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Number 393, September 28, 1998 by Phillip F. Schewe and Ben Stein
THE EXTRASOLAR PLANET PARADE continues with the discovery of two new planets with unique features. As before, astronomers Geoffrey Marcy (San Francisco State) and Paul Butler (Anglo-Australian Observatory) have inferred the presence of the planets from their observed influence on the companion star. One of the new objects orbits its star (HD187123) in a mere three days in an orbit 9 times closer than Mercury's around our sun. The other new planet has a very Earth-like orbit of 437 days around star HD21027. This comes as a reassurance to those who were beginning to wonder whether Earth was an anomaly; all previously discovered extrasolar planets have had orbits much smaller or much larger than Earth's. (San Francisco State University press release, 23 September 1998.)
MILLIKELVIN MOLECULES can now be clasped in the same sort of magnetic trap used to chill atoms down to nanokelvins. Molecules are extended objects and not so easily cooled by laser beams, normally the first step in cooling several atom species to ultracold temperatures. Instead, Harvard researchers put calcium-monohydride molecules on the road to refrigeration by mixing them with a buffer gas of helium. Thereafter they were cold enough to load into a system of magnetic fields where the more energetic molecules are allowed to escape. This evaporative cooling brings the molecular temperature to below 1 K, opening up a new regime for collision studies and spectroscopy of cold molecules. (Weinstein et al., Nature, 10 September 1998.)
MILKY WAY IN THE LABORATORY? A plasma with a spiral-shaped pattern of particle density, similar to that of the Milky Way galaxy, has been created stably in the laboratory, supporting the possibility that fluid dynamics effects rather than gravitational ones may be responsible for our home galaxy's structure. Injecting a hot argon plasma (rotating at supersonic speeds) into a cold, stationary argon gas, researchers in Japan (Takashi Ikehata,Ibariki University, ikehata@ee.ibaraki.ac.jp) observed a spiral-armed structure (with low-density halos of charged particles) that persisted for as long as they kept rotating the plasma. The vortices that typically appear in such hot plasmas became spirals because of the outward "centrifugal" forces introduced by the rotation. Curiously, the spiral structure was not observed to form in the absence of the stationary gas, suggesting that the fluid dynamics interactions between the gas and plasma are central to the spiral formation process. This experiment intensifies the fascinating (and still undecided) question of whether similar interactions occur between hot, bright stars (corresponding to the plasma) and gas clouds (analogous to the stationary gas) to form spiral galaxies. (Ikehata et al., Physical Review Letters, 31 August 1998.)
A TRAVEL GUIDE TO EUROPEAN SCIENCE would proceed from London to Paris to Moscow to Amsterdam. These cities, according to Institute of Scientific Information (ISI), were responsible for the greatest number of published scientific papers during the period 1994-1996. If one ranks by per-capita output the order of top European cities becomes Cambridge, Oxford, and then Geneva/Lausanne, (information prepared by Christian Matthiessen of the University of Copenhagen and Annette Schwarz of the Technial Knowledge Center of Denmark.) In the field of physics the leaders in producing papers are Moscow, Paris, Geneva, St. Petersburg, and Warsaw. Narrowing further to condensed matter physics, the order begins with two Russian cities, Moscow and St. Petersburg, followed by Paris, Berlin, and Stuttgart. (Science, 21 August 1998.)
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