Astronomy Picture of the Day——我们银河系的磁心
Our Galaxy's Magnetic Center
Image Credit: NASA, SOFIA, Hubble
Explanation: What's the magnetic field likein the center of our Milky Way Galaxy? To help find out, NASA's SOFIA -- anobservatory flying in a modified 747 -- imaged the central region with aninstrument known as HAWC+. HAWC+ maps magnetism by observing polarized infraredlight emitted by elongated dust grains rotating in alignment with the localmagnetic field. Now at our Milky Way's center is a supermassive black hole witha hobby of absorbing gas from stars it has recently destroyed. Our galaxy'sblack hole, though, is relatively quiet compared to the absorption rate of thecentral black holes in active galaxies. The featured image gives a clue as towhy -- a surrounding magnetic field may either channel gas into the black hole-- which lights up its exterior, or forces gas into an accretion-disk holdingpattern, causing it to be less active -- at least temporarily. Inspection ofthe featured image -- appearing perhaps like a surreal mashup of impasto artand gravitational astrophysics -- brings out this telling clue by detailing themagnetic field in and around a dusty ring surrounding Sagittarius A*, the blackhole in our Milky Way's center.
我们银河系的磁心
我们银河系中央的磁场是什么样子呢？为了找寻答案，NASA的索菲亚平流层红外天文台（SOFIA），这架由改装过的波音747搭载的望远镜使用一种名为高分辨率机载宽带摄像机（HAWC+）的设备对中央区域进行拍摄。HAWC+通过观察和局部磁场方向一致的细长尘埃颗粒发出的红外偏振光来绘制磁力图。目前，一个超大质量黑洞位于银河系中央，它能吞噬被摧毁恒星所释放的气体。然而，与活跃星系内中央黑洞相比，银河系的中央黑洞安静了许多。这幅特征图像提供了一个线索，是关于为什么周围磁场迫使气体进入吸积盘保持停滞的状态，导致黑洞变得不太活跃。仔细观察这幅特征图像，它看起来像是超现实艺术和引力天体物理学的结合，通过详细描述人马座A附近的尘埃环（银河系中央的黑洞）内部和周围磁场的细节，揭示了这条有效的线索。
参考文献：
https://apod.nasa.gov/apod/image/1906/MwCenter_SofiaHubble_1032.jpg
近期文章：
Astronomy Picture of the Day——海神庙上空的草莓月