SN 185

SN 185

Supernova SN 185
Combined X-ray image from Chandra and XMM-Newton of RCW 86. Low energy X-rays are in red, medium energies in green, and high energies in blue. RCW 86 is the probable remnant of SN 185.
Observation data (Epoch J2000)
Supernova type Type Ia?
Remnant type Shell
Host galaxy Milky Way
Constellation Circinus and Centaurus
Right ascension 14h 43m
Declination −62° 30′
Galactic coordinates G315.4−2.3
Discovery date December 7, 185
Peak magnitude (V) "as much as -8"[1]
Distance 2,800 pc (9,100 ly)[2]
Physical characteristics
Notable features Ancient records of SN 185
may be the earliest written
description of a supernova.

SN 185 (aka RCW 86) was a supernova which appeared in the year AD 185, near 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,[3] and might have been recorded in Roman literature.[1] It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist.

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[2] (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).[2] Recent X-ray studies show a good match for the expected age.[4]

New 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.[5]

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[5] to a distant, slow-moving comet[6] – 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),[5][7] similar therefore to Tycho's star (which had apparent magnitude −4 at a similar distance).

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.

See also


  1. ^ a b Stothers, Richard (1977). "Is the Supernova of A.D. 185 Recorded in Ancient Roman Literature?". Isis 68 (3): 443–447.  
  2. ^ a b c Völk HJ; Berezhko EG; Ksenofontov LT (2005). "Magnetic field amplification in Tycho and other shell-type supernova remnants". Astron Astrophys. 433 (1): 229–40.  
  3. ^ Zhao FY; Strom RG; Jiang SY (2006). "The Guest Star of AD185 Must Have Been a Supernova". Chinese J Astron Astrophys. 6 (5): 635–40.  
  4. ^ "New evidence links stellar remains to oldest recorded supernova". ESA News. 2006-09-18. Retrieved 2006-05-24. 
  5. ^ a b c "NASA Telescopes Help Solve Ancient Supernova Mystery". NASA. 2011-10-24. Retrieved 2011-10-25. 
  6. ^ Chin YN; Huang YL. "Identification of the Guest Star of AD 185 as a comet rather than a supernova". 
  7. ^ Brian J. Williams; et al. (October 2011). "RCW 86: A Type Ia Supernova in a Wind-blown Bubble". The Astrophysical Journal 741 (2): 96.  

External links

  • APOD, 28 September 2006
  • APOD, 10 November 2011
  • BBC News – Ancient supernova mystery solved (25 October 2011)