parker

explanation blue bibcodes open ADS page with paths to full text

Author name code: parker
ADS astronomy entries on 2022-09-14
author:"Parker, Eugene N."

---------------------------------------------------------
Title: Exploring the innermost solar atmosphere
Authors: Parker, Eugene N.
2020NatAs...4...19P Altcode: 2019NatAs.tmp....6P
The Parker Solar Probe spacecraft completed the first two of its 24
scheduled orbits around the Sun on 18 June 2019, making history by
flying halfway between Mercury and the Sun.

---------------------------------------------------------
Title: The FIELDS Instrument Suite for Solar Probe Plus. Measuring
the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence,
and Radio Signatures of Solar Transients
Authors: Bale, S. D.; Goetz, K.; Harvey, P. R.; Turin, P.; Bonnell,
J. W.; Dudok de Wit, T.; Ergun, R. E.; MacDowall, R. J.; Pulupa,
M.; Andre, M.; Bolton, M.; Bougeret, J. -L.; Bowen, T. A.; Burgess,
D.; Cattell, C. A.; Chandran, B. D. G.; Chaston, C. C.; Chen,
C. H. K.; Choi, M. K.; Connerney, J. E.; Cranmer, S.; Diaz-Aguado, M.;
Donakowski, W.; Drake, J. F.; Farrell, W. M.; Fergeau, P.; Fermin, J.;
Fischer, J.; Fox, N.; Glaser, D.; Goldstein, M.; Gordon, D.; Hanson,
E.; Harris, S. E.; Hayes, L. M.; Hinze, J. J.; Hollweg, J. V.; Horbury,
T. S.; Howard, R. A.; Hoxie, V.; Jannet, G.; Karlsson, M.; Kasper,
J. C.; Kellogg, P. J.; Kien, M.; Klimchuk, J. A.; Krasnoselskikh,
V. V.; Krucker, S.; Lynch, J. J.; Maksimovic, M.; Malaspina, D. M.;
Marker, S.; Martin, P.; Martinez-Oliveros, J.; McCauley, J.; McComas,
D. J.; McDonald, T.; Meyer-Vernet, N.; Moncuquet, M.; Monson, S. J.;
Mozer, F. S.; Murphy, S. D.; Odom, J.; Oliverson, R.; Olson, J.;
Parker, E. N.; Pankow, D.; Phan, T.; Quataert, E.; Quinn, T.; Ruplin,
S. W.; Salem, C.; Seitz, D.; Sheppard, D. A.; Siy, A.; Stevens, K.;
Summers, D.; Szabo, A.; Timofeeva, M.; Vaivads, A.; Velli, M.; Yehle,
A.; Werthimer, D.; Wygant, J. R.
2016SSRv..204...49B Altcode: 2016SSRv..tmp...16B
NASA's Solar Probe Plus (SPP) mission will make the first in situ
measurements of the solar corona and the birthplace of the solar
wind. The FIELDS instrument suite on SPP will make direct measurements
of electric and magnetic fields, the properties of in situ plasma waves,
electron density and temperature profiles, and interplanetary radio
emissions, amongst other things. Here, we describe the scientific
objectives targeted by the SPP/FIELDS instrument, the instrument
design itself, and the instrument concept of operations and planned
data products.

---------------------------------------------------------
Title: Fundamental Concepts Associated with Magnetic Reconnection
Authors: Gonzalez, W. D.; Parker, E. N.; Mozer, F. S.; Vasyliūnas,
V. M.; Pritchett, P. L.; Karimabadi, H.; Cassak, P. A.; Scudder,
J. D.; Yamada, M.; Kulsrud, R. M.; Koga, D.
2016ASSL..427....1G Altcode:
The chapter starts with a discussion about the importance of the concept
of magnetic field lines in space plasmas and magnetic reconnection,
followed by presentations on: (a) the meaning and validity of
empirical constructs related with magnetic reconnection research,
such as: "moving" magnetic field lines, "frozen-in" condition and
"diffusion region" of reconnection; and (b) experimental evidence of the
diffusion region and related energetics. Next, aims to link external
(MHD) with internal (non-MHD) regions of reconnection are discussed
in association with the so-called "Axford conjecture", followed by
short presentations on: (a) global equilibria in reconnection; and (b)
the role of the separatrices in global aspects of reconnection. In the
last section, we present additional discussion about the concept of
"diffusion region" and about the two fundamental questions associated
with magnetic reconnection reviewed in this chapter.

---------------------------------------------------------
Title: Rapid Reconnection and Field Line Topology
Authors: Parker, E. N.; Rappazzo, A. F.
2016ASSL..427..181P Altcode:
Rapid reconnection of magnetic fields arises where the magnetic
stresses push the plasma and field so as to increase the field
gradient without limit. The intent of the present writing is to show
the larger topological context in which this commonly occurs. Consider
an interlaced field line topology as commonly occurs in the bipolar
magnetic regions on the Sun. A simple model is constructed starting
with a strong uniform magnetic field B 0 in the z-direction
through an infinitely conducting fluid from the end plate z = 0 to z =
L with the field lines tied at both end plates. Field line interlacing
is introduced by smooth continuous random turbulent mixing of the
footpoints at the end plates. This configuration is well suited to be
modeled with the reduced magnetohydrodynamic (MHD) equations, with
the equilibria given by the solutions of the 2D vorticity equation
in this case. The set of continuous solutions to the "vorticity"
equation have greatly restricted topologies, so almost all interlaced
field topologies do not have continuous solutions. That infinite set
represents the "weak" solutions of the vorticity equation, wherein
there are surfaces of tangential discontinuity (current sheets) in the
field dividing regions of smooth continuous field. It follows then
that current sheets are to be found throughout interlaced fields,
providing potential sites for rapid reconnection. That is to say,
rapid reconnection and nanoflaring are expected throughout the bipolar
magnetic fields in the solar corona, providing substantial heating to
the ambient gas. Numerical simulations provide a direct illustration of
the process, showing that current sheets thin on fast ideal Alfvén
timescales down to the smallest numerically resolved scales. The
asymmetric structure of the equilibria and the interlacing threshold
for the onset of singularities are discussed. Current sheet formation
and dynamics are further analyzed with dissipative and ideal numerical
simulations.

---------------------------------------------------------
Title: Magnetic Reconnection
Authors: Gonzalez, Walter; Parker, Eugene
2016ASSL..427.....G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Prospects and Limitations of Chemical and Isotopic Groundwater
Monitoring to Assess the Potential Environmental Impacts of
Unconventional Oil and Gas Development
Authors: Mayer, B.; Humez, P.; Becker, V.; Nightingale, M.; Ing,
J.; Kingston, A.; Clarkson, C.; Cahill, A.; Parker, E.; Cherry, J.;
Millot, R.; Kloppmann, W.; Osadetz, K.; Lawton, D.
2015PrEPS..13..320M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Reminiscing my sixty year pursuit of the physics of the Sun
and the Galaxy
Authors: Parker, Eugene N.
2014RAA....14....1P Altcode:
Reminiscing begins with childhood and passes on to student days through
graduate school and the first real contact with research. Then early
academic positions and stumbling efforts to pursue my ideas. The
first significant progress came as a research associate with
Prof. W. M. Elsasser at the University of Utah, beginning with
an introduction to magnetohydrodynamics and the generation of the
geomagnetic field through induction in the liquid metal core of Earth. A
move to the University of Chicago to work with Prof. J. A. Simpson,
on the implications of cosmic ray variations and interplanetary
magnetic fields, led to the theory of coronal expansion and the solar
wind and then to exploring the dynamical effects of cosmic rays on
the galactic magnetic field. Spontaneous current sheets and intrinsic
rapid reconnection in interlaced magnetic field line topologies were the
next big project, leading up to retirement. Finally, it is a pleasure
to recall my many associates, whose fresh thinking helped stimulate
the daily research activities.

---------------------------------------------------------
Title: Current Sheets Formation in Tangled Coronal Magnetic Fields
Authors: Rappazzo, A. F.; Parker, E. N.
2013ApJ...773L...2R Altcode: 2013arXiv1306.6634R
We investigate the dynamical evolution of magnetic fields in closed
regions of solar and stellar coronae. To understand under which
conditions current sheets form, we examine dissipative and ideal reduced
magnetohydrodynamic models in Cartesian geometry, where two magnetic
field components are present: the strong guide field B 0,
extended along the axial direction, and the dynamical orthogonal
field b. Magnetic field lines thread the system along the axial
direction that spans the length L and are line-tied at the top and
bottom plates. The magnetic field b initially has only large scales,
with its gradient (current) length scale of the order of l b
. We identify the magnetic intensity threshold b/B 0
~ l b /L. For values of b below this threshold, field-line
tension inhibits the formation of current sheets, while above the
threshold they form quickly on fast ideal timescales. In the ideal case,
above the magnetic threshold, we show that current sheets thickness
decreases in time until it becomes smaller than the grid resolution,
with the analyticity strip width δ decreasing at least exponentially,
after which the simulations become underresolved.

---------------------------------------------------------
Title: Field Line Topology and Rapid Reconnection
Authors: Parker, Eugene N.
2012ASSP...33....3P Altcode: 2012msdp.book....3P
Consider a magnetic field extending through an infinitely conducting
fluid between end plates z = 0, z = L, with arbitrary interlacing of
the field lines throughout. The field is fixed in both endplates and
is allowed to relax to an equilibrium described by the force-free
equilibrium equation ∇ ×B = αB. The divergence of this field
equation yields ∇ ṡα = 0, requiring that the torsion coefficient α
be constant along each individual field line, and showing that the field
lines represent a family of real characteristics of the equilibrium
field equation. So the field line topology plays a direct role in
determining the nature of the equilibrium field. For an arbitrarily
prescribed interlacing field line topology a continuous field generally
cannot provide an α that is constant along field lines. Yet with
the field fixed at both ends it is obvious that every topology has
an equilibrium. So there must be a mathematical solution to the field
equation for each and every topology. This dilemma is resolved by the
fact that the field lines represent a family of real characteristics,
so that surfaces of discontinuity (current sheets) can form along
the flux surfaces. In almost all field line topologies, then, the
continuous field is cut up by surfaces of tangential discontinuity
between regions of continuous field.

---------------------------------------------------------
Title: The Dynamics of the Heliosphere from 1961 TO Voyagers i and
II in 2011
Authors: Parker, E. N.
2011AGUFMSH13C..02P Altcode:
The first MHD models of the heliosphere were produced in 1961,
illustrating the theoretical shape of the heliosphere in the two
extremes of an interstellar wind without interstellar magnetic
field and an interstellar magnetic field without a wind. The lack of
information on the density and velocity of the solar wind, and on the
interstellar wind and magnetic field, precluded any real estimate of
the dimensions of the heliosphere at that time. The plasma detector
on the Mariner II voyage to Venus in 1962 brought the realities into
focus, measuring wind densities of 5 ions/cc and velocities of 300 - 700
km/sec. The subsequent exploration of the solar wind has filled in the
picture in considerable detail. Most recently, Voyagers I and II have
determined the dimensions of the heliosphere, as well as suggesting
unanticipated dynamical effects in the heliosheath. For instance,
rapid reconnection of the magnetic sector structure into separate
magnetic bubbles is predicted. Then the curious 4 AU region of vanishing
radial wind velocity requires explanation. We have also learned that
the anomalous cosmic rays are not accelerated in the terminal shock,
at least in the regions penetrated by the Voyagers. So there is much
yet to be understood, much like the situation in 1961 fifty years ago.

---------------------------------------------------------
Title: Kinetic and Hydrodynamic Representations of Coronal Expansion
and The Solar Wind
Authors: Parker, E. N.
2010AIPC.1216....3P Altcode:
We consider the Lemaire-Scherer construction of the supersonic solar
wind as the kinetic escape of a collisionless (scatter-free) plasma
from an exosphere near the Sun. The radial electric field enforces
equality of the electron and ion densities and also equality of
the electron and ion fluxes. Consequently, the electrons form an
electrostatically confined atmosphere with the temperature declining
outward only slowly from the exosphere and becoming the work horse
that lifts and accelerates the ions to supersonic velocity.

---------------------------------------------------------
Title: Extraterrestrial Amino Acids in the Almahata Sitta Meteorite
Authors: Callahan, Michael; Aubrey, A.; Bada, J. L.; Dworkin, J. P.;
Elsila, J. E.; Glavin, D. P.; Parker, E.; Jenniskens, P.
2009DPS....41.0909C Altcode:
The recovery of meteorite fragments from the 2008 TC3 asteroid
impact, collectively named Almahata Sitta, revealed a rare, anomalous
polymict ureilite containing large carbonaceous grains (Jenniskens et
al. 2009). Here we report the first amino acid analysis of a meteorite
from an F-type asteroid as part of the Almahata Sitta meteorite sample
analysis consortium. A single fragment (piece #4, 1.2 grams) was crushed
to a powder, and separate 0.1 g aliquots of the same meteorite were
carried through identical hot-water extraction, acid hydrolysis and
desalting procedures at NASA Goddard Space Flight Center and the Scripps
Institution of Oceanography. The o-phthaldialdehyde/N-acetyl-L-cysteine
amino acid derivatives in the extracts were analyzed by high performance
liquid chromatography with UV fluorescence detection and time-of-flight
mass spectrometry. Analyses of the meteorite extracts revealed a complex
distribution of two- to six-carbon aliphatic amino acids with abundances
ranging from 0.5 to 69 parts-per-billion (ppb). Glycine was the most
abundant amino acid detected, however, since this protein amino acid
is a common terrestrial contaminant, we are currently unable to rule
out at least a partial terrestrial source. However, the D/L ratio
of alanine in the meteorite was racemic, suggesting that very little
terrestrial amino acid contamination. Several non-protein amino acids
that are rare in the biosphere were also identified in the meteorite
above background levels including D,L-4-amino-2-methybutyric acid
(65 ± 8 ppb), D-isovaline (1.3 ± 0.1 ppb), L-isovaline (1.4 ± 0.1
ppb), and α-aminoisobutryic acid (7.1 ± 5.8 ppb). The abundance of
isovaline and AIB are 1000 times lower than the abundances found in
the CM2 meteorite Murchison while D,L-4-amino-2-methybutyric acid is
similar. The very low amino acid abundances and the presence of several
amino acid decomposition products including methylamine, ethylamine,
and isopropylamine are consistent with extensive thermal alteration
of organic compounds on the parent asteroid.

---------------------------------------------------------
Title: Exploration of amino acid biomarkers in polar ice with the
Mars Organic Analyzer
Authors: Jayarajah, C.; Botta, O.; Aubrey, A.; Parker, E.; Bada, J.;
Mathies, R.
2009AGUSM.P11A..08J Altcode:
A portable microfabricated capillary electrophoresis (CE) system
named the Mars Organic Analyzer (MOA) has been developed to analyze
fluorescently-labeled biomarkers including amino acids, amines,
nucleobases, and amino sugars with the goal of life detection on Mars
(1,2). This technology has also been shown to be effective in screening
the formation of biogenic amines during fermentation (3). The MOA is
a part of the Urey instrument package that has been selected for the
2016 European ExoMars mission by ESA. The identification of recent gully
erosion sites, observations of ice on and beneath the surface of Mars,
and the discovery of large reservoirs of sub-surface ice on Mars point
to water-ice as an important target for astrobiological analyses. In
addition, the ice samples on the Moon, Mercury, Europa and Enceladus are
of interest due to the possibility that they may contain information
on biogenic material relevant to the evolution of life. We explore
here the use of the MOA instrument for the analysis of amino acids in
polar ice samples. The amino acids valine, alanine/serine, glycine,
glutamic acid, and aspartic acid were found in the parts-per-billion
range from Greenland ice-core samples. Chiral analysis of these samples
yielded D/L ratios of 0.51/0.09 for alanine/serine and 0.14/0.06 for
aspartic acid. Individual amino acids in the parts-per-trillion range
were found in Antarctic ice samples collected from the surface of a
meteorite collection area. The distinct amino acid and amine content
of these samples indicates that further biomarker characterization of
ice samples as a function of sampling location, depth, and structural
features will be highly informative. The rapid sensitive analysis
capabilities demonstrated here establish the feasibility of using
the MOA to analyze the biomarker content of ice samples in planetary
exploration. 1. Skelley, A. M.; Scherer, J. R.; Aubrey, A. D.; Grover,
W. H.; Ivester, R. H. C., Ehrenfreund, P.; Grunthaner, F. J.; Bada,
J. L.; Mathies, R. A. PNAS, 2005, 192, 1041. 2. Skelley, A. M.,
Cleaves, H. J., Jayarajah, C. N., Bada, J. L. and Mathies, R. A.,
Astrobiology 2006, 6, 824. 3. Jayarajah, C.N., Skelley, A.M., Fortner,
A.D., and Mathies, R.A., Anal. Chem. 2007, 79, 21, 8162.

---------------------------------------------------------
Title: Hydrodynamics, magnetohydrodynamics, and astrophysical plasmas
Authors: Parker, E. N.
2009cwse.conf...23P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Magnetism: The State of Our Knowledge and Ignorance
Authors: Parker, E. N.
2009SSRv..144...15P Altcode: 2008SSRv..tmp..170P
We review some longstanding scientific mysteries related to solar
magnetism, with final attention to the mystery of the “turbulent
diffusion” essential for the theoretical α ω-dynamo that is
believed to be the source of the magnetic fields of the Sun. Fundamental
difficulties with the concept of turbulent diffusion of magnetic fields
suggest that the solar dynamo problem needs to be reformulated. An
alternative dynamo model is proposed, but it remains to be shown that
the model can provide the quantitative aspects of the cyclic magnetic
fields of the Sun.

---------------------------------------------------------
Title: Solar Magnetism: The State of Our Knowledge and Ignorance
Authors: Parker, E. N.
2009odsm.book...15P Altcode:
We review some longstanding scientific mysteries related to solar
magnetism, with final attention to the mystery of the "turbulent
diffusion" essential for the theoretical α ω-dynamo that is believed
to be the source of the magnetic fields of the Sun. Fundamental
difficulties with the concept of turbulent diffusion of magnetic fields
suggest that the solar dynamo problem needs to be reformulated. An
alternative dynamo model is proposed, but it remains to be shown that
the model can provide the quantitative aspects of the cyclic magnetic
fields of the Sun.

---------------------------------------------------------
Title: Minor Planet Observations [705 Apache Point]
Authors: Becker, A.; Babylon, E.; Hollingsworth, T.; Becker, A. C.;
Puckett, A. W.; Hendrickson, S.; Vasquez, L.; Zumwalt, L.; Burton,
M.; Dilucchio, H.; Higley, E.; Warnock, L.; Brady, S.; Gablehouse,
G.; Kintz, K.; Ouellette, A.; Parker, E.; Ratley, L.; Holmes-Perry,
K.; Hovden, L.; King, C.; Leemhuis, J.; Pascall, R.; Schwebke, J.
2008MPC..64488...6B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ironstone Concretions - Analogs to Martian Hematite Spherules
Authors: Aubrey, A. D.; Parker, E.; Chalmers, J. H.; Lal, D.; Bada,
J. L.
2007LPI....38.2053A Altcode:
We report herein physical and chemical characterization of a new
terrestrial analog to the martian "blueberries" found throughout San
Diego County.

---------------------------------------------------------
Title: Conversations on Electric and Magnetic Fields in the Cosmos
Authors: Parker, Eugene N.
2007cemf.book.....P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Wind
Authors: Parker, E. N.
2007hste.book...96P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Interstellar Conditions and Planetary Magnetospheres
Authors: Parker, Eugene N.
2006ASSL..338...87P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Heating the Solar X-Ray Corona
Authors: Parker, E. N.
2005ESASP.596E...1P Altcode: 2005ccmf.confE...1P
No abstract at ADS

---------------------------------------------------------
Title: Principles of Magnetohydrodynamics, with Applications
to Laboratory and Astrophysical Plasma. By H. GOEDBLOED &amp;
S. POEDT. Cambridge University Press, 2004. 632 pp. ISBN 0521 623472,
£80 (hardback); ISBN 0521 626072, £40 (paperback)
Authors: Parker, E. N.
2004JFM...519..377P Altcode:
Available from <A
href="http://dx.doi.org/10.1017/S0022112004001466">http://dx.doi.org/10.1017/S0022112004001466</A>

---------------------------------------------------------
Title: New Seafloor Map of the Puerto Rico Trench Helps Assess
Earthquake and Tsunami Hazards
Authors: ten Brink, Uri; Danforth, William; Polloni, Christopher;
Andrews, Brian; Llanes, Pilar; Smith, Shepard; Parker, Eugene;
Uozumi, Toshihiko
2004EOSTr..85..349T Altcode: 2004EOSTr..85..349B
The Puerto Rico Trench, the deepest part of the Atlantic Ocean,
is located where the North American (NOAM) plate is subducting under
the Caribbean plate (Figure 1). The trench region may pose significant
seismic and tsunami hazards to Puerto Rico and the U.S. Virgin Islands,
where 4 million U.S. citizens reside. Widespread damage in Puerto
Rico and Hispaniola from an earthquake in 1787 was estimated to be
the result of a magnitude 8 earthquake north of the islands. A tsunami
killed 40 people in NW Puerto Rico following a magnitude 7.3 earthquake
in 1918. Large landslide escarpments have been mapped on the seafloor
north of Puerto Rico, although their ages are unknown. The Puerto Rico
Trench is atypical of oceanic trenches. Subduction is highly oblique
(10°-20°) to the trench axis with a large component of left-lateral
strike-slip motion. Similar convergence geometry is observed at the
Challenger Deep in the Mariana Trench, the deepest point on Earth. In
addition to its extremely deep seafloor, the Puerto Rico Trench is also
characterized by the most negative free-air gravity anomaly on Earth,
-380 mGal, located 50 km south of the trench, where water depth is
7950 m (Figure 2). A tilted carbonate platform provides evidence for
extreme vertical tectonism in the region. This platform was horizontally
deposited over Cretaceous to Paleocene arc rocks starting in the Late
Oligocene. Then, at 3.5 Ma, the carbonate platform was tilted by 4°
toward the trench over a time period of less than 40 kyr, such that its
northern edge is at a depth of 4000 m and its reconstructed elevation
on land in Puerto Rico is at +1300 m (Figures 1 and 2).

