Saturday, February 6, 2016

Apollo Astronaut Edgar Mitchell, Sixth Man on the Moon, Passes Away

Apollo astronaut Edgar Mitchell in front of a graphic of the mission patch. Credits: NASA

Astronaut Edgar Mitchell, lunar module pilot on Apollo 14, passed away Thursday in West Palm Beach, Fla., on the eve of the 45th anniversary of his lunar landing. Mitchell joined Apollo 14 commander Alan Shephard, Jr., the first American in space, in the lunar module Antares, which touched down Feb. 5, 1971, in the Fra Mauro highlands. Shepard and Mitchell were assigned to traverse the lunar surface to deploy scientific instruments and perform a communications test on the surface, as well as photograph the lunar surface and any deep space phenomena. It was Mitchell’s only spaceflight.

'Cannibalism' Between Stars

This is a Simulation of a gravitationally unstable circumstellar disk by means of hydrodynamic calculations. Protoplanetary 'embryo' form in the disc thanks to gravitational fragmentation. The three small pictures show the successive 'disappearance' of the lump by the star. Credit: Eduard Vorobyov, Universität Wien

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.

ULA Successfully Launches GPS IIF-12 Satellite for U.S. Air Force

An Atlas V rocket carrying the GPS IIF-12 mission lifts off from Space Launch Complex-41. Credit: ULA

United Launch Alliance (ULA) successfully launched its first mission of the year with an Atlas V rocket carrying the Global Positioning System (GPS) IIF-12 satellite for the U.S. Air Force. The rocket lifted off from Space Launch Complex-41 at the Cape Canaveral Air Force Station in Florida on Feb. 5 at 8:38 a.m. EST. GPS IIF-12 is the final satellite in the IIF-block of satellites, which are the next-generation GPS satellites that incorporate numerous improvements to provide greater accuracy, increased signals and enhanced performance for users. This mission was ULA’s 104th successful launch since the company was formed in December 2006.

Astrophysicists Use New Methods to Simulate the Common-envelope Phase of Binary Stars

Slices through the three-dimensional simulation volume after 105 days in the common envelope. In the orbital plane, the companion star and the red giant core are circling around each other. Credit: Sebastian Ohlmann / HITS

When we look at the night sky, we see stars as tiny points of light eking out a solitary existence at immense distances from Earth. But appearances are deceptive. More than half the stars we know of have a companion, a second nearby star that can have a major impact on their primary companions. The interplay within these so-called binary star systems is particularly intensive when the two stars involved are going through a phase in which they are surrounded by a common envelope consisting of hydrogen and helium. Compared to the overall time taken by stars to evolve, this phase is extremely short, so astronomers have great difficulty observing and hence understanding it. This is where theoretical models with highly compute-intensive simulations come in. Research into this phenomenon is relevant understanding a number of stellar events such as supernovae.

Pluto’s Mysterious, Floating Hills

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo: numerous, isolated hills that may be fragments of water ice from Pluto’s surrounding uplands. These hills individually measure one to several miles or kilometers across, according to images and data from NASA’s New Horizons mission. The hills, which are in the vast ice plain informally named Sputnik Planum within Pluto’s ‘heart,’ are likely miniature versions of the larger, jumbled mountains on Sputnik Planum’s western border. They are yet another example of Pluto’s fascinating and abundant geological activity.

Friday, February 5, 2016

Inside Comet 67P/Churyumov-Gerasimenko

These images of comet 67P/Churyumov-Gerasimenko were taken by Rosetta’s navigation camera between August and November 2014.  Top row, left to right: Comet pictured on 6 August 2014, at a distance of 96 km; 14 August, at a distance of 100 km; 22 August, at a distance of 64 km; 14 September, at a distance of 30 km.  Bottom row, left to right: Comet pictured on 24 September, at a distance of 28 km; 24 October, at a distance of 10 km; 26 October, at a distance of 8 km; 6 November, at a distance of 30 km. Credit: ESA/Rosetta/NavCam

There are no large caverns inside Comet 67P/Churyumov-Gerasimenko. ESA’s Rosetta mission has made measurements that clearly demonstrate this, solving a long-standing mystery. Comets are the icy remnants left over from the formation of the planets 4.6 billion years ago. A total of eight comets have now been visited by spacecraft and, thanks to these missions, we have built up a picture of the basic properties of these cosmic time capsules. While some questions have been answered, others have been raised.

A Violent Wind Blown from the Heart of a Galaxy Tells the Tale of a Merger

A pseudo-color image of NGC 6240 taken with Suprime-Cam at the Subaru Telescope. Blue, green, and red colors are attributed to the B-band, R-band, and H-alpha (emission line from ionized hydrogen gas) images, respectively. The giant ionized gas blown out from the galaxy is seen in red. Click the figure to jump to the larger image of the central region. (Credit: Hiroshima University / NAOJ)

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. 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.