2019 September 7
In Wolf’s Cave
Image Credit & Copyright: Charlie Bracken, Mladen Dugec, Max Whitby
Explanation: The mysterious blue reflection nebula found in catalogs as VdB 152 or Ced 201 really is very faint. It lies at the tip of the long dark nebula Barnard 175 in a dusty complex that has also been called Wolf’s Cave. At the center of this deep and widefield telescopic view, the cosmic apparitions are nearly 1,400 light-years away along the northern Milky Way in the royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving the the nebula its characteristic blue color. Ultraviolet light from the star is also thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in molecular clouds, this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud’s velocity. Another dense, obscuring dark nebula, LDN 1221, is easy to spot at the upper right in the frame, while the more colorful planetary nebula Dengel-Hartl 5 is just below center. Faint reddish emission from an ancient supernova remnant can also be traced (lower right to upper left) against the dust-rich complex in Cepheus.
影像提供与版权: Charlie Bracken, Mladen Dugec, Max Whitby
说明: 这个编录号为VdB 152或Ced 201的神秘蓝色反射星云，其实极为昏暗。它位在颀长暗星云巴纳德175的尖端，而巴纳德175所在的尘埃复合体则有沃夫洞穴的称号。在这幅深空大视野望远镜影像中心附近的这团幽灵状云气，位在仙王座的北天银河内，离我们约有1,400光年远。座落在一个庞大分子云边缘的这团云气，内部团状的尘埃云除了遮住后方背景恒星的星光之外，也散射内部亮星的星光，让星云带着泛蓝的特征辉光。来自这颗恒星的紫外辐射，咸认也激发云气发出黯淡的泛红晕光。虽然恒星确知会形成于分子云里，但这颗星应只是误闯此区域而已，因为它在空间运动的速度和星云极为不同。在影像的右上角，可见到另一个编录号为LDN 1221的致密不透光暗星云，而在影像中下方，则有色彩缤纷的行星状星云Dengel-Hartl 5。此外，在仙王座广袤尘埃复合体的衬托下，还可辨识出右下到左上方向上的一个古老超新星遗迹之暗淡泛红辐射。