本帖最后由 人与自然 于 2013-4-21 00:50 编辑
http://www.dailymail.co.uk/sciencetech/article-2311763/An-incredible-neigh-bula-Hubble-reveals-Horsehead-Nebula-unprecedented-detail.html
It is an astonishing new view of a unique nebula.
Researchers have used NASA's Hubble Space Telescope to photograph the iconic Horsehead Nebula in a new, infrared light to mark the 23rd anniversary of the famous observatory.
Looking like an apparition rising from whitecaps of interstellar foam, the iconic Horsehead Nebula has graced astronomy books ever since its discovery more than a century ago.
The Horsehead Nebula as viewed at near-infrared wavelengthswith the NASA/ESA Hubble Space Telescope. This thick pillar of gas and dust is sculpted by powerful stellar winds blowing from clusters of massive stars located beyond the field of this image. The bright source at the top left edge of the nebula is a young star whose radiation is already eroding the surrounding interstellar material.
Hubble has been producing ground-breaking science for two decades since its launch aboard the space shuttle Discovery on April 24, 1990.
During that time, it has benefited from a slew of upgrades from space shuttle missions, including the 2009 addition of a new imaging workhorse, the high-resolution Wide Field Camera 3 that took the new portrait of the Horsehead.
The nebula is a favorite target for amateur and professional astronomers.
It is shadowy in optical light, and appears transparent and ethereal when seen at infrared wavelengths.
'The rich tapestry of the Horsehead Nebula pops out against the backdrop of Milky Way stars and distant galaxies that easily are visible in infrared light,' said Nasa.
The nebula is part of the Orion Molecular Cloud, located about 1,500 light-years away in the constellation Orion.
It is one of the nearest and most easily photographed regions in which massive stars are being formed.
Spot the horsehead: A new view from ESA's Herschel space observatory of the iconic Horsehead Nebula in the context of its surroundings. The Horsehead Nebula resides in the constellation Orion, about 1300 light-years away, and is part of the vast Orion Molecular Cloud complex. To the left, the panoramic view also covers two other prominent sites where massive stars are forming, NGC 2068 and NGC 2071.
In the Hubble image, the backlit wisps along the Horsehead's upper ridge are being illuminated by Sigma Orionis, a young five-star system just out of view.
Along the nebula's top ridge, two fledgling stars peek out from their now-exposed nurseries.
Scientists know a harsh ultraviolet glare from one of these bright stars is slowly evaporating the nebula.
Gas clouds surrounding the Horsehead already have dissipated, but the tip of the jutting pillar contains a slightly higher density of hydrogen and helium, laced with dust.
This casts a shadow that protects material behind it from being stripped away by intense stellar radiation evaporating the hydrogen cloud, and a pillar structure forms.
Hubble has been producing ground-breaking science for two decades since its launch aboard the space shuttle Discovery on April 24, 1990.
During that time, it has benefited from a slew of upgrades from space shuttle missions, including the 2009 addition of a new imaging workhorse, the high-resolution Wide Field Camera 3 that took the new portrait of the Horsehead.
This three-panel image shows the latest near-infrared Hubble image of the Horsehead Nebula in context with the new wide-field Herschel view of the surrounding environment at far-infrared wavelengths. | 
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