画像:Gaseous Jets From Three Newly Forming Stars.jpg

[edit] Summary

These NASA Hubble Space Telescope views of gaseous jets from three newly forming stars show a new level of detail in the star formation process, and are helping to solve decade-old questions about the secrets of star birth. Jets are a common "exhaust product" of the dynamics of star formation. They are blasted away from a disk of gas and dust falling onto an embryonic star.

[upper left] - This view of a protostellar object called HH-30 reveals an edge-on disk of dust encircling a newly forming star. Light from the forming star illuminates the top and bottom surfaces of the disk, making them visible, while the star itself is hidden behind the densest parts of the disk. The reddish jet emanates from the inner region of the disk, and possibly directly from the star itself. Hubble's detailed view shows, for the first time, that the jet expands for several billion miles from the star, but then stays confined to a narrow beam. The protostar is 450 light-years away in the constellation Taurus.

[upper right] - This view of a different and more distant jet in object HH-34 shows a remarkable beaded structure. Once thought to be a hydrodynamic effect (similar to shock diamonds in a jet aircraft exhaust), this structure is actually produced by a machine-gun-like blast of "bullets" of dense gas ejected from the star at speeds of one-half million miles per hour. This structure suggests the star goes through episodic "fits" of construction where chunks of material fall onto the star from a surrounding disk. The protostar is 1,500 light- years away and in the vicinity of the Orion Nebula, a nearby star birth region.

[bottom] - This view of a three trillion mile-long jet called HH-47 reveals a very complicated jet pattern that indicates the star (hidden inside a dust cloud near the left edge of the image) might be wobbling, possibly caused by the gravitational pull of a companion star. Hubble's detailed view shows that the jet has burrowed a cavity through the dense gas cloud and now travels at high speed into interstellar space. Shock waves form when the jet collides with interstellar gas, causing the jet to glow. The white filaments on the left reflect light from the obscured newborn star. The HH-47 system is 1,500 light-years away, and lies at the edge of the Gum Nebula, possibly an ancient supernova remnant which can be seen from Earth's southern hemisphere.

The scale in the bottom left corner of each picture represents 93 billion miles, or 1,000 times the distance between Earth and the Sun. All images were taken with the Wide Field Planetary Camera 2 in visible light. The HH designation stands for "Herbig-Haro" object — the name for bright patches of nebulosity which appear to be moving away from associated protostars.

Upper Left Credit: C. Burrows (STScI & ESA), the WFPC 2 Investigation Definition Team, and NASA

Upper Right Credit: J. Hester (Arizona State University), the WFPC 2 Investigation Definition Team, and NASA

Bottom Credit: J. Morse/STScI, and NASA

Image Type: Astronomical STScI-PRC1995-24a

Source: http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/24/

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