The Sombrero, also known as Messier Object number 104 or M104, is one of the Universe's most stately and photogenic galaxies. Astronomers trained the razor-sharp eye of NASA's Hubble Space Telescope on M104 in May-June 2003.
Mexican Hat. The Sombrero Galaxy's hallmark is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. It is referred to as the Sombrero because of its resemblance to the broad rim and high-topped Mexican hat.
As seen from Earth, the galaxy is tilted nearly edge-on. Astronomers on Earth view it from just six degrees south of its equatorial plane.
Requires a Telescope. M104 is just beyond the limit of naked-eye visibility, but can be seen easily through small telescopes. It is located 28 million lightyears from Earth at the southern edge of the rich Virgo cluster of galaxies and is one of the most massive objects in that group.
The Sombrero Galaxy is 50,000 lightyears across and holds 800 billion suns.
M104 is a system rich in old globular clusters, with an estimated 2,000. That's ten times as many globular clusters as orbit our own Milky Way galaxy. The ages of the clusters around M104 are similar to the ages of the clusters in the Milky Way – ranging from 10-15 billion years old.
Black Hole Heart. There appears to be a small disk embedded in the bright core of M104. The small disk is tilted relative to the large disk of the whole galaxy. Astronomers looking at X-rays coming from the Sombrero think outer material may be falling into the compact core. They suggest there may be a massive black hole as weighty as a billion stars at the heart of the Sombrero.
Some 19th century astronomers speculated that M104 was simply an edge-on disk of luminous gas surrounding a young star. That would make the Sombrero a galaxy like our own Milky Way. However, in 1912, astronomer V. M. Slipher noticed that M104 appeared to be rushing away from Earth at 700 miles per second. Such an enormous velocity was an important clue that the Sombrero was really another galaxy, and that the universe was expanding in all directions.
The Hubble Process. The Hubble observations of M104 were made with the space telescope's Advanced Camera for Surveys. The images were recorded through three filters – red, green, and blue – which yielded a natural-color image.
The team of astronomers took six pictures of the galaxy and then stitched them together to create the final composite image. It turned out to be one of the largest Hubble mosaics ever assembled.
Looking through the telescope, the Sombrero Galaxy is nearly one-fifth the diameter of the full moon.
