阔边帽星系（梅西尔编号：M104，NGC 4594，又称草帽星系、墨西哥帽星系）位于室女座，为一个Sa-Sb型之旋涡星系，光度+8.7等，距离地球2,800万光年。这个星系的直径是大约50,000光年，有银河系的大小的30％。

天文学家最初认为光环是小而轻的旋涡星系，但史匹哲太空望远镜发现，周围的草帽星系晕是一个比以前认为的更大规模的巨大的椭圆星系。这个星系拥有星等+9.0，使得它很容易被用业余望远镜观测到，它被有些作家认为是在银河系的10 百万秒差距(megaparsecs)半径范围内最亮的星系。

The Sombrero Galaxy (also known as Messier Object 104, M104 or NGC 4594) is an unbarred spiral galaxy in the constellation Virgo located 28 million light-years (8.6 Mpc) from Earth. The galaxy has a diameter of approximately 50,000 light-years, 30% the size of the Milky Way. It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its inclined disk. The dark dust lane and the bulge give this galaxy the appearance of a sombrero. Astronomers initially thought that the halo was small and light, indicative of a spiral galaxy, but Spitzer found that the halo around the Sombrero Galaxy is larger and more massive than previously thought, indicative of a giant elliptical galaxy. The galaxy has an apparent magnitude of +9.0, making it easily visible with amateur telescopes, and it's considered by some authors to be the brightest galaxy within a radius of 10 megaparsecs of the Milky Way. The large bulge, the central supermassive black hole, and the dust lane all attract the attention of professional astronomers.