scholarly journals Coronal Mass Ejection deflection in the corona during the two last solar minima

2011 ◽  
Vol 7 (S286) ◽  
pp. 225-228
Author(s):  
Fernando Marcelo López ◽  
Hebe Cremades ◽  
Laura Balmaceda
Keyword(s):  
Magnetic Field ◽  
Working Group ◽  
Complex Structure ◽  
Angular Separation ◽  
Heliospheric Current Sheet ◽  
The Other ◽  
Statistical Comparison ◽  
Source Regions ◽  
Mass Ejection ◽  
Whole Heliosphere Interval

AbstractIn the framework of the IAU Working Group on Comparative Solar Minima, we investigate the latitudinal deflection of Coronal Mass Ejections (CMEs) with respect to the location of their uniquely identified solar source regions. Data compiled during the Whole Sun Month (WSM) and Whole Heliosphere Interval (WHI) campaigns allowed for comparisons between the two last solar minima.The analysis of the coronal streamers’ distribution during these intervals led to study of the dependence of CME deflection on the angular separation between their source regions and the nearest streamer. All performed analyses consider exclusively projected structures on the plane of the sky, disregarding longitudinal deflections as well.The results of the present study indicate that for both minima most of the events (62.5% for WSM, 84.2% for WHI) are deflected towards the nearest streamer, following the boundary conditions imposed by the heliospheric current sheet.Most of the deflections found in the WHI period could be explained by the more complex structure in the global distribution of magnetic field present during that minimum. On the other hand, the low number of events detected during the WSM period hinders the statistical comparison between both campaigns.

scholarly journals Active Region Contributions to the Solar Wind over Multiple Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (8) ◽  
Author(s):  
David Stansby ◽  
Lucie M. Green ◽  
Lidia van Driel-Gesztelyi ◽  
Timothy S. Horbury
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Holes ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Solar Cycles ◽  
Fractional Contribution ◽  
Source Regions ◽  
Mass Ejection ◽  
Coronal Structures

AbstractBoth coronal holes and active regions are source regions of the solar wind. The distribution of these coronal structures across both space and time is well known, but it is unclear how much each source contributes to the solar wind. In this study we use photospheric magnetic field maps observed over the past four solar cycles to estimate what fraction of magnetic open solar flux is rooted in active regions, a proxy for the fraction of all solar wind originating in active regions. We find that the fractional contribution of active regions to the solar wind varies between 30% to 80% at any one time during solar maximum and is negligible at solar minimum, showing a strong correlation with sunspot number. While active regions are typically confined to latitudes ±30∘ in the corona, the solar wind they produce can reach latitudes up to ±60∘. Their fractional contribution to the solar wind also correlates with coronal mass ejection rate, and is highly variable, changing by ±20% on monthly timescales within individual solar maxima. We speculate that these variations could be driven by coronal mass ejections causing reconfigurations of the coronal magnetic field on sub-monthly timescales.

scholarly journals Ground state and stability of the fractional plateau phase in metallic Shastry–Sutherland system TmB4

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matúš Orendáč ◽  
Slavomír Gabáni ◽  
Pavol Farkašovský ◽  
Emil Gažo ◽  
Jozef Kačmarčík ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Ground State ◽  
Constant Magnetic Field ◽  
Paramagnetic Phase ◽  
The Other ◽  
Zero Field ◽  
Plateau Phase ◽  
Low Field ◽  
Zero Field Cooling

AbstractWe present a study of the ground state and stability of the fractional plateau phase (FPP) with M/Msat = 1/8 in the metallic Shastry–Sutherland system TmB4. Magnetization (M) measurements show that the FPP states are thermodynamically stable when the sample is cooled in constant magnetic field from the paramagnetic phase to the ordered one at 2 K. On the other hand, after zero-field cooling and subsequent magnetization these states appear to be of dynamic origin. In this case the FPP states are closely associated with the half plateau phase (HPP, M/Msat = ½), mediate the HPP to the low-field antiferromagnetic (AF) phase and depend on the thermodynamic history. Thus, in the same place of the phase diagram both, the stable and the metastable (dynamic) fractional plateau (FP) states, can be observed, depending on the way they are reached. In case of metastable FP states thermodynamic paths are identified that lead to very flat fractional plateaus in the FPP. Moreover, with a further decrease of magnetic field also the low-field AF phase becomes influenced and exhibits a plateau of the order of 1/1000 Msat.

