SN 1054 - Importance in The Development of Modern Astronomy

Importance in The Development of Modern Astronomy

SN 1054 has been involved several times, sometimes fortuitously, in the history of astronomy.

Its remnant, the Crab Nebula, was one of the first to be discovered in 1731 by John Bevis.

In 1757, Alexis Clairaut reexamined the calculations of Edmund Halley and predicted the return of Halley's comet in late 1758 (more precisely, he predicted it would pass the perihelion in Spring 1759, with the start of its period of visibility some months earlier). It is in searching in vain for the comet that Charles Messier found the Crab nebula, which he at first thought to be Halley's comet. After some observation, noticing that the object that he was observing was not moving across the sky, Messier concluded that the object was not a comet. Messier then realised the usefulness of compiling a catalogue of celestial objects of a cloudy nature, but fixed in the sky, to avoid incorrectly cataloging them as comets.

William Herschel observed the Crab nebula numerous times between 1783 and 1809, but we do not know whether he was aware of its existence in 1783, or if he discovered it independently of Messier and Bevis. After several observations, he concluded that it was composed of a group of stars.

In 1844, William Parsons was the first to sketch the cloud, which he named the "Crab Nebula" from 1848. Although the appearance of the drawing is more suggestive of an insect than a crustacean, the epithet "crab" was quickly accepted.

In 1913, when Vesto Slipher registered his spectroscopy study of the sky, the Crab nebula was again one of the first objects to be studied. The American astronomer noticed its unique characteristics immediately.

Changes in the cloud, suggesting its small extent, were discovered by Carl Lampland in 1921. That same year, John Charles Duncan demonstrated that the remnant is expanding, while Knut Lundmark noted its proximity to the guest star of 1054, but did not mention the comments of his two colleagues.

In 1928, Edwin Hubble proposed associating the cloud to the star of 1054 (see above), an idea which remained confidential until the nature of supernovae was understood, and it was Nicholas Mayall who indicated that the star of 1054 was undoubtedly the supernova whose explosion produced the Crab Nebula. The search for historical supernovae started at that moment: seven other historical sightings have been found by comparing modern observations of supernova remnants with astronomical documents of past centuries. The oldest historical supernova sighting identified, SN 185, dates from the end of the 2nd century AD.

In the 1960s, due to the prediction and discovery of pulsars, the Crab nebula again became a major centre of interest. It was then that Franco Pacini predicted the existence of a neutron star for the first time, which would explain the brightness of the cloud. This neutron star was observed shortly afterwards in 1968, a shining confirmation of the theory of the formation of these objects at the time of certain supernovae. The discovery of the Crab pulsar, and the knowledge of its exact age (almost to the day) allows for the verification of basic physical properties of these objects, such as characteristic age and spin-down luminosity, the orders of magnitude involved (notably the strength of the magnetic field), along with various aspects related to the dynamics of the remnant. The particular role of this supernova to the scientific understanding of supernova remnants was crucial, as no other historical supernova created a pulsar whose precise age we can know for certain. The only possible exception to this rule would be SN 1181 whose supposed remnant, 3C58, is home to a pulsar, but its identification using Chinese observations from 1181 is sometimes contested.