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Sizes of solar active regions at 8 mm
Author(s) -
Kallunki J.,
Uunila M.
Publication year - 2017
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.201613196
Subject(s) - physics , brightness , solar observatory , astrophysics , magnetic field , brightness temperature , active galactic nucleus , sunspot , telescope , observatory , solar maximum , solar minimum , astronomy , atmospheric sciences , solar cycle , solar wind , quantum mechanics , galaxy
Background We investigate the sizes of 86 non‐flaring solar active regions with respect to the brightness temperature at 8 mm and active region magnetic field strength. Materials and Methods The data were collected in AprilŰSeptember, 2014, and AprilŰJuly, 2015 at Aalto University, Metsähovi Radio Observatory with the 14‐m radio telescope. The observations were made at the maximum of the solar cycle 24. We used active region magnetic field strength values measured with the Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory. Results We calculated that the mean active region size in percentage of the full solar disk is 3.7 ś 0.86%. In addition, the mean temperature of selected active regions is around 109% of the quiet Sun level and the average magnetic field strength of the studied active region is 1,400 G. Conclusions Our results show correlation between active region sizes, the total brightness temperature of the Sun, and the active region magnetic field strengths.