Measuring the footprints of violence.Measuring the footprints of violence Astronomer Randy A. Kimble had to wait eight years, but he finally completed his gaseous quest -- an elusive measurement of the helium between a hot white dwarf star white dwarf star Any of a class of small, faint stars representing the end point of the evolution of stars without enough mass to become neutron stars or black holes. and Earth, which may reveal the frequency and strength of supernova explosions and other violent outbursts in our corner of the universe. Using a sounding rocket, Kimble had attempted in 1982 to measure the interstellar in·ter·stel·lar adj. Between or among the stars: interstellar gases. interstellar Adjective between or among stars Adj. 1. helium associated with the white dwarf G191B2B (Business to Business) Refers to one business communicating with or selling to another. See B2B e-commerce, B2C and B2G. B2B - business to business , but the experiment failed. His 25 minutes of observations in 1990, using the Hopkins Ultraviolet Telescope, exceeded by a factor of five the amount of observing time available on a sounding rocket, notes Kimble, of Johns Hopkins University Johns Hopkins University, mainly at Baltimore, Md. Johns Hopkins in 1867 had a group of his associates incorporated as the trustees of a university and a hospital, endowing each with $3.5 million. Daniel C. in Baltimore. The telescope data indicate the density of neutral helium between Earth and the star, notes Arthur F. Davidsen, chief researcher on the Hopkins telescope. But by relying on previous estimates of the total (both neutral and ionized i·on·ize tr. & intr.v. i·on·ized, i·on·iz·ing, i·on·iz·es To convert or be converted totally or partially into ions. i ) helium and hydrogen left over from the Big Bang, astronomers can now infer the amount of ionized helium in the local interstellar medium created by more recent violent events. Calculating the abundance of ionized helium may reveal the intensity and frequency of these energetic events. A stream of galactic cosmic rays, leftover heat from supernova explosions, and intense radiation emitted by unseen neutron stars could all contribute to the ionization ionization: see ion. ionization Process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) by the removal or addition of negatively charged electrons. of helium in the nearby regions of the Milky Way, Davidsen says. |
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