Asteroids impacting the Earth's oceans could generate waves more powerful than once thought, strong enough to inundate huge portions of coastlines thousands of kilometers away from the impact, Los Alamos National Laboratory researchers reported this month.
     Astrophysicist Jack Hills and Charles Mader used advanced computer simulations to study the effects of the impacts of large asteroids in the Earth's oceans. Hills reported on the results at the winter meeting of the American Astronomical Society in Washington, D.C.
     Hills and Mader showed that an asteroid 5 km (3 mi.) across colliding with the mid-Atlantic would generate waves powerful enough to inundate the entire upper East Coast of the United States, all the way to the Appalachian mountains, as well as coastlines in western Europe.
     While an asteroid that large is expected to strike the Earth only once every ten million years, Hills and Mader showed even small asteroids could cause significant damage from water impacts. An asteroid only 400 m (1,300 feet) in diameter, striking in the middle of an ocean, could inflict tsunamis up to 90 m (300 ft.) high on opposite coasts.
     While it has been long known that oceanic impacts of asteroids could generate huge tsunamis (often incorrectly called tidal waves), the model of Hills and Mader is the most detailed yet to study the issue. Hills and Mader have funding for an additional three years of study the effects of such impacts in greater detail.
     Hills, while explaining the destructive power of such asteroids, noted that they were entirely avoidable if a system was built to detect and deflect, if necessary, and threatening asteroids. "It's a problem that could be solved for much less than the cost of one hurricane. We could just set it up and be done with it."

Astronomers have discovered new evidence of a massive black hole in the center of our galaxy, while another black hole in our galaxy has been found to eject a mass equal to a large asteroid in half-hour intervals.
     Astronomers have focused their attention on Sagittarius A* (Sgr A*), an unusual radio source located in the center of the galaxy. German astronomers measured the motions of stars near Sgr A* and found them moving at up to 1000 km/sec (223,000 mph). The speed implies the stars are moving around a source nearly three million times as massive as the Sun, but in an area only 100 times the size of the Solar System.
     Based on this information alone, astronomers could not rule out either a black hole or a dense cluster of stars. Another team of astronomers led by Mark Reid of the Harvard-Smithsonian Center of Astrophysics used the Very Long Baseline Array (VLBA) to measure the movement of Sgr A* itself to very high accuracy.
     Reid and his collaborations concluded that Sgr A* was moving very slowly, apparently anchored to the center of the galaxy. This movement was consistent with Sgr A* being a black hole, the researchers concluded, weighing up to three million times the Sun.
     Another team of astronomers from Caltech, MIT, and NASA's Goddard Space Flight Center focused on another, smaller, black hole in the Milky Way galaxy. Using a combination of x-ray and infrared observations, the astronomers found that x-rays emitted from hot gas circling the black hole in an accretion disk would disappear on a regular basis, every half-hour.
     At the same time the x-ray emission disappeared, jets of hot gas were visible in the infrared observations. The astronomers concluded that the hot gas was the x-ray emitting gas being hurled away from the black hole at nearly the speed of light as the disk was disrupted.
     The mass of the disrupted gas was estimated to be about 100 trillion tons, or the mass of a sizable asteroid. However, noted astrophysicist Jean Swank of NASA Goddard, the gas is hurled away at nearly the speed of light, requiring an amount of energy equal to six trillion times the annual energy consumption of the United States.
     "The system behaves like the celestial version of Old Faithful," said Craig Markwardt of Goddard. Every half-hour, more gas is disrupted and flung away from the black hole. New gas is added to the black hole from the surface of a nearby star.
     Astronomers hope the study of this black hole will give them a greater understanding of black holes and the formation of jets.

Astronomers studying the infrared background radiation of the universe have provided a better understanding of conditions early in the history of universe, while several other teams of researchers have confirmed news about the eventual fate of the universe.
     Astronomers used infrared observations from the Cosmic Background Explorer (COBE) to study the conditions of the early universe, going as far back as 300,000 years after the Big Bang.
     The infrared background radiation is emitted by dust created in the early universe. By summing all the light visible in the infrared background they were able to estimate how much energy, and thus how many stars and galaxies, existed in the early universe.
     "`What we've done is basically taken a core sample of the universe, but we've crushed it down to one dimension," said Michael Hauser of the Space Telescope Science Institute.
     Initial findings indicate that the while the early universe was very dim -- perhaps 200 times dimmer than the starlight visible on a moonlit night -- it had far more light in the far infrared than visible today. The additional light may be obscured by dust clouds or be too faint and far away to be seen.
     Five other teams of cosmologists confirmed reports circulating in recent months that the universe has far too little mass to stop its expansion and contract into a "Big Crunch." The cosmologists believe that the universe will continue to expand forever.
     "With 95 percent confidence, we can say the universe is going to expand forever," said Ruth Daly of Princeton University at the annual winter AAS meeting in Washington.
     Astronomers used observations of distant supernovae to reach their conclusions. By comparing the redshifted light of distant supernovae from the light of similar, but much closer, supernovae, astronomers computer the distances to the distant stars and measure their expansion rates, providing key information on the state of the universe.
     The findings that the universe may have as little as 20 percent of the mass needed to stop expansion could pose a problem for key Big Bang theories. "Inflation" theories, which propose that the universe underwent a brief but sudden expansion within the first second after the Big Bang, require that the mass of the universe be perfectly balanced, with just enough mass to stop the expansion.
     "Reaching out to these most distant supernovae teaches us about the 'Cosmological Constant,' which Einstein once called his greatest mistake," according to University of Stockholm astronomer Ariel Goodbar, a member of one of teams that studied the supernovae, as the cosmological constant may be the only way to rescue the inflation theories.

A warp in a disk of gas and dust surrounding the nearby Beta Pictoris may be a newly-formed planet, according to research by a NASA Goddard astronomer.
     Sally Heap reported at this month's American Astronomical Society meeting in Washington that a warped portion of the circumstellar disk around the star seen in new Hubble Space Telescope images may be one or more planets in the early stages of formation.
     Heap, pointing out that other hypotheses for explaining the disk, including radiation from a nearby star, had been ruled out, they were "left with the planetary hypothesis," she said. "It's not too unreasonable."
     Other members of the team studying the images were not as quick to agree. Team leader Al Schultz of the Space Telescope Science Institute (STScI) thought the warp could be caused by a small brown dwarf circling the star at great distances.
     Another team member, Fred Bruhweiler of the Catholic University of America, favored another hypothesis. "The distortions we are seeing may have been caused by the passing of a nearby star within the past few 100 million years since the disk was formed," he explained. "The culprit could easily be a thousand light-years away by now. We probably will never know who did it."
     Still, neither Schultz nor Bruhweiler ruled out the planet hypothesis, and all involved urged more research be performed.
     A warp in the disk of gas and dust surrounding Beta Pictoris, 60 light-years from the Earth, was first noticed in Hubble images in 1996 by Chris Burrows of STScI. At the time he proposed a large planet orbiting out of the plane of the disk could cause the warping.