Planet Mercury's metal-rich composition is a puzzle in planetary science. According to a new simulation, Mercury and other unusually metal-rich objects in the solar system may be relics left behind by collisions in the early solar system that built the other planets.

Astronomers have studied the carbon monoxide in ALESS65, a galaxy over 12 billion light years away, and found that it's literally running out of gas. The future is not dark, it's 'red and dead'.

ALESS65 was observed by the Atacama Large Millimeter Array (ALMA) in 2011 and is one of few known distant galaxies to contain carbon monoxide.

 While our galaxy, the Milky Way, has about 5 billion years before it runs out of fuel and becomes 'red and dead', ALESS65 is a gas guzzler and only has 10s of millions of years left – that is very rapid, in astronomical terms. 

Radio waves emitted from ALESS65 as observed by the Australia Telescope Compact Array. Credit: Huynh et al.

Supermassive black holes in the cores of some galaxies drive massive outflows of molecular hydrogen gas. As a result, most of the cold gas is expelled from the galaxies.

Since cold gas is required to form new stars, this directly affects the galaxies' evolution and those outflows are a key ingredient in theoretical models of the evolution of galaxies, but it is a mystery how they are accelerated. A new study provides the first direct evidence that the molecular outflows are accelerated by energetic jets of electrons that are moving at close to the speed of light. Such jets are propelled by the central supermassive black holes.

Astronomers have found a "hotspot" beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays, a discovery which may move physics toward identifying the mysterious sources of the most energetic particles in the universe.

Many astrophysicists suspect ultrahigh-energy cosmic rays are generated by active galactic nuclei, or AGNs, in which material is sucked into a supermassive black hole at the center of galaxy, while other material is spewed away in a beam-like jet known as a blazar. Another popular possibility is that the highest-energy cosmic rays come from some supernovas (exploding stars) that emit gamma rays bursts.

A newly discovered planet now named OGLE-2013-BLG-0341LBb
in a binary star system located 3,000 light-years from Earth is expanding astronomers' notions of where Earth-like—and even potentially habitable—planets can form. And how to find them.

At twice the mass of Earth, the planet orbits one of the stars in the binary system at almost exactly the same distance from which Earth orbits the sun. However, because the planet's host star is much dimmer than the sun, the planet is much colder than the Earth—a little colder, in fact, than Jupiter's icy moon Europa.

Astronomers search for exoplanets by measuring shifts in the pattern of a star's spectrum - the different wavelengths of radiation that it emits as light.

These "Doppler shifts" result from subtle changes in the star's velocity caused by the gravitational tugs of orbiting planets, but Doppler shifts of a star's absorption lines can also result from magnetic events like sunspots originating within the star itself -- giving false clues of a planet that does not actually exist.

The HESS-II (High Energy Stereoscopic System) telescope in Namibia has detected gamma rays of only 30 Giga electron volts (GeV) from the Vela pulsar, the first pulsar to be detected by HESS and the second to be spotted by ground-based gamma ray telescopes. 

The HESS experiment in Namibia is the first Cherenkov system with telescopes of different sizes detecting cosmic TeV gamma rays in sync. A fifth 28-meter telescope, placed at the center of the other four 12-meter telescopes, lowers the energy range under study down to 30 GeV. HESS-II has passed the firing test because scientists have detected a pulsed gamma-ray signal in the energy range of 30 GeV, which they attribute to the Vela pulsar. This paves the way for new observation possibilities of the inner Galaxy.

Acoustic vibrations – sound waves – are produced by radiation pressure inside stars. While physicists have long posited that young stars vibrate differently than older stars, a new study says it is the first to confirm these predications using concrete data from outer space. 

First author Konstanze Zwintz, a postdoctoral researcher at KU Leuven's Institute for Astronomy, and her colleagues studied the vibrations of 34 stars aged under 10 million years and sized between one and four times the mass of our sun.

At first glance, Titan, the largest moon of Saturn, has little in common with Earth. Titan's surface temperature dips tp nearly 300 F below zero, its seas slosh with liquid methane, and its sky is a murky shade of creamsicle.

We don't know what dark matter is but we know it must be. And now, computer hypothetically, we know it a little better, thanks to new supercomputer simulations showing a possible evolution of our corner of the cosmos, the Local Group, from the Big Bang to the present day.