Heliospheric current sheet, the largest structure in the Solar System, resulting from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. The wavy spiral shape has been likened to a ballerina's skirt, and carries a tiny 10^-10 amps/m²

An astrophysical plasma is a plasmas (an ionized gas) found in astronomy whose physical properties are studied in the science of astrophysics. Around 99% 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 (or broken 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. Image File history File links Heliospheric-current-sheet. ... Image File history File links Heliospheric-current-sheet. ... Heliospheric current sheet The Heliospheric current sheet (HCS), is the largest structure in the Solar System [1], resulting from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [2]. The current sheet occurs in Suns equatorial plane where the Sun... The interplanetary medium is the material which fills the solar system and through which all the larger solar system bodies such as planets, asteroids and comets move. ... The plasma in the Solar Wind meeting the heliopause Ion storm redirects here. ... The word plasma has a Greek root which means to be formed or molded (the word plastic shares this root). ... Spiral Galaxy ESO 269-57 Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions. ... The deepest visible-light image of the cosmos. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... An ion is an atom or group of atoms with a net electric charge. ... Gravity is the force of attraction between massive particles. ... Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...

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 quasi-neutrality. 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 Solar. The interplanetary medium is the material which fills the solar system and through which all the larger solar system bodies such as planets, asteroids and comets move. ... The plasma in the Solar Wind meeting the heliopause Ion storm redirects here. ...

In the Big Bang cosmology the entire universe was a plasma prior to recombination. Afterwards, much of the universe reionized after the first quasars formed and emitted radiation which reionized most of the universe, which largely remains in plasma form. It is believed by many scientists that very little baryonic matter is in atoms. In particular, the intergalactic medium, the interstellar medium, the interplanetary medium and solar winds are all diffuse plasmas, and stars are made of dense plasma. According to the Big Bang theory, the Universe originated in an extremely dense and hot state (bottom). ... Cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. ... Reionization is a process that occurs after the epoch of galaxy formation begins, and is the second of two major phase changes of hydrogen gas in the universe. ... This view, taken with infrared light, is a false-color image of a quasar-starburst tandem with the most luminous starburst ever seen in such a combination. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called Greek barys, meaning heavy, as they are heavier than the other main groups of particles. ... Intergalactic space is the physical space between galaxies. ... The distinctive red colour emitted by warm hydrogen plasma, known as H-II (aitch two) regions, in the interplanetary medium In astronomy, the interstellar medium (or ISM) is the matter and energy content that exists between the stars (or their immediate circumstellar environment) within a galaxy. ... The interplanetary medium is the material which fills the solar system and through which all the larger solar system bodies such as planets, asteroids and comets move. ... The plasma in the Solar Wind meeting the heliopause Ion storm redirects here. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...

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):

Astrophysical plasma may be studied in a variety of ways since they emit eletromagnetic radiation across a wide range of the electromagnetic spectrum. For example, cosmic plasmas in stars emits light as can be seen by gazing at the night sky. And because astrophysical plasmas are generally hot, (meaning that they are fully ionized), electrons in the plasmas are continually emitting X-rays through a process called bremsstrahlung, when electrons nearly collide with atomic nuclei. This raditation may be detected with X-ray observatories, performed in the upper atmosphere or space, such as by the Chandra X-ray Observatory satellite. Space plasmas also emit radio waves and gamma rays. Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Bremsstrahlung   listen?, German for braking radiation, is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. ... ROSAT image of X-ray fluorescence of, and occultation of the X-ray background by, the Moon. ... Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. ...

Research and investigation

Over 99% of the visible universe is known to be plasma, such as that seen here in the Cat's Eye Nebula, and making up all stars, much of the interstellar space between them, and the intergalactic space between galaxies

Both plasma physicists and astrophysicists are interested in active galactic nuclei, because they are the astrophysical plasmas most directly related to the plasmas studied in the laboratory, and those studied in fusion power experiments. They exhibit an array of complex magnetohydrodynamic behaviors, such as turbulence and instabilities. Although these phenomena can occur on scales as large as the galactic core, most physicists believe that most phenomena on the largest scales do not involve plasma effects. Download high resolution version (1019x932, 318 KB)Outer halo of NGC 6543. ... Download high resolution version (1019x932, 318 KB)Outer halo of NGC 6543. ... The Cats Eye Nebula: composite image using optical images from the Hubble Space Telescope and X-ray data from the Chandra X-ray Observatory The Cats Eye Nebula (NGC 6543) is a planetary nebula in the constellation of Draco. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Interstellar Space was one of the last albums recorded before the death of John Coltrane in 1967. ... Intergalactic space is the physical space between galaxies. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ... An active galaxy is a galaxy where a significant fraction of the energy output is not emitted by the normal components of a galaxy: stars, dust and interstellar gas. ... The Sun is a natural fusion reactor. ... MHD Simulation of Solar Wind Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics), is the academic discipline which studies the dynamics of electrically conducting fluids. ... In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by semi-random, stochastic property changes. ... Instability in systems is generally characterized by some of the outputs or internal states growing without bounds. ...

