Solar Ephemeral Regions Hales and Joys laws
Abstract
Besides the active regions and sunspots, the Sun produces many bipolar structures such as ephemeral regions,ERs, and even smaller magnetic bipoles. In this study, we investigate the smallest end of bipolar magnetic structures on the Sun, focusing on ERs using Helioseismic and Magnetic Imager full disk LOS magnetograms. We identify and track the emergence decay sequences of ERs to quantify their flux and morphological properties. Consistent with previous studies, we find that the flux distribution follows a log normal profile and the total unsigned flux emergence rate is estimated to be around 1.45 10^22 Mx/day. We find the ERs are almost uniformly distributed on the solar disc with a substantial fraction emerging outside the activity belts. A statistical analysis of ERs tilt angle reveals a weak adherence to Hales polarity law. The mixed signatures suggest that a majority of the ERs are associated with the large scale global dynamo, while the remainder most likely originate from the small scale dynamo. Overall, our findings indicate that even the small bipolar magnetic structures are statistically imprinted by the solar global dynamo. Our results bridge the scale between ERs and active regions, providing valuable constraints on how magnetic flux is structured and emerges across various spatial and temporal scales on the Sun.
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BibTeX
@misc{sreedevi2026solar,
title = {{Solar Ephemeral Regions Hales and Joys laws}},
author = {Anu Sreedevi and Bibhuti Kumar Jha and Bidya Binay Karak and Robert Cameron},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02456},
eprint = {2611.02456},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02456},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Solar Ephemeral Regions Hales and Joys laws
AU - Anu Sreedevi
AU - Bibhuti Kumar Jha
AU - Bidya Binay Karak
AU - Robert Cameron
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02456
UR - https://arxiv.org/abs/2611.02456
AB - Besides the active regions and sunspots, the Sun produces many bipolar structures such as ephemeral regions,ERs, and even smaller magnetic bipoles. In this study, we investigate the smallest end of bipolar magnetic structures on the Sun, focusing on ERs using Helioseismic and Magnetic Imager full disk LOS magnetograms. We identify and track the emergence decay sequences of ERs to quantify their flux and morphological properties. Consistent with previous studies, we find that the flux distribution follows a log normal profile and the total unsigned flux emergence rate is estimated to be around 1.45 10^22 Mx/day. We find the ERs are almost uniformly distributed on the solar disc with a substantial fraction emerging outside the activity belts. A statistical analysis of ERs tilt angle reveals a weak adherence to Hales polarity law. The mixed signatures suggest that a majority of the ERs are associated with the large scale global dynamo, while the remainder most likely originate from the small scale dynamo. Overall, our findings indicate that even the small bipolar magnetic structures are statistically imprinted by the solar global dynamo. Our results bridge the scale between ERs and active regions, providing valuable constraints on how magnetic flux is structured and emerges across various spatial and temporal scales on the Sun.
ER -