scholarly journals Observations of the Association of Prominences and the Surrounding Corona

1998 ◽  
Vol 167 ◽  
pp. 37-40
Author(s):  
Raymond N. Smartt ◽  
Zhenda Zhang ◽  
Vladimir S. Airapetian ◽  
Ira S. Kim
Keyword(s):  
High Temperature ◽  
Emission Line ◽  
Magnetic Reconnection ◽  
Coronal Loop ◽  
Observational Evidence ◽  
Coronal Emission ◽  
Flare Loop ◽  
Active Prominence ◽  
Coronal Region

AbstractEmission-line coronal images in Fe XIV (530.3 nm) and FeX (637.5 nm) show faint enhancements at the location of quiescent prominences. Such enhancements can appear in the outer portions of a prominence, similar to the high-temperature sheath surrounding prominences as inferred from UV and EUV observations. The observational evidence supports the interpretation that this enhanced coronal emission is due to energy carried by the prominence threads and dissipated in the adjacent coronal region. Also, observed coronal loop interactions involving partial magnetic reconnection have associated Hα structures. These structures can have the appearance of an active prominence, similar to those typically observed in post flare loop systems. It appears that the association of such active prominences with the adjacent corona is fundamentally different from that of quiescent prominences. The observations indicate that these types of active prominences arise simply as a consequence of reconnection processes in the corona itself.

scholarly journals Coronal Loop Interaction

1990 ◽  
Vol 142 ◽  
pp. 350-351
Author(s):  
Raymond. N. Smartt ◽  
Zhenda Zhang
Keyword(s):  
High Resolution ◽  
Magnetic Reconnection ◽  
Electron Density ◽  
Current Density ◽  
Coronal Loop ◽  
Cooling Time ◽  
Green Line ◽  
Flare Loop ◽  
High Resolution Images ◽  
Red Line

High–resolution images of post–flare loop systems in Fe XIV (5303Å) and FeX (6374Å) display transient enhancements at the projected intersections of some loops. The brightness of such enhancements gradually increases to a marked maximum and then fades with a typical lifetime of about thirty minutes. The maximum in the red line lags that of the green line by about ten minutes, while Hα reaches a maximum about ten minutes later, which gives a measure of the cooling time, and hence electron density. The observed phenomenon is interpreted as localized loop coalescence and partial magnetic reconnection, with the possibility of an increase in the current density, and heating of the plasma in the immediate vicinity of the X–point.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

Coronal emission line polarization

Solar Physics ◽  
1972 ◽  
Vol 23 (1) ◽  
pp. 103-119 ◽  
Author(s):  
Lewis L. House
Keyword(s):  
Emission Line ◽  
Coronal Emission ◽  
Coronal Emission Line

scholarly journals The May 1985 Superoutburst of OY Carinae: II. Phase-Resolved IUE Spectroscopy and Exosat Observations

1987 ◽  
Vol 93 ◽  
pp. 371-376 ◽  
Author(s):  
B.J.M. Hassall ◽  
T. Naylor ◽  
G.T. Bath ◽  
P.A. Charles ◽  
G. Sonneborn ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Spectrum ◽  
X Ray ◽  
Dwarf Nova ◽  
Uv Emission ◽  
Emission Line Spectrum ◽  
Coronal Region

AbstractWe present ultraviolet and X-ray observations of the eclipsing SU UMa dwarf nova OY Car early in the decline from a superoutburst. From the UV emission line spectrum and lack of X-ray eclipse, we deduce the presence of an extended coronal region.

Single-Frequency Diode Laser with a High Temperature Stability of the Emission Line

1988 ◽  
pp. 113-118
Author(s):  
Zh. I. Alferov ◽  
S. A. Gurevich ◽  
E. L. Portnoy ◽  
F. N. Timofeev
Keyword(s):  
High Temperature ◽  
Emission Line ◽  
Diode Laser ◽  
Temperature Stability ◽  
Single Frequency ◽  
High Temperature Stability

PARTICLE ACCELERATION BY MAGNETIC RECONNECTION IN A TWISTED CORONAL LOOP

2011 ◽  
Vol 729 (2) ◽  
pp. 101 ◽  
Author(s):  
Mykola Gordovskyy ◽  
Philippa K. Browning
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Coronal Loop

scholarly journals Why are CMEs large-scale coronal events: nature or nurture?

