Astronomy:SN 185

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Short description: Possible supernova event
Supernova SN 185
RCW 86.jpg
Infrared images from NASA's Spitzer Space Telescope and WISE are combined with X-ray data from the Chandra X-ray Observatory and ESA's XMM-Newton Observatory in this image of RCW 86.
Spectral classType Ia?
Date7 December 185
ConstellationCircinus and Centaurus
Right ascension 14h 43m
Declination−62° 30′
Galactic coordinatesG315.4−2.3
Distance2,800 pc (9,100 ly)[1]
HostMilky Way
Notable featuresAncient records of SN 185 may be the earliest written description of a supernova.
Peak apparent magnitude"as much as -8"[2]
Preceded byNone known
Followed bySN 386

SN 185 was a transient astronomical event observed in the year AD 185, likely a supernova. The transient occurred in the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA  14h 43m Dec −62° 30′, in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han (后汉书),[3] and might have been recorded in Roman literature.[2] It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist.


The Book of Later Han gives the following description:

In the 2nd year of the epoch Zhongping [中平], the 10th month, on the day Guihai [癸亥] [December 7, Year 185], a 'guest star' appeared in the middle of the Southern Gate [南門] [an asterism consisting of ε Centauri and α Centauri], The size was half a bamboo mat. It displayed various colors, both pleasing and otherwise.[4] It gradually lessened. In the 6th month of the succeeding year it disappeared.[5]

The gaseous shell RCW 86 is probably the supernova remnant of this event and has a relatively large angular size of roughly 45 arc minutes[1] (larger than the apparent size of the full moon, which varies from 29 to 34 arc minutes). The distance to RCW 86 is estimated to be 2,800 parsecs (9,100 light-years).[1] Recent X-ray studies show a good match for the expected age.[6]

Infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (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.[7]

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[7] to a distant, slow-moving comet[8] – with correspondingly wide-ranging estimates of its apparent visual magnitude (−8 to +4). The recent Chandra results suggest that it was most likely a Type Ia supernova (a type with consistent absolute magnitude),[7][9] and therefore similar to Tycho's Supernova (SN 1572), which had apparent magnitude −4 at a similar distance.


See also


  1. 1.0 1.1 1.2 Völk HJ; Berezhko EG; Ksenofontov LT (2005). "Magnetic field amplification in Tycho and other shell-type supernova remnants". Astron. Astrophys. 433 (1): 229–40. doi:10.1051/0004-6361:20042015. Bibcode2005A&A...433..229V. 
  2. 2.0 2.1 Stothers, Richard (1977). "Is the Supernova of A.D. 185 Recorded in Ancient Roman Literature?". Isis 68 (3): 443–447. doi:10.1086/351822. 
  3. Zhao FY; Strom RG; Jiang SY (2006). "The Guest Star of AD185 Must Have Been a Supernova". Chinese Journal of Astronomy and Astrophysics 6 (5): 635–40. doi:10.1088/1009-9271/6/5/17. Bibcode2006ChJAA...6..635Z. 
  4. Ye, Fan. Book of the Later Han. 
  5. 《後漢書·卷十二·天文下》:"中平二年十月癸亥,客星出南門中,大如半筵,五色喜怒稍小,至後年六月消。占曰:‘為兵。’至六年,司隸校尉袁紹 誅滅中官,大將軍 部曲將 吳匡 攻殺 車騎將軍 何苗,死者數千人。"
  6. "New evidence links stellar remains to oldest recorded supernova". ESA News. 2006-09-18. 
  7. 7.0 7.1 7.2 "NASA Telescopes Help Solve Ancient Supernova Mystery". NASA. 2011-10-24. 
  8. Y.-N. Chin; Y.-L. Huang (29 September 1994). "Identification of the Guest Star of AD 185 as a comet rather than a supernova" (PS). Nature 371 (6496): 398–399. doi:10.1038/371398a0. Bibcode1994Natur.371..398C. 
  9. Williams, Brian J. (October 2011). "RCW 86: A Type Ia Supernova in a Wind-blown Bubble". The Astrophysical Journal 741 (2): 96. doi:10.1088/0004-637X/741/2/96. Bibcode2011ApJ...741...96W. 
  10. "Dynastic Vibes". 

External links