131 research outputs found
Observation of a bright coronal downflow by SOHO/EIT
No full textA distinct coronal downflow has been discovered in the course of a prominence
eruption associated coronal mass ejection (CME) imaged by EIT (Extreme ultraviolet
Imaging Telescope) and LASCO (Large Angle Spectrometric Coronagraph) on board SOHO (Solar
and Heliospheric Observatory) on 5-Mar.-2000. Evolution of the prominences seen by EIT
was tracked into the LASCO/C2 and C3 field-of-view where they developed as the core of a
typical three-part CME. In contrast to the inflow structures reported earlier in the
literatures, which were dark and were interpreted as plasma voids moving down, the
downflow reported here was bright. The downflow, which was only seen in EIT FOV had an onset
time that coincided with the deceleration phase of the core of the CME. The downflow
showed a rapid acceleration followed by a strong deceleration. The downflow followed a
curved path which may be explained by material following the apex of a contracting
magnetic loop sliding down along other field lines, although other explanations are
also possible. Irrespective of the detailed geometry, this observation provides support
for the pinching off of the field lines drawn-out by the erupting prominences and
the contraction of the arcade formed by the reconnection.
Internal magnetic field structures observed by PSP/WISPR in a filament-related coronal mass ejection
No full textContext. We investigated the coronal mass ejection (CME) related to an eruptive filament over the southwestern solar limb on December 8, 2022, at around 8 UT. We tracked localized density enhancements reflecting the magnetic structures using white-light data taken with the Wide-field Instrument for Solar PRobe (WISPR) aboard the Parker Solar Probe (PSP).
Aims. We aim to investigate the 3D location, morphology and evolution of the internal magnetic fine structures of CMEs. Specifically, we focused on the physical origin of the features in the WISPR images, how the white-light structures evolve over time, and their relationship with the source region, filament, and the flux rope.
Methods. The fast tangential motion of the PSP spacecraft during its perihelion permits a single event to be viewed from multiple angles in short times relative to the event’s evolution. Hence, three-dimensional information of selected CME features can be derived from this single spacecraft using triangulation techniques.
Results. We grouped small-scale structures with roughly similar speeds, longitude, and latitude into three distinct morphological groups. We found twisted magnetic field patterns close to the eastern leg of the CME that may be related to “horns” outlining the edges of the flux-rope cavity. We identified aligned thread-like bundles close to the western leg, and they may be related to confined density enhancements evolving during the filament eruption. High density blob-like features (magnetic islands) are widely spread in longitude (∼40°) close to the flanks and the rear part of the CME. We also note that the large-scale outer envelope of the CME, seen clearly from 1 AU, was not well observed by PSP.
Conclusions. We demonstrate that CME flux ropes, apart from the blobs, may comprise different morphological groups with a cluster behavior; the blobs instead span a wide range of longitudes. This finding may hint at either the three-dimensionality of the post-CME current sheet (CS) or the influence of the ambient corona in the evolutionary behavior of the CS. Importantly, we show that the global appearance of the CME can be very different in WISPR (0.11–0.16 AU) and the instruments near 1 AU because of the shorter line-of-sight integration of WISPR
Lyric Reunion
No full textShown in this reunion image are Paul Bloom, Lawrence Swenson, Roy Thelander, Carl G. Knock, Ernest Gibson, Arthur Knock, David Knock, Luther Hanson, Emil Olson, Eugene Abrahamson, Peter Nehleen, Ernest Wallinder, E.G. Knock, H.P. Jonson, Oscar Sandahl, Nels Benson, Peter Youngdahl, C. Carlton, Ambrose Stenborg, Harry Hedberg, C.G. Erickson, Dr. P.A. Mattson, G.H. Towley, Dr. Lagerstrom, Prof. J.A. Edquist, and perhaps Rev. Chellgren
Solar slow magneto-acoustic-gravity waves: an erratum correction and a revisited scenario
