Back in 1181, there was a dramatic event in the sky that caught the attention of many. For about 185 days, a supernova explosion could be seen, lighting up the night like a temporary star in the Cassiopeia constellation.
After the supernova faded away, astronomers were eager to uncover its remnants in space. For some time, they thought the nebula 3C 58 might be the leftover from the explosion. However, upon further investigation, it was discovered that the pulsar in that area is actually older than the supernova from 1181.
Recently, in the past decade, astronomers have identified another possible candidate: Pa 30. This circular nebula with a central star located in Cassiopeia has sparked interest and curiosity among scientists.
The captivating image of Pa 30 has been put together using data from various telescopes. Different colors represent different observations: blue from the European Space Agency’s XMM-Newton telescope, cyan from NASA’s Chandra X-ray Observatory, red and pink from NASA’s Wide-field Infrared Space Explorer, green from the Hiltner telescope at the MDM Observatory in Arizona, and white from Pan-STARRS in Hawaii.
By analyzing the expansion velocity and optical spectroscopy of Pa 30, researchers are leaning towards the possibility of it being the remains of SN 1181. The age of the nebula is estimated to be around 1,000 years, which aligns with the timeline of the supernova observed 843 years ago.
The appearance of SN 1181 was documented in early August of 1181, noted in historical texts from China and Japan. This observation is significant as it is one of the few supernovae known to have been identified before the telescope was invented.
Scientists studying the chemical composition of Pa 30 believe that it was created through a thermonuclear explosion. This unique supernova event, known as a sub-luminous Type Iax event, occurs when two white dwarf stars merge. The aftermath typically does not leave a remnant, but there is a chance that a “zombie star” may remain in some cases.
NASA emphasizes the exceptional nature of Pa 30, describing it as one of the hottest stars in the Milky Way at approximately 200,000 degrees Celsius. Additionally, the star produces a swift stellar wind reaching speeds of up to 16,000 kilometers per hour. The combination of the star and nebula presents an invaluable opportunity for researchers to delve into the study of such rare explosive phenomena.