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Main Authors: Norton, Aimee, Mendez, Alex, Chen, Ruizhu, Dikpati, Mausumi, Raj, S. Aswin Amirtha
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.03646
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author Norton, Aimee
Mendez, Alex
Chen, Ruizhu
Dikpati, Mausumi
Raj, S. Aswin Amirtha
author_facet Norton, Aimee
Mendez, Alex
Chen, Ruizhu
Dikpati, Mausumi
Raj, S. Aswin Amirtha
contents Solar Cycle 24 data are used to determine how often the Sun emerges sunspots in `activity nests', i.e., regions where sunspots and active regions (ARs) repeatedly emerge. We use the Solar Photospheric Ephemeral Active Region (SPEAR) catalog created from Helioseismic and Magnetic Imager (HMI) data as well as the HMI Carrington Rotation maps of radial magnetic field, $B_r$. The Sun shows moderate nesting behavior with 41\% (48\%) of AR magnetic flux found in Northern (Southern) hemispheric nests that are short-lived (average lifetimes $\sim$3.3 - 4.0 months). Different rotation rates are used to search for nests that may not be evident `by eye'. The maximum number of nests are found with slightly prograde rotational velocities, with significant nest flux also found at synodic 451--452 nHz prograde and 409--411 nHz retrograde frequencies. Nest patterns show strong hemispheric asymmetry, indicating that the physical origin of nests identified herein must also be asymmetric or antisymmetric across the equator.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03646
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Moderate Nesting and Cross-Equatorial Asymmetry of Active Regions in Solar Cycle 24
Norton, Aimee
Mendez, Alex
Chen, Ruizhu
Dikpati, Mausumi
Raj, S. Aswin Amirtha
Solar and Stellar Astrophysics
Solar Cycle 24 data are used to determine how often the Sun emerges sunspots in `activity nests', i.e., regions where sunspots and active regions (ARs) repeatedly emerge. We use the Solar Photospheric Ephemeral Active Region (SPEAR) catalog created from Helioseismic and Magnetic Imager (HMI) data as well as the HMI Carrington Rotation maps of radial magnetic field, $B_r$. The Sun shows moderate nesting behavior with 41\% (48\%) of AR magnetic flux found in Northern (Southern) hemispheric nests that are short-lived (average lifetimes $\sim$3.3 - 4.0 months). Different rotation rates are used to search for nests that may not be evident `by eye'. The maximum number of nests are found with slightly prograde rotational velocities, with significant nest flux also found at synodic 451--452 nHz prograde and 409--411 nHz retrograde frequencies. Nest patterns show strong hemispheric asymmetry, indicating that the physical origin of nests identified herein must also be asymmetric or antisymmetric across the equator.
title Moderate Nesting and Cross-Equatorial Asymmetry of Active Regions in Solar Cycle 24
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2511.03646