Polar cap magnetic field reversals during solar grand minima: could pores play a role?

Michal Švanda (1, 2) , Allan Sacha Brun (3) , Thierry Roudier (4) , Laurène Jouve (3, 4)

1 CAS - Czech Academy of Sciences [Prague]
2 UK - Univerzita Karlova [Praha, Česká republika] = Charles University [Prague, Czech Republic]
3 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
4 IRAP - Institut de recherche en astrophysique et planétologie

We study the magnetic flux carried by pores located outside active regions with sunspots and investigate their possible contribution to the reversal of the global magnetic field of the Sun. We find that they contain a total flux of comparable amplitude to the total magnetic flux contained in polar caps. The pores located at distances of 40–100 Mm from the closest active region systematically have the correct polarity of the magnetic field to contribute to the polar cap reversal. These pores can be found predominantly in bipolar magnetic regions. We propose that during grand minima of solar activity, such a systematic polarity trend, which is akin to a weak magnetic (Babcock-Leighton-like) source term, could still be operating but was missed by the contemporary observers because of the limited resolving power of their telescopes.

Mots clés: dynamo; Sun: magnetic fields; Sun: activity; sunspots

Domaines: Astrophysique [astro-ph]; Astrophysique [astro-ph]

Michal Švanda, Allan Sacha Brun, Thierry Roudier, Laurène Jouve. Polar cap magnetic field reversals during solar grand minima: could pores play a role?. Astronomy and Astrophysics - A&A, 2016, 586, pp.A123. ⟨10.1051/0004-6361/201527314⟩. ⟨cea-01430170⟩