scholarly journals A Study of the Effects of Rain, Snow and Hail on the Atmospheric Electric Field near Ground

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 996
Author(s):  
Athanasios Karagioras ◽  
Konstantinos Kourtidis
Keyword(s):  
Frequency Distribution ◽  
Complex Structure ◽  
Potential Gradient ◽  
Weather Conditions ◽  
The Other ◽  
Fair Weather ◽  
Northern Greece ◽  
Rain Events ◽  
The Impact ◽  
Bounce Back

The purpose of the present study is to investigate the impact of rain, snow and hail on potential gradient (PG), as observed in a period of ten years in Xanthi, northern Greece. An anticorrelation between PG and rainfall was observed for rain events that lasted several hours. When the precipitation rate was up to 2 mm/h, the decrease in PG was between 200 and 1300 V/m, in most cases being around 500 V/m. An event with rainfall rates up to 11 mm/h produced the largest drop in PG, of 2 kV/m. Shortly after rain, PG appeared to bounce back to somewhat higher values than the ones of fair-weather conditions. A decrease in mean hourly PG was observed, which was around 2–4 kV/m during the hail events which occurred concurrently with rain and from 0 to 3.5 kV/m for hail events with no rain. In the case of no drop, no concurrent drop in temperature was observed, while, for the other cases, it appeared that, for each degree drop in temperature, the drop in hourly mean PG was 1000 V/m; hence, we assume that the intensity of the hail event regulates the drop in PG. The frequency distribution of 1-minute PG exhibits a complex structure during hail events and extend from −18 to 11 kV/m, with most of the values in the negative range. During snow events, 1-minute PG exhibited rapid fluctuations between high positive and high negative values, its frequency distribution extending from −10 to 18 kV/m, with peaks at −10 and 3 kV/m.

Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System

2006 ◽  
Vol 512 ◽  
pp. 195-200 ◽  
Author(s):  
Nariaki Okamoto ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita ◽  
Tetsuya Takeuchi
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Magnetocrystalline Anisotropy ◽  
Anisotropy Constant ◽  
The Other ◽  
Magnetic Shear ◽  
Maximum Value ◽  
Twinning Plane ◽  
Twinning Shear ◽  
The Difference

Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr eq. On the other hand, concerning the latter alloy, the maximum of τmag is only one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.

scholarly journals THE ENERGY EIGENVALUES OF THE TWO DIMENSIONAL HYDROGEN ATOM IN A MAGNETIC FIELD

2006 ◽  
Vol 15 (06) ◽  
pp. 1263-1271 ◽  
Author(s):  
A. SOYLU ◽  
O. BAYRAK ◽  
I. BOZTOSUN
Keyword(s):  
Magnetic Field ◽  
Hydrogen Atom ◽  
Iteration Method ◽  
Weak Magnetic Field ◽  
The Other ◽  
Asymptotic Iteration Method ◽  
Iterative Approach ◽  
Two Dimensional ◽  
Energy Eigenvalues ◽  
The Magnetic Field

In this paper, the energy eigenvalues of the two dimensional hydrogen atom are presented for the arbitrary Larmor frequencies by using the asymptotic iteration method. We first show the energy eigenvalues for the case with no magnetic field analytically, and then we obtain the energy eigenvalues for the strong and weak magnetic field cases within an iterative approach for n=2-10 and m=0-1 states for several different arbitrary Larmor frequencies. The effect of the magnetic field on the energy eigenvalues is determined precisely. The results are in excellent agreement with the findings of the other methods and our method works for the cases where the others fail.

scholarly journals Photospheric magnetic field of an eroded-by-solar-wind coronal mass ejection

