SN 1006

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SN 1006
SN 1006.jpg
SN 1006 supernova remnant
Observation data (Epoch ?)
Supernova type Type Ia (presumably)
Remnant type Shell
Host galaxy Milky Way
Constellation Lupus
Right ascension 15h 2m 8s
Declination −41° 57′
Galactic coordinates G.327.6+14.6
Discovery date May 1, 1006
April 17, 1006 (possibly)
Peak magnitude (V) −7.5[1]
Distance 7.2 thousand light-years (2.2 kpc)
Physical characteristics
Progenitor Unknown
Progenitor type Unknown
Colour (B-V) Japanese observers describe as blue-white at visible spectrum[2]
Notable features Brightest supernova in recorded history, and therefore most described of the pretelescopic era

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[3] (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,[2][4] and possibly recorded in North American petroglyphs.[5]

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").[2] 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.[2]

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 "[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".[6] 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.[3]

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.[2]

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.[5]

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.[7]

Remnant

SN 1006 remnant expansion comparison

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.[8] 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.[9] The c. 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. No associated neutron star or black hole has been found, which is the situation expected for the remnant of a Type Ia supernova (a class of explosion believed to completely disrupt its progenitor star).[10]

A survey to find surviving companions of the SN 1006 progenitor found no subgiant or giant companion stars,[11] indicating that SN 1006 probably comes from a double degenerate progenitor, that is, the merging of two white dwarf stars.[11]

Effect on Earth

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Research has suggested that Type Ia supernovae can irradiate the Earth with significant amounts of gamma-ray flux,[12] compared with the typical flux from the Sun, up to distances on the order of 1 kiloparsec. The greatest risk is to the Earth's protective ozone layer, producing effects on life and climate. While SN 1006 did not appear to have such significant effects, a signal of its outburst can be found in nitrate deposits in Antarctic ice.[13]

See also

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Burnham, Celestial Handbook, Dover, 1978, p. 1117–1122.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ The Arabic and Latin texts are in Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

Coordinates: Sky map 15h 02m 08s, −41° 57′ 00″

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