Misplaced Pages

Astrophysical plasma: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editContent deleted Content addedVisualWikitext
Revision as of 22:35, 18 January 2006 editGaius Cornelius (talk | contribs)Administrators164,008 editsm AWB assisted delete duplicate word "as".← Previous edit Latest revision as of 05:24, 22 June 2024 edit undoCitation bot (talk | contribs)Bots5,436,747 edits Added doi-access. | Use this bot. Report bugs. | Suggested by Headbomb | Linked from Misplaced Pages:WikiProject_Academic_Journals/Journals_cited_by_Wikipedia/Sandbox2 | #UCB_webform_linked 10/154 
(240 intermediate revisions by more than 100 users not shown)
Line 1: Line 1:
] is a large, low-density cloud of partially ionized gas.<ref>{{cite news|title=Sneak Preview of Survey Telescope Treasure Trove|url=http://www.eso.org/public/news/eso1403/|access-date=23 January 2014|newspaper=ESO Press Release}}</ref> ]]
], the largest structure in the Solar System, resulting from the influence of the Sun's rotating magnetic field on the plasma in the ] (]) . The wavy spiral shape has been likened to a ballerina's skirt, and carries a tiny 10<sup>-10</sup> amps/m<sup>2</sup>]]


'''Astrophysical plasma''' is ] outside of the ]. It is studied as part of ] and is commonly observed in space.<ref name="MITNews2017">{{Cite web
An '''astrophysical plasma''' is a plasmas (an ionized gas) found in astronomy whose physical properties are studied in the science of ]. Around 99% of the ] is thought to consist of plasma, a ] in which atoms and molecules are so hot, that they have ] by breaking up into their constituent parts, negatively charged ]s and positively charged ]s. Although influenced by ], because the particles are charged, they are also strongly influenced by ]s, that is, by magnetic and electric fields.
|url=https://news.mit.edu/2017/study-uncovers-new-mechanisms-astrophysical-plasma-turbulence-1201
|title=Study sheds light on turbulence in astrophysical plasmas: Theoretical analysis uncovers new mechanisms in plasma turbulence
|date=December 2017
|publisher=MIT News
|access-date=2018-02-20}}</ref> The accepted view of scientists is that much of the ]ic matter in the ] exists in this state.<ref name=BoPA2015>{{Cite book
|last1=Chiuderi
|first1=C.
|last2=Velli
|first2=M.
|chapter=Particle Orbit Theory
|series=UNITEXT for Physics
|date=2015
|title=Basics of Plasma Astrophysics
|page=17
|doi=10.1007/978-88-470-5280-2_2
|isbn=978-88-470-5280-2|bibcode=2015bps..book.....C
}}</ref>


When matter becomes sufficiently hot and energetic, it becomes ] and forms a plasma. This process breaks matter into its constituent particles which includes negatively charged ]s and positively charged ]s.<ref name="Goldbook">{{GoldBookRef|title=Ionization|file=I03183}}</ref> These electrically charged particles are susceptible to influences by local ]s. This includes ] by ]s, and weak fields which exist in ]s, in ] space, and in ] space.<ref name="Lazarian2010">{{Cite journal|author1-link=Alexandre Lazarian
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 ] (or ]) resulting in the ''heliospheric current sheet'', the largest structure in the Solar Solar.
|title=Understanding of the role of magnetic fields: Galactic perspective
|journal=Astro2010: The Astronomy and Astrophysics Decadal Survey
|volume=2010
|pages=175
|author1=Lazarian, A.|author2=Boldyrev, S.|author3=Forest, C.|author4=Sarff, P.
|bibcode=2009astro2010S.175L
|year=2009
|arxiv=0902.3618
}}</ref> Similarly, ]s are observed in some stellar astrophysical phenomena, but they are inconsequential in very low-density gaseous media.<!--This is not a totally true definition of ionisation, which is the gaining or loss of electrons to form ions.-->


