TY - JOUR

T1 - Tilt Angle of the Magnetic-Field Axis of Sunspots from Microwave Observations: Method and Measurement Results

AU - Топчило, Николай Андреевич

AU - Петерова, Наталья Георгиевна

N1 - Publisher Copyright: © 2020, Pleiades Publishing, Ltd.

PY - 2020/12

Y1 - 2020/12

N2 - Abstract—: The results of the measurements of the tilt of the magnetic-field axis of sunspots for active regions (ARs) with different morphological structures are presented. The observations are taken from the data archives of the RATAN-600 radio telescope and the Nobeyama Radioheliograph (NoRH) and processed with a new measurement method proposed by us earlier (Topchilo and Peterova, 2018). The method is based on the analysis of features of the microwave cyclotron source image above the sunspot and its dynamics with respect to the angle of view when the heliographic longitude of the sunspot changes due to the Sun’s rotation. We tested ten cases of observations and showed that the axis in most of them (~90%) is tilted toward the eastern limb and that the angle does not depend on the AR morphology. The degree of the tilt of the magnetic field axis of sunspots at the height of the lower part of the chromosphere–corona transition region (the boundary between them is at the height of ~2000 km) is ~1°–10° and increases with an increase in the height of the radiation source above the photosphere. Deviations from this rule are interpreted as the influence of neighboring ARs, as a result of which part of the magnetic flux of the main sunspot is closed, not on the tail of the AR as is the usual case, but on the neighboring, leading AR.

AB - Abstract—: The results of the measurements of the tilt of the magnetic-field axis of sunspots for active regions (ARs) with different morphological structures are presented. The observations are taken from the data archives of the RATAN-600 radio telescope and the Nobeyama Radioheliograph (NoRH) and processed with a new measurement method proposed by us earlier (Topchilo and Peterova, 2018). The method is based on the analysis of features of the microwave cyclotron source image above the sunspot and its dynamics with respect to the angle of view when the heliographic longitude of the sunspot changes due to the Sun’s rotation. We tested ten cases of observations and showed that the axis in most of them (~90%) is tilted toward the eastern limb and that the angle does not depend on the AR morphology. The degree of the tilt of the magnetic field axis of sunspots at the height of the lower part of the chromosphere–corona transition region (the boundary between them is at the height of ~2000 km) is ~1°–10° and increases with an increase in the height of the radiation source above the photosphere. Deviations from this rule are interpreted as the influence of neighboring ARs, as a result of which part of the magnetic flux of the main sunspot is closed, not on the tail of the AR as is the usual case, but on the neighboring, leading AR.

UR - http://www.scopus.com/inward/record.url?scp=85097963378&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/70fab3a3-ab8f-31e4-ab4b-5cca22c3d104/

U2 - 10.1134/S0016793220070257

DO - 10.1134/S0016793220070257

M3 - Article

VL - 60

SP - 881

EP - 888

JO - Geomagnetism and Aeronomy

JF - Geomagnetism and Aeronomy

SN - 0016-7932

IS - 7

ER -