A plenitude of pulsars.A plenitude plen·i·tude n. 1. An ample amount or quantity; an abundance: a region blessed with a plenitude of natural resources. 2. The condition of being full, ample, or complete. of pulsars Globular clusters This is a list of globular clusters. The apparent magnitude does not include an extinction correction. Milky Way These are globular clusters within the halo of the Milky Way galaxy. The diameter is in minutes of arc as seen from Earth. -- thick clumps of very old stars lying just beyond the fringes of the Milky Way -- seem a surprisingly fertile breeding ground for rapidly spinning neutron stars, or pulsars. Although these clusters, satellites of our galaxy, lie so far away that astronomers can detect only the brightest pulsars, a systematic search for pulsars within globular clusters has already pushed the tally to 20. The results suggest that a typical globular cluster may harbor at least 100 pulsars, most of which woudl be too faint to detect. Such an abundance is difficult to reconcile with conventional models of the evolution and dynamics of globular clusters. In the latest discovery, reported in the July 5 NATURE, a research team from the California Institute of Technology California Institute of Technology, at Pasadena, Calif.; originally for men, became coeducational in 1970; founded 1891 as Throop Polytechnic Institute; called Throop College of Technology, 1913–20. in Pasadena identified two additional pulsars in a globular cluster designated Messir 15 by sifting through radio-wave signals captured at the Arecibo radiotelescope in Puerto Rico. Their find brings to three the number of known pulsars in that star grouping. Because the observed pulsars probably represent only a fraction of the total pulsar pulsar, in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and his students at Cambridge Univ. population, the identification of three especially bright pulsars in a single cluster suggests that pulsars are quite common in globular clusters, the researchers say. One of the newly discovered pulsars apparently has a companion -- either another neutron star or a massive white dwarf -- in a highly elliptical orbit Highly Elliptical Orbit (HEO) is an elliptic orbit characterized by a relatively low-altitude perigee and an extremely high-altitude apogee. These extremely elongated orbits can have the advantage of long dwell times at a point in the sky during the approach to and descent from . Monitoring pulse arrival times from this binary system may enable astronomers to check for various relativistic rel·a·tiv·is·tic adj. 1. Of or relating to relativism. 2. Physics a. Of, relating to, or resulting from speeds approaching the speed of light: relativistic increase in mass. effects, including the emission of gravitational grav·i·ta·tion n. 1. Physics a. The natural phenomenon of attraction between physical objects with mass or energy. b. The act or process of moving under the influence of this attraction. 2. radiation as the orbit's period slowly decreases. "Now that we know where and how to look for millisecond pulsars, we can expect the stream of discoveries to become a torrent," comments Charles D. Bailyn of Yale University in New Haven, Conn., in the same issue of NATURE. "There should soon be many more opportunities to exploit the unique tests of gravitational theory provided by pulsars, as well as to learn more about the evolution of stars and star clusters." |
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