Astrophysical plasma is often differentiated from ], which typically refers to the plasma of the ], the ], and the ]s and ]s of the Earth and other planets.<ref name="Spacephy2006">{{cite web|url=http://www.oulu.fi/~spaceweb/textbook/
In the ] ] the entire universe was a plasma prior to recombination. Afterwards, much of the universe ] after the first ]s 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 ] matter is in atoms. In particular, the ], the ], the ] and ]s are all diffuse plasmas, and ]s are made of dense plasma.
|title=Space Physics Textbook |date=2006-11-26
|access-date=2018-02-23
|archive-url=https://web.archive.org/web/20081218061302/http://www.oulu.fi/~spaceweb/textbook/
|archive-date=December 18, 2008 }}</ref><ref name="UniSheffield2017">{{Cite web
|url=http://sp2rc.group.shef.ac.uk/
|title=The Solar Physics and Space Plasma Research Centre (SP<sup>2</sup>RC)
|publisher=MIT News
|access-date=2018-02-23}}</ref><ref name="Mathew">{{Cite journal
|last1=Owens|first1=Mathew J.
|last2=Forsyth|first2=Robert J.
|title=The Heliospheric Magnetic Field
|year=2003
|journal=Living Reviews in Solar Physics
|language=en
|volume=10
|issue=1
|pages=5
|doi=10.12942/lrsp-2013-5
|doi-access=free
|issn=2367-3648
|bibcode = 2013LRSP...10....5O |arxiv=1002.2934
|s2cid=122870891
}}</ref><ref name="Bologh">{{cite book
|first=Andrew F.|last= Nagy
|pages=1–2
|title=''Comparative Aeronomy''
|author2=Balogh, André
|author3= Thomas E. Cravens
|author4=Mendillo, Michael
|author5=Mueller-Woodarg, Ingo
|publisher=Springer
|year=2008
|isbn=978-0-387-87824-9}}</ref><ref name=Ratcliffe1972>{{cite book
|last=Ratcliffe|first=John Ashworth
|title=An Introduction to the Ionosphere and Magnetosphere
|year=1972
|publisher=]
|isbn=978-0-521-08341-6
|url=https://archive.org/details/introductiontoio0000ratc|url-access=registration}}</ref><ref>NASA Study Using Cluster Reveals New Insights Into Solar Wind, NASA, Greenbelt, 2012, p.1</ref><ref name="Cade2015">{{cite journal
|last = Cade III
|first = William B.
|author2 = Christina Chan-Park
|title = The Origin of "Space Weather"
|journal=Space Weather
|volume = 13|issue = 2|pages =99
|date=2015
|doi = 10.1002/2014SW001141
|bibcode = 2015SpWea..13...99C|doi-access = free
}}</ref>