---------------------------------------------------------
Title: The Microworld of the Solar Corona
Authors: Parker, Eugene
2004APS..APR.Q1003P Altcode:
The corona of the Sun, visible during an eclipse of the Sun, has been
a challenge to physics for more than a century, and, for all the
scientific progress, the dynamical microstructure of the corona is
only beginning to be revealed. To begin, there are three distinct
states of the million degree coronal gas: The weak-field coronal
hole, and the strong field, X-ray emitting, bipolar magnetic regions,
and the active corona surrounding the bipolar regions. Their origin
leads into the microworld of the magnetic fields, with the intense
magnetic fibrils at the visible surface, the magnetic carpet, and
the interlaced bipolar field lines, with the associated nanoflares,
microflares, and flares, and all with internal scales of 100 km or
less. Unfortunately 100 km is well below the limit of resolution of
existing telescopes. An essential step forward is the proposed Advanced
Technology Solar Telescope, a 4m ground based telescope with adaptive
optics providing resolution down to 50 km, together with rapid cadence,
high dispersion spectroscopy to follow the action.

---------------------------------------------------------
Title: Universal Magnetic Reconnection And Coronal Heating
Authors: Parker, E. N.
2004hell.conf....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Foreword (Dynamic Sun)
Authors: Parker, E. N.
2003dysu.bookD..15P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Advance Solar Telescope and Future Solar Physics
Authors: Parker, E. N.
2002AAS...200.3401P Altcode: 2002BAAS...34..690P
The magnetic activity of the Sun, with its terrestrial outreach,
is conventionally defined in terms of the larger magnetic features
on the surface of the Sun, while the evolution of the large
magnetic features is largely determined by their small-scale fibril
structure. Unfortunately the individual fibrils can be observed only
as unresolved bright blobs. Thus their frequent interactions, their
internal structure, and the associated dynamical flows all remain
a mystery, which prevents our constructing a definitive dynamical
theory of the large-scales and of solar activity in general. The
microscopic world of magnetic fibrils awaits investigation, requiring
a suitable telescope system with adaptive optics at an excellent site
so as to provide angular resolution of 0.1" or better on a regular
basis. The telescope must be of sufficient aperture ( 4m) to carry
on high resolution, high dispersion spectroscopy at rapid cadence to
determine the time dependent spatial structure of the gas flows and
magnetic fields on the smallest possible scales. It will be important
to follow the rapid evolution of the small flux bundle, or fibril,
as it first appears through the visible surface somewhere in the
interior of a supergranule, and then to follow the resulting magnetic
fibril as it is convected into the boundary downdrafts, and ultimately
into the junctions of several boundaries. The quiet photosphere,
the active photosphere, at both low and high latitudes, the umbra
and penumbra of sunspots of all sizes, the ephemeral active regions,
the microstructure of all classes of flares, and the microstructure
of spicules, surges and prominences are obvious immediate targets for
the high resolution telescope. We cannot anticipate what will be seen,
but whatever it turns out to be, it will move scientific comprehension
well ahead of the present limited conjectural state.

---------------------------------------------------------
Title: A history of the solar wind concept
Authors: Parker, E. N.
2002css1.book..225P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A history of early work on the heliospheric magnetic field
Authors: Parker, E. N.
2001JGR...10615797P Altcode:
The idea of a magnetic field in space around Earth began 400 years ago
with Gilbert's recognition that the magnetic field of Earth extends
outward into space to form what we now call the magnetosphere. The
concept of the solar wind and the heliosphere had its first glimmerings
with the recognition, about 270 years ago, that geomagnetic activity
is correlated with solar activity. It was suggested about a 100
years ago that the connection is through solar corpuscular radiation
with velocities of the order of 103km/s. The observed
acceleration of comet tails indicated the universal nature of solar
corpuscular radiation, giving rise to the first speculation on the
existence of the heliosphere. The hydrodynamic expansion of the million
degree solar corona was then shown to provide the solar wind (solar
corpuscular radiation), stretching out the magnetic fields of the Sun
to fill the heliosphere with a spiral magnetic field. The advent of
the space age soon verified the solar wind and magnetic field with
direct measurements.

---------------------------------------------------------
Title: A Critical Review of Sun-Space Physics
Authors: Parker, E. N.
2001Ap&SS.277....1P Altcode:
The Sun and the heliosphere form a single dynamical system, driven by
the convection in the Sun and the magnetic fields generated by that
convection. The magnetic fields are the primary channel for producing
the high temperatures and high velocities that extend outward to form
the heliosphere. The essential point is that, while the general picture
seems to be reasonable, several important steps in the process are not
understood, and several concepts commonly employed in explanation are
false physics. These scientific gaps should not be forgotten in the
rush to pursue new and exotic discoveries.

---------------------------------------------------------
Title: Magnetic reconnection and the lowest energy state
Authors: Parker, E. N.
2001EP&S...53..411P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Activity and Classical Physics
Authors: Parker, E. N.
2001ChJAA...1...99P Altcode:
This review of solar physics emphasizes several of the more conspicuous
scientific puzzles posed by contemporary observational knowledge
of the magnetic activity of the Sun. The puzzles emphasize how much
classical physics we have yet to learn from the Sun. The physics of
solar activity is based on the principles of Newton, Maxwell, Lorentz,
Boltzmann, et al., along with the principles of radiative transfer. In
the large, these principles are expressed by magnetohydrodynamics. A
brief derivation of the magnetohydrodynamic induction and momentum
equations is provided, with a discussion of popular misconceptions.

---------------------------------------------------------
Title: The heliosphere as viewed from Earth
Authors: Parker, E. N.
2001ohnf.conf..481P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Large-Scale Plasma Dynamics
Authors: Parker, E.
2000eaa..bookE2217P Altcode:
Most of the universe is occupied by gas that is electrically neutral but
more or less fully ionized, i.e. PLASMA, and permeated by a magnetic
field B on a large scale L. The plasma, driven by the energy of the
stars, is in a remarkably active, and often suprathermal, state. The
coronal mass ejection from the Sun is an example of the active state,
while the million degree corona of the Sun is an e...

---------------------------------------------------------
Title: Instability of the Stochastic Galactic Magnetic Field
Authors: Parker, E. N.; Jokipii, J. R.
2000ApJ...536..331P Altcode:
We examine the effects of the stochastic galactic magnetic field on the
dynamical instability of the interstellar gas and magnetic field. The
large-scale random walk, or meandering, of the magnetic field exerts
stresses across the average magnetic field direction, which suppress
the growth of perturbations having a small wavelength normal to the
field. The result is that, compared with a nonstochastic initial
magnetic field, those perturbations, which grow, are significantly
broadened in the direction normal to the field. Hence, the instability
in a stochastic magnetic field, such as that observed in our Galaxy,
should evolve into clouds that are more similar to those that are
observed than are those found in the absence of the stochastic field.

---------------------------------------------------------
Title: Solar Flares, the Solar Corona, and Solar Physics
Authors: Parker, E. N.
2000IAUS..195..455P Altcode:
The Sun serves as the local physics laboratory for studying the
suprathermal activity phenomena of stars. Scrutiny of the Sun has led
to the discovery of a host of previously unknown physical effects,
largely within the classical physics of Newton and Maxwell, but
including quantum mechanics and lepton physics as well.

---------------------------------------------------------
Title: Application of Shape Memory Alloys to Rock Splitting: A
Successful Example of Cooperation between Space Research and Industry
Authors: Carosio, S.; Zangani, D.; Parker, E.; Sutherland, I.
2000ESASP.470...27C Altcode: 2000aics.conf...27C
No abstract at ADS

---------------------------------------------------------
Title: TUTORIAL: Newton, Maxwell, and Magnetospheric Physics
Authors: Parker, E. N.
2000GMS...118....1P Altcode: 2000mcs..book....1P
The goal of magnetospheric physics is to understand the active
magnetosphere in terms of the principles of Newton and Maxwell. These
principles include Ampere's law, the Faraday induction equation, and
the dynamical interplay of the forces between the bulk plasma velocity
u, the plasma pressures p‖ and p⊥, and the
magnetic field B. It turns out, then, that these principles cannot be
written in terms of the electric current density j and the electric
field E, to the exclusion of u and B, in any generally useful form,
indicating that the electric current and field are not the fundamental
physical quantities sometimes claimed. Thus, the description of the
active magnetosphere in electrical terms does not directly address
the dynamics of the magnetosphere. The popular dynamical concepts
of the electric circuit analog and the active role of the electric
field E = -u×B/c in the solar wind have not been established from
Newton and Maxwell, and application to simple problems illustrates
their restrictions and errors. In contrast, magnetospheric physics
is making great strides forward using MHD modeling of the large-scale
dynamical magnetosphere, and this tutorial emphasizes the generality
of the MHD approach. We review the theoretical basis for the momentum
equation and the induction equation for the large-scale nonrelativistic
dynamics of the magnetosphere and ionosphere, showing the general MHD
character of the contending stresses and momenta.

---------------------------------------------------------
Title: LOTIS Limits on Prompt Optical Emission from GRBs
Authors: Hartmann, D. H.; Williams, G. G.; Park, H. S.; Ables, E.;
Band, D. L.; Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline,
T. L.; Ferguson, D. H.; Fishman, G. J.; Gehrels, N.; Hurley, K.;
Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E.; Porrata, R.
2000sgrb.conf...37H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: SOLSPA Summary Summary and Perspectives
Authors: Parker, E. N.
2000ESASP.463..263P Altcode: 2000sctc.proc..263P
No abstract at ADS

---------------------------------------------------------
Title: The physics laboratory in the sky
Authors: Parker, E. N.
1999CSci...77.1445P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Space Physics Before the Space Age
Authors: Parker, E. N.
1999ApJ...525C.792P Altcode: 1999ApJC..525..792P
No abstract at ADS

---------------------------------------------------------
Title: The separation of field and fluid in the Sun
Authors: Parker, E. N.; Thyagaraja, A.
1999SoPh..189...45P Altcode:
The magnetic field at the surface of the Sun is confined to widely
separated small, intense magnetic flux bundles or fibrils with most of
the gas in a relatively field free state in the interstices. There is
evidently a systematic field and fluid separation effect in operation,
overriding the tendency for turbulent mixing of the two phases. It is
well known that a constantly rotating volume of fluid soon excludes
any exterior magnetic field. To take the next theoretical step,
this paper examines the exclusion of magnetic field from a circular
cylinder with oscillating angular velocity. The result is that the
field is effectively excluded from any oscillating or tumbling body of
fluid that maintains coherence over a sufficiently long time. However,
there is no expectation of such long term coherence in turbulent
convection in the Sun, suggesting that the observed separation of
field and fluid does not come about by the exclusion of field from
convective cells. This leads to the conclusion that the separation
of fluid and field is a consequence of extraction of fluid from the
field through buoyancy and reconnection.

---------------------------------------------------------
Title: LOTIS Search for Early-Time Optical Afterglows: GRB 971227
Authors: Williams, G. G.; Park, H. S.; Ables, E.; Band, D. L.;
Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline, T. L.;
Ferguson, D. H.; Fishman, G. J.; Gehrels, N.; Hartmann, D. H.; Hurley,
K.; Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E.; Porrata, R.
1999ApJ...519L..25W Altcode: 1999astro.ph..2190W
We report on the very early time search for an optical afterglow
from GRB 971227 with the Livermore Optical Transient Imaging System
(LOTIS). LOTIS began imaging the “original” BATSE error box of
GRB 971227 ~14 s after the onset of gamma-ray emission. Continuous
monitoring of the position throughout the evening yielded a total
of 499 images (10 s integration). Analysis of these images revealed
no steady optical afterglow brighter than R=12.3+/-0.2 in any single
image. Co-addition of the LOTIS images also failed to uncover transient
optical emission. In particular, assuming a constant early-time
flux, no optical afterglow brighter than R=14.2+/-0.2 was present
within the first 1200 s, and no optical afterglow brighter than
R=15.0+/-0.2 was present in the first 6.0 hr. Follow-up observations
by other groups revealed a likely X-ray afterglow and a possible
optical afterglow. Although subsequent deeper observations could
not confirm a fading source, we show that these transients are not
inconsistent with our present knowledge of the characteristics of
gamma-ray burst afterglows. We also demonstrate that with the upgraded
thermoelectrically cooled CCDs, LOTIS is capable of either detecting
very early time optical afterglow or placing stringent constraints
on the relationship between the gamma-ray emission and the longer
wavelength afterglow in relativistic blast-wave models.

---------------------------------------------------------
Title: Space physics before the space age
Authors: Parker, E. N.
1999AIPC..471....3P Altcode: 1999sowi.conf....3P
The concept of space and the ponderable dynamical activity in space
have a long history of development, going back centuries and millenia,
and what is commonplace today should not be considered apriori obvious,
however “obvious” it may seem now that it has been discovered and
studied. The development of space physics over the centuries has
followed close on the heels of the development of physics. With the
fundamental laws of classical physics well in hand today, present space
physics research aims at direct discovery of the diverse phenomena
occurring in space, followed by sufficiently detailed quantitative
study to understand how the effects follow from the basic principles
of Newton, Maxwell, Boltzmann, et al. The pursuit of space physics
often turns up new twists to the “old” physics of the terrestrial
laboratory, made possible by the vastly greater dimensions of space. The
present review traces the development of physics and its application
to space physics from classical times to the early years of the space
age, when direct in situ studies of space became possible.

---------------------------------------------------------
Title: Solar physics: Sunny side of global warming
Authors: Parker, E. N.
1999Natur.399..416P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: It Started with George Ellery Hale
Authors: Parker, E. N.
1999AAS...194.5703P Altcode: 1999BAAS...31..915P
With his invention of the spectroheliograph, showing the structure
and activity of the surface of the Sun, and with his spectroscopic
determination of the magnetic character of the sunspot, Hale initiated
a line of research that has brought us deeper into the mysteries of the
Sun with each passing decade. The flare is perhaps the most spectacular
aspect of the activity, along with the more recently discovered coronal
mass ejection. However, we must not overlook the spectacular revelation,
by Grotrian, Edlen, and Lyot, that the outer atmosphere of the Sun
has a temperature of a million or more degrees K, providing both radio
and X-ray emission. It is all too often forgotten in these heady times
that, while we have a number of plausible ideas about how things work,
there is not yet a clear understanding of why a late main sequence
star should exhibit such effects. Magnetic fields generated by some
form of MHD dynamo appear to initiate the suprathermal activity in
all its many forms. The intensely fibril form of the magnetic fields
seems to be a clue to the nature of the dynamo process, and the first
observational priority now is to develop a 4m telescope with an adaptive
optics system that can properly resolve the individual fibrils at the
visible surface (0.1" or better)to determine their behavior. Indeed
the nature of the sunspot, the faculae and plages,the microflare,
etc. all lie at the limits of telescopic resolution. The varying
brightness of the Sun seems to be a byproduct of the magnetic activity,
and besides the consequences for the climate at Earth, provides another
baffling clue to the puzzle. We cannot guess what further marvels will
be discovered before the puzzle is resolved in hard scientific terms,
but we may be certain that Hale would have been enchanted, and probably
leading the charge, were he alive today.

---------------------------------------------------------
Title: Fifty Years of the Galactic Magnetic Field
Authors: Parker, E. N.
1999AAS...194.2503P Altcode: 1999BAAS...31..863P
Scientific awareness of the galactic magnetic field had its beginning
in the years 1948 - 1951 with Fermi's work on cosmic rays, and the
observation of the polarization of dust reddened starlight by Hiltner
and Hall, and the interpretation of the polarization in terms of
magnetically aligned dust grains by Spitzer and Tukey and by Davis
and Greenstein. The field was more or less along the local spiral
arm, with large fluctuations on scales of 100 pc. Faraday rotation
measurements indicated a strength of the order of a few microgauss,
and dynamical considerations on the structure of the gaseous disk of
the galaxy suggested similar values. By 1966 it was clear that the
magnetic field and the cosmic ray gas were tied to the interstellar
gas to form an unstable active tripart dynamical system. The system is
continually inflated by blast waves from supernovae and particularly by
the cosmic ray gas from supernovae, which extend lobes of the galactic
magnetic field outward at speeds of the order of 50 km/sec in both
directions from the disk of the Galaxy to form the galactic halo. The
dissipation of shock waves and the dissipation of magnetic field in
the halo evidently provide the multi-million degree gas responsible
for the x-ray emission from the halo, best seen from galaxies other
than our own. The concentration of magnetic field in and along the
spiral density waves forming the spiral arms strongly suggests that the
galactic magnetic field represents a progressive dynamo wave. However,
the dynamo theory of the galactic magnetic field has yet to establish
the nature of the field dissipation that makes the dynamo possible.

---------------------------------------------------------
Title: Magnetic Discontinuities from Field Topology
Authors: Parker, E. N.
1999Ap&SS.264....1P Altcode: 1998Ap&SS.264....1P
No abstract at ADS

---------------------------------------------------------
Title: LOTIS Constraints on Simultaneous and Early Time Optical
Emission from Gamma-Ray Bursts
Authors: Williams, G. G.; Hartmann, D. H.; Park, H. S.; Ables, E.;
Bionta, R.; Ott, L.; Parker, E.; Band, D. L.; Barthelmy, S. D.;
Butterworth, P. S.; Cline, T. L.; Gehrels, N.; Ferguson, D. H.;
Fishman, G. J.; Meegan, C. A.; Kouveliotou, C.; Hurley, K.
1998AAS...192.4304W Altcode: 1998BAAS...30..874W
LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst
(GRB) optical counterpart search experiment capable of imaging an
initial GRB error box within 10 s of the start of a burst. This early
response, often simultaneous with gamma-ray emission, is accomplished
by utilizing a fully automated rapidly slewing telescope linked to
the GRB Coordinates Network (GCN). The LOTIS telescope consists of
four cameras configured in a 2 x 2 array with a total field-of-view
of 17.4(deg) x 17.4(deg) . Since routine operations began in October
1996 LOTIS has responded to more than 40 GCN triggers. We will
report on LOTIS observations which have placed upper limits on the
ratio of simultaneous optical to gamma-ray flux. A recent upgrade to
thermoelectric cooled CCDs increased the LOTIS sensitivity to V ~ 15
(10 s integration) extending the capability of detecting or further
constraining simultaneous optical activity from GRBs. In addition to
LOTIS, Super-LOTIS, a fully automated 60 cm reflector with a limiting
magnitude of V ~ 19 will soon begin a dedicated search for optical
counterparts of GRBs. Both the upgraded LOTIS system and Super-LOTIS
will also search for very early time optical afterglow from GRBs.

---------------------------------------------------------
Title: Super-LOTIS a high-sensitive optical counterpart search
experiment
Authors: Park, H. S.; Ables, E.; Band, D. L.; Barthelmy, S. D.;
Bionta, R. M.; Butterworth, P. S.; Cline, T. L.; Ferguson, D. H.;
Fishman, G. J.; Gehrels, N.; Hartmann, D.; Hurley, K.; Kouveliotou,
C.; Meegan, C. A.; Ott, L.; Parker, E.; Williams, G. G.
1998AIPC..428..842P Altcode: 1998hgrb.symp..842P
We are constructing a 0.6 meter telescope system to search for
early time gamma-ray burst (GRB) optical counterparts. Super-LOTIS
(Super-Livermore Optical Transient Imaging System) is an automated
telescope system that has a 0.8°×0.8° field-of-view, is sensitive
to Mv~19 and responds to a burst trigger within 5 min. This telescope
will record images of the gamma-ray burst coordinates that are given
by the GCN (GRB Coordinate Network). A measurement of GRB light curves
at early times will greatly enhance our understanding of GRB physics.

---------------------------------------------------------
Title: First year results from LOTIS
Authors: Williams, G. G.; Park, H. S.; Ables, E.; Band, D. L.;
Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline, T. L.;
Ferguson, D. H.; Fishman, G. J.; Gehrels, N.; Hartmann, D. H.; Hurley,
K.; Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E.; Wurtz, R.
1998AIPC..428..837W Altcode: 1998hgrb.symp..837W
LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst
optical counterpart search experiment located near Lawrence Livermore
National Laboratory in California. The system is linked to the GCN
(GRB Coordinates Network) real-time coordinate distribution network
and can respond to a burst trigger in 6-15 seconds. LOTIS has a total
field-of-view of 17.4°×17.4° with a completeness sensitivity of mv~11
for a 10 second integration time. Since operations began in October
1996, LOTIS has responded to over 30 GCN/BATSE GRB triggers. Seven
of these triggers are considered good events subject to the criteria
of clear weather conditions, &lt;60 s response time, and &gt;50%
coverage of the final BATSE 3σ error circle. We discuss results from
the first year of LOTIS operations with an emphasis on the observations
and analysis of GRB971006 (BATSE trigger 6414).

---------------------------------------------------------
Title: The sun: the ultimate challenge to astrophysics
Authors: Parker, E. N.
1998AdSpR..21..267P Altcode:
Among the many exotic astronomical objects available for study, the
proximity of the Sun provides the principal source of new physics,
ranging from neutrinos to the mysteries of the magnetohydrodynamic
activity and to the geological evolution of terrestrial climate. For
it must be recalled that it is not known why the Sun is compelled by
the laws of nature to produce something as familiar as the sunspot or
as unexpected as the year by year variation in irradiance. The next
decade holds exciting promise of experimental exploration of neutrino
physics, advanced helioseismic exploration of magnetic fields below the
photosphere, and high resolution glimpses of the small scale activity
and magnetic fibril behavior at the visible surface (e.g. SOHO). It
behooves the solar physics community to represent the productive state
of affairs to the rest of the astrophysical world, who need the physics
in their speculations on the nature of their unresolved objects.

---------------------------------------------------------
Title: LOTIS: A Search for Simultaneous Optical Counterparts of
Gamma-Ray Bursts
Authors: Williams, G. G.; Hartmann, D. H.; Park, H. S.; Ables, E.;
Bionta, R.; Ott, L.; Parker, E.; Band, D. L.; Barthelmy, S. D.;
Butterworth, P. S.; Cline, T. L.; Gehrels, N.; Ferguson, D. H.;
Fishman, G. J.; Meegan, C. A.; Kouveliotou, C.; Hurley, K.
1998BAAS...30..762W Altcode:
LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst
(GRB) optical counterpart search experiment located near Lawrence
Livermore National Laboratory in California. The LOTIS telescope
consists of a 2 x 2 array of cameras mounted on a rapidly slewing
mount. The system is fully automated and linked to the GRB Coordinates
Network (GCN). Imaging of an initial GRB error box begins ~ 6--15 s
after the start of a burst. LOTIS can detect all objects brighter than
V ~ 11 (10 s integration) within a total field-of-view of 17.4(deg)
x 17.4(deg) . Since the beginning of routine operations in October
1996, LOTIS has responded to over 35 GCN triggers. We will report on
the results from the first year of LOTIS operations with an emphasis
on the photometric analysis of the observations.

