横跨南冕的恒星和尘埃
(原标题: Stars and Dust Across Corona Australis)
2021-08-06
浏览次数: 33
宇宙尘埃云穿过一片丰富的恒星区域，这张望远镜拍摄的照片靠近南冕的北部边界。距离不到500光年的尘埃云有效地阻挡了来自银河系中更远的背景恒星的光线。在云的估计距离上，从上到下的框架跨度约为2度或超过15光年。右上方是一组可爱的反射星云，编号分别为NGC 6726、6727、6729和IC 4812。当来自热恒星的光被宇宙尘埃反射时，就会产生一种特有的蓝色。尘埃云还遮挡了仍在形成过程中的恒星的视线。就在蓝色反射星云的上方，一个较小的NGC 6729围绕着年轻的变星南冕R。在它的右边是红色的圆弧和环，被认为是赫比格哈洛天体，与能量旺盛的新生恒星有关。壮丽的球状星团NGC 6723在画面的左下方。虽然NGC 6723看起来是这个星系群的一部分，但它的古老恒星实际上位于近3万光年远的地方，远远超出了南冕尘埃云的年轻恒星。
查看原文解释
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.
© Vikas Chander