What is Exceptional about Solar Activity in the Early Phase of Cycle 25?
Abstract
Solar Cycle 25 began in 2019 December and has been progressing nominally since. However, a closely associated pair of strong active regions, NOAA 12786 and 12785, emerged in 2020 November. The greater, northern component, 12786, attained a maximum sunspot area of 1000 μHemi. The sudden, uncharacteristic emergence of such a large concentration of intense magnetic flux in the early phase of the solar cycle has not been seen in previous cycles. Although the active region pair survived for two Carrington rotations, it did not produce any X- or M-class flares. Here we remark on the evolution of NOAA 12786 and 12785, first in the Sun's invisible and subsequently the visible hemispheres, and compare the irradiance and other characteristic profiles it manifested in the early ascending phase of cycle 25 with those of previous solar cycles.
- Publication:
-
Research Notes of the American Astronomical Society
- Pub Date:
- November 2021
- DOI:
- 10.3847/2515-5172/ac3429
- Bibcode:
- 2021RNAAS...5..253J
- Keywords:
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- Solar activity;
- Solar active regions;
- Solar flares;
- Solar oscillations;
- Solar active region velocity fields;
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