scholarly journals Observation of Reconnection Inflow of a Solar Flare

2001 ◽  
Vol 203 ◽  
pp. 344-346
Author(s):  
T. Yokoyama ◽  
K. Akita ◽  
T. Morimoto ◽  
K. Inoue ◽  
J. Newmark
Keyword(s):  
Mach Number ◽  
Solar Flare ◽  
Magnetic Reconnection ◽  
Reconnection Rate ◽  
X Ray ◽  
North East ◽  
The North ◽  
Upper Limit ◽  
Long Duration ◽  
East Limb

We find an important piece of evidence for magnetic reconnection inflow in a flare on March 18, 1999. The flare occurred on the north-east limb, displaying a nice cusp-shaped soft X-ray loop and a plasmoid ejection typical for the long-duration-events. As the plasmoid is ejected, magnetic reconnection occurs at the disconnecting point. A clear ingoing pattern toward the magnetic X-point is seen. The velocity of this apparent motion is about 5 km sec−1, which is an upper limit on reconnection inflow speed. Based on this observation, we derive the reconnection rate as MA = 0.001 − 0.03, where MA is a Alfvén Mach number of the inflow.

scholarly journals MHD Simulation of Chromospheric Evaporation in a Solar Flare Based on Magnetic Reconnection Model

1998 ◽  
Vol 188 ◽  
pp. 213-214
Author(s):  
T. Yokoyama ◽  
K. Shibata
Keyword(s):  
Heat Conduction ◽  
Solar Flare ◽  
Magnetic Reconnection ◽  
The Other ◽  
Simple Loop ◽  
X Ray ◽  
Long Duration ◽  
Chromospheric Evaporation ◽  
Anisotropic Heat Conduction ◽  
Reconnection Model

Two-dimensional magnetohydrodynamic simulation of a solar flare is performed using a newly developed MHD code including nonlinear anisotropic heat conduction effect (Fig. 1; Yokoyama & Shibata 1997a). The numerical simulation starts with a vertical current sheet which is line-tied at one end to a dense chromosphere. The flare energy is released by the magnetic reconnection mechanism stimulated initially by the resistivity perturbation in the corona. The released thermal energy is transported into the chromosphere by heat conduction and drives chromospheric evaporation. Owing to the heat conduction effect, the adiabatic slow-mode MHD shocks emanated from the neutral point are dissociated into conduction fronts and isothermal shocks (Yokoyama & Shibata 1997b). Temperature and derived soft X-ray distributions are similar to the cusp-like structure of long-duration-event (LDE) flares observed by the soft X-ray telescope aboard Yohkoh satellite. On the other hand density and radio maps show a simple loop configuration which is consistent with the observation with Nobeyama Radio Heliograph. Two interesting new features are found. One is a pair of high density humps on the evaporated plasma loops formed at the collision site between the reconnection jet and the evaporation flow. The other is the loop-top blob behind the fast-mode MHD shock.

scholarly journals Magnetic Reconnection during the Post-impulsive Phase of a Long-duration Solar Flare: Bidirectional Outflows as a Cause of Microwave and X-Ray Bursts

2020 ◽  
Vol 900 (1) ◽  
pp. 17 ◽  
Author(s):  
Sijie Yu ◽  
Bin Chen ◽  
Katharine K. Reeves ◽  
Dale E. Gary ◽  
Sophie Musset ◽  
...  
Keyword(s):  
Solar Flare ◽  
Magnetic Reconnection ◽  
Impulsive Phase ◽  
X Ray ◽  
Long Duration

On the Incidence of Abomasal Parasites in Fat Lambs from the same flock

1937 ◽  
Vol 15 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Allan H. H. Fraser ◽  
David Robertson
Keyword(s):  
Wide Difference ◽  
North East ◽  
The North ◽  
Upper Limit ◽  
Worm Infestation ◽  
Stock Farm

1. To determine the upper limit of the abomasal worm infestation of healthy lambs was the main object of the investigation. The results show that a lamb slaughtered fat before or shortly after weaning and therefore presumably a healthy lamb, may contain up to 2,100 Haemonchus and up to 4,670 Ostertagia.2. Infestation with Haemonchus conlortus is negligible until August.3. Infestation with Ostertagia remains almost steady from early May until mid-September.4. Infestation with Trichostrongylus axei occurs from May until mid-September, but is never a heavy one.5. The evidence suggests, but does not prove, that in mid-summer there is a wide difference in the infestation of single and twin lambs.6. The results, so far as they affect the seasonality of infestation are, strictly speaking, applicable only to the flock of the Duthie Experimental Stock Farm, but are probably true for the North-East area of Scotland.

