南冕座的恒星和尘埃

2021年8月6日

Stars and Dust Across Corona Australis
Image Credit & Copyright: Vikas Chander

Explanation: Cosmic dust clouds cross a rich field of stars in this telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Less than 500 light-years away the dust clouds effectively block light from more distant background stars in the Milky Way. Top to bottom the frame spans about 2 degrees or over 15 light-years at the clouds’ estimated distance. At top right is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The dust also obscures from view stars in the region still in the process of formation. Just above the bluish reflection nebulae a smaller NGC 6729 surrounds young variable star R Coronae Australis. To its right are telltale reddish arcs and loops identified as Herbig Haro objects associated with energetic newborn stars. Magnificent globular star cluster NGC 6723 is at bottom left in the frame. Though NGC 6723 appears to be part of the group, its ancient stars actually lie nearly 30,000 light-years away, far beyond the young stars of the Corona Australis dust clouds.

Tomorrow’s picture: Stereo Saturday

南冕座的恒星和尘埃
影像提供与版权: Vikas Chander

说明: 这幅广袤的望远镜影像，呈现南冕座北缘的繁星和尘埃云。这些距离不到500光年远的尘埃云，几乎完全遮住后方银河背景恒星的星光。这幅从上到下跨2度的影像，以星云所在的距离来估算，涵盖超过15光年的区域。影像右上缘附近的成群美丽反射星云，编录号分别为NGC 6726、6727、6729及IC 4812。它们特征的泛蓝色泽，来自被尘埃反射的炽热恒星之星光。这些尘埃，同时也遮掩了此区域仍处在形成阶段的恒星。紧贴在泛蓝反射星云上方的较小淡黄星云NGC 6729，则包覆着年轻变星南冕座R星。它右方带着特征泛红泽的弧状和环状结构，则是由活跃新恒星所造成的赫比格·哈罗天体天体。影像左下的壮丽球状星团编号是NGC 6723，乍看之下它像是这群星云的一部份，但它内部年老的恒星距离将近有30,000光年，其实远在南冕座尘埃云的新恒星之后方。

明日的图片: Stereo Saturday