In the annals of astronomical history, the enigmatic supernova SN 1181 has long captivated the imagination of scholars and stargazers alike. This celestial event, which blazed in the sky for six months during the year 1181, was chronicled in ancient Chinese and Japanese records as a “guest star.” Now, a groundbreaking study has shed new light on this historical supernova, revealing its astonishing aftermath: a so-called "zombie star."
SN 1181, one of the few supernovas recorded before the advent of modern telescopes, had puzzled scientists for centuries due to the lack of confirmed remnants. Recent research, however, has produced a detailed computerized model tracing the supernova’s evolution from its initial explosion to the present day. This study, published in The Astrophysical Journal, has provided compelling evidence that SN 1181 is a member of the rare Type Iax supernovae, a category characterized by its incomplete detonation and the presence of a residual white dwarf star.
The term “zombie star” refers to the intriguing white dwarf that remains at the center of the SN 1181 nebula. Unlike typical supernova remnants, this star, located approximately 7,000 light-years from Earth, has survived despite the cataclysmic explosion that should have obliterated it. The white dwarf at SN 1181’s core is notably devoid of hydrogen and helium, a stark anomaly given that these elements constitute the bulk of the universe. This unusual composition suggests that the star’s life cycle involved extraordinary cosmic events.
Albert Zijlstra, an astrophysics professor at the University of Manchester, was instrumental in pinpointing the supernova’s location within the Milky Way. His work, which followed the discovery of the nebula by amateur astronomer Dana Patchick, confirmed that SN 1181’s remnant nebula matched historical records from ancient China. Zijlstra’s research revealed that the nebula is not only a remnant of SN 1181 but also a vital clue in understanding this rare type of supernova.
In a surprising twist, recent observations have detected high-speed stellar winds emanating from the white dwarf, which began around 20 years ago. This phenomenon is perplexing because such winds are typically a by-product of a white dwarf’s rapid spinning immediately following a supernova explosion. The study suggests that this renewed activity might be due to the incomplete nature of SN 1181’s explosion, with material that was ejected not fully escaping the gravitational pull of the white dwarf.
The investigation into SN 1181's peculiarities also involves detailed analyses from instruments such as the European Space Agency's XMM-Newton telescope and NASA’s Chandra X-ray Observatory. These observations have identified two distinct shock regions within the nebula: an outer shock from the initial explosion and a more recent inner shock that may indicate renewed stellar activity. This aspect of the study remains unresolved, as the expected correlation between the star's dimming and the onset of stellar wind is not entirely clear.
Future observations using the Very Large Array of radio telescopes in New Mexico and the Subaru Telescope in Hawaii are planned to further unravel the mysteries of SN 1181. These studies are anticipated to enhance our understanding of supernova mechanics and their role in the cosmic ecosystem, including the formation of new stars and planetary systems.
In essence, SN 1181 provides a rare and invaluable opportunity to study a Type Iax supernova, a class that comprises about 20% of supernovae in our galaxy and potentially contributes significantly to the dust in the early universe. The research into SN 1181 not only enriches our comprehension of these stellar explosions but also offers insights into the elemental processes that shape the cosmos.