No full textSlow waves are commonly observed on the entire solar atmosphere. Assuming a thin flux tube approximation, the cut-off periods of slow-mode magneto-acoustic-gravity waves that travel from the photosphere to the corona were obtained in Costa et al. In that paper, however, a typo in the specific heat coefficient at constant pressure cp value led to an inconsistency in the cut-off calculation, which is only significant at the transition region. Due to the abrupt temperature change in the region, a change of the mean atomic weight (by a factor of approximately 2) also occurs, but is often overlooked in analytical models for simplicity purposes. In this paper, we revisit the calculation of the cut-off periods of magneto-acoustic-gravity waves in Costa et al. by considering an atmosphere in hydrostatic equilibrium with a temperature profile, with the inclusion of the variation of the mean atomic weight and the correction of the inconsistency aforementioned. In addition, we measure the dominant periods near a particular active region (AR 1243) as observed by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamic Observatory (SDO) on 2011 July 3 and compare them to our analytical results. The cut-off periods obtained analytically are consistent with the corresponding periods measured in observations.Fil: Zurbriggen, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Universidade Presbiteriana Mackenzie; BrasilFil: Sieyra, María Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Tecnológica Nacional. Facultad Reg.mendoza. Centro de Estudio Para El Desarrollo Sustentable; ArgentinaFil: Costa, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Esquivel, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Stenborg, G.. Spece Sciences División. Naval Research Laboratory; Estados Unido
Scalable Distribution of Watermarked Media
No full textMedia that is distributed digitally can be copied and redistributed illegally. Embedding an individual watermark in the media object for each customer will make it possible to trace pirate copies to the redistribution source. However, digital distribution methods such as broadcast and multicast are scalable and will give all customers identical copies of the media content. Distribution of individually watermarked media is more difficult to achieve. In this chapter, methods for how media with individual watermarks can be distributed scalable are presented and discussed. These methods are categorized in four groups. One group that is based on watermark embedding in the network, another group for embedding in the client, and two groups that use fragments of the media content that are unique for each customer or shared among a subgroup of customers.</jats:p
Large non-radial propagation of a coronal mass ejection on 2011 January 24
No full textUnderstanding the deflection of coronal mass ejections (CMEs) is of great interest to the space weather community because of their implications for improving the prediction of CME. This paper aims to shed light into the effects of the coronal magnetic field environment on CME trajectories. We analyze the influence of the magnetic environment on the early development of a particular CME event. On 2011 January 24 an eruptive filament was ejected in association with a CME that suffered a large deflection from its source region and expected trajectory. We characterize the 3D evolution of the prominence material using the tie-pointing/triangulation reconstruction technique on EUV and white-light images. To estimate the coordinates in 3D space of the apex of the CME we use a forward-modeling technique that reproduces the large-scale structure of the flux rope-like CME, the Graduated Cylindrical Shell model. We found that the deflection amounts to 42° in latitude and 20° in longitude and that most of it occurs at altitudes below 4R⊙. Moreover, we found a non-negligible deflection at higher altitudes. Combining images of different wavelengths with the extrapolated magnetic field obtained from a potential field source surface model we confirm the presence of two magnetic structures near the erupting event. The magnetic field environment suggests that field lines from the southern coronal hole act as a magnetic wall that produces the large latitudinal deflection; while a nearby pseudostreamer and a northward extension of the southern coronal hole may be responsible for the eastward deflection of the CME.Fil: Cécere, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Sieyra, María Valeria. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cremades Fernandez, Maria Hebe. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mierla, M.. Institute of Geodynamics of the Romanian Academy; BélgicaFil: Sahade, Abril. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Stenborg, G.. Spece Sciences División. Naval Research Laboratory; Estados UnidosFil: Costa, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: West, M. J.. Royal Observatory Of Belgium; BélgicaFil: D'Huys, E.. Royal Observatory Of Belgium; Bélgic
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