The Path from the Chinese and Japanese Observations of Supernova 1181 AD, to a Type Iax Supernova, to the Merger of CO and ONe White Dwarfs (2301.04807v2)

Abstract: In 1181 AD, Chinese and Japanese observers reported an unmoving bright Guest Star' in the constellation Chuanshe, visible for 185 days. In 2013, D. Patchick discovered what turned out to be a unique nebula surrounding a unique star, with the structure namedPa 30', while subsequent workers made connections to mergers of white dwarfs, to the supernova subclass of low-luminosity Type Iax, and to the 1181 transient. Here, I provide a wide range of new observational evidence: First, detailed analysis of the original Chinese and Japanese reports places the `Guest Star' of 1181 into a small region with the only interesting source being Pa 30. Second, the ancient records confidently place the peak magnitude as 0.0$>$$V_{\rm peak}$$>$$-$1.4, and hence peak absolute magnitude $-$14.5$>$$M_{{\rm V,peak}}$$>$$-$16.0 mag. Third, the Pa 30 central star is fading from $B$=14.9 in 1889, to $B$=16.20 in 1950, to $B$=16.58 in 2022. Fourth, recent light curves show typical variability with full-amplitude of 0.24 mag on time-scales of one day and longer, critically with no coherent modulations for periods from 0.00046--10 days to strict limits. Fifth, the spectral energy distribution from the far-infrared to the ultraviolet is a nearly-perfect power-law with $F_{\nu}\propto\nu^{0.99\pm0.07}$, observed luminosity 128$\pm$24 L${\odot}$, and absolute magnitude $M{\rm V}$=$+$1.07. I collect my new evidences with literature results to make a confident case to connect the East-Asian observations to a supernova, then to Pa 30, then to a low-luminosity Type Iax SN, then to the only possible explosion mechanism as a merger between CO and ONe white dwarfs.

• The paper demonstrates how historical astronomical records align with modern spectral and photometric data to identify SN 1181 as the progenitor of Pa 30.
• The paper employs meticulous positional and archival analysis to exclude alternative remnants such as 3C58.
• The paper supports a double-degenerate model, proposing that the merger of CO and ONe white dwarfs underlies this low-luminosity Type Iax event.

Analysis of SN 1181 and Pa 30: Tracing the Historical Supernova through Contemporary Observations

In a comprehensive analysis, Bradley E. Schaefer intricately connects historical astronomical observations to modern astrophysical theory in elucidating the origins and nature of the supernova SN 1181, verified through a rigorous set of observations and theoretical synthesis. This work not only explores historical textual evidence but also presents a robust scientific framework to demonstrate that SN 1181, a supernova witnessed nearly a millennium ago, is linked to the current astronomical objects Pa 30 and its associated Type Iax supernova classification.

Historical Context and Observational Analysis

The discourse begins with a recounting of historical records from Chinese and Japanese astronomers in 1181 AD, detailing a "Guest Star" that remained visible for 185 days with no apparent movement in the sky. Through a careful re-examination, Schaefer narrows the positional evidence, conclusively placing the "Guest Star" within a region that contains no recognized remnants apart from Pa 30, decisively excluding others like 3C58. This insistence on precision in historical astronomy reinforces the power of ancient records in delineating celestial events when cross-validated with current astronomical data.

Transition from Historical Conjecture to Supernova Remnant Identification

The discovery of Pa 30, a nebulous structure highlighted by Patchick in 2013, adds a new dimension. Subsequent analyses characterize Pa 30 as a low-luminosity Type Iax supernova remnant, evidenced by its peculiar spectral and luminosity characteristics. Schaefer's work here utilizes multi-faceted approaches, ranging from archival photometry to spectral energy distribution analysis, to establish Pa 30's characteristics: fading light curves and atypical elemental makeup predominantly constituted by non-thermal emissions, all pointing towards a supernova origin unexplained by novae or other stellar phenomena.

Characterization of SN 1181 as a Type Iax Supernova

Schaefer elaborates further by comparing the magnitude, duration, and spectral characteristics of the 1181 AD event to the contemporary framework for low-luminosity Type Iax supernovae, placing SN 1181 within the faintest decile of its class. The implications are significant; it reframes our understanding of stellar explosions by confirming the diversity within the Type Iax supernova class, especially those with luminosity and ejecta velocities markedly below typical supernova dynamics.

Nuanced Discussion on Mechanism and Remnant Nature

The paper elegantly navigates the myriad theories for Type Iax explosions, evaluating six distinct models against empirical evidence from Pa 30 and historical luminosity data. Schaefer systematically discredits incompatible models through logical inconsistencies related to ejecta mass, supernova peak luminosity, and remnant composition. His methodology permits a clear distinction between theoretical postulates, ultimately favoring a double-degenerate model involving a merger between carbon-oxygen (CO) and oxygen-neon (ONe) white dwarfs, absence of a companion being a decisive factor.

Theoretical Implications and Astrophysical Significance

The findings not only improve the specificity of supernova classification but also bear implications for the processes driving Ia and Iax supernovae, influencing our understanding of stellar evolution and end-of-life stellar dynamics. The conclusion, rooted in astronomical precision and historical acumen, fortifies the role of cross-disciplinary methods in unlocking stellar mysteries.

Looking ahead, this analysis invites further scrutiny into the variant pathways leading to supernova remnant formation, proposing a platform for future theoretical and observational campaigns to explore the complex phenomena associated with Iax events. As such, it serves as a touchstone for researchers keen on deciphering past celestial occurrences utilizing modern scientific paradigms, intertwining the past with the cosmos' present state.