Counterparts of Far Eastern Guest Stars: Novae, supernovae, or something else?

Abstract

ABSTRACT Historical observations of transients are crucial for studies of their long-term evolution. This paper forms part of a series of papers in which we develop methods for the analysis of ancient data of transient events and their usability in modern science. Prior research on this subject by other authors has focused on looking for historical supernovae and our earlier work focused on cataclysmic binaries as classical novae. In this study we consider planetary nebulae, symbiotic stars, supernova remnants, and pulsars in the search fields of our test sample. We present the possibilities for these object types to flare up visually, give a global overview on their distribution, and discuss the objects in our search fields individually. To summarize our results, we provide a table of the most likely identifications of the historical sightings in our test sample and outline our method in order to apply it to further historical records in future works. Highlights of our results include a re-interpretation of two separate sightings as one supernova observation from May 667 to June 668 CE, the remnant of which could possibly be SNR G160.9+02.6. We also suggest the recurrent nova U Sco as a candidate for the appearance observed between Scorpius and Ophiuchus in 891, which could point towards a long-term variability of eruption amplitudes. In addition, we find that the ‘shiny bright’ sighting in 1431 can be linked to the symbiotic binary KT Eri, which erupted as a naked eye classical nova in 2009.