Details

Autor(en) / Beteiligte

• Liang, Zhi-Chao
• Chou, Dean-Yi

Titel

PROBING MAGNETIC FIELDS AT THE BASE OF THE SOLAR CONVECTION ZONE WITH MERIDIONAL FLOWS

Ist Teil von

• The Astrophysical journal, 2015-08, Vol.809 (2), p.1-11

Ort / Verlag

United Kingdom: The American Astronomical Society

Erscheinungsjahr

2015

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• ABSTRACT Solar magnetic fields are responsible for most of the activities on the Sun. Many theories predict that it is generated by a dynamo near the base of the convection zone (BCZ), located at . In this study, we use the solar-cycle variations of the meridional flow to probe magnetic field variations near the BCZ. A helioseismic time-distance method is used to measure the travel-time difference between opposite directions in meridional planes, which reflects the meridional flow at different depths. Two systematic effects, the surface magnetic effect and the center-to-limb effect, are removed. Using Solar and Heliospheric Observatory/Michelson Doppler Imager data, we measure the latitudinal distribution of travel-time difference for different travel distances, corresponding to meridional flow signals in the solar interior down to , over 15 years, including two solar minima and one maximum. The travel-time differences at the maximum and the minimum behave differently in three different depth ranges. The travel-time difference at the maximum is greater than that at the minimum above the BCZ, while it is smaller around the BCZ; both are close to zero below the BCZ. The difference in the travel-time difference between the maximum and the minimum changes about 0.1 s from the region above the BCZ to the region around the BCZ, corresponding to a change in flow velocity of about 10 m s−1 around the BCZ. We tend to attribute this change in the meridional flow to the variation in the magnetic field from the minimum to the maximum near the BCZ.