2016 ◽  
Vol 12 (S327) ◽  
pp. 67-70
Author(s):  
J. Palacios ◽  
C. Cid ◽  
E. Saiz ◽  
A. Guerrero
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Mass Ejection ◽  
Coronal Hole ◽  
Interplanetary Medium ◽  
Flux Rope ◽  
Magnetic Characteristics ◽  
Interplanetary Coronal Mass Ejection ◽  
Fast Wind ◽  
Mass Ejection

AbstractWe have investigated the case of a coronal mass ejection that was eroded by the fast wind of a coronal hole in the interplanetary medium. When a solar ejection takes place close to a coronal hole, the flux rope magnetic topology of the coronal mass ejection (CME) may become misshapen at 1 AU as a result of the interaction. Detailed analysis of this event reveals erosion of the interplanetary coronal mass ejection (ICME) magnetic field. In this communication, we study the photospheric magnetic roots of the coronal hole and the coronal mass ejection area with HMI/SDO magnetograms to define their magnetic characteristics.

scholarly journals The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry

2016 ◽  
Vol 34 (4) ◽  
pp. 421-425
Author(s):  
Christian Nabert ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Necessary Conditions ◽  
The Other ◽  
Diffusion Region ◽  
Two Dimensional ◽  
Characteristic Velocity ◽  
Magnetohydrodynamic Equations ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Alfven Velocity

Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.

Fitness-for-Service Assessment for Pressure Equipment in Japan

2003 ◽  
Author(s):  
Takayasu Tahara
Keyword(s):  
High Pressure ◽  
Pressure Vessel ◽  
Working Group ◽  
Pressure Vessels ◽  
The Other ◽  
Task Group ◽  
Assessment Procedure ◽  
Storage Tanks ◽  
Task Groups ◽  
Petrochemical Industries

Pressure equipment in refinery and petrochemical industries in Japan has been getting old, mostly more than 30 years in operation. Currently, the Japanese regulations for pressure equipment in service are the same as those in existence during the fabrication of the pressure equipment. Accordingly, there is an immediate need for an up to date more advanced “Fitness For Service” (FFS) evaluation requirements for pressure equipment. In order to introduce the latest FFS methodologies to Japanese industries, the High Pressure Institute of Japan (HPI) has organized two task groups. One is a working group for development of a maintenance standard for non-nuclear industries. Its prescribed code “Assessment procedure for crack-like flaws in pressure equipment” is for conducting quantitative safety evaluations of flaws detected in common pressure equipment such as pressure vessels, piping, storage tanks. The other is a special task group to study of API RP579 from its drafting stage as a member of TG579. The FFS Handbook, especially for refinery and petrochemical industries, has been developed based on API RP579 with several modifications to meet Japanese pressure vessel regulations on April 2001. [1] It is expected that both the Standard and FFS handbook will be used as an exemplified standard with Japanese regulations for practical maintenance. This paper presents concepts of “Assessment procedure for crack-like flaws in pressure equipment” HPIS Z101, 2001 [2].

scholarly journals Measurements of vector magnetic anomalies on board the icebreaker Shirase and the magnetization of the ship

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
Y. Nogi ◽  
K. Kaminuma
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
The Other ◽  
South Indian Ocean ◽  
Permanent Magnetic Field ◽  
South Indian ◽  
Antarctic Research ◽  
Permanent Magnetization ◽  
Made In

Vector measurements of the geomagnetic field have been made in the South Indian Ocean since 1988 when a Shipboard Three Component Magnetometer (STCM) was installed on board the icebreaker Shirase by the 30th Japanese Antarctic Research Expedition (JARE-30). Twelve constants related to the ship's induced and permanent magnetic field were determined by the data obtained from the JARE-30 to the JARE-35. The constants related to the ship's magnetic susceptibility distribution are almost stable throughout the cruise and mostly depend on the ship's shape. On the other hand, the constants related to the ship's permanent magnetization are variable. However, absolute values of total intensity geomagnetic field calculated from vector geomagnetic field is possible to use, if the constraints from total intensity geomagnetic field measured by the proton magnetometer and/or satellite derived magnetic anomalies are applied.

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