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Astr111 Photography Projects, Spring 2007

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M43 (NGC 1982) , Eric Van Doren


The colorful spherical area surrounding the bright star in the center is approximately 5 arc minutes across. It actual linear size is approximately 2.3 light-years across.

M43, or the “De Mairan” Nebula was discovered in 1731 by Jean-Jacques Dortous de Mairan.  It is actually a part of the M42 Nebula complex, but separated by a turbulent  dark lane known as the “Fishes mouth”.  When first discovered, De Mairan described it as, "brilliance surrounding a star" which he thought was "very similar to the atmosphere of our Sun, if it were dense enough and extensive enough to be visible in telescopes at a similar distance."

The gas of the M43 Nebula surrounds the star NU Orionis, (HD 37061). This star creates a matter bound Stromgren sphere, or in simpler terms, a sphere of ionized gas. The size of this sphere is determined the density of the gas that surrounds the star. In the case of M43 the gas sphere consists of hydrogen gas, which in turn gives it the lightish red color. The visible color of M43 is caused by the ultraviolet radiation emitted by NU Orionis. The Ultraviolet radiation strips the Hydrogen its electron, thus ionizing the gas. Eventually the electron taken from the hydrogen atom is released and returned to it original stable position, causing the gas to emit all of the colors it is capable of, primarily the lightish red that we see in the Nebula. M43 is approximately 1500 light-years away from its larger neighbor, the Orion Nebula, with an angular separation of 11 arc minutes.







Right Ascension (J2000) 05'35'36
Declination (J2000) -05'16'00
Filters used blue(B), green(V), red(R)
Exposure time per filter 60 seconds in B, 30 seconds in V and R
Date observed

3/01/07 (BVR)