|
SN 1006 was a supernova, widely seen on Earth beginning in the year 1006; the Earth was about 7,200 light-years away from the supernova. It was the brightest apparent magnitude stellar event in recorded history, reaching an estimated −7.5 visual magnitude (over ten times as bright as Venus and visible during daytime). First appearing in the constellation of Lupus between April 30 and May 1, 1006, this "guest star" was described by observers in China, Japan, Iraq, Egypt, and Europe,〔〔Burnham, ''Celestial Handbook'', Dover, 1978, p. 1117–1122.〕 and possibly recorded in North American petroglyphs. ==Historic description== The Egyptian Arabic astrologer and astronomer Ali ibn Ridwan, writing in a commentary on Ptolemy's ''Tetrabiblos'', stated that the "spectacle was a large circular body, 2½ to 3 times as large as Venus. The sky was shining because of its light. The intensity of its light was a little more than a quarter that of Moon light" (or perhaps "than the light of the Moon when one-quarter illuminated"). Like all other observers, Ali ibn Ridwan noted that the new star was low on the southern horizon. Some astrologers interpreted the event as a portent of plague and famine.〔 The most northerly sighting is recorded in the annals of the Abbey of Saint Gall (in what is now Switzerland), at a latitude of 47.5° N. Monks at Saint Gall provide independent data as to its magnitude and location in the sky, writing that "()n a wonderful manner this was sometimes contracted, sometimes diffused, and moreover sometimes extinguished....It was seen likewise for three months in the inmost limits of the south, beyond all the constellations which are seen in the sky".〔The Arabic and Latin texts are in 〕 This description is often taken as probable evidence 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.〔 According to ''Songshi'', the official history of the Song Dynasty (sections 56 and 461), the star seen on 1 May 1006 appeared to the south of constellation Di, east of Lupus and one degree to the west of Centaurus. The size of the visual explosion was half that of the moon, and shone so brightly that objects on the ground could be seen at night. By December, it was again sighted in the constellation Di. 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, yellow in color and brilliant in its brightness, that would bring great prosperity to the state over which it appeared. The reported color yellow should be taken with some suspicion however, because Zhou may have chosen a favorable color for political reasons.〔 There appear to have been two distinct phases in the early evolution of this 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. A petroglyph by the Hohokam in White Tank Mountain Regional Park, Maricopa County, Arizona, has been interpreted as the first known North American representation of the supernova.〔 On August 25, 2015, a recently found document suggested that observers in Yemen may have seen SN 1006 on April 17, two weeks before its previously assumed earliest observation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「SN 1006」の詳細全文を読む スポンサード リンク
|