http://www.phys.ncku.edu.tw/~astrolab/mirrors/apod/ap170303.html
氫α波段進行銀河系高分辨率天文巡天
左上角可見到龐大暗淡而且聲名不顯的希文2,中右方有鄰近的M31
最近由天文學家Rogelio Bernal Andreo所拍攝的這些有趣的昏暗氫氣雲,其實是位在仙女座大星系視線方向的銀河系之內。(Sivan 2 希文2)
前段時間有人拍紅色 M31
http://www.deepskycolors.com/Clouds_of_Andromeda.html
Ionized gas in the Milky Way is ubiquitous, with a pervasive
yet faint background detectable in nearly every direction in the northern sky."
~ The Wisconsin H-Alpha Mapper Northern Sky Survey, Haffner et al.