| 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. |
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| 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 | |
| Progenitor | ? |
| Progenitor type | ? |
| Colour (B-V) | ? |
| Notable features | Ancient records of SN 185 may be the earliest written description of a supernova. |
SN 185 was a supernova which appeared in the year 185 AD, 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 may have been recorded in Roman literature.[1] 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 86 is suspected as being the supernova remnant of this event and has a relatively large angular size of roughly 45 arcmin[2] (larger than the moon [29-34 arcmin] as seen from Earth). The distance to this object 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, 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.[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).
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