m1 – The crab nebula
Lupe Rioné, Amateur astronomer (Spain)
Type
supernova remnant
Location
Constellation of Taurus
Distance
6.300 light-years
Size
10-11 light-years
Supernova remnant: results from a supernova explosion. With intense radio frequencies, they disappear as cosmic dust expands, leaving behind a neutron star, pulsar, or a black hole, depending on the mass of the star.
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History and discovery
M1 is the remnant of a supernova explosion that was observed by Chinese astronomers during the Song Dynasty in the 11th century. It is estimated that this explosion occurred between July and August of 1054 or 1056. Later, the remnant of this explosion was identified in 1731 by the amateur astronomer John Bevis, but it was Chales Messier who rediscovered it while observing a comet (1758 of the Nux). He proved that it was not moving and concluded that it was a nebula. Messier measured its position on September 12, 1758. Years later, in 1774, it was his first entry in his famous “Catalog of Nebulae and Star Clusters”.
Compiste image of M1. It uses data from three NASA observatories. The X-ray image (Chandra) is shown in blue (center of image). The optical image (Hubble) is shown in green and dark blue. The infrared image (Spitzer) in red.
This is the largest image ever taken by the Hubble Space Telescope camera. It is a set of 24 individual exposures. Credits: NASA /ESA/Hubble. J.Hester, A.Loll (ASU)
Lord Roose called the nebula the “Crab” in 1844 because of its peculiar structure. Since then, it has been an object of fascination for many astronomers and amateurs. In 1939, astronomer John Duncan determined that the nebula was expanding and probably originated from a single point. Later, astronomer Walter Baade observed in 1942 that a prominent star near the center of the nebula could be related to its origin. Scientists discovered six years later that M1 was emitting the most intense waves that any other celestial object had ever emitted. In 1954, Baade noted that M1 has outstanding magnetic fields, and in 1963, high-energy X-rays were discovered coming from the nebula.
Structure and composition
This nebula has material ejected by a supernova. The gas clouds were dispersed at a distance of approximately 10- 11 light years. The gas continues expanding at a speed of 18,000 km/s. This material is in the form of visible filaments and is composed mainly of helium and ionized hydrogen, accompanied by oxygen, carbon, iron, nitrogen, sulfur and neon. These filaments have a temperature between 11,000 and 18,000 k. And their density is based on about 1,300 particles per cubic centimeter!
Detail of the M1 filamentary structures. Credits: NASA/ESA/& The Hubble Heritage. Team (STcl)/ AURA.
Composite image. Hubble (blue) and Herschel Space Telescope (pink). Credit: ESA/HERSCHEL NASA/ ESA A. Loll and J. Hester
The supernova
In fact, the heart of this nebula houses 2 stars. However, they are not visible because the gas filaments are in the foreground. One of them is responsible for the nebula we see today. It is a star known as the Crab Pulsar or CM tau. This small, dense body is the result of the original star that caused the supernova.
A pulsar is the result of an explosion of a massive star, a dozen times the mass of the Sun. These celestial bodies emit strong electromagnetic radiation and rotate on their axis at high speeds per second.
This pulsar is about 20 km in diameter and rotates around its axis at about 30 revolutions per second, but the frequency of the pulses decreases regularly, which means that the rotation of the pulsar slows down regularly. The Crab Pulsar emits pulses of radiation at all wavelengths, from gamma rays to radio waves. The radiation from this star is so strong that it is creating a wave of matter that is simultaneously deforming the inner parts of the nebula. This provides an exceptional opportunity to observe changes of this type, since cosmic scenes of this magnitude, in time, are usually much longer.
It is frankly extraordinary that it has been possible to follow the whole process of the death of the star from the beginning to the present time, becoming a pulsar (neutron star) and creating this wonderful nebula. There is still a lot of research to be done on this spectacular phenomenon of pulsars.
Widefield photography. Credits: Manu Mejias.
M1 can be located in the Perseus arm (Milky Way). And from our position in the constellation of Taurus (Taurus) that is why it is also called Taurus A.
Somewhere, something incredible is waiting to be known
Carl Sagan
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