2020 June 12
Explanation: NGC 2359 is a helmet-shaped cosmic cloud with wing-like appendages popularly called Thor’s Helmet. Heroically sized even for a Norse god, Thor’s Helmet is about 30 light-years across. In fact, the helmet is more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble’s center inflates a region within the surrounding molecular cloud. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. NGC 2359 is located about 15,000 light-years away in the constellation of the Great Overdog. The remarkably sharp image is a mixed cocktail of data from broadband and narrowband filters using three different telescopes. It captures natural looking stars and the details of the nebula’s filamentary structures. The predominant bluish hue is strong emission from doubly ionized oxygen atoms in the glowing gas.
Tomorrow’s picture: light-weekend
影像提供与版权: Martin Pugh
说明: 这团带着侧翼的头盔状宇宙云，有雷神(索尔)的头盔之令名。然而对北欧的神祇来说，这顶宽度达30光年的头盔也是庞大无比。这顶头盔，实际上较像是是个星际气泡，是由中心附近的明亮大质量恒星所发出之高速恒星风，在周遭分子云中吹出的天体。这颗中心星是一颗沃夫-瑞叶型恒星，是一种处在前超新星演化短暂阶段的极端炽热巨星。这团编录号为NGC 2359的发射星云，位在大犬座方向，距离我们约有15,000光年远。这幅无比清晰的影像，结合了3座望远镜的宽和窄波段滤镜之影像数据，因此得以记录恒星的自然色泽和这团星云的云气丝和尘埃之细微结构。影像中鲜明的泛蓝色泽，源自辉光云气内的双电离氧原子发出的强烈辐射。(Thor’s Helmet雷神的头盔、索尔的头盔)