---------------------------------------------------------
Title: Reflections on Macrophysics and the Sun (Special Historical
Review)
Authors: Parker, E. N.
1997SoPh..176..219P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: New Constraints on Simultaneous Optical Emission From Gamma-Ray
Bursts Measured by the Livermore Optical Transient Imaging System
Experiment
Authors: Park, H. S.; Williams, G. G.; Ables, E.; Band, D. L.;
Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline, T. L.;
Ferguson, D. H.; Fishman, G. J.; Gehrels, N.; Hartmann, D.; Hurley,
K.; Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E.; Wurtz, R.
1997ApJ...490L..21P Altcode:
LOTIS is a gamma-ray burst optical counterpart search experiment
located near Lawrence Livermore National Laboratory in California. Since
operations began in 1996 October, LOTIS has responded to five triggers
as of 1997 July 30, which occurred during good weather conditions. GRB 970223 (BATSE trigger 6100) was an exceptionally strong burst,
lasting ~30 s with a peak at ~8 s. LOTIS began imaging the error box
~11 s after the burst began and achieved simultaneous optical coverage
of 100% of the region enclosed by the BATSE 3 σ error circle and the
interplanetary network annulus. No optical transients were observed
brighter than the mV~11 completeness limit of the resulting
images, providing a new upper limit on the ratio of simultaneous
optical to gamma-ray fluence of RL&lt;1.1×10-4
and on the ratio of simultaneous optical (at 700 nm) to gamma-ray (at
100 keV) flux density of RF&lt;305 for a B-type spectrum
and RF&lt;475 for an M-type spectrum.

---------------------------------------------------------
Title: New Constraints on Simultaneous Optical Emission From GRBs
Measured by the LOTIS Experiment
Authors: Park, H. S.; Williams, G. G.; Ables, E.; Band, D. L.;
Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline, T. L.;
Ferguson, D. H.; Fishman, G. J.; Gehrels, N.; Hartmann, D.; Hurley,
K.; Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E.; Wurtz, R.
1997astro.ph..8130P Altcode:
LOTIS is a gamma-ray burst optical counterpart search experiment located
near Lawrence Livermore National Laboratory in California. Since
operations began in October 1996, LOTIS has responded to five
triggers as of July 30, 1997, which occurred during good weather
conditions. GRB970223 (BATSE Trigger #6100) was an exceptionally
strong burst lasting $\sim30$ s with a peak at $\sim8$ s. LOTIS began
imaging the error box $\sim 11$ s after the burst began, and achieved
simultaneous optical coverage of 100% of the region enclosed by the
BATSE $3\sigma$ error circle and the IPN annulus. No optical transients
were observed brighter than the m$_V \sim 11$ completeness limit of
the resulting images providing a new upper limit on the simultaneous
optical to gamma-ray fluence ratio of $R_L &lt; 1.1 \times 10^{-4}$
and on the simultaneous optical (at 700 nm) to gamma-ray (at 100 keV)
flux density ratio of $R_F &lt; 305$ for a B type spectrum and $R_F &lt;
475$ for an M type spectrum.

---------------------------------------------------------
Title: Spontaneous current sheets and stellar x-ray emission
Authors: Parker, E. N.
1997PPCF...39A...9P Altcode:
The x-ray emission from a star like the sun comes from plasma
at 106-107 K and 1010 ions
cm-3- trapped in the 100 Gauss bipolar magnetic fields
of active regions. The x-ray intensity reaches 107 ergs
cm-2s-1, which is a measure of the heat input
required to maintain the temperature of the emitting gas. The basic
energy input is photospheric convection, which swirls and intermixes the
photospheric footpoints of the bipolar magnetic fields, thereby creating
an interlaced topology of the field lines in the bipolar field above the
photosphere. The basic theorem of magnetostatics asserts that almost
all field topologies develop internal tangential discontinuities as
the field relaxes to equilibrium. The discontinuities are a necessary
and sufficient condition for the Maxwell stresses to achieve static
balance. It appears that rapid reconnection across these internal
current sheets provides the principal heat source for the x-ray corona.

---------------------------------------------------------
Title: Reply
Authors: Parker, E. N.
1997JGR...102.9657P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spontaneous current sheets and stellar x-ray emission
Authors: Parker, E. N.
1997PPCF...39....9P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Adventures With the Geomagnetic Field
Authors: Parker, E. N.
1997dima.conf..143P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Galactic Dynamos and Other Questions on the Origins of
Magnetic Fields
Authors: Parker, E. N.
1997cdc..conf..309P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Mass Ejection and a Brief History of the Solar Wind Concept
Authors: Parker, E. N.
1997cwh..conf....3P Altcode: 2006mslp.conf....3P
No abstract at ADS

---------------------------------------------------------
Title: S. Chandrasekhar and Magnetohydrodynamics
Authors: Parker, E. N.
1996JApA...17..147P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The X-ray Coronae of Solitary Late-Type Stars
Authors: Parker, E. N.
1996SoPh..169..327P Altcode:
Recent observations of the motion of the footpoints of the bipolar
magnetic fields of active X-ray regions of the Sun establish that the
footpoints are intermixed on the same characteristic time and scale as
the granule motions. It follows that the bipolar magnetic fields have
an internally interlaced topology creating magnetic free energy. It
follows from the basic theorem of magnetostatics that the topology
creates internal surfaces of tangential discontinuity which effectively
dissipate the magnetic free energy into heat. This process appears
to be the cause of the X-ray coronae of solitary late Main-Sequence
stars like the Sun.

---------------------------------------------------------
Title: Comment on “Current Paths in the Corona and Energy Release
in Solar Flares”
Authors: Parker, E. N.
1996ApJ...471..489P Altcode:
The dynamical behavior of an electrically conducting fluid containing
a magnetic field B is described by Newton's and Maxwell's equations
directly in terms of the momentum density, Reynolds stress, and Maxwell
stress, all expressed simply in terms of B and v. The mathematical
solution to the equations with the appropriate initial conditions (t =
0) and boundary conditions on B and v provides a complete and unique
description of B and v for t &gt; 0 so that further modifications
are not possible. On the other hand, the electric current paradigm
urged by Melrose provides dynamical equations that are mathematically
intractable. The declaration of an electric current analog to replace a
mathematical solution of the dynamical equations yields results that are
at variance with the solutions of Newton's and Maxwell's equations. We
suggest that a proper solution of the equations in terms of B and v
is the preferable modus operandi in large-scale astronomical scenarios.

---------------------------------------------------------
Title: Inferring Mean Electric Currents in Unresolved Fibril
Magnetic Fields
Authors: Parker, E. N.
1996ApJ...471..485P Altcode:
It is shown that the curl of the transverse magnetogram of magnetic
fields composed of unresolved separate fibrils bears no direct relation
to the mean longitudinal electric current density. The mean current
density is essentially zero, regardless of the spatial variation and
torsion of the mean field.

---------------------------------------------------------
Title: The alternative paradigm for magnetospheric physics
Authors: Parker, E. N.
1996JGR...10110587P Altcode:
This paper emphasizes that the macrodynamics of the terrestrial
magnetosphere is more effectively treated in terms of the primary
variables B and v (the B, v paradigm). The common practice of relating
the dynamics to E and j (the E, j paradigm) provides direct answers
in a variety of symmetric cases, but breaks down in even so simple
a static problem as a flux bundle displaced (perhaps by reconnection
with the magnetic field in the solar wind) from its normal equilibrium
position in a static dipole field. The essential point is that a
direct derivation from the equations of Maxwell and Newton leads
to field equations written in terms of the continuum fields B and
v. The equations can be recast in terms of E and j, of course, but
they are then unwieldy, being integrodifferential equations. Hence
the E, j paradigm, when correctly applied, is seriously limited
in its effectiveness in dynamical problems. Circumventing the
limitations with the common declaration that E is the prime mover,
actively penetrating from the solar wind into the magnetosphere,
provides dynamics that is unfortunately at variance with the results
that follow directly from Maxwell and Newton. The paper outlines the
standard derivation of the basic field equations and then goes on to
treat a variety of circumstances to illustrate the effectiveness of
the deductive B, v paradigm in the continuum dynamics of the magnetic
field and plasma. There is no attempt to develop a comprehensive model
of magnetospheric activity. However we suggest that the ultimate task
is more effectively attacked with the B, v paradigm.

---------------------------------------------------------
Title: The Sun as the Ultimate Challenge to Astrophysics: The Vital
Phase of Solar Physics
Authors: Parker, E. N.
1996mpsa.conf..399P Altcode: 1996IAUCo.153..399P
No abstract at ADS

---------------------------------------------------------
Title: Solar variability and teffestrial climate.
Authors: Parker, E. N.
1996sube.conf..117P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Questions and conjectures on the origin of stellar and galactic
magnetic fields.
Authors: Parker, E.
1996ASIC..481....1P Altcode:
The magnetic fields of the Sun and the Galaxy, as prototypes of the
fields of other stars and galaxies, appear to originate in some form
or variant of the well known αω-dynamo. However, the αω-dynamo
can function only in the presence of irreversible diffusion and
dissipation of the small-scale internal magnetic fields, requiring
effective diffusion coefficients of the order of 1012
and 1025 cm2/sec for the Sun and Galaxy,
respectively. It is hypothesized that the magnetic field of the Sun
is in an intensely fibril state throughout the convective zone, with
rapid reconnection wherever nonparallel fibrils are pressed together
by the fluid motions. The result of this scenario would seem to be a
sufficiently rapid irreversible interdiffusion of fields for successful
operation of the solar dynamo. For the Galaxy it is hypothesized that
rapid reconnection between the extended magnetic lobes or Ω-loops
that form the halo accomplished the irreversibility necessary for the
operation of the galactic dynamo.

---------------------------------------------------------
Title: Some implications of solar and stellar activity.
Authors: Parker, E.
1996ASIC..481..337P Altcode:
The astonishing variability and suprathermal activity of the Sun and
similar stars is presened as a problem in physics, about which there is
currently more conjecture than hard fact. Attention is directed to the
coronal hole, the active X-ray corona, and to the overall variation in
solar brightness. The variation of solar brightness has profound effect
on terrestrial climate. The observational difficulties are listed.

---------------------------------------------------------
Title: Theoretical Properties of Omega -Loops in the Convective Zone
of the Sun. V. Coriolis Force and the Centrifugal Potential Barrier
Authors: Parker, E. N.
1995ApJ...454..927P Altcode:
The effect of Coriolis force and centrifugal force on a rising sheet
of fluid in an otherwise rigidly rotating fluid body (representing
an idealized solar convective zone) is treated, showing the minor
effect on the Kelvin-Helmholtz instability of the rising sheet. The
principal effect is the reduction of the small centrifugal force on an
element of fluid responding to the Coriolis force. The result is that
a substantially steeper ambient superadiabatic temperature gradient
is required if the rising fluid is not to be cut off by the ambient
hydrostatic pressure. This result suggests the theoretical possibility
that there may be substantial activity of buoyant flux bundles in the
lower convective zone that is prevented from showing itself at the
visible surface of the Sun.

---------------------------------------------------------
Title: Subrahmanyan Chandrasekhar, 19 October 1910 - 21 August 1995.
Authors: Parker, E. N.
1995PhT....48k.106P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Theoretical Properties of the Omega -Loops in the Convection
Zone of the Sun. IV. Stability of Updrafts
Authors: Parker, E. N.
1995ApJ...448..942P Altcode:
This paper treats the Kelvin-Helmholtz instability of a two-dimensional
stream of fluid simulating the convective updraft described in the
two previous papers. It appears that the instability is strong enough
by itself to dismember at least the upper end of a columnar updraft
extending up from the bottom of the convective zone. On the other
hand, the tension in the vertical legs of accumulated Ω-loops may
suppress the instability in the upper portion of the updraft if the
magnetic field is in an intense fibril state. The eddy viscosity of the
ambient convection may be as large as 1013 cm2
s-1, in which case it too may stabilize the updraft
to some degree. In conclusion, it appears that the updraft may be
sufficiently stable to be recognizable as a coherent dynamical form,
thereby fulfilling the observational requirement that the Ω-loops
emerge through a localized (and only slowly shifting) site at the
visible surface. The coherence over the height of the convective zone
is the basis for the conjecture that the updraft, created by successive
emerging Ω-loops, is the principal cause of the enhancement of solar
irradiance during periods of high solar activity.

---------------------------------------------------------
Title: Physics of the Sun: The Ultimate Challenge to Astrophysics
Authors: Parker, E. N.
1995SPD....26.1212P Altcode: 1995BAAS...27..985P
No abstract at ADS

---------------------------------------------------------
Title: Theoretical Properties of Omega -Loops in the Convective Zone
of the Sun. III. Extended Updrafts
Authors: Parker, E. N.
1995ApJ...442..405P Altcode:
It was pointed out in an earlier paper that the continuing emergence
of Omega-loops at localized sites on the surface of the Sun indicates
a continuing updraft at those sites. The updraft evidently extends
all the way from the base of the convective zone to somewhat near
(approximately 109cm) the surface. We pointed out that
such updrafts enhance the convective heat transport to the surface,
accounting for a major part of the increased solar brightness or
irradiance during times of solar activity. The problem is to work out,
as much as possible, the dynamical nature of the extended updrafts,
initiated as the wakes of successive rising Omega-loops and driven
thereafter by the convective forces. The question is, does the updraft
take on a long-lived columnar form of its own, or does it never devlop
beyond a sequence of rising wakes, resembling beads on a string? The
dynamics of a columnar updraft is complicated by both the large
Reynolds number and the strong stratication of the atmosphere, and by
a total lack of direct observational information. Extended slender
updrafts are not a spontaneous occurrence in numerical simulations
of thermal convection in a stratified atmosphere, although slender
concentrated downdrafts commonly occur. This paper examines several
aspects of a columnar updrft in a convective atmosphere under various
idealized circumstances to investigate to what extent that state can
be maintained against the diminishing vorticity and expansion in the
updraft. It appears that the successive passage of Omega-loops from
the bottom to the top of the convective zone is an essential feature
of the continuing existence of the updraft.

---------------------------------------------------------
Title: Theoretical Properties of Omega -Loops in the Convective Zone
of the Sun. II. The Origin of Enhanced Solar Irradiance
Authors: Parker, E. N.
1995ApJ...440..415P Altcode:
The brightness of the Sun is observed to vary by 0.2% with the 11 yr
activity cycle. We suggest that the brightness increase with magnetic
activity is a direct result of the enhanced heat transport provided
by the vertical wakes of the successive Omega-loops of magnetic
field that produce the activity. The dynamics of a vertical wake in
a stratified atmosphere is relatively complicated, but the observed
rapid succession of emergence of Omega-loops at a localized site in
the middle of a bipolar active region can be understood only if an
established concentrated updraft extends up from the bottom of the
convective zones. It is these updrafts that we suggest are the major
cause of the brightness enhancement. The next paper examines some of
the dynamical characteristics of vertical wakes.

---------------------------------------------------------
Title: GONG and The Solar Dynamo
Authors: Parker, E. N.
1995ASPC...76....3P Altcode: 1995gong.conf....3P
No abstract at ADS

---------------------------------------------------------
Title: The Magnetic Field of the Galaxy
Authors: Parker, E. N.
1995fras.conf..115P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Vital phase of space science
Authors: Parker, E. N.
1994JGR....9919155P Altcode:
Space science began with the indirect phase where the activity in
space was inferred from such terrestrial phenomena as geomagnetic
storms, ionospheric variations, and fluctuations in the cosmic ray
intensity. The direct phase was initiated with spaceflight placing
instruments directly in space and permitting the direct observation of
UV and X rays, as well as precision observations of solar luminosity
variations. The evidence from these many direct studies, together
with the historical record of terrestrial conditions, shows that
the variations of the luminosity of the Sun affect the terrestrial
atmosphere at all levels, with devastating changes in climate tracking
the major changes in the activity level and luminosity of the Sun. The
quantification and understanding of this vital connection should be
the first priority of space science and geophysics, from oceans and
atmosphere through the ionosphere, magnetosphere, and all the way to the
convective zone of the Sun. It becomes the vital phase of space science,
focused on the basic science of the changing habitability of Earth.

---------------------------------------------------------
Title: Theoretical Properties of Omega -Loops in the Convective Zone
of the Sun. I. Emerging Bipolar Magnetic Regions
Authors: Parker, E. N.
1994ApJ...433..867P Altcode:
It is proposed that the observed 500 G intensity of the magnetic fields
emerging through the surface of the Sun can be understood from the
Bernoulli effect in the upwelling Omega-loops of magnetic field. It is
also proposed that the inferred 105 G azimuthal flux bundles
below the base of the convective zone can be understood as a consequence
of the large-scale buoyancy associated with the upwelling fluid in and
around the rising Omega-loop. The process fits in naturally with the
Babcock-Leighton form of the solar alpha-omega-dynamo. The emerging
Omega-loop implies the coherence of the upwelling all the way from the
bottom of the convective zone, enhancing the convective heat transport
to account for the observed variation of the solar irradiance by about
two parts in 103.

---------------------------------------------------------
Title: Comments and Perspectives
Authors: Parker, E. N.
1994ASPC...68..413P Altcode: 1994sare.conf..413P
No abstract at ADS

---------------------------------------------------------
Title: Origins of the Solar Magnetic Field
Authors: Parker, E. N.
1994smf..conf...94P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Summary comments
Authors: Parker, E. N.
1994seit.conf..527P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Replacement Concepts for Turbulent Diffusion of Magnetic
Fields in Stars and Galaxies
Authors: Parker, E. N.
1994ASIC..422..123P Altcode: 1994coma.conf..123P
No abstract at ADS

---------------------------------------------------------
Title: Theoretical Interpretation of Magnetic Activity
Authors: Parker, E. N.
1994svsp.coll..264P Altcode: 1994IAUCo.143P.264P
No abstract at ADS

---------------------------------------------------------
Title: Spontaneous current sheets in magnetic fields : with
applications to stellar x-rays
Authors: Parker, Eugene Newman
1994ISAA....1.....P Altcode: 1994QB529.P36......
Expanding upon the ideas first proposed in his seminal book Cosmical
Magnetic Fields , Eugene N. Parker here offers the first in-depth
treatment of the magnetohydrodynamic theory of spontaneous magnetic
discontinuities. In detailing his theory of the spontaneous formation
of tangential discontinuities (current sheets) in a magnetic field
embedded in highly conducting plasma, Parker shows how it can be used
to explain the activity of the external magnetic fields of planets,
stars, interstellar gas clouds, and galaxies, as well as the magnetic
fields in laboratory plasmas. Provocative and fascinating, Spontaneous
Current Sheets in Magnetic Fields presents a bold new theory that will
excite interest and discussion throughout the space physics community.

---------------------------------------------------------
Title: Anomalous Resistivity and the Evolution of Magnetic Field
Topology
Authors: Parker, E. N.
1993ApJ...414..389P Altcode:
This paper explores the topological restructuring of a force-free
magnetic field caused by the hypothetical sudden onset of a
localized region of strong anomalous resistivity. It is shown that
the topological complexity increases, with the primitive planar
force-free field with straight field lines developing field lines that
wrap half a turn around each other, evidently providing a surface of
tangential discontinuity in the wraparound region. It is suggested
that the topological restructuring contributes to the complexity of
the geomagnetic substorm, the aurora, and perhaps some of the flare
activity on the sun, or other star, and the Galactic halo.

---------------------------------------------------------
Title: A Solar Dynamo Surface Wave at the Interface between Convection
and Nonuniform Rotation
Authors: Parker, E. N.
1993ApJ...408..707P Altcode:
A simple dynamo surface wave is presented to illustrate the basic
principles of a dynamo operating in the thin layer of shear and
suppressed eddy diffusion beneath the cyclonic convection in the
convection zone of the sun. It is shown that the restriction of the
shear delta(Omega)/delta(r) to a region below the convective zone
provides the basic mode with a greatly reduced turbulent diffusion
coefficient in the region of strong azimuthal field. The dynamo takes
on the character of a surface wave tied to the lower surface z =
0 of the convective zone. There is a substantial body of evidence
suggesting a fibril state for the principal flux bundles beneath the
surface of the sun, with fundamental implications for the solar dynamo.

---------------------------------------------------------
Title: Resistive Dissipation and Magnetic Field Topology in the
Stellar Corona
Authors: Parker, E. N.
1993ApJ...407..342P Altcode:
Tangential discontinuities, or current sheets, in a magnetic
field embedded in a fluid with vanishing resistivity are created
by discontinuous fluid motion. Tangential discontinuities are also
created when a magnetic field is allowed to relax to magnetostatic
equilibrium after mixing by fluid motions (either continuous or
discontinuous) into any but the simplest topologies. This paper
shows by formal examples that the current sheets arising solely
from discontinuous fluid motions do not contribute significantly to
the dissipation of magnetic free energy when a small resistivity is
introduced. Dissipation that is significant under coronal conditions
occurs only by rapid reconnection, which arises when, and only when,
the current sheets are required by the field topology. Hence it is
topological dissipation that is primarily responsible for heating
tenuous coronal gases in astronomical settings, whether the fluid
displacements of the field are continuous or discontinuous.

---------------------------------------------------------
Title: On the Generation of “Strong” Magnetic Fields
Authors: Vainshtein, S. I.; Parker, E. N.; Rosner, R.
1993ApJ...404..773V Altcode:
We rediscuss the nature of magnetic field generation in astrophysical
systems. We show that as a result of ineffective three-dimensional
turbulent diffusion in the presence of strong azimuthal magnetic fields,
the standard dynamo equations are not likely to provide a reasonable
description of magnetic dynamos in systems such as late-type stars
and galaxies. Instead, we propose a new set of dynamo equations,
which take into account the modifications of turbulent diffusion by
strong magnetic fields.

---------------------------------------------------------
Title: Galactic cosmic rays and galactic halo X-ray emission
Authors: Parker, Eugene N.
1993cac..book....3P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Fast Dynamos, Cosmic Rays, and the Galactic Magnetic Field
Authors: Parker, E. N.
1992ApJ...401..137P Altcode:
It is suggested here that the dynamo believed to be responsible
for the magnetic field of the Galaxy is a fast dynamo due to the
dynamical reconnection of the azimuthal field of the Galaxy as the
field is deformed by the instability of the gaseous disk and the
rapid inflation of magnetic lobes by the cosmic-ray gas to form the
Galactic halo. The reconnection of adjacent lobes carries out both the
alpha effect and field dissipation essential for the existence of the
Galactic alpha-omega dynamo. The azimuthal field is generated primarily
in the gaseous disk, while the alpha effect is carried out in the halo.

---------------------------------------------------------
Title: Electron and Nuclear Counters
Authors: Parker, Eugene N.; Korff, Serge
1992NYASA..65...30P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Vortex Attraction and the Formation of Sunspots
Authors: Parker, E. N.
1992ApJ...390..290P Altcode:
A downdraft vortex ring in a stratified atmosphere exhibits universal
attraction for nearby vertical magnetic flux bundles. It is speculated
that the magnetic fields emerging through the surface of the sun
are individually encircled by one or more subsurface vortex rings,
providing an important part of the observed clustering of magnetic
fibrils to form pores and sunspots.

---------------------------------------------------------
Title: The X Ray Corona, the Coronal hole, and the Heliosphere
Authors: Parker, E. N.
1992JGR....97.4311P Altcode:
The X ray emission from the Sun arises primarily from the gas
trapped in the bipolar magnetic fields of both small and large active
regions. It appears that the trapped gas is heated by the intermittent
dissipation of magnetic energy (nanoflares) at the current sheets
that arise spontaneously in any magnetic field subject to continuous
deformation. The solar wind issues from regions of weak field pushed
open by the expanding corona. Most of the heat input is close to
the Sun, in the first 1-2 RS, raising the gas slowly out
through the gravitational field and gradually accelerating it through
the speed of sound at a distance of perhaps 3-5 RS. The
waves generated by photospheric convection dissipate only at distances
of 5 RS and beyond, where their heat input and momentum
accelerate the wind to the high velocities of 600-800 km/s sometimes
observed. The only source for the principle heat input close to the
Sun appears to be the network activity, as suggested by Martin, Porter,
and Moore. Thus the mass loss and the formation of the heliosphere are
primarily a consequence of the smallest-scale activity supplemented
by occasional flares and coronal mass ejections. The X ray emission
is largely a consequence of the smallest flares, the nanoflares,
supplemented by occasional X ray bursts from large flares. It is
presumed that the mass loss and associated circumstellar spheres and
the X ray emission from most other stars arise in the same manner,
although there is no possibility for detailed observation, of course.

---------------------------------------------------------
Title: Heating coronal holes and accelerating the solar wind
Authors: Parker, E. N.
1992sws..coll...79P Altcode:
The special energy requirements of a coronal hole combined with current
knowledge of the limited dissipation of Alfven and fast mode MHD waves
in the solar corona suggest a unique source of heat for the coronal
hole. The near coronal hole requires approximately 3 - 4 x 10 exp 5
ergs/sq cm s, which can come only from the fluid jets, fast particles,
and short period MHD waves from the network activity. The high speed
streams of solar wind from coronal holes show that there is substantial
heating, of 1 - 2 x 10 exp 5 ergs/sq cm s, beyond the sonic point in
the wind, which can come only from the dissipation by thermal conduction
of long period (approximately equal or greater than 100 sec) MHD waves
from subphotospheric convection. Although the Alfven wave flux from the
photosphere is generally taken for granted in the literature, we point
out that it is a crucial phenomenon that has yet to be established on
either a theoretical or observational scientific basis.

---------------------------------------------------------
Title: The Sunspot Phenomenon - a Commentary
Authors: Parker, E. N.
1992ASIC..375..413P Altcode: 1992sto..work..413P
The current knowledge of the sunspot phenomenon is summarized, and
some of the unanswered questions are identified. It is noted that
the reason for the formation of sunspots remains the basic unanswered
question. Attention is given to background considerations, formation
of sunspots, the penumbra phenomenon, sunspot structure, and general
theoretical problems.

---------------------------------------------------------
Title: Dynamical Buoyancy of Hydrodynamic Eddies
Authors: Parker, E. N.
1991ApJ...380..251P Altcode:
The dynamical pressure reduction within a vortex tube produces
both a tension along the tube and a general buoyancy, analogous to
magnetic flux tubes. The dynamical buoyancy causes convective cells
to rise at speeds comparable to the rms fluid velocity within the
cell. Consequently, the convective cells in a stratified atmosphere are
more active than indicated by the standard anelastic approximation. The
coherent convective cells at each level actively crowd upward into
the convective cells above, elbowing weaker cells out of the way
and flattening themselves and others against the upper surface of
the convective region. These effects can be seen in the recent SOUP
observations of the solar granulation. Deeper in the convective zone
the inhomogeneity of the buoyancy may explain the random character of
the convective motions that turns up in recent numerical simulations.

---------------------------------------------------------
Title: The optical analogy for vector fields
Authors: Parker, E. N.
1991PhFlB...3.2652P Altcode:
This paper develops the optical analogy for a general vector field. The
optical analogy allows the examination of certain aspects of a vector
field that are not otherwise readily accessible. In particular,
in the cases of a stationary Eulerian flow v of an ideal fluid and a
magnetostatic field B, the vectors v and B have surface loci in common
with their curls. The intrinsic discontinuities around local maxima in
absolute values of v and B take the form of vortex sheets and current
sheets, respectively, the former playing a fundamental role in the
development of hydrodyamic turbulence and the latter playing a major
role in heating the X-ray coronas of stars and galaxies.

---------------------------------------------------------
Title: Space plasma and its origin at the sun
Authors: Parker, E. N.
1991PhFlB...3.2367P Altcode:
This paper provides a concise review of the large picture of space
plasmas, concentrating on the heliosphere and the origin of the
X-ray corona and coronal hole at the sun. It is tentatively suggested
that the active X-ray corona is heated primarily by the dissipation
of magnetic energy at the spontaneous tangential discontinuities
(current sheets) in the confining bipolar magnetic fields of active
regions. The discontinuities arise because of the continuous mapping
of the footpoints of the field by the photospheric convection. The
coronal holes appear to be heated by a combination of Alfven waves,
providing the high-speed streams in the solar wind, and the microflaring
in the small-scale network fields.

---------------------------------------------------------
Title: The Magnetic Field of the Galaxy
Authors: Parker, E. N.
1991ICRC....5...35P Altcode: 1991ICRC...22e..35P
No abstract at ADS

---------------------------------------------------------
Title: The Phase Mixing of Alfven Waves, Coordinated Modes, and
Coronal Heating
Authors: Parker, E. N.
1991ApJ...376..355P Altcode:
Phase mixing has been a popular theoretical mechanism invoked to
dissipate the photospheric plane shear Alfven waves hypothesized to
penetrate up into the coronal hole and solar wind, thereby maintaining
the expanding coronal gas at 1.5 million K and serving as the principal
energy source for the solar wind. However, phase mixing requires
an ignorable coordinate, which is not available in the presumably
filamentary coronal hole. The filamentary density and temperature of
the coronal hole couple the waves into a coordinated mode with a unique
phase velocity omega/k, which provides the other popular theoretical
mechanism, viz, resonant absorption where the local Alfven speed C is
equal to omega/k. This provides coronal heating at radial distances
O(10 solar radii), where it serves to accelerate the solar wind to
high velocity. But it does not provide the principal heat input in
the first 1-2 solar radii, required by Withbroe's (1988) analysis of
the observed structure of the coronal hole.

---------------------------------------------------------
Title: Heating Solar Coronal Holes
Authors: Parker, E. N.
1991ApJ...372..719P Altcode:
It has been shown that the coronal hole, and the associated high-speed
stream in the solar wind, are powered by a heat input of the order of
500,000 ergs/sq cm s, with most of the heat injected in the first 1-2
solar radii, and perhaps 100,000 ergs/sq cm s introduced at distances
of several solar radii to provide the high speed of the issuing solar
wind. The traditional view has been that this energy is obtained
from Alfven waves generated in the subphotospheric convection, which
dissipate as they propagate outward, converting the wave energy into
heat. This paper reviews the generation of waves and the known wave
dissipation mechanisms, to show that the necessary Alfven waves are
not produced under the conditions presently understood to exist in
the sun, nor would such waves dissipate significantly in the first
1-2 solar radii if they existed. Wave dissipation occurs only over
distances of the order of 5 solar radii or more.

---------------------------------------------------------
Title: Convection, Spontaneous Discontinuities, and Stellar Winds
and X-Ray Emission. (Karl Schwarzschild Lecture 1990)
Authors: Parker, E. N.
1991RvMA....4....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Micro/Nanoflare Coronal Heating (With 8 Figures)
Authors: Parker, E. N.
1991mcch.conf..615P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Intrinsic magnetic discontinuities and solar X-ray emission
Authors: Parker, E. N.
1990GeoRL..17.2055P Altcode:
The fundamental theorem of magnetostatic equilibrium predicts that the
bipolar magnetic fields of active regions on the Sun contain tangential
discontinuities as an intrinsic part of their equilibrium. It appears
that rapid reconnection at these many tangential discontinuities
(nanoflares) is the primary source of heat that produces the X-ray
emitting corona. The X-ray corona Is then a cloud of nanoflares.

---------------------------------------------------------
Title: The solar probe mission
Authors: Feldman, W. C.; Anderson, J.; Bohlin, J. D.; Burlaga, L. F.;
Farquhar, R.; Gloeckler, G.; Goldstein, B. E.; Harvey, J. W.; Holzer,
T. E.; Jones, W. V.; Kellogg, P. J.; Krimigis, S. M.; Kundu, M. R.;
Lazarus, A. J.; Mellott, M. M.; Parker, E. N.; Rosner, R.; Rottman,
G. J.; Slavin, J. A.; Suess, S. T.; Tsurutani, B. T.; Woo, R. T.;
Zwickl, R. D.
1990AIPC..203..101F Altcode: 1990pacr.rept..101F
The Solar Probe will deliver a 133.5 kg science payload into a 4 Rs
perihelion solar polar orbit (with the first perihelion passage in 2004)
to explore in situ one of the last frontiers in the solar system-the
solar corona. This mission is both affordable and technologically
feasible. Using a payload of 12 (predominantly particles and
fields) scientific experiments, it will be possible to answer many
long-standing, fundamental problems concerning the structure and
dynamics of the outer solar atmosphere, including the acceleration,
storage, and transport of energetic particles near the Sun and in the
inner (&lt;65 Rs) heliosphere.

---------------------------------------------------------
Title: Solar and stellar coronae
Authors: Parker, E. N.
1990AdSpR..10i..17P Altcode: 1990AdSpR..10...17P
A review of the observational facts of the X-ray corona of the sun
suggests that the dissipation of waves plays at most a minor role in
heating the corona. On the other hand, the random continuous shuffling
and mixing of the footpoints of the bipolar magnetic fields, in which
the X-ray corona resides, causes the spontaneous appearance of current
sheets. Current sheets are highly dissipative, with a tendency to
transient bursts of magnetic reconnection. Detailed observations show
that the X-ray corona is made up of large numbers of small intense
impulsive events of the same magnitude as expected from the bursts of
reconnection. It appears, then, that it is the spontaneous current
sheets that are the direct cause of the X-ray corona, driven by the
continuous motions of the footpoints of the field in the photospheric
convection.

---------------------------------------------------------
Title: The Magnetic Field of the Sun - an Object Lesson
Authors: Parker, E. N.
1990IAUS..140....1P Altcode:
The magnetic field of the sun is created by a magnetohydrodynamic
dynamo under conditions bearing some qualitative similarities to the
apparent generation of the Galactic field in the gaseous disk of the
Galaxy. There is a similarity, too, in the extension of bipolar lobes
of the solar field above the surface of the sun and the extension of
bipolar lobes of the solar field above the surface of the sun and the
extension of bipolar lobes of the Galactic field outward from both sides
of the disk. The expected origin and activity of the galactic field
can be studied by examining the behavior of the magnetic field of the
sun. The origin of the solar magnetic field far below the surface can
be investigated as can the theoretical origin of the Galactic field,
where there is so little direct observation of the small scale motions
and magnetic fields. The activity of the magnetic field of the sun,
producing prominences, flares and X-ray corona, a solar wind, and
coronal mass ejection, can all have counterparts in the activity of
the Galactic field above the surface of the gaseous disk.

---------------------------------------------------------
Title: Bowie medal to Eugene N. Parker; Citation and reply
Authors: Jokipii, J. R.; Parker, E. N.
1990EOSTr..71..783J Altcode:
On May 30, 1990, at the Spring Meeting in Baltimore, Md., AGU
honored Eugene N. Parker of the University of Chicago with its most
prestigious award, the William Bowie Medal. The annual award is
given for outstanding contributions to fundamental geophysics and for
unselfish cooperation in research. The award citation and Parker's
response are presented below.

---------------------------------------------------------
Title: Spontaneous Discontinuities in Galactic Magnetic Fields and
the Creation of Galactic X-Ray Halos
Authors: Parker, E. N.
1990IAUS..140..169P Altcode:
The magnetic field in the gaseous disk of the Galaxy is dynamically
unstable to undulations with wavelenghts of the order of 1 kpc. The
elevated portions of the field are subject to rapid inflation
(of about 5 km/sec) by the cosmic rays produced within the gaseous
disk. The result is a magnetic halo of 1-3 x 10 to the -6th gauss,
composed of close packed bipolar lobes of field extending outward from
the surface of the disk to distances of several kpc. The inflation is
presumably irregular, producing tangential discontinuities (current
sheets) throughout the extended bipolar fields. A major portion of the
magnetic energy is dissipated by rapid reconnection at these current
sheets, heating the tenuous halo gas to temperatures of 10 to the 6th
to 10 to the 7th K and producing the X-ray emission observed from the
halos of many spiral galaxies.

---------------------------------------------------------
Title: The basic magnetostatic theorem.
Authors: Parker, E. N.
1990ppst.conf....3P Altcode:
The purpose of this paper is to familiarize the reader with a basic
theorem of magnetohydrodynamics, that tangential discontinuities
(current sheets) are an intrinsic part of the magnetostatic equilibrium
of all but the simplest field topologies. A tangential discontinuities
here refers to a surface (flux surface) across which the magnitude of
the field is continuous but the direction is not. This theorem can be
applied to the theory of heating the solar corona.

---------------------------------------------------------
Title: The cause of the solar X-ray corona.
Authors: Parker, E. N.
1990ppst.conf...63P Altcode:
This lecture takes a critical look at the cause of the active X-ray
corona of the Sun to determine how this remarkable suprathermal
phenomenon is produced. The traditional ideas run into serious
quantitative difficulty when confronted with observation. The
theoretical considerations suggest that the active X-ray corona is
maintained largely by many small reconnection events in the tangential
discontinuities that arise spontaneously in the bipolar magnetic
fields. Alfvén waves are undoubtedly present in the bipolar fields,
but their total contribution to the energy input to the active corona
is, evidently, minor.

---------------------------------------------------------
Title: Tangential discontinuities and the optical analogy for
stationary fields. VII. Effects of resistivity
Authors: Parker, E. N.
1990GApFD..55..161P Altcode:
The relatively large resistivity in the solar photosphere and
chromosphere softens the ideal tangential discontinuities of
magnetostatic equilibrium into continuous transitions in field direction
over scales of 0.1-10 km. This softening is communicated upward at the
Alfvén speed into the active solar corona. The degree of softening
is a vital part of the theory of magnetic heat input to the active
X-ray corona, because the very low resistivity of the coronal gas
provides effective dissipation only if the current sheets are reduced
to a thickness of 10-2km. A close examination of the problem shows
that the Alfvén transit time up into the corona is large compared
to the characteristic time of 1 sec in which the coronal tangential
discontinutities are formed. It also shows that the principal effect of
the resistivity is to create a thin surface layer of fluid on adjacent
flux bundles, which causes a general drift of the flux but does not
directly broaden the current sheets higher up in the field. In fact
the motions of the surface layers do not extend upwards beyond the
first winding pattern at each end of a coronal loop. It appears that
the photospheric and chromospheric resistivity is without striking
consequences for magnetic heating in the corona.

---------------------------------------------------------
Title: Spontaneous tangential discontinuities and the optical analogy
for static magnetic fields. VI. Topology of current sheets
Authors: Parker, E. N.
1990GApFD..53...43P Altcode:
The electric surface current in a tangential discontinuity in a
force-free magnetic field is conserved. The direction of the current
is halfway between the direction of the continuous fields on either
side of the surface of discontinuity. Hence the current sheets,
i.e. the surface of tangential discontinuity, have a topology that is
distinct from the lines of force of the field. The precise nature of
the topology of the current sheet depends upon the form of the winding
patterns in the field. Hence, invariant winding patterns and random
winding patterns are treated separately. Current sheets may have edges,
at the junction of two or more topological separatrices. The current
lines may, in special cases, be closed on themselves. The lines of force
that lie on either side of a current sheet somewhere pass off the sheet
across a junction onto another sheet. In most cases the current sheets
extending along a field make an irregular honeycomb. The honeycomb
pattern varies along the field if the winding pattern of the field
varies. The surface current density in a tangential discontinuity
declines inversely, or faster, with distance from its region of
origin. The edges of weaker tangential discontinuities (originating
in more distant regions) are bounded by the stronger tangential
discontinuities (of nearby origin). An examination of the force-free
field equations in a small neighborhood of the line of intersection
of two tangential discontinuities shows that the lines of force twist
around to cross the line of intersection at right angles. If the angle
between the tangential discontinuities exceeds /2, there is also the
possibilitity that the lines twist around so as to come tangent to
the line of intersection as they cross it.

---------------------------------------------------------
Title: Tangential discontinuities and the optical analogy for
stationary fields. v. formal integration of the force-free field
equations
Authors: Parker, E. N.
1990GApFD..52..183P Altcode:
This paper demonstrates the appearance of tangential discontinuities
in deformed force-free fields by direct integration of the field
equation x B = B. To keep the mathematics tractable the initial
field is chosen to be a layer of linear force-free field Bx = +
B0cosqz, By = - B0sinqz, Bz = 0, anchored at the distant cylindrical
surface π = (x2 + y2)1/2 = R and deformed by application of a local
pressure maximum of scale l centered on the origin x = y = 0. In the
limit of large R/l the deformed field remains linear, with α = q[1 +
O(l2/R2)]. The field equations can be integrated over π = R showing a
discontinuity extending along the lines of force crossing the pessure
maximum. On the other hand, examination of the continuous solutions to
the field equations shows that specification of the normal component
on the enclosing boundary π = R completely determines the connectivity
throughout the region, in a form unlike the straight across connections
of the initial field. The field can escape this restriction only by
developing internal discontinuities. Casting the field
equation in a form that the connectivity can be specified explicitly,
reduces the field equation to the eikonal equation, describing the
optical analogy, treated in papers II and III of this series. This
demonstrates the ubiquitous nature of the tangential discontinuity in
a force-free field subject to any local deformation.

---------------------------------------------------------
Title: Tangential discontinuities and the optical analogy for
stationary fields IV. High speed fluid sheets
Authors: Parker, E. N.
1990GApFD..50..229P Altcode:
It was shown in the previous paper that a sufficiently strong pressure
maximum applied to an equilibrium flux surface, by the fields on either
side of the surface, produces a gap in the flux surface. The fields
on either side make contact through the gap to produce a surface of
tangential discontinuity (current sheet). It is shown in the present
paper that there is a high speed sheet of fluid and field sliding over
the surface of discontinuity when the applied pressure moves slowly
across the flux surface. Conditions in the active X-ray corona of the
sun suggest that such sheets are generally present, with velocities
of the order of 102 km/sec, but with thicknesses too small to be
observed. More substantial high speed sheets of fluid may occur in
solar flares.

---------------------------------------------------------
Title: Intermittent Behavior of Galactic Dynamo Activities
Authors: Ko, C. M.; Parker, E. N.
1989ApJ...341..828K Altcode:
Recent observations by Beck and Golla of far-infrared and radio
continuum emission from nearby spiral galaxies suggest that the
galactic magnetic field strength is connected to the current star
formation rate. The role of star formation on the generation of
large-scale galactic magnetic field is studied in this paper. Using
a simple galactic model, it is shown how the galactic dynamo depends
strongly on the turbulent velocity of the interstellar medium. When
the star formation efficiency is high, the ISM is churned which
in turn amplifies the galactic magnetic field. Between active star
formation epochs, the magnetic field is in dormant state and decays
at a negligible rate. If density waves trigger star formation, then
they also turn on the otherwise dormant dynamo.

---------------------------------------------------------
Title: Solar and Stellar Magnetic Fields and Atmospheric Structures
- Theory
Authors: Parker, E. N.
1989SoPh..121..271P Altcode: 1989IAUCo.104..271P
This presentation reviews selected ideas on the origin of the magnetic
field of the Sun, the dynamical behavior of the azimuthal field in the
convective zone, the fibril state of the field at the photosphere,
the formation of sunspots, prominences, the spontaneous formation
of current sheets in the bipolar field above the surface of the Sun,
coronal heating, and flares.

---------------------------------------------------------
Title: Tangential discontinuities and the optical analogy for
stationary fields III. Zones of exclusion
Authors: Parker, E. N.
1989GApFD..46..105P Altcode:
This paper presents a number of formal examples of the bifurcation
of individual flux surfaces by the pressure maxima imposed by
the fields on either side. An approximate necessary and sufficient
criterion for the convexity of the pressure maximum is provided, with
application to fields with and without gaps in their flux surfaces. Gaps
automatically produce tangential discontinuities in almost all cases,
by permitting fields otherwise separated by finite distance to come in
contact. Both Euclidean and non Euclidean flux surfaces are examined,
showing that positive curvature fosters the formation of gaps while
negative curvature opposes it. The special conditions for producing
single or double gaps are pointed out. The general conditions for
producing gaps are so mild as to indicate the special character of the
familiar continuous solutions to the force-free equilibrium equations,
in which the maxima and minima of the field pressure are so arranged
as to provide flux surfaces without gaps.

---------------------------------------------------------
Title: Spontaneous tangential discontinuities and the optical analogy
for static magnetic fields. I. Force-free fields, potential fields,
and discontinuities
Authors: Parker, E. N.
1989GApFD..45..159P Altcode:
The lines of force of a magnetic field extending through an infinitely
conducting fluid between footpoints on the planes z=0 and z=L can be
wrapped and interwoven by bounded continuous motions of the footpoints
into a random sequence of arbitrary topological patterns along the
field. The sign of the topological helicity of the winding pattern
of the field vanes at random along the field. On the other hand, in
force-free equilibrium the relative helicity (=B. B/B2) is rigorously
constant along each line of force. Indeed in the limit of an endless
random sequence of independent winding patterns along the field,
the helicity falls asymptotically to zero and the field becomes curl
free. A field with constant helicity along each line of force is
obliged to create internal tangential discontinuities (in which the
sign of the curl and the helicity is arbitrary) if it is to follow
the varying topological helicity imposed by the twists and turns of
the succession of independent winding patterns.

---------------------------------------------------------
Title: Tangential discontinuities and the optical analogy for
stationary fields II. The optical analogy
Authors: Parker, E. N.
1989GApFD..45..169P Altcode:
It is shown that any stationary three-dimensional velocity field
or magnetic field is a potential field in the two dimensional
subspace of the Bernoulli surfaces S(Q) or isobaric surfaces S(p),
respectively. From this it is shown that the streamlines and the lines
of force follow the optical ray paths in S(Q) and S(p) for indices of
refraction v and B, respectively. This formal analogy shows how the
lines are refracted by variations of the pressure applied by the fluid
and field on either side. In particular, it is shown how continuous
variations of the pressure produce discontinuities (bifurcations)
in the field, forming tangential discontinuities.

---------------------------------------------------------
Title: Nanoflares and the Solar X-Ray Corona
Authors: Parker, E. N.
1988ApJ...330..474P Altcode:
Observations of the sun with high time and spatial resolution in UV and
X-rays show that the emission from small isolated magnetic bipoles is
intermittent and impulsive, while the steadier emission from larger
bipoles appears as the sum of many individual impulses. We refer
to the basic unit of impulsive energy release as a nanoflare. The
observations suggest, then, that the active X-ray corona of the sun
is to be understood as a swarm of nanoflares. This interpretation
suggests that the X-ray corona is created by the dissipation at the
many tangential discontinuities arising spontaneously in the bipolar
fields of the active regions of the sun as a consequence of random
continuous motion of the footpoints of the field in the photospheric
convection. The quantitative characteristics of the process are inferred
from the observed coronal heat input.

---------------------------------------------------------
Title: Dynamical Oscillation and Propulsion of Magnetic Fields in
the Convective Zone of a Star. V. Instability and Propulsion of
Flux Bundles
Authors: Parker, E. N.
1988ApJ...326..395P Altcode:
Simple analysis of the hydrodynamics initiated by the presence of a
coherent flux bundle in the lower half of the convective zone of a star
like the Sun indicates that bundles with diameters comparable to the
local pressure scale height (∼5 x 109 cm) are subject to
sidewise motions perhaps as fast as 103 cms-1. The
motions arise as a consequence of the bundle being squeezed between
the cool shadow above and the accumulating heat below, and because
of convective propulsion. This suggests that the equatorward motion
(102 cm s-1) of the azimuthal fields, inferred
from observations of the Sun, may be as much a consequence of the
hydrodynamics of flux bundles and meridional circulation as it is of
the dynamo effects that create the flux.

---------------------------------------------------------
Title: Dynamical oscillation and propulsion of magnetic fields in the
convective zone of a star. VI - Small flux bundles, network fields,
and ephemeral active regions
Authors: Parker, E. N.
1988ApJ...326..407P Altcode:
Simple analysis of the hydrodynamics initiated by the presence of a
coherent flux bundle in the lower half of the convective zone of a star
like the Sun indicates that bundles with diameters comparable to the
local pressure scale height (5 x 10 cm) are subject to sidewise motions
perhaps as fast as 10 cm 51 The motions arise as a consequence of the
bundle being squeezed between the cool shadow above and the accumulating
heat below, and because of convective propulsion. This suggests
that the equatorward motion (102 cm s1) of the azimuthal fields,
inferred from observations of the Sun, may be as much a consequence
of the hydrodynamics of flux bundles and meridional circulation as
it is of the dynamo effects that create the flux. Subject headings:
hydromagnetics - stars: interiors stars: magnetic

---------------------------------------------------------
Title: Dynamical Oscillation and Propulsion of Magnetic Fields in
the Convective Zone of a Star. IV. Eruption to the Surface
Authors: Parker, E. N.
1988ApJ...325..880P Altcode:
It was shown in the previous paper that the heat accumulating beneath
the azimuthal field in the convective zone of the sun initiates
a Rayleight-Taylor instability, causing tongues of gas to intrude
upward into the field. The present paper works out the conditions in an
intruding tongue of gas, showing that it penetrates all the way through
the field, emerging into the atmosphere above with a specific entropy
significantly in excess of the ambient value. The entropy is large
enough that the gas rises to the visible surface in 10 to the 6th s or
less, where it produces a bipolar magnetic region. Once the eruption to
the surface has carried away the accumulated hot gas below the field,
there remains only the general downdraft which retracts the magnetic
flux from the surface in a characteristic time of 10 to the 7th s.

---------------------------------------------------------
Title: The origins of the stellar corona.
Authors: Parker, E. N.
1988sscd.conf....2P Altcode:
This paper is a critical review of present observational facts and
theoretical developments relating to the cause of the active X-ray
corona and to the coronal holes of the sun and other late type stars.

---------------------------------------------------------
Title: Magnetic Monopole Plasma Oscillations and the Survival of
Galactic Magnetic Fields
Authors: Parker, E. N.
1987ApJ...321..349P Altcode:
This paper explores the general nature of magnetic-monopole plasma
oscillations as a theoretical possibility for the observed Galactic
magnetic field in the presence of a high abundance of magnetic
monopoles. The modification of the hydromagnetic induction equation
by the monopole oscillations produces the half-velocity effect,
in which the magnetic field is transported bodily with a velocity
midway between the motion of the conducting fluid and the monopole
plasma. Observational studies of the magnetic field in the Galaxy, and
in other galaxies, exclude the half-velocity effect, indicating that the
magnetic fields is not associated with monopole oscillations. In any
case the phase mixing would destroy the oscillations in less than 100
Myr. The conclusion is that magnetic monopole oscillations do not play
a significant role in the galactic magnetic fields. Hence the existence
of galactic magnetic fields places a low limit on the monopole flux,
so that their detection - if they exist at all - requires a collecting
area at least as large as a football field.

---------------------------------------------------------
Title: The Dynamical Oscillation and Propulsion of Magnetic Fields
in the Convective Zone of a Star. II. Thermal Shadows
Authors: Parker, E. N.
1987ApJ...321..984P Altcode:
The dynamics of thermal shadows which develop in the convective zone
of a star around an insulating obstacle such as a horizontal band in
intense magnetic field are studied. The depth of the shadow on the
cool side of the obstacle is found to depend largely on the width of
the obstacle multiplied by the temperature gradient. Thermal shadows
pressing fields up to 10,000 G downward against the bottom of the
convective zone are produced by the broad bands of the azimuthal field
in the sun's convective zone. In the third part, the time-dependent
accumulation of heat beneath a thermal barrier simulating such a band
in the lower convective zone of the sun is considered. The resulting
Rayleigh-Taylor instability is shown to cause tongues of heated gas
to penetrate upward through the field, providing the emerging magnetic
fields that give rise to the activity of the sun.

---------------------------------------------------------
Title: The Dynamical Oscillation and Propulsion of Magnetic Fields
in the Convective Zone of a Star. III. Accumulation of Heat and the
Onset of the Reyleigh-Taylor Instability
Authors: Parker, E. N.
1987ApJ...321.1009P Altcode:
This paper studies the time-dependent accumulation of heat beneath a
thermal barrier simulating a broad band of intense azimuthal field in
the lower convective zone of the Sun, or other star. The accumulating
heat causes the gas density beneath the field to decline (Δρ/ρ =
-ΔT/T) to the point that the gas is less dense than the gas within the
magnetic field (where Δρ/ρ = -β2/8πp). The resulting
Rayleigh-Taylor instability causes tongues of heated gas to penetrate
upward through the field. We suggest that the tongues of hot gas take
on the nature of thermal plumes, extending all the way to the surface,
where they provide the emerging magnetic fields that give rise to the
activity of the Sun. The whole process, beginning with the accumulation
of heat, followed by the onset of the Rayleigh-Taylor instability,
and the extension of tongues of hot gas into thermal plumes to the
surface, is estimated to take a week or two, in agreement with the
observed weekly emergence of thermal plumes and magnetic flux in
activity complexes at the surface.

---------------------------------------------------------
Title: Stimulated dissipation of magnetic discontinuities and the
origin of solar flares.
Authors: Parker, E. N.
1987SoPh..111..297P Altcode:
It is proposed that the principal cause of the confined solar flare is
the dissipation of magnetic energy at the many small-scale pre-existing
tangential dscontinuities in the local bipolar magnetic field. The
discontinuities are a consequence of the continuous shuffling and
intermixing of the footpoints of the bipolar field by the turbulent
photospheric granules. The X-ray corona within the bipolar field
is presumed to be a consequence of the continuing dissipation by
reconnection at these discontinuities. A flare results when static
deformation and/or internal agitation of the field stimulates the onset
of rapid reconnection at the many small internal discontinuities. The
discontinuities are partially exhausted by the flare, so that the
post-flare X-ray emission of that particular loop is substantially below
the pre-flare level for a period of some hours while the discontinuities
are being rejuvenated.

---------------------------------------------------------
Title: Small-scale energy storage and release as the cause of the
stellar X-ray corona.
Authors: Parker, E. N.
1987NASCP2483...89P Altcode: 1987tphr.conf...89P
It has yet to be established why ordinary stars possess X-ray
coronas. Detailed observations of the Sun make it doubtful that the
X-ray corona is produced by the dissipation of Alfven waves. The
uniform X-ray brightness over all scales from 10,000 to 100,000 km
simply does not look like a resonance phenomenon. It is demonstrated
that the arbitrary winding patterns introduced into the bipolar magnetic
fields of X-ray corona produce discontinuities within the field. It is
suggested that the random motions of the footprints of the field cause
the accumulation of internal strains in the field, which dissipate
through neutral reconnection across the associated discontinuities to
provide the primary heat source for the X-ray corona. It is emphasized,
however, that the essential high resolution observations of the Sun
have yet to be carried out, and until the theory is firmly established
for the Sun, it cannot be known how to interpret the X-ray emission
of the Sun or of the other stars.

---------------------------------------------------------
Title: Why do stars emit x rays?
Authors: Parker, Eugene N.
1987PhT....40g..36P Altcode:
Because X-ray emission is the principal means of energy loss from
most stellar coronas, X-ray luminosity may be taken as a measure of
the energy input needed to produce the corona. If, moreover, it were
known why the sun is made to generate patches of bright X-ray corona,
the X-ray emission could be used as a diagnostic tool for probing
the properties of other stars. Attention is presently given to stars
with surface temperatures below about 7000 K, such as the sun, to
elucidate such phenomena as wrapping and interweaving of the magnetic
lines of force in a bipolar magnetic region, the twisting of a single
flux bundle in an otherwise uniform field, and future prospects being
developed by NASA for more intensive study of solar X-ray processes.

---------------------------------------------------------
Title: Magnetic Reorientation and the Spontaneous Formation of
Tangential Discontinuities in Deformed Magnetic Fields
Authors: Parker, E. N.
1987ApJ...318..876P Altcode:
This paper provides an explicit illustration of the formation of
tangential discontinuities (current sheets) in a force-free magnetic
field whose footpoints have been subjected to bounded continuous
displacement and shuffling, so that the lines of force are wound about
each other in complex but continuous patterns. The discontinuities
appear spontaneously because of the reorientation of the field under
the enhanced pressure where two regions of different field topology
are pressed together by the general winding and wrapping.

---------------------------------------------------------
Title: The energy source of the interplanetary medium and the
heliosphere.
Authors: Parker, Eugene N.
1987NASCP2464...75P Altcode: 1987ess..nasa...75P
The activity of the interplanetary medium arises from occasional
transient outbursts of the active corona and, for the most part, from
the interaction of fast and slow streams in the solar wind. The basic
driver is the heat input to the corona, both transient and steady. The
fast streams issue from coronal holes where the heat input may be Alfven
waves with root mean squared (rms) fluid velocities of nearly 100
km/sec or may be wholly or in part the waves refracted into the hole
from neighboring active regions. If the latter, then the character of
the wind from the coronal hole depends upon the proximity and vigor of
active regions, with significant differences between the polar and low
altitude solar wind. In any case, there is no observational support for
any of these ideas, so that the primary cause of the wind from the Sun,
as well as any other similar star is not without mystery. It is to be
hoped that ground-based observations together with the input from the
Solar Optical Telescope and the International Solar Polar Mission may
in time succeed in clearing up some of the basic questions.

---------------------------------------------------------
Title: The Dynamo Dilemma
Authors: Parker, E. N.
1987SoPh..110...11P Altcode:
The recent determination that the angular velocity Ω of the Sun
declines downward through the convective zone raises serious questions
about the nature of the solar dynamo. The principal qualitative features
of the Sun are the azimuthal fields that migrate toward the equator
in association with an oscillating poloidal field which reverses at
about the time of maximum appearance of bipolar magnetic regions. If
Ω decreases downward, or is negligible, the horizontal gradient in Ω
produces a dynamo with some of these essential characteristics. There
is reason to think that the dynamo is confined to the lower half of
the convective zone where α has the opposite sign from the usual (α
&gt; 0 in the northern hemisphere) producing equatorward migration
but reversing the sign of the associated poloidal field. Meridional
circulation may play an essential role in shaping the dynamo. At the
present time it is essential to measure Ω accurately and determine
the nature of the meridional circulation.

---------------------------------------------------------
Title: The dynamical origin of active magnetic regions at the surface
of theSun and other stars.
Authors: Parker, E. N.
1987PBeiO...9....2P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Activity Complexes, Thermal Relaxation Oscillations,
and the Dynamics of the Azimuthal Magnetic Field of a Star
Authors: Parker, E. N.
1987ASSL..137..289P Altcode: 1987isav.symp..289P
The large amount of magnetic flux cycling through an activity complex
in a period of six months suggests that the azimuthal magnetic field in
the convective zone of the Sun is not less than 3×103gauss
and probably is considerable more. A field of 3 kilogauss or more
has the effect of blocking the convective heat transport, producing a
cool shadow above the azimuthal field and causing heat to accumulate
below. The incremental weight of the cool shadow is sufficient to
overpower the magnetic buoyancy, pressing the field against the bottom
of the convective zone. The accumulation of heat underneath produces a
thermal relaxation oscillation that erupts to the surface at intervals
of the order of a week, supplying the intermittent emergence of magnetic
flux observed in the activity complex.

---------------------------------------------------------
Title: The causes of the corona of a star.
Authors: Parker, E. N.
1987PBeiO...9....7P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical Oscillation and Propulsion of Magnetic Fields
in the Convective Zone of a Star. I. General Considerations
Authors: Parker, E. N.
1987ApJ...312..868P Altcode:
Observations of the sun show that the magnetic flux of the large
activity complexes emerges in localized sites in brief bursts at
intervals of many days or a few weeks. The quantity of flux arriving
at the surface suggests that the mean aximuthal field of the sun in
the lower convective zone is not less than 3000 G and may perhaps be
considerably more. Such a field inhibits the convective transport of
heat. Hence there is a cool shadow on the upper side of the field,
and that cool shadow presses downward so hard as to suppress the
magnetic buoyancy, forcing the field to remain in the lower convective
zone. The accumulation of heat below the field forces intruding fingers
of gas up through the field, forming thermal plumes extending up to
the visible surface. It is suggested that the process is intermittent,
providing a thermal relaxation oscillation with a period of the order
of one week. The activity complexes observed at the surface are the
consequence of these eruptions of fluid and entrained field from the
lower convective zone.

---------------------------------------------------------
Title: Magnetic Nonequilibrium and Current Sheet Formation
Authors: Vainshtein, S. I.; Parker, E. N.
1987sman.work..201V Altcode:
This paper investigates the equilibrium of a cluster of long
straight twisted magnetic flux tubes extending in the z-direction
in a highly conducting fluid, subject to the boundary condition that
the transverse component of the field (produced by the twisting) goes
continuously to zero at the outer boundary of the flux tubes. It is
shown that equilibrium requires that the length of the periphery of
the tube remains invariant during any deformation of the tube. From
this principle it is shown that there is equilibrium only for axial
symmetry, i.e. only for a single twisted flux tube. These examples
provide another perspective on the general absence of equilibrium,
and consequent rapid dissipation, of any magnetic field subject to
small-scale internal strains, such as the field extending outward from
the convective zones of stars.

---------------------------------------------------------
Title: Heating of the stellar corona.
Authors: Parker, E. N.
1986NASCP2442....9P Altcode: 1986copp.nasa....9P
The present state of development of the theory of coronal heating is
summarized. Coronal heating is the general cause of stellar X-ray
emission, and it is also the cause of stellar mass loss in most
stars. Hence a quantitive theory of coronal heating is an essential
part of X-ray astronomy, and the development of a correct theory of
coronal heating should be a primary concern of X-ray astronomers. The
magnetohydrodynamical effects involved in coronal heating are not
without interest in their own right, representing phenomena largely
unknown in the terrestrial laboratory. Until these effects can be
evaluated and assembled into a comprehensive theory of coronal heating
for at least one star, the interpretation of the X-ray emissions of
all stars is a phenomenological study at best, based on arbitrary
organization and display of X-ray luminosity against bolometric
luminosity, rotation rate, etc. The sun provides the one opportunity
to pursue the exotic physical effects that combine to heat a stellar
corona.

---------------------------------------------------------
Title: Stellar challenge
Authors: Parker, Eugene N.
1986Natur.323..210P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Physics of the Sun - V.I - the Solar Interior
- V.II - the Solar Atmosphere - V.III - Astrophysics and Solar /
Terrestrial Relations
Authors: Sturrock, P. A.; Holzer, T. E.; Mihalas, D. M.; Ulrich,
R. K.; Parker, E. N.
1986Natur.323..210S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Nonequilibrium and Current Sheet Formation
Authors: Vainshtein, S. I.; Parker, E. N.
1986ApJ...304..821V Altcode:
This paper investigates the equilibrium of a cluster of long,
straight, twisted magnetic flux tubes extending in the z-direction
in a highly conducting fluid, subject to the boundary condition
that the cluster is surrounded by a uniform pressure P. It is shown
that there is equilibrium only for axial symmetry, i.e., only for a
single twisted flux tube. Any more complicated cluster of twisted
tubes is subject to nonequilibrium reconnection of the transverse
component of the field. The example provides another perspective on
the general absence of equilibrium, and consequent rapid dissipation,
of any magnetic field subject to random small-scale internal strains,
such as the fields extending outward from the convective zones of stars.

---------------------------------------------------------
Title: Present Knowledge, Problems and Questions concerning the
Fibril Field of the Sun
Authors: Parker, E. N.
1986ssmf.conf...13P Altcode:
This paper reviews some of the dilemmas presently posed by the magnetic
fields of the sun, particularly the intense fibril state of the field
at the visible surface. The fibril state has been conjectured to extend
throughout the convective zone, although there is now evidence to the
contrary. It is the agitation of the fibrils that supplies the energy
to heat the active X-ray corona, presumably through dissipation in the
thin current sheets arising from the intermixing of the footpoints. The
coronal holes are presumed to be heated by Alfvén waves from the
general agitation of fibrils. The active motion of the fibrils is a
fundamental datum in the theory of the stellar corona, and it is to
be hoped that the motions can be determined by observation in the next
few years.

---------------------------------------------------------
Title: Equilibrium of magnetic fields with arbitrary interweaving
of the lines of force. I - Discontinuities in the torsion
Authors: Parker, E. N.
1986GApFD..34..243P Altcode:
Consideration is given to the static force-free equilibrium of a
magnetic field in which all of the lines of force connect without
knotting between parallel planes. The field is formed by continuous
deformation from an initial uniform field, and is conventiently
described in terms of the scalar function psi, which is the stream
function for the incompressible wrapping and interweaving of the
lines of force. Local compression and expansion of the lines of force
is described in terms of the scalar function Phi. Equilibrium in the
field requires satisfaction of two independent equations which cannot be
accomplished without the full freedom of both psi and Phi. It is shown
that discontinuities in the torsional characteristics of the lines occur
when psi is predetermined by an arbitrary pattern. Discontinuities in
the winding pattern of the lines can lead to discontinuities in the
associated current sheets.

---------------------------------------------------------
Title: Equilibrium of magnetic fields with arbitrary interweaving
of the lines of force. II. Discontinuities in the field.
Authors: Parker, E. N.
1986GApFD..35..277P Altcode:
The surfaces of discontinuity (SDs) identified by Parker (1986) in
the torsion of a force-free magnetic field in an infinitely conducting
fluid contained betweeen two fixed boundary planes are characterized
analytically. It is shown that field discontinuities (current sheets)
occur whenever an SD terminates within the fluid or intersects with
another SD, that intersections occur in most cases, and that the
resulting current sheets are responsible for most field dissipation
in highly conducting fluids. The astrophysical implications of these
findings and a number of unresolved problems are discussed.

---------------------------------------------------------
Title: The Magnetic Structure of Solar and Stellar Atmospheres
Authors: Parker, E. N.
1986LNP...254..341P Altcode: 1986csss....4..341P
No abstract at ADS

---------------------------------------------------------
Title: The magnetic structure of solar and stellar atmospheres
Authors: Parker, E. N.
1986LNP...254..339P Altcode:
This paper summarizes the present state of knowledge and understanding
of the remarkable structure of the magnetic field of the one star where
the structure can be observed. The discussion emphasizes several of
the outstanding puzzles in the form of the field above and below the
visible surface and provides a brief survey of present theoretical
understanding, so far as it goes. Emphasis is given to the basic
observational and theoretical work that remains before we have what
might be called a theory of solar and stellar activity.

---------------------------------------------------------
Title: The Heliospheric Energy Source
Authors: Parker, E. N.
1986ASSL..123...33P Altcode: 1986shtd.symp...33P
The solar wind and the heliosphere exist as a consequence of the heat
input to the corona, particularly the coronal holes. The necessary
energy input to coronal holes has been estimated to be 10 to the 6th
erg/sq cm sec, requiring Alfven waves with rms fluid velocities of 100
km/sec. Observational upper limits on coronal fluid velocities are of
the order of 25 km/sec, which may not apply to the transparent coronal
hole. Alternatively it has been suggested that coronal holes may be
heated by agitation from neighboring active regions, suggesting that the
vigor of a coronal hole depends upon its location. The Ulysses Mission
will provide a direct comparison of the strength of the high speed wind
from coronal holes at low latitude and coronal holes at high latitude,
from which the nature of the presently unknown energy sources of the
coronal holes and the resulting structure of the heliosphere may be
better judged. The question is fundamental to the dynamics of the
windspheres of all stars.

---------------------------------------------------------
Title: The Future of Solar Physics
Authors: Parker, E. N.
1985SoPh..100..599P Altcode:
The future of solar physics is founded on the existing fundamental
unsolved problems in stellar physics. Thus, for instance, the physics
of stellar interiors has been called into serious question by the very
low-measured neutrino flux. The 71Ga neutrino detection
experiment is the next step in unravelling this mystery. If that
experiment should find the expected neutrino flux from the basic p-p
reaction in the Sun, then astrophysics is in a difficult situation,
because the most likely explanation for the low neutrino flux found in
the 37Cl experiment would be an error in our calculation of
the opacity or an error in our understanding of the elemental abundances
in stellar interiors, with serious implications for present ideas on
stellar structure and the age of the galaxy.

---------------------------------------------------------
Title: Stellar fibril magnetic systems. II - Two-dimensional
magnetohydrodynamic equations. III - Convective counterflow
Authors: Parker, E. N.
1985ApJ...294...47P Altcode:
The dynamics of magnetic fibrils in the convective zone of a star
is investigated analytically, deriving mean-field equations for
the two-dimensional transverse motion of an incompressible fluid
containing numerous small widely spaced circular cylinders. The
equations of Parker (1982) are extended to account for the inertial
effects of local flow around the cylinders. The linear field equation
for the stream function at the onset of convection is then rewritten,
neglecting large-scale heat transport, and used to construct a model
of convective counterflow. The Kelvin impulse and fluid momentum,
convective motion initiated by a horizontal impulse, and the effects
of a viscous boundary layer are considered in appendices.

---------------------------------------------------------
Title: Stellar Fibril Magnetic Systems - Part Three - Convective
Counterflow
Authors: Parker, E. N.
1985ApJ...294...57P Altcode:
The linearized equations of motion of a fibril magnetic field and
the mean fluid motion through that field are used to illustrate the
convective counterflow effect. The calculations show that starting
from static equilibrium, a vertical impulse applied to a cluster of
fibrils (represented by a cluster of parallel circular cylinders)
may result in the fluid moving either upward or downward across
the cluster, depending on the eccentricity of the cross section of
the cluster and the strength of the aerodynamic drag coupling the
fluid and fibrils. Specifically, a flattened cluster of fibrils,
with a width in excess of twice the thickness, may be carried in the
opposite direction from the initial applied impulse by the associated
counter convective motion. It appears that this counterflow effect may
operate in the upper few thousand km of the convective zone of the Sun,
where it would play a role in suppressing the buoyant rise of magnetic
flux tubes to the surface. Hence the convective counterflow may take
an active part in controlling the emergence of flux tubes through the
surface of a star like the Sun, perhaps regulating to some degree the
form and general level of the activity of the star.

---------------------------------------------------------
Title: The vector structure of active magnetic fields
Authors: Parker, E. N.
1985svmf.nasa....7P Altcode:
Observations are needed to show the form of the strains introduced into
the fields above the surface of the Sun. The longitudinal component
alone does not provide the basic information, so that it has been
necessary in the past to use the filamentary structure observed in
Halpha to supplement the longitudinal information. Vector
measurements provide the additional essential information to determine
the strains, with the filamentary structure available as a check for
consistency. It is to be expected, then, that vector measurements
will permit a direct mapping of the strains imposed on the magnetic
fields of active regions. It will be interesting to study the relation
of those strains to the emergence of magnetic flux, flares, eruptive
prominences, etc. In particular we may hope to study the relaxation
of the strains via the dynamical nonequilibrium.

---------------------------------------------------------
Title: Heating the corona of the sun.
Authors: Parker, E. N.
1985rbcc.conf..299P Altcode:
The author suggests that coronal holes are heated by the dissipation of
Alfvén waves. He also suggests that the active corona is heated by the
random walk of the footpoints of the magnetic field, causing cumulative
small-scale strains in the magnetic field. These quasi-static strains
dissipate as a consequence of the absence of magnetostatic equilibrium
for random topological distortions of the field, producing current
sheets and neutral point reconnection.

---------------------------------------------------------
Title: Equilibrium of magnetic fields with arbitrary interweaving
of the lines of force i. discontinuities in the torsion
Authors: Parker, E. N.
1985GApFD..34..243P Altcode:
This paper considers the static force-free equilibrium V×B=B of a
magnetic field in which all of the lines of force connect without
knotting between parallel planes. The field is formed by continuous
deformation from an initial uniform field, and is conveniently
described in terms of the scalar function , which is effectively the
stream function for the incompressible wrapping and interweaving of
the lines of force, and the scalar function , which describes the
local compression and expansion. Equilibrium requires satisfaction
of two independent equations (the third equation defines ), which
cannot be accomplished without the full freedom of both functions
and . It is shown by integration along the characteristics of the
equilibrium equations that, when is predetermined by an arbitrary
winding pattern, there appear discontinuities in . Discontinuities in
have discontinuities in the field (i.e. current sheets) associated with
them. We expect such discontinuities to be produced in the magnetic
fields extending outward from the convecting surfaces of the cooler
stars.

---------------------------------------------------------
Title: Solar Physics as Related to Stellar Physics
Authors: Parker, E. N.
1985spit.conf...13P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The vector structure of active magnetic fields.
Authors: Parker, E. N.
1985NASCP2374....7P Altcode:
Observations are needed to show the form of the strains introduced into
the fields above the surface of the sun. The longitudinal component
alone does not provide the basic information, so that it has been
necessary in the past to use the filamentary structure observed in
Hα to supplement the longitudinal information. Vector measurements
provide the additional essential information to determine the strains,
with the filamentary structure available as a check for consistency. It
is to be expected, then, that vector measurements will permit a direct
mapping of the strains imposed on the magnetic fields of active regions.

---------------------------------------------------------
Title: Magnetic Buoyancy and the Flux Ejection Effect in Stellar
Dynamos
Authors: Parker, E. N.
1985spit.conf..360P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Rapid Dissipation of Stellar Magnetic Fields and the
Production of X-Ray Coronas
Authors: Parker, E. N.
1985spit.conf..925P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Fields in the Radiative Interior of Stars - Part Two -
Forced Convection and the 7LI Abundance
Authors: Parker, E. N.
1984ApJ...286..677P Altcode:
Magnetic fields of various forms, and of strengths ranging up to
5×108gauss, in the radiative core of the Sun have been
hypothesized by various authors. This paper points out that the
thermal shadows of magnetic inhomogeneities in the radiative core
cause vertical mixing of fluid, with possible consequences for the
7Li abundance in the Sun. Magnetic fields of the order
of 4×105gauss with scales of 3×104km are
sufficient to provide the partial depletion of 7Li inferred
from observation. It is found that the rms field in the outer radiative
zone cannot much exceed 4×105gauss.

---------------------------------------------------------
Title: Magnetic fields in the radiative interior of stars. I Thermal
shadows and forced convection.
Authors: Parker, E. N.
1984ApJ...286..666P Altcode:
It is pointed out that magnetic fields in the radiative interior of a
star cause a slight reduction in the gas pressure, by a fraction of the
order of B2/8πp. The effect is a proportionate reduction in
the opacity and an increase in the effective heat transport coefficient,
so that magnetic inhomogeneities cast thermal shadows in the general
outflow of radiant energy. The shadows involve horizontal temperature
gradients, forcing convective circulation in the otherwise stably
stratified radiative zone. The associated vertical mixing may have
important consequences for the thermonuclear burning of 7Li
in the outer envelope of the star.

---------------------------------------------------------
Title: The rapid dissipation of magnetic fields with internal strains.
Authors: Parker, E.
1984JRASC..78..205P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Stellar fibril magnetic systems. I - Reduced energy state
Authors: Parker, E. N.
1984ApJ...283..343P Altcode:
The remarkable fibril structure of the magnetic fields at the
surface of the sun (with fibrils compressed to 1,000-2,000 gauss)
lies outside existing statistical theories of magnetohydrodynamic
turbulence. The total energy of the fibril field is enhanced by a
factor of more than 100 above the energy for the mean field in a
continuum state. The magnetic energy density within a fibril is of
the order of 100 times the local kinetic energy density, so that
no simple application of equipartition principles is possible. It
is pointed out that the total energy of the atmosphere (thermal +
gravitational + magnetic) is reduced by the fibril state of the field
by avoiding the magnetic inhibition of the convective overturning,
suggesting that the formation of the observed intense fibril state
may be in response to the associated energy reduction. Calculation
of the minimum total energy of a polytropic atmosphere permeated by
magnetic fibrils yields theoretical fibril fields of the order of 1-5
kilogauss when characteristics appropriate to the solar convective
zone are introduced, in rough agreement with the actual fields of 1-2
kilogauss. The polytrope model, although crude, establishes that a
large reduction in total energy is made possible by the fibril state.

---------------------------------------------------------
Title: Magnetic buoyancy and the escape of magnetic fields from stars
Authors: Parker, E. N.
1984ApJ...281..839P Altcode:
Magnetic buoyancy causes the azimuthal magnetic fields of stars to
rise rapidly to the surface, from where they are generally assumed
to escape freely into space. However, a closer look at the problem
reveals the simple fact that disengagement of the field from the gas,
and escape into space, require a convoluted field configuration,
producing neutral point reconnection of the flux in the tenuous gas
above the surface of the star. Only that flux which reconnects can
escape. Recent observations of the magnetic fields emerging
through the surface of the Sun show that even at sunspot maximum the
gaps in longitude between bipolar magnetic regions are so wide as to
limit severely the reconnection between regions. We suggest from the
observations that no more than perhaps 3% of the flux that is observed
to emerge through the surface is able to reconnect and escape. Hence
the surface of the Sun approximates to an impenetrable barrier rather
than an open surface, with quantitative consequences for theoretical
dynamo models. Recent observations of the retraction of bipolar
fields at the end of their appearance at the surface suggest active
dynamical control by the convection beneath the surface.

---------------------------------------------------------
Title: Depth of origin of solar active regions
Authors: Parker, E. N.
1984ApJ...280..423P Altcode:
Observations show that the individual bipolar magnetic regions on
the sun remain confined during their decay phase, with much of the
magnetic field pulling back under the surface, in reverse of the
earlier emergence. This suggests that the magnetic field is held on
a short rein by subsurface forces, for otherwise the region would
decay entirely by dispersing across the face of the sun. With the
simple assumption that the fields at the surface are controlled from
well-defined anchor points at a depth h, it is possible to relate the
length l of the bipolar region at the surface to the depth h, with
h about equal to l. The observed dimensions l about equal to 100,000
km for normal active regions, and l about equal to 10,000 km for the
ephemeral active regions, indicate comparable depths of origin. More
detailed observational studies of the active regions may be expected
to shed further light on the problem.

---------------------------------------------------------
Title: The role of flux ejection in stellar dynamos
Authors: Parker, E. N.
1984ApJ...276..341P Altcode:
Magnetic buoyancy causes the magnetic field in the convective zone of a
star to escape through the surface in times short compared to the period
of the magnetic cycle. The sun serves as a prototype, where fields of
100-1000 gauss or stronger are present in the convective zone, as part
of the 22 year magnetic cycle. The theoretical alpha-omega dynamo effect
cannot cope with the rapid escape (in a year or so) because increasing
the rate of generation of field serves also to shortern the period, to
a value comparable to the escape time. It is suggested that the flux
ejection dynamo effect may be operating in the deep convective zone,
where the cyclonic rotation of the convective cells may be as large
as 180 deg. If so, then the flux ejection effectively opposes the
buoyant rise. It is shown that the net effect of flux ejection in the
lower convective zone, and unopposed buoyancy in the upper convective
zone, permits the alpha-omega-dynamo effect to carry on the cyclic
regeneration of the magnetic field much as in the absence of either
buoyancy or flux ejection, except that the magnetic field is strongly
concentrated against the bottom of the convective zone. It is suggested
that the lower and upper regions of the dynamo may be related to the
normal and ephermeral active regions, as has already been suggested
by others on the basis of the observed distinctions in distribution.

---------------------------------------------------------
Title: Magnetic Reconnection and Magnetic Activity
Authors: Parker, E. N.
1984mrsl.conf...32P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic reconnection and magnetic activity
Authors: Parker, E. N.
1984GMS....30...32P Altcode: 1984GMS.........32P
A large-scale magnetic field extending through a highly conducting
tenuous fluid may become distorted on a small scale as a consequence
of slow small-scale shuffling of the magnetic lines of force at
the boundaries of the tenuous fluid. Any slow wrapping and winding
introduced at the boundaries is distributed along the field (at
the Alfven speed). It is a curious and little-known fact that such
wrapping and winding possesses no static equilibrium (except for a
set of solutions of extreme symmetry). The result is neutral-point
reconnection of the strains in the field, rapidly dissipating the
wrapping and winding. It is suggested that this is the principal cause
of the extreme heating that produces the active corona of the sun and
other stars. The shuffling of the footpoints of the magnetic field in
the photospheric turbulence introduces small-scale wrapping and twisting
into the coronal loops. The work done by the turbulence in twisting
the fields is dissipated within a matter 10-20 hours by neutral-point
reconnection, introducing heat into the corona at a rate of about
10 Mergs/sq cm sec for photospheric turbulence of 0.5 km/sec. It is
suggested that this is the basic cause of the X-ray corona.

---------------------------------------------------------
Title: Heating the Corona of the Sun
Authors: Parker, E. N.
1984rcch.conf..299P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Galactic magnetic fields and magnetic monopoles.
Authors: Parker, E. N.
1984mono.conf..125P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Alfvén waves in a thermally stratified fluid.
Authors: Parker, E. N.
1984GApFD..29R...1P Altcode:
The propagation of Alfvén waves along a uniform horizontal field in a
highly conducting incompressible fluid, subject to the convective forces
produced by a uniform vertical temperature gradient, is treated in a
Boussinesq approximation. It is shown that there are exact solutions
with large amplitude but restricted form.

---------------------------------------------------------
Title: Alfvén waves in a thermally stratified fluid.
Authors: Parker, E. N.
1984GApFD..29Q...1P Altcode:
The propagation of Alfvén waves along a uniform horizontal field in
a highly conducting incompressible fluid, subject to the convective
forces produced by a uniform vertical temperature gradient, is treated
in a Boussinesq approximation. It is shown that there are exact
solutions with large amplitude but restricted form. Their restricted
form means that an arbitrary disturbing force produces other motions
as well as Alfvén waves. An arbitrary initial disturbance of small
amplitude produces waves whose state of polarization varies along the
direction of propagation. For large amplitudes, however, any mixtures
of polarization states causes scattering into new modes.

---------------------------------------------------------
Title: Alfven waves in a thermally stratified fluid
Authors: Parker, E. N.
1984GApFD..29....1P Altcode:
The properties of Alfven waves propagating along a uniform horizontal
field in a highly conducting incompressible medium in the presence
of strong convective instability are examined in the Boussinesq
approximation. In particular, it is sought to determine whether
there are exact solutions to the dynamical equations in the presence
of convective forces. It is shown that a class of exact solutions
of arbitrary amplitude, but of limited form, which may be of some
physical interest, does exist. For large amplitudes, any mixtures of
polarization states are shown to cause scattering into new modes.

---------------------------------------------------------
Title: Direct coronal heating from dissipation of magnetic field.
Authors: Parker, E. N.
1983NASCP.2280..23P Altcode: 1983sowi.conf...23P
The visible corona of the Sun appears to be heated by direct dissipation
of magnetic fields. The magnetic fields in the visible corona are
tied at both ends to the photosphere where the active convection
continually rotates and shuffles the footpoints in a random pattern. The
twisting and wrapping of flux tubes about each other produce magnetic
neutral sheets in a state of dynamical nonequilibrium such that the
current sheets become increasingly concentrated with the passage of
time. Dissipation of the high current densities takes place regardless
of the high electrical conductivity of the fluid. The convection on
the feet of the lines of force at the surface of the Sun goes directly
(within a matter of 10 to 20 hours) into heat in the corona. The rate
of doing work seems adequate to supply the necessary 10 to the 7th
power ergs/square cm. sec for the active corona.

---------------------------------------------------------
Title: Invited Talk (Solar Division): "Theoretical MHD Structure of
Stellar Atmospheres, and Close Observations of the Sun"
Authors: Parker, Eugene
1983BAAS...15..950P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic fields in the cosmos
Authors: Parker, E. N.
1983SciAm.249b..44P Altcode: 1983SciAm.249...44P; 1983SciAm.249...36P
Descriptive models for the dynamo processes that generate magnetic
fields around celestial objects are reviewed. Magnetic fields are
produced, along with an electric current, when a conductor is moved
perpendicularly through a magnetic field, so long as the resulting
current is fed back into the conductor to amplify the current and
field. In MHD theory, the lines of force of the magnetic field
travel with the conducting fluid. A weak current or field must be
present initially to generate the field. Planets have molten cores
and stars have ionized gases to act as the conductors, and all space
has sufficient gas with free electrons. The rotations of the planets,
stars, and galaxy enhance the magnetic fields. Convective patterns
have been characterized in the earth's molten core because of anomalies
observed in the magnetic field at the surface. It has been shown that
the faster a planet rotates, the more powerful its magnetic field
is. However, fluid motions will produce fields only if the fluid motion
is helical. The exact mechanism in stars could be primordial magnetism
trapped during formation. However, in galaxies, the Biermann battery
effect, wherein free electrons move along the surfaces of stars,
could create enough of a field for the amplification process to proceed.

---------------------------------------------------------
Title: Up to a frontier of astrophysics
Authors: Parker, E. N.
1983Natur.303..262P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic neutral sheets in evolving fields. I - General theory.
Authors: Parker, E. N.
1983ApJ...264..635P Altcode:
The problem of the hydrostatic equilibrium of a large-scale magnetic
field embedded in a fluid with infinite electrical conductivity
is considered. It is pointed out that a necessary condition for
static equilibrium is the invariance of the small-scale pattern in
the field along the large-scale direction. A varying topological
pattern implies that no fluid pressure distribution exists for which
the field is everywhere static. Magnetic neutral sheets form, and
dynamical reconnection of the field takes place. It is shown here that
the invariance is also a sufficient condition for the existence of a
fluid pressure distribution producing static equilibrium. Even in the
simplest cases, however, the requirements on the fluid pressure are
extreme and, a priori, are unlikely. It is concluded that almost all
twisted flux tubes packed together produce dynamical nonequilibrium
and dissipation of their twisting. This is the basic effect underlying
the long-standing conjecture that the shuffling of the footpoints of
the bipolar magnetic fields in the sun is responsible for heating the
active corona. Attention is then given to the consequences of this
general dynamical dissipation in the magnetic fields that produce the
active corona of the sun. The footpoints of the field are continually
manipulated by the subphotospheric convection in such a way that the
lines of force are continually wrapped and rotated about one another.

---------------------------------------------------------
Title: Magnetic Neutral Sheets in Evolving Fields - Part Two -
Formation of the Solar Corona
Authors: Parker, E. N.
1983ApJ...264..642P Altcode:
It is shown in the previous paper that whenever twisted flux tubes
are bundled together, they are subject to dynamical nonequilibrium
and internal neutral point reconnection, causing rapid dissipation
of their torsion. In the present paper we explore the consequences
of this general dynamical dissipation in the magnetic fields that
produce the active corona of the Sun. The footpoints of the field are
continually manipulated by the subphotospheric convection, so that the
lines of force are continually wrapped and rotated about each other. The
dynamical dissipation of the wrapping and rotation transfers the work
done on the footpoints directly into heat in the corona, at a rate
estimated to be of the order of 107 ergs cm-2
s-1. The effect appears to be the principal source of heat to
the visible corona. This general picture implies that all magnetic
fields extending outward from convecting astronomical bodies produce
intense heating of the tenuous outer atmospheres of those bodies, in
general agreement with the observed fact of the universal activity of
stars and galaxies.

---------------------------------------------------------
Title: Generation of solar magnetic fields. I. II
Authors: Parker, E. N.
1983ASSL..104..101P Altcode: 1983stp..conf..101P
Attention is given to those magnetic field properties which allow
the fields to destroy themselves rapidly, thereby producing solar,
stellar and geomagnetic activity. Magnetic fields actively figure in
the production of flares, plages, eruptions and streamers. The existence
of magnetic fields in other stars is inferred from the X-rays that can
be observed to radiate from them. In the second part of this paper,
the discussion in the first part of the generation of magnetic fields
from the motion of conducting fluids is further developed through
the proposal of the 'short, sudden' idealization, and quick bursts
of turbulence during which any degree of twisting and rotation can be
accomplished are introduced. After these quick bursts of motion, the
fluid is held motionless so that small scale irregularities subside,
leaving a smooth, average and large scale state. This cycle is repeated
at time intervals tau, producing the dynamo equations for the mean
vector potential.

---------------------------------------------------------
Title: The propagation of torsion along flux tubes subject to
dynamical nonequilibrium
Authors: Parker, E. N.
1983GApFD..24..245P Altcode:
The dynamical nonequilibrium of close-packed flux tubes is driven by
the torsion in the individual tubes so that, wherever tubes with the
same sense of twisting come into contact, there is reconnection of their
azimuthal field components. The reconnection consumes the local torsion,
causing the propagation of torsional Alfven waves into the region
from elsewhere along the tubes. The formal problem of the propagation
of the torsion along twisted flux tubes is presented and some of the
basic physical properties worked out in the limit of small torsion. It
is pointed out that in tubes with finite twisting the propagation of
torsional Alfven waves can be a more complicated phenomenon. Application
to the sun suggests that the propagation of torsion from below the
visible surface up into the corona is an important energy supply to
the corona for a period of perhaps 10-20 hours after the emergence
of the flux tubes through the surface of the sun, bringing up torsion
from depths of 104km or more. Torsion is continually supplied by the
manipulation and shuffling of the field by the convection, of course.

---------------------------------------------------------
Title: Heating of the outer solar atmosphere. I. II
Authors: Parker, E. N.
1983ASSL..104..129P Altcode: 1983stp..conf..129P
The magnetic field coming up through the surface of the sun is
responsible for the solar activity that heats the outer solar
atmosphere. The field behaves in ways that are unexpected and little
understood. Beckers and Schroeter (1969) found that the field of the sun
has a fibril structure made up of separate, compressed flux tubes having
fields of 1000-2000 G and 100-500 km diameters. Immediately above the
solar surface, the field expands to fill the available volume. Nothing
is known about the state beneath the surface of the sun. Attention is
presently given to the state of knowledge on the heating of the corona
as well as to a model for magnetic merging. In the second part of this
presentation, the mutual wrapping and shuffling of the lines of force
of a bipolar magnetic field above the photosphere and the structure
of the cross section through a flux tube bundle are discussed.

---------------------------------------------------------
Title: Absence of equilibrium among close-packed twisted flux tubest
Authors: Parker, E. N.
1983GApFD..23...85P Altcode:
The general absence of static equilibrium of a close-packed array
of parallel twisted flux tubes in a highly conducting medium
is demonstrated by showing that the solutions to the equilibrium
equation V2A+4P'(A) = 0 do not generally preserve the flux connections
around each twisted tube as the functional form of P(A) is varied. A
special constraint on the variation of P(A) is introduced, then,
by the requirement that the flux connections be preserved. Hence we
conclude that while a particular array of twisted tubes, described
by the internal circulation of flux within each tube, may have an
equilibrium for some suitably chosen functional form P(A), the array
is generally in a state of nonequilibrium for lack of that precise
functional form in the real world.

---------------------------------------------------------
Title: The hydrodynamics of magnetic nonequilibrium
Authors: Parker, E. N.
1983GApFD..24...79P Altcode:
Because the dynamical nonequilibrium of closely packed twisted flux
tubes is essentially the problem of two-dimensional MHD turbulence,
the extensive literature on two-dimensional turbulence represents
the hydrodynamics of magnetic nonequilibrium. Many features of
the turbulence can conversely be understood as a consequence of the
dynamical nonequilibrium. Attention is presently given to the dynamics
of the strong fluid jets, issuing from reconnection points, that are
exhibited by numerical simulations of two-dimensional turbulence. Simple
examples are given which show that the uniformity of jet width
observed is a consequence of the form of the pressure of the magnetic
fields between which the jets are confined. The general hydrodynamics
of a layer of fluid confined by steady pressures is reducible to a
quadrature, so that a variety of effects may be considered, including
gravitation. The dissipation of the solar corona is discussed.

---------------------------------------------------------
Title: Cosmic magnetic fields. Their origin and manifestation. In
two parts.
Authors: Parker, E.
1983cmft.book.....P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Generation of Solar Magnetic Fields II
Authors: Parker, Eugene N.
1983ASSL..104..113P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Heating of the Outer Solar Atmosphere II
Authors: Parker, Eugene N.
1983ASSL..104..139P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The rapid dissipation of magnetic fields in highly conducting
fluids
Authors: Parker, E. N.
1982GApFD..22..195P Altcode:
This paper treats the dynamical conditions that obtain when long
straight parallel twisted flux tubes in a highly conducting fluid
are packed together in a broad array. It is shown that there is
generally no hydrostatic equilibrium. In place of equilibrium there
is a dynamical nonequilibrium, leading to neutral point reconnection
and progressive coalescence of neighboring tubes (with the same sense
of twisting), forming tubes of larger diameter and reduced twist. The
magnetic energy in the twisting of each tube declines toward zero,
dissipated into small-scale motions of the fluid and thence into
heat. The physical implications are numerous. For instance, it has been
suggested that the subsurface magnetic field of the sun is composed
of close-packed twisted flux tubes. Any such structures are short
lived, at best. The footpoints of the filamentary magnetic fields
above bipolar magnetic regions on the sun are continually shuffled and
rotated by the convection, so that the fields are composed of twisted
rubes. The twisting and mutual wrapping is converted directly into
fluid motion and heat by the dynamical nonequilibrium, so that the work
done by the convection of the footpoints goes directly into heating
the corona above. This theoretical result is the final step, then, in
understanding the assertion by Rosner, Tucker, and Valana, and others,
that the observed structure of the visible corona implies that it is
heated principally by direct dissipation of the supporting magnetic
field. It is the dynamical nonequilibrium that causes the dissipation,
in spite of the high electrical conductivity. It would appear that
any bipolar magnetic field extending upward from a dense convective
layer into a tenuous atmosphere automatically produces heating, and
a corona of some sort, in the sun or any other convective star.

---------------------------------------------------------
Title: Magnetic monopoles and the survival of galactic magnetic fields
Authors: Turner, Michael S.; Parker, E. N.; Bogdan, T. J.
1982PhRvD..26.1296T Altcode:
The most stringent, mass-independent limit on the flux of magnetic
monopoles is based upon the survival of the galactic magnetic
fields, the so-called "Parker limit": F&lt;~10-16
cm-2sr-1sec-1. We reexamine this limit,
taking into account the monopole's mass and velocity distribution,
and the observed structure of the galactic magnetic field. We derive
flux limits which depend upon the monopole's mass and velocity,
and the strength, coherence length, and regeneration time of the
galactic magnetic field. The largest monopole flux consistent with
both the survival of the galactic magnetic field and the bounds from
the mass density contributed by monopoles is F~=10-12
cm-2sr-1sec-1, arising for monopoles
of mass ~= 1019 GeV with velocity ~=3×10-3c
which cluster with the Galaxy. An observed flux greater than this
would have profound implications for our understanding of the galactic
magnetic field, and we briefly explore some exotic possibilities. Of
course, this bound is not applicable to a local source (e.g., the Sun,
atmospheric cosmic-ray production, etc.).

---------------------------------------------------------
Title: The Flux Ejection Dynamo with Small Diffusivity - Part One -
Basic Properties
Authors: Parker, E. N.
1982Ap&SS..85..167P Altcode:
The flux ejection dynamo in an infinitely broad convective layer
of finite depth is treated in the limit of large electrical
conductivity. The upper surface of the convective layer is open
to empty space while the lower surface is closed to the passage of
fluid and field. An idealized convective overturning is employed,
permitting an exact description of the symmetry and distribution of
the magnetic field carried with the fluid. Escape of the reverse field
through the free surface restores the initial vertical distribution
of mean field and adds a thin sheet of flux in the initial direction
across the bottom of the convective layer. The total flux in the mean
horizontal field grows linearly with the number of convective cycles. We
discuss the boundary conditions to be applied to an astronomical body
with the flux ejection dynamo operating at its surface. It is pointed
out that if there were a flux ejection dynamo operating in the Sun,
the implications of the magnetic bipolar regions emerging through the
surface would be the opposite of the usual.

---------------------------------------------------------
Title: The Flux Ejection Dynamo with Small Effusivity - Part Two -
Illustrative Examples
Authors: Parker, E. N.
1982Ap&SS..85..183P Altcode:
A number of examples are worked out to illustrate the consequences
of reverse flux ejection from the surface of a convective layer of
conducting fluid. Generally the reverse flux ejection has the opposite
effect of magnetic buoyancy, tending to bury the fields rather than
bringing them through the surface. Even a weak flux ejection effect
prevents the excape of magnetic field through the surface. Reverse
flux ejection at the surface of an αω-dynamo profoundly alters
the character of the solutions of the dynamo equations. Altogether,
flux ejection serves to obscure the interpretation of magnetic
observations. The outstanding problem now is to determine under what
circumstances there exists cyclonic convection with rotations in excess
of ±1/2π in the rising columns of fluid. Negative turbulent diffusion
is expected to be a close companion of the flux ejection effect.

---------------------------------------------------------
Title: The Dynamics of Fibril Magnetic Fields - Part Four - Trapping
in Closed Convective Rolls
Authors: Parker, E. N.
1982ApJ...256..746P Altcode:
The equations of motion for a slender, buoyant flux tube extending
horizontally along a closed convective roll are solved to illustrate
the motion of the flux tube relative to the fluid. The principal effect
of the buoyant rise u of the flux tube is to offset the path of the
tube (which remains closed) from the closed circulation pattern of
the fluid. Further investigation shows that an upward decrease of ρ
u causes the position of the tube to spiral inward to the dynamical
equilibrium point where the convective downdraft is equal to the buoyant
rise. Any variation of the convective velocity along the length of the
roll has the same effect, so that flux tubes, or fibrils, are stably
trapped in any closed convective flow that exceeds u. The effect
may be operative in the convective zone of the Sun and other stars
where the meridional circulation is larger than the rate of rise of
the standard fibril. Even if there is no long-term trapping of the
field, the position of emergence of flux tubes at the surface of the
Sun may be widely removed from their birthplace. A number of examples
are given to illustrate the possibilities.

---------------------------------------------------------
Title: The dynamics of fibril magnetic fields. III - Fibril
configurations in steady flows.
Authors: Parker, E. N.
1982ApJ...256..736P Altcode:
The present investigation has the objective to provide an illustration
of the equilibrium form of a hypothetical fibril field beneath the
surface of the sun. Equilibrium fibril paths in static and moving
atmospheres are considered. The provided examples are related to
horizontal flows in an atmosphere in which the two anchor points
of the arched fibril lie along the flow direction relative to each
other. A brief introduction to the subject of the motion of horizontal
fibrils in convective rolls is also presented, taking into account
some implications for the sun. The equations of motion for a slender,
buoyant flux tube extending horizontally along a closed convective
roll are solved to illustrate the motion of the flux tube relative to
the fluid, and attention is given to theoretical possibilities for the
escape of flux tubes from a large horizontal convective roll in the sun.

---------------------------------------------------------
Title: The Dynamics of Fibril Magnetic Fields - Part Two - the Mean
Field Equations
Authors: Parker, E. N.
1982ApJ...256..302P Altcode:
A variety of scenarios for the origin and activity of magnetic fields in
the convective zone of the Sun have been put forth in recent years. In
particular, a number of authors have urged that the magnetic field
is in a generally fibril state, much as observed at the surface,
with a variety of suggestions as to the consequences. The present
paper works out the mean field equations for intense thin fibrils of
fixed cross section under the assumption of some significant local
ordering. The aim is to establish to what degree new effects may arise
as a result of the fibril state. It is shown that the fibril state of
a mean field B enhances the tension in the field and the buoyancy of
the field by the compression factor m of the field in the individual
fibrils. New qualitative effects appear in the slip velocity u of the
fibrils through the ambient fluid and in the neutral point reconnection
of neighboring fibrils. Some of the novel features are illustrated in
later papers in this series. One of the most important consequences is
the simplification of the theory of turbulent diffusion by eliminating
the looping and tangling that arises when a continuum field is carried
in a chaotic turbulent flow. We have been unable to find any effects
that would admit of a new concept for the origin of the solar magnetic
fields.

---------------------------------------------------------
Title: The dynamics of fibril magnetic fields. I - Effect of flux
tubes on convection.
Authors: Parker, E. N.
1982ApJ...256..292P Altcode:
Observations have established the general fibril state of the magnetic
field at the visible surface of the sun. This extraordinary state of the
field, in separate intense flux tubes, implies that the convection has
a relatively permanent, closed topology, in spite of the large Reynolds
number. This paper explores some of the effects of the separate flux
tubes on the convective motions, generally pushing the convective
cells toward aligning their downdrafts with the flux tubes so as to
minimize the dissipation.

---------------------------------------------------------
Title: Compression of magnetic field in a viscous boundary layer.
Authors: Parker, E. N.
1982SoPh...77....3P Altcode:
Galloway, Proctor, and Weiss have shown by numerical experiment that
the magnetic field extending across a convective cell in a highly
conducting viscous fluid may be concentrated into sheets with energy
density B2/8π larger than the kinetic energy density
1/2ϱv2 of the convection by a factor (v/η)1/2
or more. This paper employs conventional boundary layer theory for high
Reynolds number to provide a simple analytical example illustrating
this remarkable effect of field concentration.

---------------------------------------------------------
Title: The flux ejection dynamo effect
Authors: Parker, E. N.
1982GApFD..20..165P Altcode:
The mean-field effects of cyclonic convection become increasingly
complex when the cyclonic rotation exceeds ½-. Net helicity is not
required, with negative turbulent diffusion, for instance, appearing in
mirror symmetric turbulence. This paper points out a new dynamo effect
arising in convective cells with strong asymmetry in the rotation
of updrafts as against downdrafts. The creation of new magnetic flux
arises from the ejection of reserve flux through the open boundary of
the dynamo region. It is unlike the familiar -effect in that individual
components of the field may be amplified independently. Several formal
examples are provided to illustrate the effect. Occurrence in nature
depends upon the existence of fluid rotations of the order of in the
convective updrafts. The flux ejection dynamo may possibly contribute
to the generation of field in the convective core of Earth and in the
convective zone of the sun and other stars.

---------------------------------------------------------
Title: Photospheric flow and stellar winds
Authors: Parker, E. N.
1981ApJ...251..266P Altcode:
The effect of the photospheric outflow on the expansion of the strongly
bound coronas of dwarf main-sequence stars is examined. The extended
temperatures of the strongly bound coronas cause the stars to expand
and form tenuous stellar winds, with a slight mean upward motion
of the gas in the photosphere to replenish the mass loss through the
coronal expansion. A formal solution of the time-dependent hydrodynamic
equations illustrates the effects of the photospheric velocity at large
distances, and the effect of blocking the upward flow in the photosphere
is calculated using the sun as an example. Results indicate that the
expansion of a strongly bound corona is insensitive over historical
time scales to the small outflow of gas in the photosphere.

---------------------------------------------------------
Title: The hydromagnetic dynamo
Authors: Parker, E. N.
1981ESASP.161...23P Altcode: 1981plas.work...23P
No abstract at ADS

---------------------------------------------------------
Title: The non-equilibrium of magnetic fields
Authors: Parker, E. N.
1981ESASP.161...31P Altcode: 1981plas.work...31P
No abstract at ADS

---------------------------------------------------------
Title: The magnetohydrodynamic dynamo
Authors: Parker, E. N.
1981plap.rept...23P Altcode:
A mechanism for the maintenance of the magnetic fields of planets,
stars, and galaxies is postulated. It appears that cyclonic convection
and nonuniform rotation within the liquid metal cores of planets,
the convective zones of stars, and the gaseous disks of galaxies
provide an efficient dynamo mechanism for the production of these
fields. The dominant field within the body is azimuthal, produced
by nonuniform rotation from the poloidal field. The interaction of
cyclonic convection within the azimuthal field produces loops of flux
in meridional planes whose net effect is a meridional circulation of
field in the same sense as the original poloidal field. Both stationary
and oscillatory fields can be generated in this way.

---------------------------------------------------------
Title: The nonequilibrium of magnetic fields
Authors: Parker, E. N.
1981plap.rept...31P Altcode:
The more subtle properties of magnetic fields which create
nonequilibrium and lead to vigorous activity in otherwise sluggish
gas-field systems are evaluated for gross hydromagnetic effects. The
gentle manipulation of magnetic fields on a large scale leads to the
production of small scale variations and discontinuities, providing
intense dissipation of magnetic field in a large scale system. A
magnetic field embedded in a conducting fluid possesses a static
equilibrium only if the topology of the lines of force is suitably
invariant along the direction of the field. When the field does not
possess the necessary invariance, it is subject to internal neutral
point reconnection. The magnetic fields of most stars suffer such
nonequilibrium, and consequent enhanced dissipation, providing an
important source of heat in their outer atmospheres.

---------------------------------------------------------
Title: The Dissipation of Inhomogeneous Magnetic Fields and the
Problem of Coronae - Part Two - the Dynamics of Dislocated Flux
Authors: Parker, E. N.
1981ApJ...244..644P Altcode:
When any of the flux tubes that collectively make up a magnetic field
continuum is dislocated and misaligned relative to the rest of the
field, there is a dynamical steepening of field gradients. Consequently,
there is rapid dissipation of the dislocated field no matter how
large the electrical conductivity of the medium. This paper presents
some formal illustrations of local conditions along a misaligned flux
tube, showing the simultaneous onset of diffusion, fluid motion, and
hydromagnetic wave propagation. The examples show that the total effect
is complicated and subject only to estimation, rather than formal
calculation, at the present time. We suggest that dislocation
dissipation occurs in the magnetic fields of active regions on the
Sun, contributing to the enhanced corona. Estimates of the dislocation
dissipation in the active corona are carried out based on the observed
properties of active coronal arches and filaments. The estimates show
that the dissipation may contribute a significant portion of the coronal
heating. It is pointed out that dislocation dissipation must occur in
the active terrestrial magnetosphere and in the active gaseous disk of
the Galaxy, although we make no attempt at a quantitative assessment
of the rates.

---------------------------------------------------------
Title: The dissipation of inhomogeneous magnetic fields and the
problem of coronae. I - Dislocation and flattening of flux tubes. II -
The dynamics of dislocated flux
Authors: Parker, E. N.
1981ApJ...244..631P Altcode:
Attention is given to the dynamical dissipation arising in a magnetic
field extending up through a tenuous atmosphere when an elemental
flux tube in the field (1) is displaced from its equilibrium position
and/or (2) is inflated by an internal fluid pressure different from
the external fluid pressure. It is pointed out that as a consequence
the tension in the lines of force of the ambient field flattens the
dislocated tube so that the thickness of the tube decreases without
limit and that the local field gradients increase rapidly with the
passage of time until destroyed by one or more dissipative effects. The
magnetic energy of a dislocated flux tube is therefore soon converted
into thermal energy no matter how low the molecule resistivity of
the fluid. Some formal illustrations of local conditions along a
misaligned flux tube are presented, showing the simultaneous onset
of diffusion, fluid motion, and hydromagnetic wave propagation. The
examples demonstrate that the total effect is complicated and subject
only to estimation, rather than formal calculation, at the present time.

---------------------------------------------------------
Title: Residual fields from extinct dynamos
Authors: Parker, E. N.
1981GApFD..18..175P Altcode:
The paper explores some of the many facets of the problem of the
generation of magnetic fields in convective zones of declining vigor
and/or thickness. The ultimate goal of such work is the explanation
of the magnetic fields observed in A-stars. The present inquiry
is restricted to kinematical dynamos, to show some of the many
possibilities, depending on the assumed conditions of decline of the
convection. The examples serve to illustrate in what quantitative
detail it will be necessary to describe the convection in order to
extract any firm conclusions concerning specific stars. The first
illustrative example treats the basic problem of diffusion from a
layer of declining thickness. The second adds a buoyant rise to the
field in the layer. The third treats plane dynamo waves in a region
with declining eddy diffusivity, dynamo coefficient, and large-scale
shear. The dynamo number may increase or decrease with declining
convection, with an increase expected if the large-scale shear does
not decline as rapidly as the eddy diffusivity. It is shown that one
of the components of the field may increase without bound even in the
case that the dynamo number declines to zero.

---------------------------------------------------------
Title: The spontaneous concentration of magnetic field in the
photosphere of the sun.
Authors: Parker, E. N.
1981ASIC...68...33P Altcode: 1981spss.conf...33P
The basic physics of magnetic flux tubes in the solar photosphere is
reviewed, with areas still open to conjecture pointed out. The question
of the concentration of individual small flux tubes to levels of 1-2
kilogauss, when the average solar surface magnetic field is on the
order of 10 gauss, by processes of twisting and the formation of flux
ropes made up of tubes wound around each other is considered together
with the effects of turbulence on the flux tube. Mechanisms for tube
compression by the evacuation of the gas contained within a flux tube
are then examined, and the possibility of field concentration through
the cooling of the gas within the tube in a superadiabatic process is
suggested. Attention is then given to possible mechanisms serving to
maintain the concentration of flux tubes far below the surface of the
sun which gives rise to sunspots and pores as the flux tree emerges
through the surface.

---------------------------------------------------------
Title: Summary Commentary - Solar Phenomena in Stars and Stellar
Systems
Authors: Parker, E. N.
1981ASIC...68..551P Altcode: 1981spss.conf..551P
No abstract at ADS

---------------------------------------------------------
Title: A review of: "Solar flare magnetohydrodynamics"
Authors: Parker, E. N.
1981GApFD..18..332P Altcode:
Edited by E. R. Priest (Volume 1 of "The Fluid Mechanics of Astrophysics
and Geophysics"). Gordon and Breach Science Publishers, 1981. xii +
563 pp. (Cloth Bound $89.50). (ISBN 0 677 0553 7 and ISSN 0 2604353).

---------------------------------------------------------
Title: Solar System Plasma Physics.
Authors: Lanzerorotti, L. J.; Kennel, C. F.; Parker, E. N.
1980JPlPh..24..191L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Solar System Plasma Physics
Authors: Kennel, C. F.; Lanzerotti, L.; Parker, E. N.; Akasofu, S. I.
1980Natur.285..598K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Cosmical Magnetic Fields
Authors: Parker, E. N.; de Groot, M.
1980IrAJ...14..189P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Solar System Plasma Physics
Authors: Kennel, C. F.; Lanzerotti, L. J.; Parker, E. N.; Hultqvist, B.
1980SSRv...26R.449K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux
tubes. VIII. Overstability in a magnetic field in a downdraft.
Authors: Parker, E. N.
1979ApJ...233.1005P Altcode:
The dynamical properties of convective overstability in a vertical
magnetic field with a downdraft are considered. A variety of effects
is illustrated. The overstability produces Alfven waves propagating
both upward or downward along the magnetic field. The favored direction
of emission may be upward or downward depending upon the magnitude of
the heat transport coefficient. The largest asymmetry is produced by a
difference in reflectivity between the upper and lower boundaries. It is
shown that a very modest reflection coefficient of the upper boundary,
with no reflection at the lower boundary, causes most of the waves
to be emitted downward, and vice versa. Applying these results to
the flux tubes extending up through the convective zone of the Sun,
it follows that those flux tubes are dynamically active beneath the
surface, as suggested earlier by ourselves and others, but there
is no reason to expect any significant wave flux to appear in the
field above the surface. The waves propagate downward into the Sun
and are presumably dispersed there by the nonlinear interaction with
the turbulent convection, etc.

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux tubes. IX. Umbral
dots and longitudinal overstability.
Authors: Parker, E. N.
1979ApJ...234..333P Altcode:
The dynamical properties of the sunspot field and of a column of
hot gas confined by such a vertical magnetic field are examined in
order to understand the umbral dot within the context of the magnetic
sunspot structure. Attention is given to the conditions necessary
for gas intrusion, longitudinal as well as convective overstability,
the growing modes, and the even mode. With the hypothesis that the
subsurface magnetic field of a sunspot splits into many separate flux
tubes with field-free gas between, it is suggested that the field-free
columns occasionally punch their way up through the overlying magnetic
field to the surface, appearing there as the bright, field-free umbral
dots. Effects fostering the phenomenon are also discussed, that is, the
enhanced temperature of a column of rising gas, the strongly reduced
overhead magnetic pressure, and the initiated upward intrusion; these
effects are illustrated with examples.

---------------------------------------------------------
Title: Sunspots and the Physics of Magnetic Flux Tubes. VII. Heat
Flow in a Convective Downdraft
Authors: Parker, E. N.
1979ApJ...232..291P Altcode:
The heat flux in the familiar Boussinesq convective cell with free
upper and lower boundaries is plotted to show the suppression of the
upward heat flow by a downdraft. Application to the solar convective
zone shows that downdrafts of 1-2 km 1 at depths of 1 x 1O km beneath
the visible surface of the Sun are sufficient to reduce the upward heat
flux to a small fraction of the ambient value. Hence the downdraft
that is postulated to operate beneath the sunspot, to account for
the gathering of flux tubes to form the spot, would be sufficient
to reduce the heat flux to values comparable to those observed in
sunspot umbrae. This greatly relieves the demands on cooling by the
convective generation of Alfve'n waves in order to form the observed
intense fields of 3000 gauss or more. Subject headings: convection -
hydromagnetics - Sun: sunspots

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux tubes. VI. Convective
propulsion.
Authors: Parker, E. N.
1979ApJ...232..282P Altcode:
The effect of negative aerodynamic drag in an ideal fluid subject to
convective instability is considered. It is shown that a cylinder moving
in such a fluid is propelled forward in its motion by the convective
forces and that the characteristic acceleration time is comparable to
the onset time of convective motions in the fluid. It is suggested that
convective propulsion plays an important role in the dynamics of flux
tubes extending through the surface of the sun. The suppression of the
upward heat flow in a Boussinesq convective cell with free upper and
lower boundaries by a downdraft is then analyzed. Application to the
solar convection zone indicates that downdrafts of 1 to 2 km/s at depths
of 1000 to 4000 km beneath the visible surface of the sun are sufficient
to reduce the upward heat flux to a small fraction of the ambient value.

