scholarly journals Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

2009 ◽  
Vol 27 (10) ◽  
pp. 3909-3922 ◽  
Author(s):  
A. B. Galvin ◽  
M. A. Popecki ◽  
K. D. C. Simunac ◽  
L. M. Kistler ◽  
L. Ellis ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
Large Scale ◽  
Slow Solar Wind ◽  
Transient Event ◽  
Large Scale Structures ◽  
Close Proximity ◽  
Scale Structures

Abstract. STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h) sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007) which includes minor ion (He, Fe, O) kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.

scholarly journals The Dipolar Solar Minimum Corona

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 507
Author(s):  
Daniele Telloni
Keyword(s):  
Solar Wind ◽  
Solar Minimum ◽  
Large Scale ◽  
Slow Solar Wind ◽  
Kinetic Temperature ◽  
Solar Cycles ◽  
Heliospheric Observatory ◽  
Oxygen Ions ◽  
Uv Emission ◽  
The Magnetic Field

The large-scale configuration of the UV solar corona at the minimum activity between solar cycles 22 and 23 is explored in this paper. Exploiting a large sample of spectroscopic observations acquired by the Ultraviolet Coronagraph Spectrometer aboard the Solar and Heliospheric Observatory in the two-year period of 1996–1997, this work provides the first-ever monochromatic O vi 1032 Å image of the extended corona, and the first-ever two-dimensional maps of the kinetic temperature of oxygen ions and the O vi 1037/1032 Å doublet intensity ratio (a proxy for the outflow velocity of the oxygen component of the solar wind), statistically representative of solar minimum conditions. A clear dipolar magnetic structure, both equator- and axis-symmetric, is distinctly shown to shape the solar minimum corona, both in UV emission and in temperature and expansion rate. This statistical approach allows for robust establishment of the key role played by the magnetic field divergence in modulating the speed and temperature of the coronal flows, and identification of the coronal sources of the fast and slow solar wind.

Dynamics of helium abundance in magnetic clouds

2021 ◽  
Author(s):  
Alexander Khokhlachev ◽  
Maria Riazantseva ◽  
Liudmila Rakhmanova ◽  
Yuri Yermolaev ◽  
Irina Lodkina
Keyword(s):  
Solar Wind ◽  
Relative Abundance ◽  
Large Scale ◽  
Magnetic Cloud ◽  
Magnetic Clouds ◽  
Helium Abundance ◽  
Local Correlation ◽  
Plasma Parameters ◽  
Large Scale Structures ◽  
Scale Structures

<p>Helium is the second most abundant ion component of the solar wind. The relative abundance of helium can differ significantly in various large-scale structures of the solar wind generated by the nonstationarity and inhomogeneity of the solar corona. For example the helium abundance is ~3% in slow streams and ~4% in fast streams. The maximum helium abundance is usually observed inside magnetic clouds and can reach >10%. The relative abundance of helium can also dynamically vary inside large-scale structures, which can be the result of local processes in plasma.</p><p> In magnetic clouds, the distribution of the helium abundance has an axisymmetric peak with a maximum in the central region of the magnetic cloud, where the ion current flows [Yermolaev et al., 2020]. This research examines the different-scale dynamics of the relative abundance of helium in magnetic clouds. For this purpose, the dependences of the helium abundance on some plasma parameters were studied on different datasets of the OMNI database from 1976 to 2018. It is shown that the helium abundance increases with an increase in the modulus of the interplanetary magnetic field B and with a decrease in the proton plasma parameter β in the center of the magnetic cloud. The scale of this region is ~1 million kilometers. Similar relations of the helium abundance to interplanetary magnetic field direction angles and other solar wind parameters were studied.</p><p>In addition, the work studied intermediate-scale changes (at scale <1 hour) in helium abundance inside magnetic clouds and compression regions in front of them in comparison with other large-scale wind types. For this aim, a correlation analysis of the time series of density and relative abundance of helium was carried out on base of measurements on SPEKTR-R and WIND spacecraft located at a considerable distance from each other. The dependences of the local correlation coefficients (at scale ~1 hour or less) between measurements at two points on the solar wind plasma parameters are considered. Meanwhile these dependencies are compared with the same for other types of solar wind. It is shown that the median values of the local correlation coefficient in the regions of compressed plasma ahead of magnetic clouds exceed the values in other types of wind by about 15%. In addition, the local correlation coefficient increases with an increase in the amplitude of fluctuations of the investigated parameter and the proton velocity. Thus, intermediate-scale fluctuations in the relative helium abundance observed in these structures are quite stable and apparently are formed in the corona acceleration region and then propagate without changes.<br>The work is supported by <span>RFBR grant № <span>19-02-00177</span>a.</span></p><p>References.<br>Yermolaev, Y.I. et al., Dynamics of large-scale solar-wind streams obtained by the double superposed epoch analysis. 4. Helium abundance, Journal of Geophysical Research, 125 (7) DOI: 10.1029/2020JA027878</p>

scholarly journals Dynamics of interplanetary CMEs and associated type II bursts

2008 ◽  
Vol 4 (S257) ◽  
pp. 287-290 ◽  
Author(s):  
Alejandro Lara ◽  
Andrea I. Borgazzi
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Interplanetary Medium ◽  
Hydrodynamic Theory ◽  
Type Ii ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Ambient Solar Wind ◽  
Inner Heliosphere

