submit urlsubmit rss feedadd directory

article

An astrophysical plasma is a plasma (an ionized gas) found in astronomy whose physical properties are studied in the science of astrophysics. The vast majority of the baryonic matter of the universe is thought to consist of plasma, a state of matter in which atoms and molecules are so hot, that they have ionized by breaking up into their constituent parts, negatively charged electrons and positively charged ions. Although influenced by gravity, because the particles are charged, they are also strongly influenced by electromagnetic forces, that is, by magnetic and electric fields.

All known astrophysical plasmas are magnetic. They also contain equal numbers of electrons and ions so that they are electrically neutral overall. And because plasmas are highly conductive, any charge imbalances are readily neutralised. However, because plasma phenonenon are very complex, charge imbalances can occur, resulting in a characteristic known as quasineutrality. An example is the influence of our Sun's magnetic field on the electrons and ions in the interplanetary medium (or Solar wind) resulting in the heliospheric current sheet, the largest structure in the Solar system.

Characteristics


Space plasma pioneers Hannes Alfvén and Carl-Gunne Fälthammar divided cosmic plasmas into three different categories (note that other characteristics of low-particle-density interstellar and intergalactic plasmas, means that they are characterised as medium density):
Classification of Magnetic Cosmic Plasmas
CharacteristicSpace plasma density categories
(Note that density does not refer to only particle density)
Ideal comparison
High densityMedium DensityLow Density
Criterionλ << ρλ << ρ << lclc << λlc << λD
ExamplesStellar interior
Solar photosphere
Solar chromosphere/corona
Interstellar/intergalactic space
Ionopshere above 70km
Magnetosphere during
magnetic disturbance.
Interplanetary space
Single charges
in a high vacuum
DiffusionIsotropicAnisotropicAnisotropic and smallNo diffusion
ConductivityIsotropicAnisotropicNot definedNot defined
Electric field parallel to B
in completely ionized gas
SmallSmallAny valueAny value
Particle motion in plane
perpendicular to B
Almost straight path
between collisions
Circle
between collisions
CircleCircle
Path of guiding centre
parallel to B
Straight path
between collisions
Straight path
between collisions
Oscillations
(eg. between mirror points)
Oscillations
(eg. between mirror points)
Debye Distance λDλD << lcλD << lcλD << lcλD >> lc
Magnetohydrodynamics
suitability
YesApproximatelyNoNo
λ=Mean free path. ρ= Larmor radius (gyroradius) of electron. λD=Debye length. lc=Characteristic length
Adapted From Cosmical Electrodynamics (2nd Ed. 1952) Alfvén and Fälthammar

More on [ Astrophysical plasma ]


directory of related categories

 
directory of related topics

Interstellar Medium :: Astronomy
Solar System :: Astronomy
Astrophysics :: Physics

 
Space_Plasmas RSS feed
POP: Ionospheric, Solar-System, and Astrophysical Plasmas

A stochastic structural stability theory model of the drift wavezonal flow system
Brian F. Farrell and Petros J. Ioannou A remarkable phenomenon in turbulent flows is the spontaneous emergence of coherent large spatial scale zonal jets. In this work a comprehensive theory for the interaction of jets with turbulence, stochastic structural stability theory, is applied to the problem of understanding the formation and ma ... [Phys. Plasmas 16, 112903 (2009)] published Mon Nov 30, 2009.
Impulsive magnetic pulsations and electrojets in the loop footpoint driven by the fast reconnection jet
M. Ugai It is well known that magnetic pulsations of long periods impulsively occur in accordance with the sudden onset of geomagnetic substorms and drastic enhancement of electrojets in the ionosphere. On the basis of the spontaneous fast reconnection model, the present paper examines the physical mechanis ... [Phys. Plasmas 16, 112902 (2009)] published Wed Nov 25, 2009.
Numerical experiments on plasmoids entering a transverse magnetic field
H. Gunell, J. J. Walker, M. E. Koepke, T. Hurtig, N. Brenning et al. Plasma from the Earth's magnetosheath has previously been observed inside the magnetosphere. Inhomogeneities in the magnetosheath plasma, here called plasmoids, can impact the magnetopause and doing so set up a polarizing field that allows it to penetrate the magnetopause and enter the magnetosphere ... [Phys. Plasmas 16, 112901 (2009)] published Tue Nov 24, 2009.
Kinetic Alfven waves turbulence in the Earth's magnetosphere
Sachin Kumar and R. P. Sharma The numerical simulations of the model equation governing the nonlinear dynamics of kinetic Alfven waves in the intermediate-beta plasmas are performed. When the nonlinearity arises due to the ponderomotive force driven density perturbations of kinetic Alfven waves, the model equation turns out to b ... [Phys. Plasmas 16, 102904 (2009)] published Wed Oct 28, 2009.
Quasi-thermal noise in space plasma: kappa distributions
G. Le Chat, K. Issautier, N. Meyer-Vernet, I. Zouganelis, M. Maksimovic et al. The transport of energy in collisionless plasmas, especially in space plasmas, is far from being understood. Measuring the temperature of the electrons and their nonthermal properties can give important clues to understand the transport properties. Quasi-thermal noise (QTN) spectroscopy is a reliabl ... [Phys. Plasmas 16, 102903 (2009)] published Fri Oct 9, 2009.
Kinetic theory for the ion humps at the foot of the Earth's bow shock
D. Jovanovic and V. V. Krasnoselskikh The nonlinear kinetic theory is presented for the ion acoustic perturbations at the foot of the Earth's quasiperpendicular bow shock, that is characterized by weakly magnetized electrons and unmagnetized ions. The streaming ions, due to the reflection of the solar wind ions from the shock, provide t ... [Phys. Plasmas 16, 102902 (2009)] published Mon Oct 5, 2009.

