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Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination

Stephenson, F. Richard; Willis, David M.; Hayakawa, Hisashi; Ebihara, Yusuke; Scott, Christopher J.; Wilkinson, Julia; Wild, Matthew N.

Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination Thumbnail


Authors

F. Richard Stephenson

David M. Willis

Hisashi Hayakawa

Yusuke Ebihara

Christopher J. Scott

Julia Wilkinson

Matthew N. Wild



Abstract

The enhancement of carbon-14 in tree rings around AD 774/775 has generated wide interest in solar activity at that time. The historical auroral records have been examined critically. Of particular interest was the “white vapour” observed in China on AD 776 January 12/13. Both Usoskin et al. (Astron. Astrophys.55, L3, 2013; U13) and Stephenson (Adv. Space Res.55, 1537, 2015; S15) interpreted this record as an auroral display. Subsequently, Neuhäuser and Neuhäuser (Astron. Nachr.336, 225, 2015; NN15) proposed five “criteria” for the likeliness of aurorae and on this basis rejected an auroral interpretation. Instead, they interpreted it as a lunar halo, and suggested there were no auroral records as a proxy of solar activity in the interval AD 774 – 785. We consider if their “lunar halo hypothesis” and their auroral criteria could be of use in future researches on historical auroral candidates. We first show a counter-example for the lunar halo hypothesis from a parallel record on 1882 November 17, which was seen as a whitish colour, in the southerly direction, and near the Moon. We then consider NN15’s criteria on colour, direction, and sky brightness and investigate other counter-examples from early-modern auroral observations. We also consider the extension of the white vapour in AD 776 according to the distribution of Chinese asterisms, and show that its large extension was inconsistent with the lunar halo hypothesis. Conversely, the streaks of white vapour penetrating the eight Chinese asterisms can be reproduced if we consider auroral-ray structures at altitudes between 97 km and 170 km, along geomagnetic field lines between the L -shells L=1.55 and 1.64. Our investigations show that we should consider candidate auroral records in historical documents not on the basis of the newly suggested a priori criteria by NN15 but based on all the available observational evidence.

Citation

Stephenson, F. R., Willis, D. M., Hayakawa, H., Ebihara, Y., Scott, C. J., Wilkinson, J., & Wild, M. N. (2019). Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination. Solar Physics, 294(4), Article 36. https://doi.org/10.1007/s11207-019-1425-7

Journal Article Type Article
Acceptance Date Feb 15, 2019
Online Publication Date Apr 1, 2019
Publication Date Apr 30, 2019
Deposit Date Apr 17, 2019
Publicly Available Date Apr 17, 2019
Journal Solar Physics
Print ISSN 0038-0938
Electronic ISSN 1573-093X
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 294
Issue 4
Article Number 36
DOI https://doi.org/10.1007/s11207-019-1425-7
Public URL https://durham-repository.worktribe.com/output/1298488

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Copyright Statement
© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.






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