Barnard's Loop(astronomy)

Barnard's Loop

To understand the concept of Barnard's Loop, we have to understand some certain things as follows:-

1) Nebula:-

 It is an interstellar cloud of dust,hydrogen, helium and other ionized gases. Most Nebulae(plural form of nebula) are of vast size. Some of them are hundred light years in diameter. 

2) Orion Nebula:- 

Orion nebula 

It is a diffuse nebula situated in the Milky way, Being south of the orion's belt it is one of the brightest nebula and is visible to the naked eye in the night sky. 

3) Horsehead Nebula :-

It is small dark nebula in the constellation orion. As it looks like the shape of a head of a horse so it is called horse head nebula.  The nebula is located just to the south of Alnitak, the eastermost star of orion's belt. 

Horsehead nebula

4) Emission nebula:- 

It  is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. 

Emission nebula

5) Orion Molecular Cloud Complex :-

 It is a star forming region with stellar ages ranging upto 12 million light years. Two gaint molecular clouds are part of it, like orion A and Orion B. 

Orion molecular cloud complex 

Above I mentioned some particular terms which will quite helpful for us to understand the term Barnard's Loop.

It is thought that it is originated in a supernova explosion about 2 million years ago, which may have also created several known runaway stars, including AE Aurigae, Mu Columbae and 53 Arietis, which are believed to have been part of a multiple star system in which one component exploded as a supernova.

Also it  is said that Barnard's loop is about 1600 light years away from earth. It is part of orion complex. It is a semicircular arc that is about 300 light year across. In the center of Barnard's loop there are two nebula's such as orion nebula and horsehead nebula.  The stars within the orion nebula believed to be responsible for ionizing the loop. This loop extends over 600 arc minutes as seen from earh covering much of orion. Barnard loop is made up of hot gas. The red colour of Barnard's loop comes from hydrogen gas.