AbstractCoronal mass ejections (CMEs) are large scale structures of plasma (~1016g) and magnetic field expelled from the solar corona to the interplanetary medium. During their travel in the inner heliosphere, these “interplanetary CMEs” (ICMEs), suffer acceleration due to the interaction with the ambient solar wind. Based on hydrodynamic theory, we have developed an analytical model for the ICME transport which reproduce well the observed deceleration of fast ICMEs. In this work we present the results of the model and its application to the CME observed on May 13, 2005 and the associated interplanetary type II burst.

STUDY OF MID-LATITUDE POSITIVE BAYS DURING SUBSTORMS OVER SCANDINAVIA – A CASE STUDY

2021 ◽  
Vol 44 ◽  
pp. 28-31
Author(s):  
V. Guineva ◽  
◽  
I. Despirak ◽  
R. Werner ◽  
R. Bojilova ◽  
...  
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Large Scale ◽  
Slow Solar Wind ◽  
The Earth ◽  
First Case ◽  
The Mean ◽  
The One ◽  
Latitudinal Range

The purpose of this work is to study the midlatitude effects during substorms observed in different interplanetary conditions over Scandinavia. To identify the substorm disturbances, data from the magnetometer networks IMAGE, SuperMAG and INTERMAGNET in the range 31.8° - 75.25° CGMLat and 92° - 104° CGMLon were used. To verify the interplanetary and geomagnetic conditions, data from the CDAWeb OMNI (http://cdaweb.gsfc.nasa.gov/), the catalog of large-scale solar wind phenomena (ftp://ftp.iki.rssi.ru/omni/) and from the WDC for geomagnetism at Kyoto (http://wdc.kugi.kyoto-u.ac.jp/index.html) were taken. Two isolated substorms were chosen, with different intensity: ALmin values ~ -270 nT and ~ -1300 nT, respectively. The first substorm occured on 6 February 2018, at 21:25 UT, under quiet conditions: during slow solar wind streams. The second substorm, at 19:10 UT on 27 September 2020, originated under moderately disturbed conditions: during a high-speed stream (HSS) in the solar wind, just after the passage of EJECTA by the Earth. It was found out, that the latitude of the bay sign conversion from negative to positive values in the case of quiet solar wind conditions, appeared at latitude, 7° higher than the one in the case of disturbed conditions. In both cases, the amplitude of the positive bays, after a maximum near the sign conversion latitude decreased gradually towards the lower latitudes, with a difference between the minimal and maximal amplitude of about 50%. The magnetic bays kept their duration throughout the whole latitudinal range, ~115 min. for the first case and ~ 60 min. for the second one. It was ascertained, that the mean positive bays amplitude in the case of disturbed conditions was 4 times higher than the amplitude during quiet conditions.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

scholarly journals The organization and control of an evolving interdependent population

2015 ◽  
Vol 12 (108) ◽  
pp. 20150044 ◽  
Author(s):  
Dervis C. Vural ◽  
Alexander Isakov ◽  
L. Mahadevan
Keyword(s):  
Evolutionary Game Theory ◽  
Large Scale ◽  
Social Evolution ◽  
Evolutionary Game ◽  
Large Scale Structures ◽  
External Perturbations ◽  
Emergence Of Cooperation ◽  
Scale Structures ◽  
And Control ◽  
Evolutionarily Stable

Starting with Darwin, biologists have asked how populations evolve from a low fitness state that is evolutionarily stable to a high fitness state that is not. Specifically of interest is the emergence of cooperation and multicellularity where the fitness of individuals often appears in conflict with that of the population. Theories of social evolution and evolutionary game theory have produced a number of fruitful results employing two-state two-body frameworks. In this study, we depart from this tradition and instead consider a multi-player, multi-state evolutionary game, in which the fitness of an agent is determined by its relationship to an arbitrary number of other agents. We show that populations organize themselves in one of four distinct phases of interdependence depending on one parameter, selection strength. Some of these phases involve the formation of specialized large-scale structures. We then describe how the evolution of independence can be manipulated through various external perturbations.

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