HIGH-ENERGY ASTROPHYSICS: X-ray Satellites Seek Clues to Bursts

Last month the High Energy Transient Explorer 2, the first satellite dedicated to spotting gamma ray bursts, rocketed successfully into orbit, bolstering a handful of x-ray satellites whose instruments are trained on the mysterious explosions. But some researchers say setbacks to the fleet have left unfortunate gaps in coverage.     

AAS HIGH-ENERGY ASTROPHYSICS DIVISION: X-rays Hit the Spot for Astrophysicists

About 500 astronomers flocked to Waikiki Beach from 6 to 10 November for a meeting of the American Astronomical Society's High-Energy Astrophysics Division. Looking splendid in their complimentary aloha shirts, speakers told tales of intense radiation from deep space, including x-rays from baby stars and from quasars, which could help refine estimates of how quickly the universe is expanding.     

ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory

Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars.     

ASTROPHYSICS: Neutron Stars Imply Relativity's a Drag

A new finding, based on x-rays from distant neutron stars, could be the first clear evidence of a weird relativistic effect called frame dragging, in which a heavy chunk of spinning matter wrenches the space-time around it like an eggbeater. Using data from NASA's Rossi X-ray Timing Explorer, three astronomers in Amsterdam found circumstantial evidence for frame dragging in the flickering of three neutron stars in binary systems. They announced their results in the 1 September issue of The Astrophysical Journal.     

Gamma rays: further evidence for lack of a threshold dose for lethality to human cells

In experiments designed to measure human cell survival sith +/- 2 percent accuracy it was found that low doses (21 to 87 rad) of gamma-rays inactivated the colony-forming ability of cultured human cells with a probability of 0.00226 +/- 0.00012 per rad. There appears to be no threshold for the lethality of radiation to human cells in vitro.