SN 1006
Encyclopedia
SN 1006 was a supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

, 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
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 stellar event in recorded history reaching an estimated -7.5 visual magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

. First appearing in the constellation of Lupus
Lupus (constellation)
Lupus is a constellation in the southern sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations...

 between April 30 and May 1 of that year, this "guest star" was described by observers in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

, Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

, and possibly North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.

Historic description

Chinese
Chinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...

 and Arab astronomers
Islamic astronomy
Islamic astronomy or Arabic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age , and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and...

 provide the most complete historical descriptions of this supernova.

The Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

ian Arabic astrologer and astronomer Ali ibn Ridwan
Ali ibn Ridwan
Abu'l Hasan Ali ibn Ridwan Al-Misri was an Egyptian Muslim physician, astrologer and astronomer, born in Giza.He was a commentator on ancient Greek medicine, and in particular on Galen; his commentary on Galen's Ars Parva was translated by Gerardo Cremonese...

, writing in a commentary on Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

's Tetrabiblos, stated that the "...spectacle was a large circular body, 2-1/2 to 3 times as large as Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

. The sky was shining because of its light. The intensity of its light was a little more than a quarter that of Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 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". This description is often taken as anecdotal evidence that the supernova was of Type Ia
Type Ia supernova
A Type Ia supernova is a sub-category of supernovae, which in turn are a sub-category of cataclysmic variable stars, that results from the violent explosion of a white dwarf star. A white dwarf is the remnant of a star that has completed its normal life cycle and has ceased nuclear fusion...

. 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
Frank Winkler
P. Frank Winkler is an astronomer and noted subject matter expert on supernova. He received his doctorate from Harvard and is currently the Gamaliel Painter Bicentennial Professor in Physics at Middlebury College located in Middlebury, Vermont.Dr...

 has said that "in the spring of 1006, people could probably have read manuscripts at midnight by its light."

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
Extinction (astronomy)
Extinction is a term used in astronomy to describe the absorption and scattering of electromagnetic radiation by matter between an emitting astronomical object and the observer. Interstellar extinction—also called Galactic extinction, when it occurs in the Milky Way—was first...

 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
Root (Chinese constellation)
The Root mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the eastern mansions of the Azure Dragon.-Asterisms:...

, east of Lupus
Lupus (constellation)
Lupus is a constellation in the southern sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations...

 and one degree to the west of Centaurus
Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...

. 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
Astrologer
An astrologer practices one or more forms of astrology. Typically an astrologer draws a horoscope for the time of an event, such as a person's birth, and interprets celestial points and their placements at the time of the event to better understand someone, determine the auspiciousness of an...

 Zhou Keming, who was on his return to Kaifeng
Kaifeng
Kaifeng , known previously by several names , is a prefecture-level city in east-central Henan province, Central China. Nearly 5 million people live in the metropolitan area...

 from his duty in Guangdong
Guangdong
Guangdong is a province on the South China Sea coast of the People's Republic of China. The province was previously often written with the alternative English name Kwangtung Province...

, 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
Petroglyph
Petroglyphs are pictogram and logogram images created by removing part of a rock surface by incising, picking, carving, and abrading. Outside North America, scholars often use terms such as "carving", "engraving", or other descriptions of the technique to refer to such images...

 by the Hohokam
Hohokam
Hohokam is one of the four major prehistoric archaeological Oasisamerica traditions of what is now the American Southwest. Many local residents put the accent on the first syllable . Variant spellings in current, official usage include Hobokam, Huhugam and Huhukam...

 in White Tank Mountain Regional Park
White Tank Mountain Regional Park
The White Tank Mountain Regional Park is a large regional park located in west-central Maricopa County, Arizona. Encompassing of desert and mountain landscape, it is the largest regional park in the county...

 Maricopa County, Arizona, has been interpreted as the first known North American representation of the supernova.

Remnant

The associated supernova remnant
Supernova remnant
A supernova remnant is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way.There are two...

 from this explosion was not identified until 1965, when Doug Milne and Frank Gardner used the Parkes radio telescope
Parkes Observatory
The Parkes Observatory is a radio telescope observatory, 20 kilometres north of the town of Parkes, New South Wales, Australia. It was one of several radio antennas used to receive live, televised images of the Apollo 11 moon landing on 20 July 1969....

 to demonstrate that the previously known radio source PKS 1459-41, near the star Beta Lupi
Beta Lupi
Beta Lupi is a B-type, 3rd-magnitude star in the constellation Lupus.In Chinese, , meaning Imperial Guards, refers to an asterism consisting of β Lupi, γ Lupi, δ Lupi, κ Centauri, λ Lupi, ε Lupi, μ Lup, π Lupi, ο Lupi and α Lupi. Consequently, β Lupi itself is known as...

, had the appearance of a 30-arcminute circular shell. 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.
High Energy Stereoscopic System
High Energy Stereoscopic System or H.E.S.S. is a next-generation system of Imaging Atmospheric Cherenkov Telescopes for the investigation of cosmic gamma rays in the 100 GeV and TeV energy range...

 gamma-ray observatory
Gamma-ray astronomy
Gamma-ray astronomy is the astronomical study of the cosmos with gamma rays. Gamma-rays are the most energetic form of "light" that travel across the universe, and gamma-rays thus have the smallest wavelength of any wave in the electromagnetic spectrum.Gamma-rays are created by celestial events...

 announced the detection of very-high-energy gamma-ray
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...

 emission from the remnant. The ~0.5° diameter remnant
Supernova remnant
A supernova remnant is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way.There are two...

 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
Type Ia supernova
A Type Ia supernova is a sub-category of supernovae, which in turn are a sub-category of cataclysmic variable stars, that results from the violent explosion of a white dwarf star. A white dwarf is the remnant of a star that has completed its normal life cycle and has ceased nuclear fusion...

, no associated neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

 or black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...

 has been found.

See also


External links

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