ESA’s orbiting gamma-ray observatory, Integral, has made the first unambiguous discovery of highly energetic X-rays coming from a galaxy cluster. The find has shown the cluster to be a giant particle accelerator.

The Ophiuchus galaxy cluster is one of brightest in the sky at X-ray wavelengths. The X-rays detected are too energetic to originate from quiescent hot gas inside the cluster and suggest instead that giant shockwaves must be rippling through the gas. This has turned the galaxy cluster into a giant particle accelerator.

Most of the X-rays come from hot gas in the cluster, which in the case of Ophiuchus is extremely hot, at 100 million degrees Kelvin. Four years ago, data from the Italian/ Dutch BeppoSAX satellite showed a possible extra component of high-energy X-rays in a different cluster, the Coma cluster.

When the Stardust mission returned to Earth with samples from the comet Wild 2 in 2006, scientists knew the material would provide new clues about the formation of our solar system, but they didn’t know exactly how.

Contrary to expectations for a small icy body, much of the comet dust returned by the Stardust mission formed very close to the young sun and was altered from the solar system’s early materials.

New research by scientists at Lawrence Livermore National Laboratory and collaborators reveals that, in addition to containing material that formed very close to the young sun, the dust from Wild 2 also is missing ingredients that would be expected in comet dust.

On January 14, 2008, more than three decades after the third Mariner 10 flyby, the last spacecraft visit of Mercury, MESSENGER passed 200 kilometers above Mercury's surface. Extensive scientific observations were executed during this flyby encounter, including imaging a large portion of Mercury's surface that has never before been seen by a spacecraft.

Neutron stars can be considerably more massive than previously believed and it is more difficult to form black holes, according to new research developed by using the Arecibo Observatory in Arecibo, Puerto Rico. Paulo Freire, an astronomer from the observatory, will present his research at the American Astronomical Society national meeting in Austin on Jan. 11.

In the cosmic continuum of dead, remnant stars, the Arecibo astronomers have increased the mass limit for when neutron stars turn into black holes.

“The matter at the center of a neutron star is highly incompressible. Our new measurements of the mass of neutron stars will help nuclear physicists understand the properties of super-dense matter,” said Freire.

Four years of observations from the European Space Agency’s Integral (INTErnational Gamma-Ray Astrophysics Laboratory) satellite may have cleared up one of the most vexing mysteries in our Milky Way: the origin of a giant cloud of antimatter surrounding the galactic center.

As reported by an international team in the January 10 issue of Nature, Integral found that the cloud extends farther on the western side of the galactic center than it does on the eastern side.

For the first time astronomers are able to see indirect evidence of dark matter and how this invisible force impacts on the crowded and violent lives of galaxies. University of British Columbia researcher Catherine Heymans has produced the highest resolution map of dark matter ever captured before.

Scientists believe that dark matter is the invisible web that houses galaxies. And as the universe evolves, the gravitational pull of this unseen matter causes galaxies to collide and swirl into superclusters.

Heymans and the University of Nottingham’s Meghan Gray led an international team to test this theory that dark matter determines the location of galaxies.

Hundreds of millions — or even billions — of years after planets would have initially formed around two unusual stars, a second wave of planetesimal and planet formation appears to be taking place, UCLA astronomers and colleagues believe.

"This is a new class of stars, ones that display conditions now ripe for formation of a second generation of planets, long, long after the stars themselves formed," said UCLA astronomy graduate student Carl Melis, who reported the findings today at the American Astronomical Society meeting in Austin, Texas.

Using the powerful one-two combo of NASA’s Swift satellite and the Gemini Observatory, astronomers have detected a mysterious type of cosmic explosion farther back in time than ever before. The explosion, known as a short gamma-ray burst (GRB), took place 7.4 billion years ago, more than halfway back to the Big Bang.

"This discovery dramatically moves back the time at which we know short GRBs were exploding. The short burst is almost twice as far as the previous confirmed record holder," says John Graham of the Johns Hopkins University, in Baltimore, Md.

A new 11-year cycle of heightened solar activity, bringing with it increased risks for power grids, critical military, civilian and airline communications, GPS signals and even cell phones and ATM transactions, showed signs it was on its way late Thursday when the cycle’s first sunspot appeared in the sun’s Northern Hemisphere, NOAA scientists said.

“This sunspot is like the first robin of spring,” said solar physicist Douglas Biesecker of NOAA’s Space Weather Prediction Center. “In this case, it’s an early omen of solar storms that will gradually increase over the next few years.”

A sunspot is an area of highly organized magnetic activity on the surface of the sun.

New observations from Suzaku, a joint Japanese Aerospace Exploration Agency (JAXA) and NASA X-ray observatory, have challenged scientists’ conventional understanding of white dwarfs. Observers had believed white dwarfs were inert stellar corpses that slowly cool and fade away, but the new data tell a completely different story.

At least one white dwarf, known as AE Aquarii, emits pulses of high-energy (hard) X-rays as it whirls around on its axis. "We’re seeing behavior like the pulsar in the Crab Nebula, but we’re seeing it in a white dwarf," says Koji Mukai of NASA Goddard Space Flight Center in Greenbelt, Md. The Crab Nebula is the shattered remnant of a massive star that ended its life in a supernova explosion.