2025年01月31日:变光星云NGC 2261-（The Variable Nebula NGC 2261）

2025年01月31日:变光星云NGC 2261-（The Variable Nebula NGC 2261）--原图下载

Image Credit &Copyright:Tommy Lease(Denver Astronomical Society)
说明: 这幅清晰望远镜影像所呈现的星际尘埃与气体云，其外观在数星期之间就会有明显的变化。发现于200多年前、编录号为NGC 2261的这个扇形星云，扇头镶着亮星麒麟R（R Mon）。NGC 2261的宽度约有1光年，距离我们约2,500光年远，在上世纪初，因天文学家哈伯曾对它进行研究，故这团谜样的宇宙云有哈伯变光星云（Hubble's Variable Nebula）之称。 那么，为何哈伯星云会变光呢？NGC 2261是个尘埃反射星云，扇形的顶端为麒麟R。最可信的变光假说认为，麒麟R附近在移动的緻密不透光尘埃结，把影子投射在尘埃云上，造成我们见到的变光现象。

原文：

Image Credit &Copyright:Tommy Lease(Denver Astronomical Society)
Explanation: The interstellar cloud of dust and gas captured in thissharp telescopic snapshot is seen to change its appearancenoticeably over periods as short as a few weeks.Discovered over 200 years ago and cataloged as NGC 2261,bright star R Monocerotis lies at the tip of the fan-shaped nebula.About one light-year across and 2500 light-years away,NGC 2261 was studiedearly last century by astronomer Edwin Hubble andthe mysterious cosmic cloud is now more famous asHubble's Variable Nebula.So what makes Hubble's nebula vary?NGC 2261 is composed of a dustyreflection nebula fanning out from the starR Monocerotis.The leading variability explanationholds that dense knots of obscuring dust pass close to R Mon and cast moving shadowsacross the dust clouds in the rest of Hubble's Variable Nebula.