charles 2009-3-23 10:31
昴宿五星光
Reflecting Merope
[img]http://i16.tinypic.com/2qt8oj5.jpg[/img]
影像提供: Hubble Heritage Team, George H. Herbig & Theodore Simon (IfA, U. Hawaii), NASA
[color=navy]Explanation: [/color]
In the well known Pleiades star cluster, starlight is slowly destroying this wandering cloud of gas and dust. The star Merope lies just off the upper left edge of this picture from the Hubble Space Telescope. In the past 100,000 years, part of the cloud has by chance moved so close to this star - only 3,500 times the Earth-Sun distance - that the starlight itself is having a very dramatic effect. Pressure of the star's light significantly repels the dust in the reflection nebula, and smaller dust particles are repelled more strongly. As a result, parts of the dust cloud have become stratified, pointing toward Merope. The closest particles are the most massive and the least affected by the radiation pressure. A longer-term result will be the general destruction of the dust by the energetic starlight.
[color=navy]說明: [/color]
在著名的昴宿星團裡，來自昴宿五的星光，正慢慢地摧毀這團氣體和塵埃雲。昴宿五 (Merope)位在在這張由哈伯太空望遠鏡所拍攝的影像之左上角外。在過去的10萬年裡，這團雲氣恰好以只有3500倍地球-太陽的距離通過昴宿五附近，因此星光對雲氣造成非常特殊的效應。星光的光壓吹走了這個反射星雲大部份的塵埃，顆粒愈小的塵埃被吹走的比例也愈高。因此，部份塵埃雲形成指向昴宿五的層狀結構，最靠近昴宿五的塵埃粒質量也最大，因為它們受到輻射壓的影響最小，更長期的效應是塵埃微粒會被高能量星光給全部破壞。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]