The study of astrophysical plasmas is part of the mainstream of academic astrophysics (and is taken in account for in the cosmological standard model). It is also distinct from (but plays a major role in) plasma cosmology, which states that plasmas are responsible for long-range interactions in the universe. According to the Big Bang theory, the Universe originated in an extremely dense and hot state (bottom). ... Plasma cosmology is a non-standard cosmological model based on the electromagnetic properties of astrophysical plasmas. ...

History

In 1913, Norwegian explorer and physicist Kristian Birkeland may have been the first to predict that space is not only a plasma, but also contains "dark matter". He wrote: "It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. We have assumed that each stellar system in evolutions throws off electric corpuscles into space. It does not seem unreasonable therefore to think that the greater part of the material masses in the universe is found, not in the solar systems or nebulae, but in "empty" space. ^[2] Kristian Birkeland Kristian Birkeland (December 13, 1867 - June 15, 1917) was born in Christiania (Oslo today) and wrote his first scientific paper at the age of 18. ... The word plasma has a Greek root which means to be formed or molded (the word plastic shares this root). ... In cosmology, dark matter refers to hypothetical matter particles, of unknown composition, that do not emit or reflect enough electromagnetic radiation to be detected directly, but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... An ion is an atom or group of atoms with a net electric charge. ... A star system or stellar system is a group of stars (and possibly smaller bodies such as planets or asteroids) that orbit one another (a system with planetary bodies orbiting stars, are referred to as solar systems or planetary systems). ...

In 1937, when interstellar space was thought to be a vacuum, plasma physicist Hannes Alfvén argued that if plasma pervaded the universe, then it could carry electric currents that could generate a galactic magnetic field. During the 1940s and 50s, Alfvén develeoped magnetohydrodynamics (MHD) which enables plasmas to be modelled as as waves in a fluid, for which Alfvén won the 1970 Nobel Prize for physics. MHD is a standard astronomical tool. Interstellar Space was one of the last albums recorded before the death of John Coltrane in 1967. ... For other uses, see vacuum cleaner and Vacuum (musical group). ... Hannes Olof Gösta Alfvén (May 30, 1908; Norrköping, Sweden - April 2, 1995; Djursholm, Sweden) was a Swedish electrical power engineer. ... MHD Simulation of Solar Wind Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics), is the academic discipline which studies the dynamics of electrically conducting fluids. ...

However, Hannes Alfvén and co-author Carl-Gunne Fälthammar, wrote in their book Cosmical Electrodynamics (1952, 2nd Ed.): Hannes Olof Gösta Alfvén (May 30, 1908; Norrköping, Sweden - April 2, 1995; Djursholm, Sweden) was a Swedish electrical power engineer. ...

"It should be noted that the fundamental equations of magnetohydrodynamics rest on the assumption that the conducting medium can be considered as a fluid. This is an important limitation, for if the medium is a plasma it is sometimes necessary to use a microscopic description in which the motion of the constituent particles is taken into account. Examples of plasma phenomena invalidating a hydromagnetic description are ambipolar diffusion, electron runaway, and generation of microwaves".

In 1974, Alfvén's theoretical work on field-aligned electric currents in the aurora, based on earlier work by Kristian Birkeland, was confirmed by satellite, and Birkeland currents were discovered. Plasma Cosmology, an alternative theory to the Big Bang, is based on Alfvén's work. Alfvén subsequently highlighted the importance of treating astrophsyical plasmas as such, writing [3]: Ambipolar diffusion is diffusion of positive and negative particles in a plasma at the same rate due to their interaction via the electric field. ... Kristian Birkeland Kristian Birkeland (December 13, 1867 - June 15, 1917) was born in Christiania (Oslo today) and wrote his first scientific paper at the age of 18. ... The aurora on Jupiter, powered by Jovian Birkeland currents [Ref. ... Plasma cosmology is a non-standard cosmological model based on the electromagnetic properties of astrophysical plasmas. ... According to the Big Bang theory, the Universe originated in an extremely dense and hot state (bottom). ...

"The basic difference between the first and second approaches is to some extent illustrated by the terms ionized gas and plasma which, although in reality synonymous, convey different general notions. The first term gives an impression of a medium that is basically similar to a gas, especially the atmospheric gas we are most familiar with. In contrast to this, a plasma, particularly a fully ionized magnetized plasma, is a medium with basically different properties: Typically it is strongly inhomogeneous and consists of a network of filaments produced by line currents and surfaces of discontinuity. These are sometimes due to current sheaths and, sometimes, to electrostatic double layers."

References

• ^  Polar Magnetic Phenomena and Terrella Experiments, in The Norwegian Aurora Polaris Expedition 1902-1903 (publ. 1913, p.720)

Links

• "US / Russia Collaboration in Plasma Astrophysics"