NGC 6164: 龙蛋星云及其外晕

2022年12月26日

NGC 6164: Dragon’s Egg Nebula and Halo
Image Credit & Copyright: Russell Croman

Explanation: The star at the center created everything. Known as the Dragon’s Egg, this star — a rare, hot, luminous O-type star some 40 times as massive as the Sun — created not only the complex nebula (NGC 6164) that immediately surrounds it, but also the encompassing blue halo. Its name is derived, in part, from the region’s proximity to the picturesque NGC 6188, known as the fighting Dragons of Ara. In another three to four million years the massive star will likely end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry making it similar in appearance to more common planetary nebulae – the gaseous shrouds surrounding dying sun-like stars. Also like many planetary nebulae, NGC 6164 has been found to have an extensive, faint halo, revealed in blue in this deep telescopic image of the region. Expanding into the surrounding interstellar medium, the material in the blue halo was likely expelled from an earlier active phase of the O-star. NGC 6164 lies 4,200 light-years away in the southern constellation of the Carpenter’s Square (Norma).

Tomorrow’s picture: all the way around

NGC 6164: 龙蛋星云及其外晕
图像提供与版权: Russell Croman

说明: 图像中心的恒星创造了这一切。这颗称为龙蛋的恒星，是一颗质量约为40倍太阳的希有、炽热且明亮的O型星，而它不但创造了身旁的复杂星云（NGC 6164），还创造了包围着它的泛蓝外晕。它的名号，有部分是来自此区邻近风景如画、有天坛战龙之称的NGC 6188。再过三、四百万年，这颗大质量恒星很可能会以超新星爆炸终结它的生命。宽度约为4光年的此星云，具有双极瓣对称性，因此其外观类似较常见、由垂死类太阳恒星外层气壳所形成之行星状星云。而与许多行星状星云一样，观测发现NGC 6164也有庞大且昏暗的外晕，如上面这幅此区的深空望远镜图像里泛蓝的结构所示。泛蓝外晕的物质，很可能是O型星在早期活跃的阶段所排出的，然后逐渐扩张并推挤周围的星际物质。NGC 6164位于南天以木匠角尺为名的矩尺座方向约4,200光年远之处。

明日的图片: all the way around