Telescope unveils a stellar deception.A heavenly masquerade may shed light on the nature of astrophysical jets--the beams of material spewed by a wide variety of celestial objects. Astronomers came upon the stellar puzzle while observing a dust-shrouded body called Hen 2-90 with 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. . The object had been classified as the remains of a dying, lightweight star. The new images reveal, however, that the object exhibits behavior unlike that of any corpse. Hen 2-90 has a pair of oppositely directed jets that spout clumps of gas. Newborn stars possess jets, but Hen 2-90 is too hot and luminous to qualify as a youngster, notes Raghvendra Sahai of NASA's Jet Propulsion Laboratory “JPL” redirects here. For other uses, see JPL (disambiguation). Jet Propulsion Laboratory (JPL) is a NASA research center located in the cities of Pasadena and La Cañada Flintridge, near Los Angeles, California, USA. in Pasadena, Calif. Instead, he and Lars-Ake Nyman 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. in Santiago, Chile, and the Onsala Space Observatory Onsala Space Observatory (OSO) is the Swedish National Facility for Radio Astronomy located 45 km south of Gothenburg in Onsala. It operates two radio telescopes in the mm and cm wavelength regions. in Sweden propose that the body consists of two aging stars hidden behind a lane of dust. One member of the unseen duo may be an elderly, bloated star known as a red giant. The outer layers of such a star are easily captured by the tug of a companion star. The gas then forms a swirling disk around the companion. This second star is likely to be a recently formed white dwarf, the compact remnant of a sunlike star, Sahai and Nyman suggest in the Aug. 1 ASTROPHYSICAL JOURNAL LETTERS. The jets may derive from gas piling onto the disk and creating periodic instabilities, the researchers suggest. Other systems also produce jets when one star rips matter from another. Sahai says that other Hubble images showing a dark disk around Hen 2-90 lend credence to his team's hypothesis. This lopsided disk is too large to be the swirling gas around just the white dwarf, but it indicates that material surrounding Hen 2-90 doesn't have a spherical distribution. That's what astronomers would expect if one star were dumping matter onto a companion. Spectra of Hen 2-90 could reveal the chemistry of the hidden duo, Sahai adds. "This is one of the most beautiful, best behaved, and most collimated In a straight line. Collimated light beams are parallel rays of light. bipolar jets ejected by a stellar source of any sort," comments John F. Bally of the University of Colorado University of Colorado may refer to:
1. in microscopy, the process of making light rays parallel; the adjustment or aligning of optical axes. 2. of stellar jets," he says. |
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