Backtracking Bipolar Magnetic Regions to their emergence: Two groups and their implication in the tilt measurements

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Main Authors: Sreedevi, Anu, Karak, Bidya Binay, Jha, Bibhuti Kumar, Gupta, Rambahadur, Banerjee, Dipankar
Format: Preprint
Published: 2025
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author Sreedevi, Anu
Karak, Bidya Binay
Jha, Bibhuti Kumar
Gupta, Rambahadur
Banerjee, Dipankar
author_facet Sreedevi, Anu
Karak, Bidya Binay
Jha, Bibhuti Kumar
Gupta, Rambahadur
Banerjee, Dipankar
contents Bipolar Magnetic Regions (BMRs) that appear on the solar photosphere are surface manifestations of the Suns internal magnetic field. With modern observations and continuous data streams, the study of BMRs has moved from manual sunspot catalogs to automated detection and tracking methods. In this work, we present an additional module to the existing BMR tracking algorithm, AutoTAB, that focuses on identifying emerging signatures of BMRs. Specifically, for regions newly detected on the solar disk, this module backtracks the BMRs to their point of emergence. From a total of about 12,000 BMRs identified by AutoTAB, we successfully backtracked 3,080 cases. Within this backtracked sample, we find two distinct populations. One group shows the expected behavior of emerging regions, in which the magnetic flux increases significantly during the emerging phase. The other group consists of BMRs whose flux, however, does not exhibit substantial growth during their evolution, the instances where our algorithm fails to capture the initial emergence of the BMRs. We classify these as discarded BMRs and examine their statistical properties separately. Our analysis shows that these discarded BMRs do not display any preferred tilt angle distribution and do not show systematic latitudinal tilt dependence, in contrast to the trends typically associated with emerging BMRs. This indicates that including such regions in statistical studies of BMR properties can distort or mask the underlying physical characteristics. We therefore emphasise the importance of excluding the discarded population from the whole dataset when analysing the statistical behavior of BMRs.
format Preprint
id arxiv_https___arxiv_org_abs_2509_17157
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Backtracking Bipolar Magnetic Regions to their emergence: Two groups and their implication in the tilt measurements
Sreedevi, Anu
Karak, Bidya Binay
Jha, Bibhuti Kumar
Gupta, Rambahadur
Banerjee, Dipankar
Solar and Stellar Astrophysics
Instrumentation and Methods for Astrophysics
Bipolar Magnetic Regions (BMRs) that appear on the solar photosphere are surface manifestations of the Suns internal magnetic field. With modern observations and continuous data streams, the study of BMRs has moved from manual sunspot catalogs to automated detection and tracking methods. In this work, we present an additional module to the existing BMR tracking algorithm, AutoTAB, that focuses on identifying emerging signatures of BMRs. Specifically, for regions newly detected on the solar disk, this module backtracks the BMRs to their point of emergence. From a total of about 12,000 BMRs identified by AutoTAB, we successfully backtracked 3,080 cases. Within this backtracked sample, we find two distinct populations. One group shows the expected behavior of emerging regions, in which the magnetic flux increases significantly during the emerging phase. The other group consists of BMRs whose flux, however, does not exhibit substantial growth during their evolution, the instances where our algorithm fails to capture the initial emergence of the BMRs. We classify these as discarded BMRs and examine their statistical properties separately. Our analysis shows that these discarded BMRs do not display any preferred tilt angle distribution and do not show systematic latitudinal tilt dependence, in contrast to the trends typically associated with emerging BMRs. This indicates that including such regions in statistical studies of BMR properties can distort or mask the underlying physical characteristics. We therefore emphasise the importance of excluding the discarded population from the whole dataset when analysing the statistical behavior of BMRs.
title Backtracking Bipolar Magnetic Regions to their emergence: Two groups and their implication in the tilt measurements
topic Solar and Stellar Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2509.17157