What is a Galaxy?
The term galaxy is used to refer to a group of stars forming a particular arrangement that is concentrated to a center. In general this galaxy is formed from 10 million years to 10 trillion stars. So the distance of a galaxy from one end to another can range from thousands to hundreds of thousands of light years. As Objects of galaxy research include complicated phenomena. Because the space where it is (the universe) very spacious.
From the results of research to various corners of the universe, it is estimated that the existing galaxy brjumlah hundreds of billions! It has not been included in a constellation that is difficult to observe because of the extraordinary distance away
How is the Galaxy Formed?
Until now the formation of galaxies still big question mark for astronomers. The emerging theory is divided into two broad categories: top-down and bottom up. Theories that fall into the top-down category usually mention the existence of protogalaxy elements (celestial body particles) clustered into galaxies. This theory mentions the required duration of about 100 million years. Sedagkan from the bottom-up theory, astronomers believe a number of adjacent stars (globular clusters) .
1. Sombrero Galaxy
The Sombrero Galaxy (also known as M104 or NGC 4594) is an unbarred spiral galaxy in the constellation Virgo. It has a bright core, an unusually large central bulge, and the leading dust tends to way in the disc. The dark dust line and the bulge give this galaxy the appearance of a sombrero. The galaxy has a visible magnitude of 9.0, making it easily visible with an amateur telescope. The huge bulge, the center of supermassive black holes, and the dust of the road all attracted the attention of professional astronomers. Which occurred in the Milky Way itself. The light from the supernova reached the earth on 23 February 1987. As the first supernova discovered in 1987, it was labeled "1987a". The brightness peaked in May with a clear magnitude of about 3 and slowly declines in subsequent months. This is the first opportunity for modern astronomers to look closely at the supernova.
2. Black Eye Galaxy
A spiral galaxy in the constellation Coma Berenices, Messier 64, the famous "Black Eye" galaxy or "Sleeping Princess galaxy," has a spectacular dark band absorbing dust in front of the intelligent galactic nucleus. It is well known among amateur astronomers because of its appearance in small telescopes.
3. 2MASX J00482185-2507365 occulting pair
2MASX J00482185-2507365 occulting pair is a pair of overlapping spiral galaxies found around NGC 253, the Galaxy Sculptor. The two galaxies farther away from the NGC 253, against the background of the galaxy, 2MASX J00482185-2507365, lie in a z = 0.06 red shift, and the NGC galaxy's foreground lies between 253 and the galaxy in the background (0.0008 <0 , 06). This pair illuminates the galaxy of galactic dust distribution beyond the visible spiral arms of the galaxy. As far as before this unexpected dust goes beyond the starry borders of the arm, it shows a new area for the study of extragalactic astronomy. The dusty arm extends six times with the radius of the starry hands of the galaxy, and is shown a silhouette image in the HST against the center and the galactic core in the background.
4. The Whirlpool Galaxy
The Whirlpool Galaxy is also known as Messier 51A, M51a, or NGC 5194, the Whirlpool Galaxy is a grand-design interacting spiral galaxy located at a distance of about 23 million light-years across the constellation of Venatici Sticks. It is one of the most famous spiral galaxies in the sky. Galaxies and companions (NGC 5195) are easily observed by amateur astronomers, and both galaxies can even be seen with binoculars. The Whirlpool Galaxy is also a popular target of professional astronomers, who study into galaxies better understanding the structure (especially structures associated with spiral arms) and galaxy interactions.