==Observing and studying astrophysical plasma==
==Characteristics==
Plasmas in stars can both generate and interact with ], resulting in a variety of dynamic astrophysical phenomena. These phenomena are sometimes observed in spectra due to the ]. Other forms of astrophysical plasmas can be influenced by preexisting weak magnetic fields, whose interactions may only be determined directly by ] or other indirect methods.<ref name="Lazarian2010" /> In particular, the ], the ], the ] and ]s consist of diffuse plasmas.
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):
<center>
'''Classification of Magnetic Cosmic Plasmas'''
<table cellspacing=0 cellpadding=2 border=1 bgcolor=white>
<tr align=center bgcolor=#eeeeee><td rowspan=2>'''Characteristic'''</td><td colspan=3>'''Space plasma density categories'''<br>(Note that density does not refer to only particle density)</td><td rowspan=2>'''Ideal comparison'''</td></tr>
<tr align=center bgcolor=#eeeeee><td>High density</td><td>Medium Density</td><td>Low Density</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Criterion'''</td><td>&lambda; &lt;&lt; &rho;</td><td>&lambda; &lt;&lt; &rho; &lt;&lt; l<sub>c</sub></td><td>l<sub>c</sub> &lt;&lt; &lambda;</td><td>l<sub>c</sub> &lt;&lt; &lambda;<sub>D</sub></td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Examples'''</td><td>Stellar interior<br>Solar photosphere</td><td>Solar chromosphere/corona<br>Interstellar/intergalactic space<br>Ionopshere above 70km</td><td>Magnetosphere during<br>magnetic disturbance.<br>Interplanetary space</td><td>Single charges<br>in a high vacuum</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Diffusion'''</td><td>Isotropic</td><td>Anisotropic</td><td>Anisotropic and small</td><td>No diffusion</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Conductivity'''</td><td>Isotropic</td><td>Anisotropic</td><td>Not defined</td><td>Not defined</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Electric field parallel to B<br>in completely ionized gas'''</td><td>Small</td><td>Small</td><td>Any value</td><td>Any value</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Particle motion in plane<br>perpendicular to B'''</td><td>Almost straight path<br>between collisions</td><td>Circle<br>between collisions</td><td>Circle</td><td>Circle</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Path of guiding centre<br>parallel to B'''</td><td>Straight path<br>between collisions</td><td>Straight path<br>between collisions</td><td>Oscillations<br>(eg. between mirror points)</td><td>Oscillations<br>(eg. between mirror points)</td></tr>
<tr align=center><td bgcolor=#eeeeee>'''Debye Distance &lambda;<sub>D</sub>'''</td><td>&lambda;<sub>D</sub> &lt;&lt; l<sub>c</sub></td><td>&lambda;<sub>D</sub> &lt;&lt; l<sub>c</sub></td><td>&lambda;<sub>D</sub> &lt;&lt; l<sub>c</sub></td><td>&lambda;<sub>D</sub> &gt;&gt; l<sub>c</sub></td></tr>
<tr align=center><td bgcolor=#eeeeee>''']<br>suitability'''</td><td>Yes</td><td>Approximately</td><td>No</td><td>No</td></tr>
</table>
&lambda;=]. &rho;= Lamor radius of electron. &lambda;<sub>D</sub>=]. l<sub>c</sub>=Characteristic length<br>
<small>Adapted From ''Cosmical Electrodynamics'' (2nd Ed. 1952) Alfv&eacute;n and F&auml;lthammar</small>
</center>


==Possible related phenomena==
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 ], (meaning that they are fully ionized), ]s in the plasmas are continually emitting ]s through a process called ], when electrons nearly collide with atomic nuclei. This raditation may be detected with ], performed in the upper atmosphere or space, such as by the ] satellite. Space plasmas also emit radio waves and gamma rays.


Scientists are interested in ] because such astrophysical plasmas could be directly related to the plasmas studied in laboratories.<ref>{{Cite journal|title=Lab experiments mimic the origin and growth of astrophysical magnetic fields|journal=Physics Today|volume=71|issue=4|pages=20–22|date=April 2018|doi = 10.1063/PT.3.3891|bibcode = 2018PhT....71d..20B|last1 = Berkowitz|first1 = Rachel}}</ref> Many of these phenomena seemingly exhibit an array of complex ] behaviors, such as ] and ].<ref name="MITNews2017" />
==Research and investigation==
], and making up all ]s, much of the ] between them, and the ] between galaxies]]


In ] ], the entire universe was in a plasma state prior to ].<ref name="Peebles 1968">{{Cite journal
Both ] and astrophysicists are interested in ], because they are the astrophysical plasmas most directly related to the plasmas studied in the laboratory, and those studied in ] experiments. They exhibit an array of complex ] behaviors, such as ] and ]. 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.
|title=Recombination of the Primeval Plasma
|journal=Astrophysical Journal
|volume=153
|pages=1
|author=Peebles, P. J. E.
|bibcode= 1968ApJ...153....1P
|year=1968
|doi=10.1086/149628
}}</ref>


==Early history==
The study of astrophysical plasmas is part of the mainstream of academic astrophysics (and is taken in account for in the ]).


