SOLARNET Conference: The Many Scales of the Magnetic Sun

Revisiting the long-term evolution of the Sun’s magnetic field: Solar wind sources and coronal rotation

11 May 2023, 14:15

15m

Haus H, Telegrafenberg

Oral presentation 4) Variations of magnetic fields with the solar cycle – synoptic observations and Theory Variations of magnetic fields with the solar cycle – synoptic observations and Theory

Speaker

Dr Adam Finley (CEA Paris-Saclay)

Description

The Sun’s large-scale magnetic field undergoes periodic reversals due to the activity of the dynamo within the solar interior. The evolution of the Sun’s magnetic field has a clear impact on the structure of the corona and solar wind above. Here we show results from the spherical harmonic decomposition of the Sun’s photospheric magnetic field, using WSO, SOHO/MDI and SDO/HMI synoptic magnetograms that span sunspot cycles 21-24, plus cycle 25 to present. From this, trends in the magnetic field components (notably the lowest order, dipole, quadrupole and octupole) are extracted and compared between cycles. In addition, we perform potential field source surface modeling of the coronal magnetic field, in order to make inferences about the solar wind sources and likely coronal rotation rate. These results are compared against scattered whitelight observations of the corona from MLSO/K-Cor and SOHO/LASCO-C2. The role of nested flux emergence and poleward surges of magnetic flux will be discussed in this context, with future links to heliospheric missions like Solar Orbiter and Parker Solar Probe.