Space

At the cores of many galaxies, supermassive black holes expel powerful jets of particles at nearly the speed of light. Just how they perform this feat has long been one of the mysteries of astrophysics. The leading theory says the particles are accelerated by tightly-twisted magnetic fields close to the black hole, but confirming that idea required an elusive close-up view of the jet's inner throat. Now, using the unrivaled resolution of the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), astronomers have watched material winding a corkscrew outward path and behaving exactly as predicted by the theory.


Data from the ESA/NASA spacecraft SOHO shows clearly that powerful starquakes ripple around the Sun in the wake of mighty solar flares that explode above its surface. The observations give solar physicists new insight into a long-running solar mystery and may even provide a way of studying other stars.

The outermost quarter of the Sun’s interior is a constantly churning maelstrom of hot gas. Turbulence in this region causes ripples that criss-cross the solar surface, making it heave up and down in a patchwork pattern of peaks and troughs.


Huge star streams in the outskirts of two nearby spiral galaxies have allowed astronomers to obtain a panoramic overview of ' galactic cannibalism' similar to that involving the Sagittarius dwarf galaxy in the vicinity of the Milky Way.

The detection of these immense stellar fossils confirms the predictions of the cold dark matter model of cosmology, which proposes that present-day grand design spiral galaxies were formed from the merging of less massive stellar systems.

The first of these debris structures surrounds the galaxy NGC 5907, located 40 million light-years from Earth and formed from the destruction of one of its dwarf satellite galaxies at least four billion years ago.


Using NASA, Japanese, and European X-ray satellites, a team of Japanese astronomers has discovered that our galaxy’s central black hole let loose a powerful flare three centuries ago.

The finding helps resolve a long-standing mystery: why is the Milky Way’s black hole so quiescent? The black hole, known as Sagittarius A* (pronounced "A-star"), is a certified monster, containing about 4 million times the mass of our Sun. Yet the energy radiated from its surroundings is billions of times weaker than the radiation emitted from central black holes in other galaxies.

"We have wondered why the Milky Way’s black hole appears to be a slumbering giant," says team leader Tatsuya Inui of Kyoto University in Japan. "But now we realize that the black hole was far more active in the past. Perhaps it’s just resting after a major outburst."


By studying in great detail the 'ringing' of a planet-harbouring star, a team of astronomers using ESO's 3.6-m telescope have shown that it must have drifted away from the metal-rich Hyades cluster. This discovery has implications for theories of star and planet formation, and for the dynamics of our Milky Way.

The yellow-orange star Iota Horologii, located 56 light-years away towards the southern Horologium ("The Clock") constellation, belongs to the so-called "Hyades stream", a large number of stars that move in the same direction.

Previously, astronomers using an ESO telescope had shown that the star harbours a planet, more than 2 times as large as Jupiter and orbiting in 320 days (ESO 12/99).

UK astronomers have produced the most sensitive infrared map of the distant Universe ever undertaken. Combining data over a period of three years, they have produced an image containing over 100,000 galaxies over an area four times the size of the full Moon. Some of the first results from the project were presented by Dr Sebastien Foucaud from the University of Nottingham at the RAS National Astronomy Meeting in Belfast.

Due to the finite speed of light, these observations allow astronomers to look back in time over 10 billion years, producing images of galaxies in the Universe's infancy. The image is so large and so deep that thousands of galaxies can be studied at these early epochs for the first time. By observing in the infrared, astronomers can now peer further back in time, since light from the most distant galaxies is shifted towards redder wavelengths as it travels through the expanding Universe.


A study of active and inactive galaxies by Paul Westoby, Carole Mundell and Ivan Baldry from the Astrophysics Research Institute of Liverpool John Moores University has given new insights into the complex interaction between super-massive black holes at the heart of Active Galactic Nuclei (AGN) and star formation in the surrounding galaxy.

The team studied the properties of light from 360,000 galaxies in the local Universe to understand the relationship between accreting black holes, the birth of stars in galaxy centres and the evolution of the galaxies as a whole.

The study finds that gas ejected during the quasar stage of AGN snuffs out star formation, leaving the host galaxies to evolve passively. The study also reveals a strong link between galaxy mergers and the formation of super-massive black holes in AGN, but shows that if the environment becomes too crowded with galaxies, then the likelihood of firing up a supermassive black hole becomes suppressed.


Scientists have discovered a possible terrestrial-type planet orbiting a star in the constellation Leo. The new planet lies at a distance of 30 light years from the Earth and has a mass five times that of our planet but is the smallest found to date. One full day on the new planet would be equivalent to three weeks on Earth.

A team of astronomers from the Spanish Research Council (CSIC) working with Dr Jean-Philippe Beaulieu, a visiting astrophysicist at University College London (UCL), made the discovery from model predictions of a new exoplanet orbiting a star in the constellation of Leo. Simulations show that the exoplanet, dubbed GJ 436c, orbits its host star (GJ 436) in only 5.2 Earth days, and is thought to complete a revolution in 4.2 Earth days, compared to the Earth’s revolution of 24 hours and full orbit of 365 days.




A rare type of galax with a higher number of X-rays than thought possible has been detected.

Quasars are cosmic 'engines' that pump energy into their surroundings - theorists speculate that an enormous black hole drives each one. As matter falls into the black hole, it collects in a swirling reservoir called the accretion disc, which heats up. Computer simulations suggest that powerful radiation and magnetic fields present in the region eject some of gas from the gravitational clutches of the black hole, throwing it back into space.



Using data from the Hinode and RHESSI solar observatories, astronomers have discovered that solar flares - explosions in the atmosphere of the sun - get much hotter when they stay "focused."

Dr Ryan Milligan of Oak Ridge Association of Universities, Tennessee, who is stationed at NASA’s Goddard Space Flight Center in the US, will present his result on Wednesday 2 April at RAS National Astronomy Meeting in Belfast.

Solar flares are caused by the sudden release of magnetic energy. The largest can release as much energy as a billion one-megaton nuclear bombs. However, the flare observed in this study was a much more common "micro" flare. Researchers at space agencies like NASA and ESA want to understand flares because they generate radiation that can be hazardous to unprotected astronauts, like those walking on the surface of the Moon.