 
Subscribe to Space_Plasmas RSS feed

directory of related sites

CLUSTER satellite - Magnetospheric physics with the 4 CLUSTER satellites

Darthmouth University Space Plasma Theory - Physics of the inner magnetosphere

404 Imperial College Space Physics Department - Homepage of Imperial College's Space Physics group

ISCAT - The company provides modelling and numerical simulations for space plasmas related issues.

Lockheed Martin Space Plasmas Group - The Space Physics Laboratory (LMSPL) is a Department within Lockheed Martin Missiles and Space Company's Advanced Technology Center.

Microgravity Combustion Science - A NASA-Glenn Research Center site devoted to microgravity and combustion science experiments.

Modeling of the Atmosphere Magnetosphere Ionosphere System (MAMI) - This investigation is part of the International Solar Terrestrial Project (ISTP). The program combines satellite and ground based observations with theory and modeling to better understand the energetics and dynamics of the near Earth environment.

NASA Cosmic and Heliospheric Learning Center - Tutorial on solar wind, calendar of solar wind meetings and activities, links to solar wind news articles.
Meta Description: [ Cosmicopia at NASA/GSFC -- Sun -- Solar Wind ]

NGDC/STP - On-Line Glossary of Solar-Terrestrial Terms - Extensive glossary of space plasma and heliospheric lingo.
Meta Description: [ NOAA National Geophysical Data Center Solar-Terrestrial Physics Division and collocated World Data Center for Solar-Terrestrial Physics, Boulder. ]

Our Star, The Sun - A short tutorial (in English and Spanish) about the Sun and solar effects on Earth prepared at the Space Environment Laboratory of the National Oceanic and Atmospheric Administration.

Plasmas - the 4th State of Matter - Tutorial on many types of plasmas by Contemporary Physics Education Project.

Rutherford Appleton Laboratory - Space Science and Technology Department, Rutherford Appleton Laboratory

Solar Physics Tutorial by Marshall Space Flight Center - The site offers an extensive introduction to the sun and space weather, including news stories and related projects.

Space and Plasma Physics at Univ Maryland - SPP Group conducts research in many areas of space and plasma physics

Space Plasma Group, University of London - Simulations of space plasmas and experimental spacecraft data analysis.

Space Plasma Physics - Science projects: Investigations of the auroral phenomenon, magnetic fields and electrodynamics of dense interstellar plasma clouds. Based at the Alfvén Laboratory, Royal Institute of Technology in Stockholm, Sweden.
Meta Description: [ Space and Plasma Physics, Alfvén Laboratory, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm. ]

Space Plasma Physics at RAL - Space Plasma Physics at RAL. Plasma, Research fields, People, Space missions with which the Rutherford Appleton Laboratory is or has been involved.
Meta Description: [ Solar System Science at the Rutherford Appleton Laboratory ]

404 Space Plasma Simulations Group at UCLA - Global magnetosphere simulations.
Meta Description: [ San Diego Super Computer Center ]

Space Wander - Fly through the Universe. Explore space plasma and deep-space mysteries. Real space pictures from NASA. In English, French, Italian, Spanish and Russian.
Meta Description: [ Fly to Mars and Jupiter! Travel through deep space! SpaceWander's award-winning multimedia space trip features real NASA images! Check out our space store for space book, space videos, telescopes, and NASA hats. You can even buy a REAL SPACE TRAVEL! SpaceWander's trip through the Universe fea... ]

U. Iowa Space Plasma Wave Research - Site of the University of Iowa research group describes various undertaken space plasma wave projects including those involving Earth-orbiting and planetary spacecraft.
Meta Description: [ Web home of the radio and plasma wave research group led by Professor Donald Gurnett at the University of Iowa ]

500 UCSD Solar and Heliospheric Physics Group - The site describes a number of UCSD projects on solar and heliospheric physics including the solar mass ejection imager and space weather forecasting.
Meta Description: [ UCSD's Center for Astrophysics & Space Sciences Solar and Heliospheric Phsyics Group- UCSD's research unit in solar and heliospheric physics ]

University of New Hampshire Experimental Space Plasma Group - Satellite and sounding rocket experiments

Space_Plasmas related videos
Dead Space Plasma Cutter Only Walkthrough part 3
Next Video
Space_Plasmas related videos

 

HOMEADVERTISINGABOUT US

articlesartsbusinesscomputersgameshealthhospitalshomekids & teensnewsmobilephysiciansrecreationreferenceregionalscienceshoppingsocietysportsworld


Submit a Site About Become an Editor