The Sombrero Galaxy is located about 30 million light-years away, in the constellation Virgo. Although it is one of the brightest galaxies located in the region of the sky covered by this constellation, this galaxy remains invisible to the naked eye. This image was captured by the Dark Energy Camera (DECam), which is mounted on the Víctor M. Blanco Telescope of the U.S. National Science Foundation in Chile.
The central region of the galaxy is dominated by its exceptionally bright core, which is surrounded by approximately 2,000 globular clusters, which is about ten times as many as those in our own Milky Way. Globular clusters are very old star clusters containing anywhere from a few tens of thousands to a few million stars, clustered within a spherical region, with a diameter that usually does not exceed 150 light-years. Because of the strong gravitational pull between all the stars they contain, globular clusters maintain their cohesion intact for billions of years, unlike open clusters, which contain far fewer stars and are therefore prone to stellar “escape.”
About 50,000 light-years from the galactic center, a thin, dark band of dust and hydrogen gas encircles the galactic disk, delimiting the wider region of the Sombrero Galaxy, where the highest rate of star formation is observed. The galaxy itself, however, has a much larger diameter. In other words, if we also take into account its faint outer regions, which extend beyond the visible dust lane, its diameter reaches 100,000 light-years.
The image also reveals the vast spherical halo surrounding it—a brilliant halo with a diameter exceeding 150,000 light-years. In fact, this may well be the first time that the Sombrero Galaxy’s halo has been mapped in such detail and on such a large scale. DECam's remarkable sensitivity also captured an extensive, faint curved structure extending from the lower part of the galaxy. Both the halo and this curved structure are composed of stars that have been torn away from their galaxies, suggesting an earlier galactic merger between the Sombrero and a smaller galaxy.
The supermassive black hole at the center of the galaxy contains the mass of 9 billion stars like the Sun. Despite its enormous mass, observations from the Hubble Space Telescope show that the central black hole of the Sombrero Galaxy is relatively “quiet,” as it is not actively absorbing vast amounts of matter from its accretion disk. That is why it is classified as a low-luminosity active galactic nucleus.
Photo: The Sombrero Galaxy [Credit: CTIO/NOIRLab/DOE/NSF/AURA]
Image Processing: T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin & M. Zamani (NSF NOIRLab)]