Norwegian explorer and physicist ] predicted that space is filled with ]. He wrote in 1913: {{quote|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 ]s of all kinds. We have assumed that each ] through its evolution throws off electric corpuscles into space.}}Birkeland assumed that most of the mass in the universe should be found in "empty" space.<ref name="NAPE">{{cite book |last=Birkeland|first=Kristian
==History==
|title=The Norwegian Aurora Polaris Expedition 1902–1903
In 1913, Norwegian explorer and physicist ] may have been the first to predict that space is not only a ], but also contains "]". He wrote: "It seems to be a natural consequence of our points of view to assume that the whole of space is filled with ]s and flying electric ]s of all kinds. We have assumed that each ] 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. {{ref|PolarMag}}
|year=1908
|page=
|publisher=H. Aschehoug & Co
|location=New York and Christiania (now Oslo)
|url=https://archive.org/details/norwegianaurorap01chririch}} out-of-print, full text online.</ref>


In 1937, when ] was thought to be a ], plasma physicist ] 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 ] (MHD) which enables plasmas to be modelled as waves in a fluid, for which Alfvén won the 1970 Nobel Prize for physics. MHD is a standard astronomical tool.


{{Reflist|group=note}}
However, ] and co-author Carl-Gunne Fälthammar, wrote in their book ''Cosmical Electrodynamics'' (1952, 2nd Ed.):


==References==
:"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 ], electron runaway, and generation of microwaves".
{{Reflist}}


==External links==
In 1974, Alfvén's theoretical work on field-aligned electric currents in the aurora, based on earlier work by ], was confirmed by satellite, and ]s were discovered. ], a onetime ] to the ] now considered discredited by most in the astronomical community, is, in part, based on Alfvén's work. Alfvén subsequently highlighted the importance of treating astrophsyical plasmas as such, writing :
* "''''"

:"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."

<center>
'''Pseudo-Plasma Versus Real Plasma'''
<TABLE BORDER=1 CELLSPACING=0 cellpadding=1 width="90%">
<TR bgcolor=#eeeeee align=center><TD width="45%">'''First approach''' (pseudo-plasma)</TD>
<TD width="45%">'''Second approach''' (real plasma)</TD></TR>
<TR><TD>Homogeneous models</TD>
<TD>Space plasmas often have a complicated inhomogeneous structure</TD></TR>
<TR><TD>Conductivity &sigma;<sub>E</sub> = &infin;</TD>
<TD>&sigma;<sub>E</sub> depends on current and often suddenly vanishes</TD></TR>
<TR><TD>Electric field E<SUB>||</SUB> alongmagnetic field = 0</TD>
<TD>E<SUB>||</SUB> often <> &infin;</TD></TR>
<TR><TD>Magnetic field lines are "frozen-in" and "move" with the plasma</TD>
<TD>Frozen-in picture is often completely misleading</TD></TR>
<TR><TD>Electrostatic double layers are neglected</TD>
<TD>Electrostatic double layers are of decisive importance in low-density plasma</TD></TR>
<TR><TD>Instabilities are neglected</TD>
<TD>Many plasma configurations are unrealistic because they are unstable</TD></TR>
<TR><TD>Electromagnetic conditions are illustrated by magnetic field line pictures</TD>
<TD>It is equally important to draw the current lines and discuss the electric circuit</TD></TR>
<TR><TD>Filamentary structures and current sheets are neglected or treated inadequately</TD>
<TD>Currents produce filaments or flow in thin sheets</TD></TR>
<TR><TD>Maxwellian velocity distribution</TD>
<TD>Non-Maxwellian effects are often decisive Cosmic plasmas have a tendency to produce high-energy particles</TD></TR>
<TR><TD>Theories are mathematically elegant and very "well developed"</TD>
<TD>Theories are not very well developed and are partly phenomenological</TD></TR>
</TABLE>
Source: Evolution of the Solar System, TABLE 15.3.1.
</center>

==References==
* {{note|PolarMag}} Polar Magnetic Phenomena and Terrella Experiments, in ''The Norwegian Aurora Polaris Expedition 1902-1903'' (publ. 1913, p.720)


{{Authority control}}
==Links==
* "''''"


]
]
] ]
]
]
]

Latest revision as of 05:24, 22 June 2024

Lagoon Nebula is a large, low-density cloud of partially ionized gas.

