Astronomers have recently revealed that the giant elliptical galaxy M87, previously assumed to be symmetrical, is actually asymmetrical, resembling a russet potato. Utilizing observations from the Hubble and Keck telescopes, researchers tracked the motion of stars around M87’s supermassive black hole, which has a mass estimated at 5.37 billion times that of the sun. This measurement is crucial for studying the black hole’s spin, a characteristic that remains poorly understood for these cosmic giants. The analysis confirmed M87’s triaxial structure, with its shortest axis being approximately 72.2% of its longest axis. The findings also indicated that the galaxy rotates relatively slowly at 25 km/s, though not around its major axes. The researchers used the Keck Cosmic Web Imager to gather precise observations across a region of 70,000 light-years, enabling the first reconstruction of M87’s 3D geometry. This improved understanding of M87 and its black hole could enhance knowledge about the formation of galaxies and black holes, as well as aid in interpreting gravitational wave signals. The study was led by UC Berkeley astronomer Chung-Pei Ma, with findings published in The Astrophysical Journal Letters.
