SN 185
SN 185 was a 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...

 which appeared in the year 185 AD, near the direction of Alpha Centauri
Alpha Centauri
Alpha Centauri is the brightest star in the southern constellation of Centaurus...

, between the constellations Circinus
The constellation Circinus is a small constellation in the southern sky, first defined in the 18th century. Its name is Latin for compass, referring to the drafting tool used for drawing circles; it should not be confused with Pyxis, a constellation that represents a mariner's...

 and 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:...

, centered at RA
Right ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...

In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...

 , in Circinus. This "guest star" was observed by Chinese astronomers
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."...

 in the Book of Later Han
Book of Later Han
The Book of the Later Han or the History of the Later Han is one of the official Chinese historical works which was compiled by Fan Ye in the 5th century, using a number of earlier histories and documents as sources...

, and may have been recorded in Roman
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 literature. It remained visible in the night sky for eight months. This is believed to have been the first supernova recorded by humankind.

The gaseous shell RCW
RCW Catalogue
The RCW Catalogue is an Astronomical catalogue of Hα-emission regions in the southern Milky Way, described in . It has 180 objects and includes many of the earlier Gum Catalog objects, and the later Caldwell catalogue included some RCW...

 86 is suspected as being the 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...

 of this event and has a relatively large angular size of roughly 45 arcmin (larger than the moon [29-34 arcmin] as seen from Earth). The distance to this object is estimated to be 2800 parsec. Recent X-ray studies show a good match for the expected age. >

New infrared observations from NASA's Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...

 and Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer is a NASA infrared-wavelength astronomical space telescope launched on December 14, 2009, and decommissioned/hibernated on February 17, 2011 when its transmitter was turned off...

, or WISE, reveal how the supernova occurred and how its shattered remains ultimately spread out to great distances. The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.

Differing modern interpretations of the Chinese records of the guest star have led to quite different suggestions for the astronomical mechanism behind the event, from a core-collapse supernova to a distant, slow-moving comet – with correspondingly wide-ranging estimates of its apparent visual magnitude (−8 to +4). The recent Chandra
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...

 results suggest that it was most likely a Type Ia supernova (a type with consistent absolute magnitude), similar therefore to Tycho's star
SN 1572
SN 1572 , "B Cassiopeiae" , or 3C 10 was a supernova of Type Ia in the constellation Cassiopeia, one of about eight supernovae visible to the naked eye in historical records...

 (which had apparent magnitude −4 at a similar distance).

See also

External References

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