SN 1006

SN 1006 was a Supernova that occured in the year 1006 AD. It was the highest relative magnitude stellar event in recorded history. First appearing in the constellation of Lupus between April 30 and May 1 of that year, this "guest star" was described by observers in Switzerland, Egypt, Iraq, China, Japan, and possibly North America.

Historic description

The Chinese has left us the most complete historical description of the supernova. According to Songshi in the section of 56 and 461, the star was seen on May 1, 1006 which appeared to the south of constellation Di, east of Lupus and one degree to the west of Centaurus. It was equal to that of half a moon and shone so brightly that the objects on ground could be seen at night. During the September, it went below the horizon following the rotation of the heavens. By the December, it was again sighted at the constellation Di. It is worth noting that the Chinese astrologer Zhou Keming who was on his return to Kaifeng from his duty in Guangdong interpreted the star to the emperor on May 30 as an auspicious star, which is yellow in its colour and brilliant in its brightness, and would bring great prosperity to the state over which it appeared.

The Egyptian astrologer Ali bin Ridwan, writing in a commentary on Ptolemy's Tetrabiblos, has left us some historical description of the supernova. He says that the object was 2-1/2 to three times as large as the disc of Venus, and about one-quarter the brightness of the Moon, and, like all other observers, says that the star was low on the southern horizon. Monks at the Benedictine abbey at St. Gall broadly corroborate bin Ridwan's observations as to magnitude and location in the sky, additionally writing that "^*n a wonderful manner this was sometimes contracted, sometimes diffused, and moreover sometimes extinguished." This last is often taken as proof that the supernova was of Type Ia. Some sources state that the star was bright enough to cast shadows; it was certainly seen during daylight hours for some time, and the modern-day astronomer Frank Winkler has said that "in the spring of 1006, people could probably have read manuscripts at midnight by its light."

There appear to have been two distinct phases to the observation of the supernova. There was first a three-month period at which it was at its brightest; after this period it diminished, then returned for a period of about eighteen months. While most astrologers interpreted the event as a portent of warfare and famine.

A petroglyph of the Hohokam has been discovered which may be the first known North American representation of the supernova.^*

Remnant as seen by modern Astronomy

The supernova has left as its remnant a faint, shell-type distorted nebula, but it was well into the era of radio astronomy before it was found. In 1965, Douglas K. Milne and F. F. Gardner discovered a 30-arcsecond circular expansion shell in the radio portion of the spectrum near Beta Lupi, and by 1976, both X-ray and optical components had been found as well. The expansion wave has most recently been understood to be 2.2 kiloparsecs distant, approximately 20 parsecs in diameter, expanding at some 2,800 km/s, and has come to be called PKS 1459-41 in all wavelength bands. As expected in the remnant of a Type Ia supernova, no pulsar or black hole has been found at the center of the nebula.

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Historic description

Remnant as seen by modern Astronomy

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