Bibcode
Luna, M.; Karpen, J.; Ballester, J. L.; Muglach, K.; Terradas, J.; Kucera, T.; Gilbert, H.
Bibliographical reference
The Astrophysical Journal Supplement Series, Volume 236, Issue 2, article id. 35, 30 pp. (2018).
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6
2018
Citations
38
Refereed citations
38
Description
We have cataloged 196 filament oscillations from the Global Oscillation
Network Group Hα network data during several months near the
maximum of solar cycle 24 (2014 January–June). Selected examples
from the catalog are described in detail, along with our statistical
analyses of all events. Oscillations were classified according to their
velocity amplitude: 106 small-amplitude oscillations (SAOs), with
velocities <10 {km} {{{s}}}-1, and 90 large-amplitude
oscillations (LAOs), with velocities >10 {km} {{{s}}}-1.
Both SAOs and LAOs are common, with one event of each class every two
days on the visible side of the Sun. For nearly half of the events, we
identified their apparent trigger. The period distribution has a mean
value of 58 ± 15 minutes for both types of oscillations. The
distribution of the damping time per period peaks at τ/P = 1.75 and
1.25 for SAOs and LAOs, respectively. We confirmed that LAO damping
rates depend nonlinearly on the oscillation velocity. The angle between
the direction of motion and the filament spine has a distribution
centered at 27° for all filament types. This angle agrees with the
observed direction of filament-channel magnetic fields, indicating that
most of the cataloged events are longitudinal (i.e., undergo
field-aligned motions). We applied seismology to determine the average
radius of curvature in the magnetic dips, R ≈ 89 Mm, and the average
minimum magnetic field strength, B ≈ 16 G. The catalog is available
to the community online and is intended to be expanded to cover at least
1 solar cycle.
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