=宇宙級的龍捲風=

Cosmic Tornado HH49/50



影像提供: J. Bally (Univ. of Colo.) et al., JPL-Caltech, NASA

Explanation:
Light-years in length, this cosmic tornado is actually a powerful jet
cataloged as HH (Herbig-Haro) 49/50 blasting down from the top of a Spitzer
Space Telescope view. Though such energetic outflows are well known to be
associated with the formation of young stars, the exact cause of the
spiraling structures apparent in this case is still mysterious. The
embryonic star responsible for the 100-kilometer per second jet is located
just off the top of the picture, while the bright star seen near the tip of
the jet may just by chance lie along the line of sight. In the false-color
infrared image, the tornado glows with infrared light generated as the
outflow heats surrounding dust clouds. The color coding shows a trend from
red to blue hues at the tornado's tip indicating a systematic increase in
emission at shorter wavelengths. The trend is thought to indicate an
increase in molecular excitation closer to where the head of the jet is
impacting interstellar gas. HH49/50 is about 450 light-years distant,
located in the Chamaeleon I molecular cloud.

說明:
這道長數光年的宇宙
級龍捲風，實際上是一道編號為HH49/50的強大噴流，它從這幅史匹哲太空望遠鏡影像的上端向下噴。雖然這種強大的物質噴流通常和年輕恆星的形成過程有
關，但像這個範例中的螺旋結構到底是怎麼造成的，則仍然未知。造成這道秒速一百公里噴流的胎星，位在這幅影像頂端的外頭，而噴流頂點附近的亮星可能只是湊
巧位在同一個方向而已。在這張假色紅外光影像裡，噴流之所會發出紅外輻射，是來自被噴流所加熱的周遭塵埃雲氣。這道噴流頂點的色澤由紅漸次轉變成藍色，顯
示所發出的短波長輻射系統性地循序增強。一般認為這種取向顯示愈靠近噴流頂點，噴流衝撞星際雲所所造成的分子激發也愈強烈。HH49/50位在堰蜓座
(Chamaeleon)一號分子雲內，距離我們約有450光年遠。(HH = Herbig-Haro -- 赫比格-赫羅)


資料來源: Scientific American
Department of Physics, NCKU