Hubble images reveal unusual galactic jet.Viewed from Earth in visible light, the elliptical galaxy NGC NGC New General Catalogue (of Nebulae and Star Clusters; astronomy) NGC National Geographic Channel (TV) NGC National Guideline Clearinghouse 3862 doesn't look like much. Indeed, its flat emission pattern apparently devoid of sharp peaks and dips in intensity, once prompted researchers to describe this galaxy as "optically dull." But orbiting 380 miles above Earth, the Hubble Space Telescope Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the clearest view yet obtained of the universe. now reveals that the nucleus of NGC 3862 spews out a short jet of radiation, too short to have been detected with ground-based telescopes, in both visible light and the near ultraviolet. Moreover, this jet shines more brightly in the ultraviolet -- at the shorter end of the electromagnetic spectrum -- than at longer wavelengths, a feature diametrically di·a·met·ri·cal also di·a·met·ric adj. 1. Of, relating to, or along a diameter. 2. Exactly opposite; contrary. di opposite to the energy output of any other galactic jet yet observed. "It appears that we are seeing a new type of phenomenon," says Philippe Crane of the European Southern Observatory European Southern Observatory (ESO), an intergovernmental organization for astronomical research with headquarters in Garching, near Munich, Germany. The ESO began in 1962 as a consortium among Belgium, Denmark, France, Germany, the Netherlands, and Sweden. (ESO) in Garching, Germany. Researchers believe that a typical jet, possibly powered by a massive black hole or other potent energy source at the center of a galaxy, radiates because of the acceleration of electrons that circle strong galactic magnetic fields. This radiation, know as synchrotron radiation, has a higher intensity at redder, or longer, wavelengths. The well-studied jet in the galaxy M87, for example, fits this model perfectly, says Crane (SN: 1/25/92, p.52). Crane speculates that the unique radiation pattern from NGC 3862, a resident of the Abell cluster of galaxies cluster of galaxies Gravitationally bound grouping of galaxies, numbering from the hundreds to the tens of thousands. Large clusters of galaxies often exhibit extensive X-ray emission from intergalactic gas heated to tens of millions of degrees. , could represent a combination of two types of emissions: standard synchrotron radiation as well as radiation, primarily in the ultraviolet, from atoms that surround the jet and are heated by it. If this interpretation proves correct, it would mark the first time that astronomers have observed both types of radiation from a jet. Crane notes, however, that recent observations with the ESO's New Technology Telescope The New Technology Telescope, or NTT is a 3.6m telescope located at La Silla Observatory, Chile. It saw first light in 1989 and is owned by ESO. It is fitted with active optics (not to be confused with adaptive optics) allowing it to obtain an excellent image quality in La Serena, Chile La Serena ("the serene one") is the second oldest city in Chile. The city, located 471 km north of Santiago, has a population of 147,815, according to the 2002 census. There are also 12,333 inhabitants of the immediately surrounding countryside. , found no evidence of atomic emissions. Alternatively, he adds, the jet's output may stem from galactic mechanisms not yet understood. |
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