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Veil Nebula (NGC 6995) & De Mairan's Nebula (M 43)
Trevor Krause & Sophia Bryson

NGC 6995 M 43
Veil Nebula - Trevor Krause De Mairan's Nebula - Sophia Bryson

Nebulae are vast, interstellar clouds composed of ionized gases. The majority of their composition is hydrogen and helium and the energy to ionize these gases can come from a number of sources: gravitational collapse, supernova explosions, and radiation from the death of a low mass star can all lead to the formation of a nebula, the characteristics of which will differ based on the means and conditions of formation.  Many nebulae a stellar nurseries, regions characterized by star formation, resulting from the accumulation and conglomeration of gas, dust, and other materials from within the nebula. The bright colors and intriguing shapes of nebulae have made them the common target of observation for centuries since the discovery of the Orion Nebula, one of the most prominent and visible objects of this kind, in 1610. Despite the intriguing appearance of many nebulae, others are not able to be detected without special filters and a long exposure time due to their highly diffuse nature.

A diffuse nebula is a large cloud of dust, hydrogen, helium, and several other gasses that lacks any defined boundary. The material we see in the Veil Nebula, also known as NGC 6995, came from the remainders of an exploding nearby star, known as a supernova.The supernova that created this area of dust and gas blew up about 8,000 years ago and was so massive that its material covers a distance of 110 light years and is 1,470 light years from earth. This nebula was first discovered on September 5, 1784 by William Herschel as part of the constellation Cygnus. Because the Veil Nebula is so bright and close to the earth, it is a very common object for young observers to examine and explore.

De Mairan’s Nebula, also classified as Messier 43, is one of the nearest massive star formation regions, situated at a distance of approximately 1,400 light years from Earth and possessing an apparent magnitude of 9.0. Along with a number of other nebulae, it makes up the Orion molecular cloud complex, a stellar nursery located within the Orion constellation. An H II region, it is composed of ionized hydrogen which will gradually dissipate from stellar winds and supernova explosions from the stars forming within it. The vicinity and activity of this region have made M 43 an object of particular interest for observation by the Hubble Space Telescope, which has been able to observe the formation of young stars and the impacts of stellar winds on these gaseous clouds, among other phenomena and objects.  Yet observation of the De Mairan’s Nebula has not been limited to the relatively recent work via the Hubble Space Telescope: it was first discovered and noted in 1731 by the French astronomer Jean-Jacques d’Ortous de Mairan and subsequently cataloged by Charles Messier in 1769. Each of these astronomers contextualized M 43 by its vicinity to the Orion Nebula (Messier 42), the larger star forming nebula along with which is composes part of the Orion Molecular Cloud Complex, located in the Orion constellation. De Mairan’s Nebula’s relative vicinity and apparent size make it observable with small telescopes or even binoculars, though greater detail is visible with the use of more powerful telescopes.

Both the De Mairan’s Nebula and the Veil Nebula are both clouds of hot, ionized gas which have been described as having the appearance of rope-like filaments of gas. They share common tones of red, blue, and purple, the result of heating the dust and gas that they contain. The dust and gas that these nebulae contain both came from emissions. Emission nebulae emit their own light and are composed of ionized hydrogen that are gradually dissipating via the solar winds. Both nebulae are also close in their relative distance to the earth as well as their relation to a constellation. M 43 is located just under Orion’s Belt, while the Veil Nebula is located in the Cygnus constellation. This makes both very easy and desirable to observe because you do not need expensive equipment to see them. One final similarity between the two nebulae is that both were discovered and catalogued within 15 years of each other and without use of modern day telescopes. Both were discovered in the vicinity of bright stars that made it easier to see the colors of reflected gas and dust.

However, these two objects differ in a number of substantial ways: De Mairan’s Nebula is a H II region, forming out of the collapse of a giant molecular cloud under the influence of shockwaves, while the Veil Nebula is a diffuse nebula that remained following a supernova collapse. They differ in both apparent magnitude and visibility, with De Mairan’s Nebula having a magnitude of 9 and being far more visible due to both brightness and composition. The Veil Nebula, while closer by approximately 200 light years, only has a magnitude of 7, and requires the use of an OIII filter to be clearly visible due to the area over which it is spread. The shape of the Veil Nebula is long and thin, a curved sliver, compared to the terminated circular shape of the De Mairan’s Nebula. The two objects also differ in activity: while the Veil Nebula is the slowly cooling remnant of a Supernova explosion that is continuing to expand, the De Mairan’s Nebula is a H II region where new stars form.  Despite their shared classification as nebulae, these objects are significantly different from one another. 


References:

"H II regions." Wikipedia 12 Oct. 2016, https://en.wikipedia.org/wiki/H_II_region. Accessed 28 Nov. 2016.

"Messier 43: De Mairan’s Nebula." Messier Objects 15 May 2015, www.messier-objects.com/messier-43- de-mairans-nebula/. Accessed 14 Nov. 2016.

"Messier 43." Wikipedia 26 June 2016, https://en.wikipedia.org/wiki/Messier_43. Accessed 14 Nov. 2016.

"Nebula." Wikipedia 22 Nov. 2016,  https://en.wikipedia.org/wiki/Nebula#Diffuse_nebulae  Accessed 27 Nov. 2016.

"Orion’s lesser-known nebula takes centre stage." Hubble Space Telescope, ESA, https://www.spacetelescope.org/images/potw1109a/. Accessed 14 Nov. 2016.

“Veil Nebula.” Wikipedia

“Veil Nebula Supernova Remnant.” Nasa 24 September 2015, https://www.nasa.gov/image-feature/veil-nebula-supernova-remnant. Accessed 14 Nov. 2016.

 

Object Veil Nebula De Mairan's Nebula
Right Ascension (J2000) 20:57:06 05:35:36
Declination (J2000) +31:12:60 -05:16:00
Filters used B (Blue), C (Clear), R (Red), V (Green) B (Blue), V (Green), R (Red), and C (Clear)
Exposure time per filter B (180s x 2), V (180s), R (240s); C (180s x 2) B (20s), V (10s), R (5s), C (2s)
Image dimension 870x644 pixels; 18.85x13.95 arcminutes 719x545 pixels; 15.6x11.8 arcminutes
Date/time observed October 07, 2016, 13:32 UT October 19, 2016, 12:08 UT

 

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