A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection

Nature ◽  
1994 ◽  
Vol 371 (6497) ◽  
pp. 495-497 ◽  
Author(s):  
S. Masuda ◽  
T. Kosugi ◽  
H. Hara ◽  
S. Tsuneta ◽  
Y. Ogawara
Keyword(s):  
Solar Flare ◽  
Magnetic Reconnection ◽  
X Ray

scholarly journals Numerically investigating the morphology of the supernova remnant SN 1006 in the ambient medium with a density discontinuity

2019 ◽  
Vol 491 (2) ◽  
pp. 2460-2464 ◽  
Author(s):  
Jun Fang ◽  
Jingwen Yan ◽  
Lu Wen ◽  
Chunyan Lu ◽  
Huan Yu
Keyword(s):  
Supernova Remnant ◽  
Ambient Medium ◽  
X Rays ◽  
X Ray ◽  
North West ◽  
Density Discontinuity ◽  
North East ◽  
The North ◽  
South West ◽  
Type Ia

ABSTRACT Multiband observations on the Type Ia supernova remnant SN 1006 indicate peculiar properties in its morphologies of emission in the radio, optical, and X-ray bands. In the hard X-rays, the remnant is bilateral with two opposite bright limbs with prominent protrusions. Moreover, a filament has been detected at the radio, optical, and soft X-ray wavelengths. The reason for these peculiar features in the morphologies of the remnant is investigated using 3D HD simulations. With the assumption that the supernova ejecta are evolved in the ambient medium with a density discontinuity, the radius of the remnant’s boundary is smaller in the tenuous medium, and the shell consists of two hemispheres with different radii. Along particular line of sights, protrusions appear on the periphery of the remnants since the emission from the edge of the hemisphere with a larger radius is located outside that from the shell of the small hemisphere. Furthermore, the north-west filament of SN 1006 arises as a result of the intersection of the line of sight and the shocked material near the edges of the two hemispheres. It can be concluded that the protrusions on the north-east and south-west limbs and the north-west filament in the morphologies of SN 1006 can be reproduced as the remnants interacting with the medium with a density discontinuity.

scholarly journals On the Thermalisation of Flare-Time Energetic Electrons Observed at Radio and X-Ray Wavelengths

1980 ◽  
Vol 91 ◽  
pp. 223-226
Author(s):  
S. S. Degaonkar ◽  
H. S. Sawant ◽  
R. V. Bhonsle
Keyword(s):  
Solar Flare ◽  
Energetic Electrons ◽  
Gradual Rise ◽  
X Ray ◽  
Slow Decay ◽  
Microwave Burst ◽  
Long Duration ◽  
Microwave Bursts

An interesting microwave event at 2800 MHz was recorded at Ahmedabad on September 19, 1977 at 1026 UT at the same time as the H-Alpha solar flare of importance 3B. The microwave burst was of impulsive nature, with as many as twenty impulses in seventy minutes with a quasi-periodicity of 1 to 5 minutes. An X-ray burst recorded by GOES Satellite in 1-8A band showed at the same time a smooth soft X-ray profile with apparently no sign of hard X-ray bursts. This indicates that the acceleration of discrete electron streams which produced impulsive microwave bursts was not sufficient to produce the hard X-ray component but got thermalised to produce soft X-ray emission, with a gradual rise and a slow decay covering a long duration of more than 2 1/2 hours.

Wairakite, the calcium analogue of analcime, a new zeolite mineral

1955 ◽  
Vol 30 (230) ◽  
pp. 691-698 ◽  
Author(s):  
A. Steiner
Keyword(s):  
New Zealand ◽  
Hydrothermal Alteration ◽  
New Mineral ◽  
X Ray ◽  
X Ray Crystallography ◽  
Volcanic Region ◽  
North East ◽  
The North

During the study of hydrothermal alteration of cores recovered Dfrom holes drilled at Wairakei during the exploration for geothermal steam, an unusual zeolite mineral was found. Optical, chemical, and X-ray data indicate that this zeolite is a new mineral, the calcium analogue of analcime. The name wairakite is given to the new mineral after the locality Wairakei in New Zealand. Wairakei is situated in the central part of the North Island, approximately 4 miles north-north-east from Lake Taupo, in an active volcanic region. The material was submitted to Dr. D. S. Coombs, Department of Geology, University of Otago, Dunedin, for an investigation of its X-ray crystallography.

