اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدFormation and evolution of an active region filament
125
0
0.0
(
0
)
تأليف
C. Kuckein
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Several scenarios explaining how filaments are formed can be found in literature. In this paper, we analyzed the observations of an active region filament and critically evaluated the observed properties in the context of current filament formation models. This study is based on multi-height spectropolarimetric observations. The inferred vector magnetic field has been extrapolated starting either from the photosphere or from the chromosphere. The line-of-sight motions of the filament, which was located near disk center, have been analyzed inferring the Doppler velocities. We conclude that a part of the magnetic structure emerged from below the photosphere.
قيم البحث
اقرأ أيضاً
We present a formation process of a filament in active region NOAA 12574 during the period from 2016 August 11 to 12. Combining the observations of GONG H$alpha$, Hida spectrum and SDO/AIA 304 A, the formation process of the filament is studied. It i
s found that cool material ($Tsim10^4$ K) is ejected by a series of jets originating from the western foot-point of the filament. Simultaneously, the magnetic flux emerged from the photosphere in the vicinity of the western foot-point of the filament. These observations suggest that cool material in the low atmosphere can be directly injected into the upper atmosphere and the jets are triggered by the magnetic reconnection between pre-existing magnetic fields and new emerging magnetic fields. Detailed study of a jet at 18:02 UT on August 11 with GST/BBSO TiO observations reveals that some dark threads appeared in the vicinity of the western foot-point after the jet and the projection velocity of plasma along the filament axis was about 162.6$pm$5.4 km/s. Using with DST/Hida observations, we find that the injected plasma by a jet at 00:42 UT on August 12 was rotating. Therefore, we conclude that the jets not only supplied the material for the filament, but also injected the helicity into the filament simultaneously. Comparing the quantity of mass injection by the jets with the mass of the filament, we conclude that the estimated mass loading by the jets is sufficient to account for the mass in the filament.
We present a detailed study of the formation of an inverse S-shaped filament prior to its eruption in active region NOAA 11884 from October 31 to November 2, 2013. In the initial stage, clockwise rotation of a small positive sunspot around the main n
egative trailing sunspot formed a curved filament. Then the small sunspot cancelled with negative magnetic flux to create a longer active-region filament with an inverse S-shape. At the cancellation site a brightening was observed in UV and EUV images and bright material was transferred to the filament. Later the filament erupted after cancellation of two opposite polarities under the upper part of the filament. Nonlinear force-free field (NLFFF) extrapolation of vector photospheric fields suggests that the filament may have a twisted structure, but this cannot be confirmed from the current observations.
We studied the dynamics of the solar atmosphere in the region of a large quiet-Sun filament, which erupted on 21 October 2010. The filament eruption started at its northern end and disappeared from the H$alpha$ line-core filtergrams line within a few
hours. The very fast motions of the northern leg were recorded in ultraviolet light by AIA. We aim to study a wide range of available datasets describing the dynamics of the solar atmosphere for five days around the filament eruption. This interval covers three days of the filament evolution, one day before the filament growth and one day after the eruption. We search for possible triggers that lead to the eruption of the filament. The surface velocity field in the region of the filament were measured by means of time-distance helioseismology and coherent structure tracking. The apparent velocities in the higher atmosphere were estimated by tracking the features in the 30.4 nm AIA observations. To capture the evolution of the magnetic field, we extrapolated the photospheric line-of-sight magnetograms and also computed the decay index of the magnetic field. We found that photospheric velocity fields showed some peculiarities. Before the filament activation, we observed a temporal increase of the converging flows towards the filaments spine. In addition, the mean squared velocity increased temporarily before the activation and peaked just before it, followed by a steep decrease. We further see an increase in the average shear of the zonal flow component in the filaments region, followed by a steep decrease. The photospheric l.o.s. magnetic field shows a persistent increase of induction eastward from the filament spine. The decay index of the magnetic field at heights around 10 Mm shows a value larger than critical at the connecting point of the northern filament end.
The nature of flows in tornado-prominences is an open issue. While the AIA imager aboard the Solar Dynamics Observatory (SDO) allowed us to follow the global structure of a tornado-like prominence during five hours, the Interface Region Imaging Spect
rograph (IRIS), and the Multi subtractive Double pass spectrograph (MSDP) permitted to obtain plasma diagnostics of its fine structures. We aim to address two questions. Is the observed plasma rotation conceptually acceptable in a flux rope magnetic support configuration with dips? How is the plasma density distributed in the tornado-like prominence? We calculated line-of-sight velocities and non-thermal line widths using Gaussian fitting for Mg II lines and bisector method for H-alpha line. We determined the electron density from Mg II line integrated intensities and profile fitting methods using 1D NLTE radiative transfer theory models. The global structure of the prominence observed in H-alpha, and Mg II h and k lines fits with a magnetic field structure configuration with dips. Coherent Dopplershifts in red- and blue-shifted areas observed in both lines were detected along rapidly-changing vertical and horizontal structures. However, the tornado at the top of the prominence consists of multiple-fine threads with opposite flows suggesting counter streaming flows rather than rotation. Surprisingly we found that the electron density at the top of the prominence could be larger (10^11 cm^{-3}) than in the inner part of the prominence. We suggest that the tornado is in a formation state with cooling of hot plasma in a first phase, and following that, a phase of leakage of the formed blobs with large transverse flows of material along long loops extended away of the UV prominence top. The existence of such long magnetic field lines on both sides of the prominence would avoid the tornado-like prominence to really turn around its axis.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
