The Great Orion nebula  This nebula, perhaps is the most popular,it belongs in the constellation of Orion. It is a constellation easily viewed, that dominates in the wintry sky. Because of his special characteristics, but also because of the objects that it contains. I decided to be extended more from usual, not only for the nebula, but also for his constellation in its entirety.Orion

Overview of the constellation

It is one of the most outstretched constellations, extending on either side of the celestial equator. The brightest star of this constellation is alpha Orion (Betelgeuse, red supergiant, variable size 0.4-1.3).  From the four bright stars in characteristic quadrangle of this constellation, this is the only old star. It lies only 425 light years from us and is a candidate for a future supernova (future type II supernova, it will become a neutron star, large as a small town. This will be happened in a thousand years or it is already happened! This supernova will be easily seen during the day and it will outshine our Moon during the night!!). This star is 40.000 to 100.000 more luminous than our sun, with 650 times his diameter (as a variable star, his diameter varies from 550 to 900 times our sun' s diameter)and his volume is 160.000,000 times greater. It is one of the largest known stars. It ’s mass is 15 to 17 solar masses with a density of 10-4 density of our air. Therefore it is characterized as "red hot vacuum".  The rest of the quartet is the white-blue Bellatrix ( c Orion, size 1.64, one of the hotter naked eye stars. In few million years he will become an orange giant, and will die quitly as a white dwarf) , the blue-white supergiant Rigel ( b -Orion, size 0.18, 11.000 K surface temperature, luminosity of 40.000 sun 's. Is the most luminous star in our local region. If it were at a distance of Sirius, then his apparent magnitude were -10.0, as bright as half moon! ) and finally the blue Saiph ( k -Orion, size 2.07, 26.000 K surface temperature, hotter than Rigel. He lies at the same distance from us as Rigel, but he is fainter because he radiates in the invisible ultraviolet. He has 65.000 the luminosity of our sun, and 15-17 his mass).One of the known most famous nebula and of the most photographed celestial bodies is  the Great Orion Nebula ( M42 or NGC 1976), south of the belt of Orion. Just 1.344 (± 20) light years from us and is one of the biggest ' stellar nurseries ' of the Milky Way visible to the naked eye in a clear sky. His actual diameter is estimated to be 24 light years. It is the most appropriate for stellar studies because of his proximity and size. The m42 is just a small part of a much larger cloud of dust and gas, known as the OMC1 (Orion Molecular complex),  that is extended in an area of 100 of the sky. The M42 has a spherical shape and his density peaks  in his central area (core). His temperature rises to 10,000 in the center, however, it falls greatly in circumference. Around the Oriontheta 1 (the trapezium area), extends an ionized region that emits the most ionizing radiation. This area is enclosed by a region of higher density ionized cloud. Outside of this area, clumps neutral gas.As earlier said, the M42 nebula is part of a much larger nebula complex known as the Orion molecular cloud, extending over most of the constellation (the Barnard's loop that mainly contains the Horsehead nebula, the Flame nebula , the M42-43 and M78 ) . The Great Orion Nebula contains an open cluster,  known as trapezium of Orion. The cluster appears to be part of a larger cluster of 2.000 stars in an area spanning 20 light years. Is a relative young star cluster, grouping around 2.000 stars These stars are too close together, thus gravitationally unstable. Theta 1, the more massive of this group, in a close future will explode as a supernova. And other stars of the group will follow, giving rise in a new star formation.

 

Technical data

 

Telescope : FSQ 106 ED, Camera : QSI 863

Mount  : NEQ6

Frames

Ha, O, S 10 x 300 sec's eachLum 19x300s,  RGB 9x300sec's each 

Processed   in PixinSight, Photoshop

Eubia Island, Greece, 2013-2014.