Space plasmas
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Astrophysical plasma is
plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...
outside of the Solar System. It is studied as part of
astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...
and is commonly observed in space. The accepted view of scientists is that much of the baryonic matter in the universe exists in this state. When matter becomes sufficiently hot and energetic, it becomes ionized and forms a plasma. This process breaks matter into its constituent particles which includes negatively-charged electrons and positively-charged ions. These electrically-charged particles are susceptible to influences by local
electromagnetic field An electromagnetic field (also EM field or EMF) is a classical (i.e. non-quantum) field produced by (stationary or moving) electric charges. It is the field described by classical electrodynamics (a classical field theory) and is the classical c ...
s. This includes strong fields generated by
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s, and weak fields which exist in star forming regions, in interstellar space, and in intergalactic space. Similarly,
electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
s are observed in some stellar astrophysical phenomena, but they are inconsequential in very low-density gaseous mediums. Astrophysical plasma is often differentiated from space plasma, which typically refers to the plasma of the Sun, the solar wind, and the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
s and
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynam ...
s of the Earth and other planets.


Observing and studying astrophysical plasma

Plasmas in stars can both generate and interact with magnetic fields, resulting in a variety of dynamic astrophysical phenomena. These phenomena are sometimes observed in spectra due to the Zeeman effect. Other forms of astrophysical plasmas can be influenced by preexisting weak magnetic fields, whose interactions may only be determined directly by polarimetry or other indirect methods. In particular, the intergalactic medium, the
interstellar medium In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...
, the interplanetary medium and solar winds consist of diffuse plasmas. Astrophysical plasma may also be studied in a variety of ways as they emit electromagnetic radiation across a wide range of the electromagnetic spectrum. Because astrophysical plasmas are generally hot, electrons in the plasmas are continually emitting X-rays through the process called bremsstrahlung. This radiation may be detected with X-ray telescopes located in the upper atmosphere or in space. Astrophysical plasmas also emit radio waves and gamma rays.


Possible related phenomena

Scientists are interested in active galactic nuclei because such astrophysical plasmas could be directly related to the plasmas studied in laboratories. Many of these phenomena seemingly exhibit an array of complex magnetohydrodynamic behaviors, such as turbulence and instabilities. Although these phenomena may occur on astronomical scales as large as the galactic core, many astrophysicists suggest that they do not significantly involve plasma effects but are caused by matter consumed by super massive black holes. In
Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...
cosmology, the entire universe was in a plasma state prior to recombination. Afterwards, much of the universe reionized after the first
quasar A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a m ...
s formed. Studying astrophysical plasmas is part of mainstream academic astrophysics. Though plasma processes are part of the standard cosmological model, current theories indicate that they might have only a minor role to play in forming the very largest structures, such as
voids Void may refer to: Science, engineering, and technology * Void (astronomy), the spaces between galaxy filaments that contain no galaxies * Void (composites), a pore that remains unoccupied in a composite material * Void, synonym for vacuum, a s ...
, galaxy clusters and
supercluster A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in turn ...
s.


Early history

Norwegian explorer and physicist Kristian Birkeland predicted that space is filled with
plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...
. He wrote in 1913: Birkeland assumed that most of the mass in the universe should be found in "empty" space. out-of-print, full text online. In 1937, plasma physicist Hannes Alfvén argued that if plasma pervaded the universe, then it could generate a galactic magnetic field. During the 1940s and 1950s, Alfvén developed magnetohydrodynamics which enables plasmas to be modeled as waves in a fluid. Alfvén received the 1970 Nobel Prize in Physics for this development. Alfvén later proposed this as the possible basis of
plasma cosmology Plasma cosmology is a non-standard cosmology whose central postulate is that the dynamics of ionized gases and plasmas play important, if not dominant, roles in the physics of the universe at interstellar and intergalactic scales. recount: It ...
, although this theory has faced scrutiny.


See also

* List of plasma physics articles


References


External links

* "
US / Russia Collaboration in Plasma Astrophysics
'" {{Authority control Plasma physics Solar phenomena Space physics Stellar phenomena