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The Crab Nebula

An overview

Of the 270 known supernova remnants, the Crab Nebula is one of the more well known in popular science, originating from a violent supernova explosion first discovered by Chinese astronomer Wang Yei-te in July of 1054 AD. Yei-te reported the appearance of a “guest star” so bright that it was visible during the day for three weeks, and at night for 22 months. 


In 1731, English astronomer John Bevis rediscovered the object, which was then observed by Charles Messier in 1758 prompting the nebula’s lesser-known name, Messier 1. Located approximately 6,500 light years from Earth, the nebula cannot be seen with the naked eye but observations in different wavelengths gives rise to the beautiful colored images often published.  


The Crab Nebula is the result of a violent explosion process that signals what astronomers call “star death.” This occurs when the star runs out of fuel for the fusion process in its core that produces an outward pressure counteracting the constant inward pressure of the star’s outer shells. With the loss of outward pressure, these layers suddenly collapse inwards and produce an explosion astrophysicists call a supernova. 


Following the explosion, the original star, named SN1054 in this case, collapsed into a rapidly spinning neutron star, also known as a pulsar, which is generally roughly the size of Manhattan, New York. The pulsar is situated at the center of the nebula and ejects two beams of radiation that, while the pulsar rotates, makes it appear as if the object is pulsing 30 times per second. 


Studies of the Crab Nebula were primarily conducted by the Hubble Space Telescope. Hubble spent three months capturing 24 images that were assembled into a colorful mosaic resembling not what is visible with human eyes, but rather a kind of paint-by-number image where each color mapped to a particular element. Traces of hydrogen, neutral oxygen, doubly ionized oxygen, and sulfur have been detected across multiple wavelengths as the remains span an expanding six to eleven light-year-wide remnant of the supernova event. 


It was not until 1942 that the Crab Nebula was officially found to be related to the recorded supernova explosion of 1054. This establishment was jointly provided by Professor J. J. L. Duyvendak of Leiden University as well as astronomers N. U. Mayall and J. Oort. Due to its long history of rediscovery and inherent beauty, the Crab Nebula remains as one of the most studied celestial objects today and continues to provide valuable insight into astrophysical processes. 


Written by Amber Elinsky



REFERENCES


Hester, J. Jeff. “The Crab Nebula: An Astrophysical Chimera,” Annual Review of Astronomy and Astrophysics 46 (2008): 127-155. https://doi.org/10.1146/annurev.astro.45.051806.110608.


Hester, J. and A. Loll. “Messier 1 (The Crab Nebula),” NASA. https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-1/.

Image ref.: European Space Agency; Space Australia; dreamstime.


Mayall, N. U., and J. H. Oort. “FURTHER DATA BEARING ON THE IDENTIFICATION OF THE CRAB NEBULA WITH THE SUPERNOVA OF 1054 A. D. PART II. THE ASTRONOMICAL ASPECTS.” Publications of the Astronomical Society of the Pacific 54, no. 318 (1942): 95–104. http://www.jstor.org/stable/40670293

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