Astrophysical plasma is plasma outside of the Solar System. It is studied as part of astrophysics 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 fields. This includes strong fields generated by stars, and weak fields which exist in star forming regions, in interstellar space, and in intergalactic space. Similarly, electric fields are observed in some stellar astrophysical phenomena, but they are inconsequential in very low-density gaseous media.

Astrophysical plasma is often differentiated from space plasma, which typically refers to the plasma of the Sun, the solar wind, and the ionospheres and magnetospheres 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, the interplanetary medium and solar winds consist of diffuse plasmas.

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.

In Big Bang cosmology, the entire universe was in a plasma state prior to recombination.

Early history

Norwegian explorer and physicist Kristian Birkeland predicted that space is filled with plasma. He wrote in 1913:

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 through its evolution throws off electric corpuscles into space.

Birkeland assumed that most of the mass in the universe should be found in "empty" space.


References

  1. "Sneak Preview of Survey Telescope Treasure Trove". ESO Press Release. Retrieved 23 January 2014.
  2. ^ "Study sheds light on turbulence in astrophysical plasmas: Theoretical analysis uncovers new mechanisms in plasma turbulence". MIT News. December 2017. Retrieved 2018-02-20.
  3. Chiuderi, C.; Velli, M. (2015). "Particle Orbit Theory". Basics of Plasma Astrophysics. UNITEXT for Physics. p. 17. Bibcode:2015bps..book.....C. doi:10.1007/978-88-470-5280-2_2. ISBN 978-88-470-5280-2.
  4. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Ionization". doi:10.1351/goldbook.I03183
  5. ^ Lazarian, A.; Boldyrev, S.; Forest, C.; Sarff, P. (2009). "Understanding of the role of magnetic fields: Galactic perspective". Astro2010: The Astronomy and Astrophysics Decadal Survey. 2010: 175. arXiv:0902.3618. Bibcode:2009astro2010S.175L.
  6. "Space Physics Textbook". 2006-11-26. Archived from the original on December 18, 2008. Retrieved 2018-02-23.
  7. "The Solar Physics and Space Plasma Research Centre (SPRC)". MIT News. Retrieved 2018-02-23.
  8. Owens, Mathew J.; Forsyth, Robert J. (2003). "The Heliospheric Magnetic Field". Living Reviews in Solar Physics. 10 (1): 5. arXiv:1002.2934. Bibcode:2013LRSP...10....5O. doi:10.12942/lrsp-2013-5. ISSN 2367-3648. S2CID 122870891.
  9. Nagy, Andrew F.; Balogh, André; Thomas E. Cravens; Mendillo, Michael; Mueller-Woodarg, Ingo (2008). Comparative Aeronomy. Springer. pp. 1–2. ISBN 978-0-387-87824-9.
  10. Ratcliffe, John Ashworth (1972). An Introduction to the Ionosphere and Magnetosphere. CUP Archive. ISBN 978-0-521-08341-6.
  11. NASA Study Using Cluster Reveals New Insights Into Solar Wind, NASA, Greenbelt, 2012, p.1
  12. Cade III, William B.; Christina Chan-Park (2015). "The Origin of "Space Weather"". Space Weather. 13 (2): 99. Bibcode:2015SpWea..13...99C. doi:10.1002/2014SW001141.
  13. Berkowitz, Rachel (April 2018). "Lab experiments mimic the origin and growth of astrophysical magnetic fields". Physics Today. 71 (4): 20–22. Bibcode:2018PhT....71d..20B. doi:10.1063/PT.3.3891.
  14. Peebles, P. J. E. (1968). "Recombination of the Primeval Plasma". Astrophysical Journal. 153: 1. Bibcode:1968ApJ...153....1P. doi:10.1086/149628.
  15. Birkeland, Kristian (1908). The Norwegian Aurora Polaris Expedition 1902–1903. New York and Christiania (now Oslo): H. Aschehoug & Co. p. 720. out-of-print, full text online.

External links

Categories: