2017/08/03 by Hisashi Hayakawa, Kiyomi Iwahashi, Harufumi Tamazawa +5
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Geomagnetism and Paleomagnetism Studies #Historical Astronomy and Related Studies #Historical record #Latitude #Solar and Space Plasma Dynamics #Solar cycle #Solar minimum #Solar physics #Sunspot #Sunspot number #astro-ph.SR #physics.hist-ph #physics.space-ph
paper · pdf · doi:10.1093/pasj/psx087
2017/08/02 accepted for publication in PASJ
arxiv created 2017/08/03 · openalex created_date 2017/08/17 · openalex publication_date 2017/10/15 · arxiv updated 2017/12/20 · openalex updated_date 2026/08/05
Abstract We present the results of the surveys on sunspots and auroral candidates in Rikkokushi, Japanese official histories from the early 7th century to 887, to review the solar and auroral activities. In total, we found one sunspot record and 13 auroral candidates in Rikkokushi. We then examine the records of the sunspots and auroral candidates, compare the auroral candidates with the lunar phase to estimate their reliability, and compare the records of the sunspots and auroral candidates with the contemporary total solar irradiance reconstructed from radioisotope data. We also identify the locations of the observational sites to review possible equatorward expansion of the auroral oval. These discussions suggest a major gap in auroral candidates from the late 7th to early 9th centuries, which includes the candidate of the grand minimum reconstructed from the radioisotope data, a similar tendency as the distributions of sunspot records in contemporary China, and a relatively high magnetic latitude of observational sites with a higher potential for observing aurorae more frequently than at present.