Dynamic and Thermal Disappearance of Prominences and Their Geoeffectiveness |
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Authors: | Lela Taliashvili Zadig Mouradian Jorge Páez |
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Institution: | (1) Space Science Research Center, University of Costa Rica, 2060 San Jose, Costa Rica;(2) Observatoire de Paris-Meudon, CNRS, UPMC, Université Paris Diderot, 5 Place Jules Janssen, 92190 Meudon, France |
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Abstract: | This paper is a qualitative study of 42 events of solar filament/prominence sudden disappearances (“disparitions brusques”;
henceforth DBs) around two solar minima, 1985 – 1986 and 1994. The studied events were classified as 17 thermal and 25 dynamic
disappearances. Associated events, i.e. coronal mass ejections (CMEs), type II bursts, evolution of nearby coronal holes, as well as solar wind speed, and geomagnetic
disturbances are discussed. We have found that about 50% of the thermal DBs with adjacent (within 15° from the DB) coronal
holes were associated with CMEs within a selected time window. All the studied thermal disappearances with adjacent coronal
holes or accompanied by dynamic disappearances were associated with weak and medium geomagnetic storms. Also, nearly 64% of
dynamic DBs were associated with CMEs. Ten (40%) dynamic disappearances were associated with intense geomagnetic storms, even
when no CMEs was reported, six (24%) dynamic disappearances corresponded to extreme storms, and five (20%) corresponded to
medium geomagnetic storms. The extreme geomagnetic storms appeared to be related to combined events, involving dynamic disappearances
with adjacent coronal holes or including thermal disappearances. Furthermore, the geomagnetic activity (Dst index) increased
if the source was close to the central meridian (±30°). The highest interplanetary magnetic field (B), longest duration, lowest southward direction B
z
component, and lowest Dst were highly correlated for all studied events. The Sun – Earth transit time computed from the starting
time of the sudden disappearance and the time its effect was measured at Earth was about 4.3 days and was mainly well correlated
with the solar wind speed measured in situ (daily value). |
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