Stars and Dust Across Corona Australis
影像提供: Adam Block, NOAO, AURA, NSF
Explanation:
A cosmic dust cloud sprawls across a rich field of stars in this gorgeous wide field telescopic vista looking toward Corona Australis, the Southern Crown. Probably less than 500 light-years away and effectively blocking light from more distant, background stars in the Milky Way, the densest part of the dust cloud is about 8 light-years long. At its tip (lower left) is a series of lovely blue nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. Their characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The tiny but intriguing yellowish arc visible near the blue nebulae marks young variable star R Coronae Australis. Magnificent globular star cluster NGC 6723 is seen here below and left of the nebulae. While NGC 6723 appears to be just outside Corona Australis in the constellation Sagittarius, it actually lies nearly 30,000 light-years away, far beyond the Corona Australis dust cloud.
說明:
在南冕座這幅壯麗的廣角望遠鏡視野裡，一個塵埃雲蜿蜒穿過繁星點點的星場。這朵塵埃雲的距離可能不到五百光年遠，它遮掩了來自銀河較遙遠背景恆星的星光。塵埃雲最緻密的區域全長約為八光年，它左下端點處有一系列美麗的反射星雲，其編號分別為NGC 6726、6727、 6729、及IC 4812，它們特有的藍色色澤則來自塵埃反射了熾熱恆星的星光。藍色星雲附近有個小但很有趣的黃色弧，它標定了年輕變星南冕座R星之所在，反射星雲左下方的壯麗球狀星團是NGC 6723。乍看之下，NGC 6723好像只在南冕座外面一些的半人馬座內，實際上它的距離將近有三萬光年，比南冕座塵埃雲要遠得很多。
資料來源: Scientific American
Department of Physics, NCKU