2008 ◽  
Vol 26 (10) ◽  
pp. 3077-3088 ◽  
Author(s):  
L. van Driel-Gesztelyi ◽  
G. D. R. Attrill ◽  
P. Démoulin ◽  
C. H. Mandrini ◽  
L. K. Harra
Keyword(s):  
Magnetic Reconnection ◽  
Large Scale ◽  
Observational Evidence ◽  
Angular Width ◽  
Small Scale ◽  
Apparent Contradiction ◽  
Lower Corona ◽  
Magnetic Structures ◽  
Source Regions ◽  
Scale Response

Abstract. The apparent contradiction between small-scale source regions of, and large-scale coronal response to, coronal mass ejections (CMEs) has been a long-standing puzzle. For some, CMEs are considered to be inherently large-scale events – eruptions in which a number of flux systems participate in an unspecified manner, while others consider magnetic reconnection in special global topologies to be responsible for the large-scale response of the lower corona to CME events. Some of these ideas may indeed be correct in specific cases. However, what is the key element which makes CMEs large-scale? Observations show that the extent of the coronal disturbance matches the angular width of the CME – an important clue, which does not feature strongly in any of the above suggestions. We review observational evidence for the large-scale nature of CME source regions and find them lacking. Then we compare different ideas regarding how CMEs evolve to become large-scale. The large-scale magnetic topology plays an important role in this process. There is amounting evidence, however, that the key process is magnetic reconnection between the CME and other magnetic structures. We outline a CME evolution model, which is able to account for all the key observational signatures of large-scale CMEs and presents a clear picture how large portions of the Sun become constituents of the CME. In this model reconnection is driven by the expansion of the CME core resulting from an over-pressure relative to the pressure in the CME's surroundings. This implies that the extent of the lower coronal signatures match the final angular width of the CME.

scholarly journals Solar activities observed with the New Vacuum Solar Telescope

2015 ◽  
Vol 11 (S320) ◽  
pp. 315-320
Author(s):  
Shuhong Yang ◽  
Jun Zhang
Keyword(s):  
Magnetic Reconnection ◽  
Flux Rope ◽  
Observational Evidence ◽  
Small Scale ◽  
Solar Telescope ◽  
New Name ◽  
Direct Observations ◽  
Filament Activation ◽  
First Time

AbstractBased on the New Vacuum Solar Telescope observations, some new results about the solar activities are obtained. (1) In the Hα line, a flux rope tracked by filament activation is detected for the first time. There may exist some mild heating during the filament activation. (2) The direct observations illustrate the mechanism of confined flares, i.e., the flares are triggered by magnetic reconnection between the emerging loops and the pre-existing loops and prevented from being eruptive by the overlying loops. (3) The solid observational evidence of magnetic reconnection between two sets of small-scale loops is reported. The successive slow reconnection changes the conditions around the reconnection area and leads to the rapid reconnection. (4) An ensemble of oscillating bright features rooted in a light bridge is observed and given a new name, light wall. The light wall oscillations may be due to the leakage of p-modes from below the photosphere.

The formation and interpretation of the Fe XIII 10747 A coronal emission line

1982 ◽  
Vol 255 ◽  
pp. 764 ◽  
Author(s):  
C. W. Querfeld
Keyword(s):  
Emission Line ◽  
Coronal Emission ◽  
Coronal Emission Line

scholarly journals An Observational Evidence of the Common Envelope Phase

2004 ◽  
Vol 194 ◽  
pp. 37-38
Author(s):  
Marek J. Sarna ◽  
Jeremy J. Drake
Keyword(s):  
Abundance Ratio ◽  
Observational Evidence ◽  
Coronal Emission ◽  
X Ray ◽  
Common Envelope ◽  
Transmission Grating ◽  
Processed Material ◽  
The Common ◽  
Red Giant ◽  
First Time

AbstractChandra Low Energy Transmission Grating Spectrograph observations of the pre-cataclysmic binary V471 Tau have been used to estimate the C/N abundance ratio of the K dwarf component for the first time. While the white dwarf component dominates the spectrum longward of 50 Å, at shorter wavelengths the observed X-ray emission is entirely due to coronal emission from the K dwarf. The H-like 2p 2Р3/2, 1/2 → 1s 2S1/2 resonance lines of С and N yield an estimate of their logarithmic abundance ratio relative to the Sun of [C/N]= –0.38 ± 0.15—half of the currently accepted solar value. We interpret this result as the first clear observational evidence for the presumed common envelope phase of this system, during which the surface of the K dwarf was contaminated by CN-cycle processed material dredged up into the red giant envelope

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