Flame Nebula Close-Up
Credit & Copyright: Robert Gendler, Jan-Erik Ovaldsen
Explanation:
Of course, the Flame Nebula is not on fire. Also known as NGC 2024, the nebula's suggestive reddish color is due to the glow of hydrogen atoms at the edge of the giant Orion molecular cloud complex some 1,500 light-years away. The hydrogen atoms have been ionized, or stripped of their electrons, and glow as the atoms and electrons recombine. But what ionizes the hydrogen atoms? In this close-up view, a dark lane of absorbing interstellar dust stands out in silhouette against the hydrogen glow and actually hides the true source of the Flame Nebula's energy from optical telescopes. Behind the dark lane lies a cluster of hot, young stars, seen at infrared wavelengths through the obscuring dust. A young, massive star in that cluster is the likely source of energetic ultraviolet radiation that ionizes the hydrogen gas in the Flame Nebula.
說明:
當然，火焰星雲並不是真的著火。眾所皆知的 NGC 2024 ，星雲的紅色是來自於獵戶座(Orion) 的巨分子雲(giant molecular cloud)的 氫原子發光，距離我們約 1,500 光年遠。 當氫原子被游離，拿掉一個電子，重新與電子結合(recombine)時會發光。 但是什麼東西導致游離 氫原子呢? 從這張放大的影像來看，一道黑暗的吸收星際雲塵，就在發光的氫原子 前顯得格外明顯，事實上也藏著火焰星雲的可見光能量的來源。 在暗帶背後藏匿著熾熱年輕的星球，可以利用 紅外線波段來觀測，因為紅外線可以穿過星塵。 一個年輕且重質量的星球最 有可能是高能的紫外線來源，游離火焰星雲內的氫氣。
資料來源: Scientific American
Department of Physics, NCKU
