CTIO/NOIRLab/DOE/NSF
In early December 185 AD, Chinese astronomers recorded a bright “guest star” in the night sky. This star shined in the direction of Alpha Centauri for eight months before fading away. It is most likely the earliest recorded supernova in the historical record. The image above offers a rare glimpse of the entire battered remains of an old explosion, captured by the Dark Energy Camera (DECam) mounted on a 4-meter telescope at the Cerro Tololo Inter-American Observatory in the Andes Mountains. . Chile. DECam has been operational since his 2012, and was originally designed as part of the ongoing dark energy investigation, but can also be used by other astronomers for their research. This new wide-field perspective of the SN 185 remnant should help astronomers learn more about stellar evolution.
As I wrote earlier, there are two known types of supernovae, depending on the mass of the original star. Iron-collapse supernovae occur in massive stars (greater than 10 solar masses) and collapse so violently that they produce catastrophic explosions. The temperature and pressure become so high that the carbon in the star’s core fuses together. This stops the decay of the core, at least temporarily, and the process repeats itself over and over, making the nucleus progressively heavier. Eventually, when the fuel runs out completely, the iron core (by then) collapses into a black hole or neutron star.
Next is a type Ia supernova. Smaller stars (up to about eight times the mass of the Sun) cool gradually into dense cores of ash known as white dwarfs. If a white dwarf star that has run out of nuclear fuel is part of a binary star system, it can siphon matter from its partner, adding mass until its core reaches a temperature high enough for carbon fusion to occur. These are the brightest supernovae, and they shine with very consistent peak luminosity, making them invaluable “standard candles” for astronomers to determine cosmic distances.
Few valuable details about the SN185 provided in . Later Han dynasty. Astronomers suspected a connection between SN 185 and a remnant structure called RCW 86, but the event that formed RCW 86 took about 10,000 years to form the remnant structure. It has long been thought to be such a core-collapse supernova. to arrive at its present form.
In 2006, new X-ray data collected by the European Space Agency’s XMM-Newton Observatory and NASA’s Chandra X-ray Observatory showed that RCW 86 is much younger than previously thought: about 2,000. age. The authors were able to calculate how quickly the shock wave inside RCW 86 expanded. They find denser areas where the shock wave spreads more slowly, misleading astronomers into thinking the wreckage is older than it really is. Because of this, there are other regions where the shock wave is still inside the bubble and expanding rapidly.
New dating estimates have greatly strengthened the case that RCW 86 is a remnant of SN 185. remaining. A white dwarf devouring a partner in a binary system created a high-velocity wind that pushed gas and dust outward, creating a cavity before the white dwarf exploded. This allowed all the debris to spread outwards very quickly, creating the impressive shabby structures that exist today.
