SN 1006 was a supernova, widely seen on Earth beginning in the year 1006 AD; 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.[2] First appearing in the constellation of Lupus between April 30 and May 1 of that year, this "guest star" was described by observers in China, Egypt, Iraq, Japan, Switzerland, and possibly North America.[citation needed]
Chinese and Arab astronomers provide the most complete historical descriptions of this supernova. 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, 2-1/2 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." Like all other observers, Ali ibn Ridwan noted that the new star was low on the southern horizon. Monks at the Benedictine abbey at St. Gallen provide independent data as to its magnitude and location in the sky, writing that "[i]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".[3] This description is often taken as anecdotal 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, 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."[2] The reports from Switzerland are particularly noteworthy, as the supernova would have been very low in the sky there, rising to at most 5 degrees above the southern horizon and being visible for only 4–5 hours at a time. Atmospheric extinction and the need to find a site with a clear southern horizon make seeing even bright objects this low difficult; the "sometimes contracted, diffused, extinguished" remarks quoted above hint at atmospheric effects caused by the low apparent altitude of the object. 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. 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. Most astrologers interpreted the event as a portent of warfare and famine. 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.[4] Remnant The associated supernova remnant from this explosion was not identified until 1965, when Doug Milne and Frank Gardner used the Parkes radio telescope to demonstrate that the previously known radio source PKS 1459-41, near the star Beta Lupi, had the appearance of a 30-arcminute circular shell.[5] Over the next few years, both X-ray and optical emission from this remnant were also detected, and in 2010 the H.E.S.S. gamma-ray observatory announced the detection of very-high-energy gamma-ray emission from the remnant.[6] The ~0.5° diameter remnant of SN 1006 lies at an estimated distance of 2.2 kiloparsecs from Earth, making its linear diameter approximately 20 parsecs. As expected for the remnant of a Type Ia supernova, no associated neutron star or black hole has been found. See also List of supernovae References ^ Winkler, P. Frank; Gupta, Gaurav; Long, Knox S. (2003). "The SN 1006 Remnant: Optical Proper Motions, Deep Imaging, Distance, and Brightness at Maximum". The Astrophysical Journal 585 (1): 324–335. arXiv:astro-ph/0208415. Bibcode 2003ApJ...585..324W. doi:10.1086/345985. External links
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