Bibcode
Salabert, D.; García, R. A.; Pallé, P. L.; Jiménez-Reyes, S. J.
Bibliographical reference
SOHO-23: Understanding a Peculiar Solar Minimum ASP Conference Series Vol. 428, proceedings of a workshop held 21-25 September 2009 in Northeast Harbor, Maine, USA. Edited by Steven R. Cranmer, J. Todd Hoeksema, and John L. Kohl. San Francisco: Astronomical Society of the Pacific, 2010, p.51
Advertised on:
6
2010
Citations
4
Refereed citations
3
Description
We study the response of the low-degree solar p-mode frequencies to the
unusual extension of the minimum of solar surface activity since 2007.
Helioseismic observations collected by the space-based, Sun-as-a-star
GOLF instrument and by the ground-based, multi-site network GONG
(integrated signal) are analyzed. Temporal variations of the low-degree
(l=0,1,2), p-mode frequencies are obtained. Although the known
correlation of the frequency changes with solar surface activity is
recovered for the period 1996â??2007, since the second half of
2007 and until July 2009 (the latest period analyzed) we notice a
peculiar behavior amongst modes of different angular degrees. In
particular, a clear increase of the l=0 and l=2 p-mode frequencies is
obtained consistently since late 2007, while the l=1 frequencies follow
the general decreasing trend of surface activity. We interpret these
differences in the frequency shifts of individual low-degree modes as
indicative of variations at high latitudes in the magnetic flux beneath
the surface of the Sun related to the onset of solar cycle 24.