeuse image and a copy of the paper that accompanies it, entitled ‘e-MERLIN resolves Betelgeuse at wavelength 5 cm: hotspots at 5R*,’ are available on request.

e-MERLIN, the UK’s national radio astronomy facility, is operated from the Jodrell Bank Observatory by The University of Manchester on behalf of the UK Science and Technology Facilities Council. Its power lies in its combination of the sharpness of view afforded by telescope separations of up to 217km, and its ability to detect very faint signals resulting from the array’s high bandwidth optical fibre connections. By connecting seven large radio telescopes, stretching from Cambridge to Cheshire (including the Lovell Telescope at Jodrell Bank), e-MERLIN is able to produce images with the same detail as the Hubble Space Telescope but at radio rather than visible wavelengths. The signals from the telescopes are brought to Jodrell Bank on a dedicated optical fibre network whose high bandwidth allows the detection of very faint sources of radio emission. At Jodrell Bank 210 Gb of data arrive from the seven telescopes each second. These signals are combined in the correlator, a specialised supercomputer which carries out one thousand million million operations per second. For the signals from each telescope to be accurately combined, they must be synchronised at the level of a few million millionths of a second. The application of these fibre technologies and signal synchronisation techniques have led to e-MERLIN being designated as a pathfinder for what is planned to be the world’s largest radio telescope, the Square Kilometre Array.