IV.—The Fluvio-glacial Gravels of the Thames Valley

1916 ◽  
Vol 3 (3) ◽  
pp. 111-117
Author(s):  
R. M. Deeley
Keyword(s):  
Main Stream ◽  
North East ◽  
The North ◽  
Upper Limit ◽  
Boulder Clay ◽  
River Thames ◽  
Glacial Fan

At about 55 miles we reach the Hendon Lobe fan. At Dollis Hill the base of the fluvio-glacial beds lies at a height of about 200 feet, whilst their upper limit at Hendon is about 280 feet. On Finchley Hill to the north-east the Boulder-clay lies between the levels of 240 and 340 feet. This was a small lobe, and the fluvio-glacial fan may have sloped rapidly towards the fluvio-glacial gravels of the main stream. On the section, Fig. 2, the heights are shown without correction for slope towards the River Thames.

Near-isothermal exhumation of lower crust in the Caledonian Orogen: Metamorphic path of kyanite eclogite from the Danmarkshavn area, North-East Greenland Caledonides

2021 ◽  
Author(s):  
Wentao Cao ◽  
Jane Gilotti ◽  
Hans-Joachim Massonne
Keyword(s):  
Local Equilibrium ◽  
East Greenland ◽  
Equilibrium Modeling ◽  
X Ray ◽  
North East ◽  
The North ◽  
Garnet Core ◽  
The Matrix ◽  
Area North ◽  
Peak Assemblage

<p>Kyanite eclogite from the North-East Greenland Caledonides – the upper plate of the Caledonian orogeny – preserves a mineral assemblage and petrographic texture that are consistent with an initial near-isothermal exhumation path. Two medium-grained kyanite eclogites from the Danmarkshavn area (76°46’N, 18°40’W) located west of the Germania Land shear zone contain the peak assemblage of garnet + omphacite + kyanite + phengite + amphibole + rutile. Subhedral garnet encloses monomineralic omphacite and polymineralic inclusions of clinopyroxene + plagioclase ± quartz ± amphibole ± K-feldspar ± kyanite. X-ray mapping of garnet indicates a homogenous core with a composition of Py<sub>51–52</sub>Alm<sub>28–29</sub>Gr<sub>19–20</sub>Sp<sub>0–1</sub>, along with a slightly zoned rim of Py<sub>54</sub>Alm<sub>31</sub>Gr<sub>15</sub>Sp<sub>1</sub> that is replaced by a corona of symplectitic amphibole + plagioclase. Omphacite (X<sub>Na</sub> up to 0.41), rarely present in the matrix, is indicated by symplectite of clinopyroxene + amphibole + plagioclase. Symplectites of corundum + plagioclase, spinel + plagioclase and sapphirine + plagioclase replace former kyanite. These symplectites are typically surrounded by a plagioclase corona with decreasing Ca (from X<sub>An</sub> = 92–97 to X<sub>An</sub> = 47–53) from the symplectite to the matrix. Isochemical phase equilibrium modeling along with homogenous garnet core and peak omphacite compositions yielded a peak metamorphic pressure-temperature (<em>P-T</em>) condition at 1.9 GPa, 840 ˚C. Assuming local equilibrium at the microscopic scale, an attempt to model a symplectite of spinel + sapphirine + plagioclase after kyanite using a pseudosection yielded estimated <em>P-T</em> conditions at 0.8–1.3 GPa and 700–900 ˚C. Integrating the calculated <em>P-T</em> conditions and previous geochronological results, an initial exhumation path from 1.9 GPa to ~1.0 GPa from ~415–390 Ma to ~375 Ma is nearly isothermal at around 800 ˚C.</p>

scholarly journals Eruption of a Twisted Filament and Associated Phenomena

1998 ◽  
Vol 167 ◽  
pp. 338-341
Author(s):  
Wahab Uddin ◽  
V.K. Verma
Keyword(s):  
Solar Flare ◽  
Geomagnetic Storms ◽  
Magnetic Energy ◽  
Radio Bursts ◽  
X Ray ◽  
Filament System ◽  
Long Duration ◽  
Major Flare ◽  
Ccd Observations ◽  
Microwave Bursts

AbstractIn this paper we present CCD observations between February 14–20, 1994 and analysis of the giant twisted filament evolved in the active region NOAA 7671. The dynamic eruption of the filament was accompanied by a major flare (3B/M4), CME, long duration type II, IV radio bursts, great microwave bursts, a long duration soft X-ray burst, SIDs, strong geomagnetic storms and a very energetic proton flare. We analysed and estimated the twist, length, volume, mass and energy associated with filament system between February 14 and 20, 1994. The present study shows that the magnetic energy required for the solar flare came from the filament system associated with the solar flare and associated phenomena.

Sign in / Sign up

Export Citation Format

Share Document