NOTABLE NAMED NEBULA

• Barnard's Loop
• Boomerang Nebula
• Cat's Eye Nebula
• Crab Nebula
• Eagle Nebula
• Eskimo Nebula
• Eta Carinae Nebula
• Helix Nebula
• Hourglass Nebula
• Horsehead Nebula
• Lagoon Nebula
• Orion Nebula
• Pelican Nebula
• Red Square Nebula
• Ring Nebula
• Rosette Nebula
• Tarantula Nebula
•  Ant Nebula

#credit: http://en.wikipedia.org/wiki/Nebula

TYPE OF NEBULA

The omega nebula, an example of an emission nebula

 

 The Horsehead Nebula, an example of a dark nebula

 

The cats Eye Nebula, an example of a planetary nebula

 The Crab Nebula, an example of a supernova remnant

 The Red Rectangle Nebula, an example of a protoplanetary nebula

# credit: http://en.wikipedia.org/wiki/Nebula

FORMATION

Many nebulae or stars from the gravitational collapse of gas in the interstellar medium or ISM. As the material collapses under its own weight, massive stars may from in the center, and their ultraviolet radion ionizes the surrounding gas, making it visible at optical wavelengths. Example of these types of nebulae are the rosette Nebula and the Pelican Nebula. The size of these nebulae, known as HII regions, varies depending on the size of the original cloud of gas. New star are formed in the nebulae. The formed star are sometimes known as a young, loose cluster.

Some nebulae are formed as the result of supernova explosions, the death throes of massive, short-lived stars. The material thrown off from the supernova explotion are ionized by the energy and the compact object that it can produce. One  of the best examples of this is the Crab Nebula, in Tarus. The supernova event was recorded in the year 1054 and is labelled SN 1054.The compact object that was created after the explosion lies in the center of the Crab Nebula and is a neutron star.

 Other nebulae may form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's sun. Stars with amass up to 8–10 solar masses evolve into red giants and slowly lose their outer layers during pulsations in their atmospheres. When a star has lost enough material, its temperature increases and the ultraviolet radiation it emits can ionize the surrounding nebula that it has thrown off. The nebula is almost 97% hydrogen and 3% helium, plus trace amounts of other elements.

HISTORY

Around A.D. 150, Claudius Ptolemaeus (Ptolemy) recorded, in books VII-VIII of his Almagest, five stars that appeared nebulous. He also noted a region of nebulosity between the Constellations Ursa Major and Leo that was not associated with any star. The first true nebula, as distinct from a star cluster, was mentioned by the Arabic/Muslim astronomer, Abd al-Rahman al Sufi,in his Book of Fixed Stars (964). He noted "a little cloud" where the Andromeda Galaxy is located. He also cataloged the Omicron Volerum star cluster as a "nebulous star" and other nebulous objects, such as Brocchi's Cluster. The supernova that created the Crab Nebula,the SN 1054, was observed by Arabic and Chinese astronomer in 1054. 

 On November 26, 1610 Nicolas-Claude Fabri de Peiresc discovered the Orion Nebula using a telescope.This nebula was also observed by Johann Baptist Cysat in 1618. However, the firt detailed study of the Orion Nebula wouldn't be performed until 1659 by Christian Huvgen, who also believed himself to be the first person to discovered this nebulosity.

 

 In 1715, Edmund Halley published a list of six nebulae. This number steadily increased during the century, wiht Jean-Philippe de Cheseaux compiling a list of 20 in 1746. From 1746-53, Nicolas Louis de Lacaille cataloged 42 nebulae from the Cape of Good Hope, with most of them being previously unknown Charles Messier then compiled a catalog of 103 "nebulae" by 1781; his interest was detecting comets, and these were object might be mistaken for them.

NEBULA

A Nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way. Nebula are often star-forming regions, such as in the Eagle Nebula. This Nebula is depicted one of NASA's most faous images,the "pillar of creation". In these regions the information of gas, dust, and other materials "clump" together from larger masses, which attract further matter, and eventually will become massive enough to from stars. The remaining material are then believed to from planets., and other planetary system objects.