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux tubes. V. Mutual
hydrodynamic forces between neighboring tubes.
Authors: Parker, E. N.
1979ApJ...231..270P Altcode:
The mutual hydrodynamic forces between parallel cylinders in a moving
fluid are illustrated through several formal examples. Parallel tubes
in a uniform flow are attracted or repelled depending on whether
they are side by side or one ahead of the other, respectively. A
pulsating or undulating tube attracts all other neighboring tubes toward
itself. These hydrodynamic effects suggest that the separate flux tubes
beneath the sunspots exert significant attractive forces on each other.

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux
tubes. III. Aerodynamic lift.
Authors: Parker, E. N.
1979ApJ...231..250P Altcode:
The aerodynamic lift exerted on a magnetic flux tube by the asymmetric
flow around the two sides of the tube is calculated as part of
an investigation of the physics of solar flux tubes. The general
hydrodynamic forces on a rigid circular cylinder in a nonuniform flow of
an ideal fluid are derived from the first derivatives of the velocity
field. Aerodynamic lift in a radial nonuniform flow is found to act
in the direction of the flow, toward the region of increased flow
velocity, while in a shear flow, lift is perpendicular to the free
stream and directed toward increasing flow velocity. For a general,
three dimensional, large-scale stationary incompressible equilibrium
flow, an expression is also derived relating the lift per unit length
to the dynamical pressure, cylinder radius and the gradient of the
free-stream velocity. Evidence from an asymmetric airfoil in a uniform
flow indicates that lift is enhanced in a real fluid in the presence
of turbulence.

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux
tubes. II. Aerodynamic drag.
Authors: Parker, E. N.
1979ApJ...230..914P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sunspots and the physics of magnetic flux tubes. I. The
general nature of the sunspots.
Authors: Parker, E. N.
1979ApJ...230..905P Altcode:
Analysis of the dynamical stability of a large flux tube suggests
that the field of a sunspot must divide into many separate tubes
within the first 1000 km below the surface. Buoyancy of the Wilson
depression at the visible surface and probably also a downdraft beneath
the sunspot hold the separate tubes in a loose cluster. Convective
generation of Alfven waves, which are emitted preferentially downward,
cools the tubes. Aerodynamic drag on a slender flux tube stretched
vertically across a convective cell is also studied. Since the drag
is approximately proportional to the local kinetic energy density,
the density stratification weights the drag in favor of the upper
layers. Horizontal motions concentrated in the bottom of the convective
cell may reverse this density effect. A downdraft of about two km/sec
through the flux tubes beneath the sunspot is hypothesized.

---------------------------------------------------------
Title: The Instability of a Horizontal Magnetic Field in an Atmosphere
Stable Against Convection
Authors: Parker, E. N.
1979Ap&SS..62..135P Altcode:
The theoretical problem posed by the buoyant escape of a magnetic
field from the interior of a stably stratified body bears directly on
the question of the present existence of primordial magnetic fields in
stars. This paper treats the onset of the Rayleigh-Taylor instability
of the upper boundary of a uniform horizontal magnetic field in a
stably stratified atmosphere. The calculations are carried out in
the Boussinesq approximation and show the rapid growth of the initial
infinitesimal perturbation of the boundary. This result is in contrast
to the extremely slow buoyant rise of a separate flux tube in the
same atmosphere. Thus for instance, at a depth of 1/3R ⊙
beneath the surface of the Sun, a field of 102 G develops
ripples over a scale of 103 km in a characteristic time
of 50 years, whereas the characteristic rise time of the same field
in separate flux tubes with the same dimensions is 1010
years. Thus, the development of irregularities proceeds quickly,
soon slowing, however, to a very slow pace when the amplitude of the
irregularities becomes significant. Altogether the calculations show
the complexity of the question of the existence of remnant primordial
magnetic fields in stellar interiors.

---------------------------------------------------------
Title: INVITED PAPER - George Ellery Hale and Active Mangetic Fields
Authors: Parker, E. N.
1979BAAS...11..423P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Cosmical magnetic fields. Their origin and their activity
Authors: Parker, E. N.
1979cmft.book.....P Altcode:
The physics of large-scale magnetic fields in fluids of high electrical
conductivity is examined, with emphasis on the generation of magnetic
fields in astronomical bodies and interactions of the fields with
those bodies. The role and nature of cosmic magnetic fields are
described and solutions to the basic electromagnetic equations are
developed. Consideration is given to magnetic field stress and
energy and the problem of magnetic equilibrium. The propagation
of disturbances in a magnetic fluid is discussed, and the basic
properties and interactions of isolated flux tubes and twisted flux
tubes are considered. The topology of magnetic lines of force, the
nonequilibrium of invariant and non-invariant fields, the breakup
and escape of submerged magnetic fields, the rapid reconnection of
magnetic lines of force, the exclusion of magnetic fields from closed
circulation patterns, and the generation and nature of magnetic fields
in turbulent fluids, including the dynamo problem, are treated, and
planetary, solar, stellar and galactic magnetic fields are examined.

---------------------------------------------------------
Title: Gearing up to answer question posed by the sun.
Authors: Parker, E. N.
1979PhT....32i...9P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The University of Chicago: Department of Astronomy and
Astrophysics, Chicago, Illinois 60637; The Yerkes Observatory,
Williams Bay, Wisconsin 53191. Report.
Authors: Parker, E. N.; Hobbs, L. M.
1979BAAS...11...80P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The enigma of solar activity.
Authors: Parker, E. N.
1979psa..conf....8P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Cosmical Magnetic Fields - Their Origin and
Their Activity
Authors: Parker, E. N.
1979AstQ....3..201P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar system plasma physics. Vol.1: Solar and solar wind plasma
physics; Vol.2: Magnetospheres; Vol.3: Solar system plasma processes
Authors: Parker, E. N.; Kennel, Charles F.; Lanzerotti, Louis J.
1979sspp.book.....P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Summary Remarks
Authors: Parker, E. N.
1979AIPC...56..425P Altcode: 1979pama.work..425P
No abstract at ADS

---------------------------------------------------------
Title: Solar system plasma physics. Volume 3 - Solar system plasma
processes
Authors: Lanzerotti, L. J.; Kennel, C. F.; Parker, E. N.
1979anh..book.....L Altcode:
The papers deal with such solar system plasma processes as shocks
in collisionless space plasmas; magnetic field reconnection,
hydrodynamic waves; plasma processes in the earth's radiation belts;
and magnetospheric plasma waves. Some papers deal with the ionospheric
plasma; the physics of heavy ions in the magnetosphere; impacts
of ionospheric-magnetospheric processes on terrestrial science and
technology; and impacts of the solar system environment on man, and
vice versa.

---------------------------------------------------------
Title: Solar system plasma physics. Volume 1 - Solar and solar wind
plasma physics
Authors: Parker, E. N.; Kennel, C. F.; Lanzerotti, L. J.
1979sswp.book.....P Altcode:
The paper covers such aspects of solar physics as the mechanisms which
drive solar phenomena (such as heating of the corona, the acceleration
of particles in flares, the dissipation of magnetic energy in current
sheets, and the generation of the solar wind), the structure and
energetics of the quiet solar atmosphere, the structure of the corona,
the solar composition, and solar terrestrial interactions. Phenomena
associated with solar flares are discussed, and physical mechanism which
have been advanced to explain them are examined. The impact of solar
physics on the development of plasma physics and magnetohydrodynamics
is noted. The mathematical framework describing the microscopic and
macroscopic aspects of the solar wind plasma is outlined

---------------------------------------------------------
Title: A broad look at solar physics adapted from the solar physics
study of August 1975
Authors: Parker, E.; Timothy, A.; Beckers, J.; Hundhausen, A.; Kundu,
M. R.; Leith, C. E.; Lin, R.; Linsky, J.; MacDonald, F. B.; Noyes, R.
1979sswp.book....3P Altcode: 1979sswp.book....3B
The current status of our knowledge of the basic mechanisms involved
in fundamental solar phenomena is reviewed. These include mechanisms
responsible for heating the corona, the generation of the solar
wind, the particle acceleration in flares, and the dissipation of
magnetic energy in field reversal regions, known as current sheets. The
discussion covers solar flares and high-energy phenomena, solar active
regions; solar interior, convection, and activity; the structure and
energetics of the quiet solar atmosphere; the structure of the corona;
the solar composition; and solar terrestrial interactions. It also
covers a program of solar research, including the special observational
requirements for spectral and angular resolution, sensitivity, time
resolution, and duration of the techniques employed.

---------------------------------------------------------
Title: Solar system plasma physics. Volume 2 - Magnetospheres
Authors: Kennel, C. F.; Lanzerotti, L. J.; Parker, E. N.
1979magn.book.....K Altcode:
The present volume covers such topics as global problems in
magnetospheric plasma physics; magnetosphere, ionosphere, and
atmosphere interactions; Jupiter's magnetosphere and radiation belts,
the magnetosphere of Mercury; interactions of the solar wind with
the planets Mars, Venus, and Mercury; and interactions between the
solar wind and comets. The theory of planetary dynamics is outlined,
and the contemporary basis for the development of a comparative theory
of magnetospheres is examined.

---------------------------------------------------------
Title: The mutual attraction of magnetic knots.
Authors: Parker, E. N.
1978ApJ...222..357P Altcode:
It is observed that the magnetic knots associated with active regions
on the sun have an attraction for each other during the formative
period of the active regions, when new magnetic flux is coming to
the surface. The attraction disappears when new flux ceases to rise
through the surface. Then the magnetic spots and knots tend to come
apart, leading to disintegration of the sunspots previously formed. The
dissolution of the fields is to be expected, as a consequence of the
magnetic repulsion of knots of like polarity and as a consequence of
the hydromagnetic exchange instability. The purpose of this paper is to
show that the mutual attraction of knots during the formative stages
of a sunspot region may be understood as the mutual hydrodynamic
attraction of the rising flux tubes. Two rising tubes attract each
other, as a consequence of the wake of the leading tube when one is
moving behind the other, and as a consequence of the Bernoulli effect
when rising side by side.

---------------------------------------------------------
Title: Hydraulic concentration of magnetic fields in the solar
photosphere. VI. Adiabatic cooling and concentration in downdrafts.
Authors: Parker, E. N.
1978ApJ...221..368P Altcode:
The remarkable concentration of the general field of the Sun into
isolated intense flux tubes at the visible surface must be a direct
consequence of conditions immediately beneath the surface. It is pointed
out that the convective heat transport in the magnetic field swept into
the downdrafts in the junctions of supergranule boundaries is strongly
suppressed by the magnetic field. The net heat transport is reduced to
such a degree that the temperature of the downdraft within the field
increases nearly adiabatically below the visible surface, and hence
is significantly cooler than the surrounding ambient gas. The reduced
temperature enhances the downdraft within the field and permits the
gravitational field to evacuate the flux tube. The magnetic field is
then strongly compressed by the external gas pressure, leading to the
extraordinary observed strengths of 1500 gauss or more. It is suggested
that the magnetic knots found in active regions are formed wholly or
partly by the same effect. The general occurrence of superadiabatic
temperature gradients and convective heat transport in the dwarf and
subdwarf main-sequence stars suggests that their magnetic fields are
generally broken up and concentrated by this effect, much as in the
Sun. Subject headings: convection hydromagnetics - Sun: granulation -
Sun: magnetic fields

---------------------------------------------------------
Title: The University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin. Reports.
Authors: Parker, E. N.; Hobbs, L. M.
1978BAAS...10Q..77P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois. The Yerkes Observatory, Williams Bay,
Wisconsin. Reports.
Authors: Parker, E. N.; Hobbs, L. M.
1978BAAS...10R..77P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Physics in Broad Perspective
Authors: Parker, E. N.
1978nsp..conf....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The relative diffusion of strong magnetic fields and tenuous
gases.
Authors: Parker, E. N.
1977ApJ...215..374P Altcode:
General equations are given for treating the diffusion of a magnetic
field in a fluid with electrical conductivity and a resistive diffusion
coefficient. Consequences of nonnegligible gas motion are investigated
by considering the one-dimensional problem where a tenuous isothermal
gas with pressure expressed as a function of x-coordinate and time is
enmeshed in a magnetic field in the y-direction. Approximate equations
are obtained for the case of weak fluctuations in gas or field
pressure, and the properties of a nonlinear diffusion equation are
illustrated with the example of an initial thin slab of gas confined
by a uniform field on either side. The advance of a gas front into a
nonvanishing gas density is illustrated by using the progressive wave
solution. Application of the results to the evolution of streamers
and filaments observed in the solar corona is briefly discussed

---------------------------------------------------------
Title: The generation of magnetic fields in astrophysical
bodies. XI. The effect of magnetic buoyancy on the growth and
migration of dynamo waves in the sun.
Authors: Parker, E. N.
1977ApJ...215..370P Altcode:
The hydromagnetic dynamo equations are solved including a simple
magnetic buoyancy term to demonstrate the effect of the buoyant
rise of the magnetic field on the operation of the solar dynamo. The
calculations show that the strength of the fluid motions necessary
for the generation of field is sharply increased in a dynamo driven
principally by vertical shear, as a consequence of the rapid, buoyant
loss of field out of the free upper surface. In a dynamo driven by
horizontal shear, such as the observed nonuniform rotation of the
Sun, the necessary fluid motions are stronger or weaker depending
upon whether the vertical migration of the dynamo waves is upward or
downward, respectively. Unfortunately, our present ignorance of the
fluid motions in the Sun excludes any more detailed conclusion than the
general remark that the buoyancy has important quantitative effects on
the operation of the solar dynamo. Subject headings: hydromagnetics -
Sun: magnetic fields

---------------------------------------------------------
Title: A comment on the thermal structure of sunspots
Authors: Parker, E. N.
1977MNRAS.179P..93P Altcode:
Summary. It is pointed out that, at the present time, there is no
certain explanation for the spontaneous self-concentration of magnetic
fields to form the cool sunspots on the surface of the Sun. A brief
discussion is presented, with comments on a recent paper by Cowling.

---------------------------------------------------------
Title: Comment on "the Elementary Theory of Twisted Flux
Tubes. Equilibrium Configurations
Authors: Parker, E. N.
1977ApJ...214..616P Altcode:
It is pointed out that Wilson's calculations confirm the validity of our
earlier results on the variation of fields along a slender force-free
magnetic flux tube with slowly varying radius R(z) ( R/ z 1). The
field distributions across tube are correct, neglecting terms O( R/ z)
compared to one. Subject headings: hydromagnetics - Sun: magnetic fields

---------------------------------------------------------
Title: Cosmic-ray propagation and containment.
Authors: Parker, E. N.
1977NASCP...2..283P Altcode: 1977scgr.nasa..283P; 1977NASCP.002..283P
The cosmic rays are an active gaseous component of the disk of
the galaxy, and their propagation and containment is a part of the
general dynamics of the disk. The sources of cosmic rays are a matter
of speculation. The disk is inflated by the cosmic-ray gas pressure,
P, comparable to the magnetic pressure B super 2/ 8 pi, but the rate
of inflation is unknown. The time spent by the individual cosmic-ray
particles in the disk is inversely proportional to the cosmic-ray
production rate and may be anything from 100,000 to more than 10 million
years. It is evident from the decay of Be(10) that the cosmic rays
circulate through a volume of space perhaps ten times the thickness of
the gaseous disk, suggesting a magnetic halo extending out approximately
1 kpc from either face of the disk. The cosmic rays may be responsible
for the halo by inflating the magnetic fields of the disk. Extension
of the fields to 1 kpc would imply a high production rate and short
life of cosmic rays in the dense gaseous disk of the galaxy.

---------------------------------------------------------
Title: The University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin. Observatory reports.
Authors: Parker, E. N.; Hobbs, L. M.
1977BAAS....9...73P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The origin of solar activity.
Authors: Parker, E. N.
1977ARA&A..15...45P Altcode:
The basis physical problems and principles of solar activity are
reviewed, insofar as they are understood, concentrating on the general
question of why magnetic fields produce activity. The continuous
emergence of magnetic flux tubes through the solar surface is examined,
the origin of solar magnetic fields is considered, and the behavior
of the magnetic fields is investigated. Magnetic buoyancy is analyzed
together with flux-tube twisting, the variation of twisting along
a flux tube, magnetic-field concentration into isolated flux tubes,
and dynamical dissipation of magnetic fields. It is concluded that the
fluid motions which produce the magnetic fields in the convecting sun
generally prevent the fields from achieving the perfect topological
symmetry necessary for the existence of an equilibrium, that these
fields should be active (i.e., perpetually in a state of reconnection),
and that this seems to be the cause of the continuous activity of the
magnetic fields which emerge through the surface of the sun.

---------------------------------------------------------
Title: Hydraulic concentration of fields in the solar
photosphere. IV. Evolution of fields near equipartition.
Authors: Parker, E. N.
1976ApJ...210..810P Altcode:
It has previously been inferred that small isolated flux tubes appearing
in supergranule boundaries are compressed to 1500 gauss or more. This
paper considers whether some dynamic condition within a flux tube
exists which provides both stability and a 'mechanical advantage'
so that a small force over a small period of time can accomplish the
enormous compression from the weak-field to the strong-field state. It
is found that the equipartition solutions to the hydromagnetic
equations apparently may have the desired property of permitting
an infinitesimal external pressure to convert a gentle flow of gas
along a weak field into a very intense field through a succession of
equipartition states. An illustrative example is presented, and field
compression by convective forces is analyzed.

---------------------------------------------------------
Title: Hydraulic Concentration of Fields in the Solar
Photosphere. V. Dynamical Effects in a Stratified Atmosphere
Authors: Parker, E. N.
1976ApJ...210..816P Altcode:
The dynamical equations are presented for the steady flow of an inviscid
ideal gas along a magnetic tube of force extending vertically across a
stratified atmosphere with temperature T(z) in a uniform gravitational
acceleration g. It is shown that under usual conditions an equilibrium
dynamical solution extends across the full height of the atmosphere
only if there is a point somewhere in the atmosphere where d(kT/mg)/dz
= . If such a critical point exists, then the dynamical solutions
extend across the atmosphere and possess the property of strong
concentration of field in the general neighborhood of the critical
point, where the fluid and field cross over equipartition, pV2 =
B2/8ir. It is shown that the necessary condition on the temperature
gradient is satisfied in the Sun in the top 50 km of the convective
zone, suggesting that the observed concentration of magnetic field
to 10 gauss or more in the photosphere is a localized phenomenon
attributable at least in part to the dynamical flow of gas along the
field. A crucial observational test for the occurrence of dynamical
concentration would be a determination of the gas velocity ( j 5 km s
-1) in the region of concentration. Subject headings: hydromagnetics -
Sun: atmosphere - Sun: magnetic fields

---------------------------------------------------------
Title: Basic Properties of Magnetic Flux Tubes and Restrictions on
Theories of Solar Activity
Authors: Parker, E. N.
1976Ap&SS..44..107P Altcode:
It is shown that the mean longitudinal field in a magnetic flux tube
is reduced, rather than enhanced, by twisting the tube to form a
rope. It is shown that there is no magnetohydrostatic equilibrium
when one twisted rope is wound around another. Instead there is
rapid line cutting (neutral point annihilation). It is shown that the
twisting increases, and the field strength decreases, along a flux
tube extending upward through a stratified atmosphere. These facts are
at variance with Piddington's recent suggestion that solar activity
is to be understood as the result of flux tubes which are enormously
concentrated by twisting, which consist of several twisted ropes wound
around each other, and which came untwisted where they emerge through
the photosphere.

---------------------------------------------------------
Title: On the physical interpretation of the cosmic-ray transport
equations.
Authors: Jokipii, J. R.; Parker, E. N.
1976ApJ...208..220J Altcode:
It is pointed out that an earlier paper (Jokipii and Parker, 1967)
had discussed in detail the question of the interpretation of the
energy-change terms in the general equation for cosmic-ray transport
in the solar wind, so that no need exists to reassess the physical
interpretation, as urged by Gleeson and Webb (1974). The question
concerns the expression for the adiabatic deceleration, which is
'replaced' by an expression for the mean rate of change of momentum of
fast particles. It is pointed out that these two expressions represent
two essentially different quantities. The adiabatic deceleration refers
to the mean rate loss of kinetic energy of an individual particle
as a result of the expansion of the gas and magnetic field of the
wind. This parameter can in no way depend on the gradient of the fast
particle density, as does the mean rate of change of momentum of the
fast particles.

---------------------------------------------------------
Title: Astronomers' Petition
Authors: Schramm, David N.; Anders, Edward; Chandrasekhar, S.; Palmer,
Patrick; Parker, Eugene; Simpson, J. A.
1976Sci...191.1124S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Hydraulic concentration of magnetic fields in the solar
photosphere. III. Fields of one or two kilogauss.
Authors: Parker, E. N.
1976ApJ...204..259P Altcode:
Detailed analysis of weak and strong lines suggests that the magnetic
fields in isolated intense flux tubes in supergranule boundaries in
the solar photosphere may be as large as 2000 gauss. This paper is a
concise systematic review of hydrodynamic effects that might compress a
magnetic field to great intensity. The properties of force-free fields
are reviewed to show that they do not contribute to concentration of
magnetic fields, in spite of the popular notion to the contrary. Of
the seven effects considered, it is concluded that only cooling of the
gas within the field can produce the high field densities inferred
from observation. It is shown that inhibition of convection appears
not to possess the necessary qualitative cooling features and that
overstability, generating transverse hydromagnetic waves - essentially
Alfven waves - is the only way to account for the cooling and field
intensification.

---------------------------------------------------------
Title: The Enigma of Solar Activity
Authors: Parker, E. N.
1976IAUS...71....3P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Acceleration of Particles to High Energy
Authors: Parker, E. N.
1976ASIC...28..137P Altcode: 1976pntr.conf..137P
No abstract at ADS

---------------------------------------------------------
Title: The Basic Physical Properties of a Galactic Magnetic Field
Authors: Parker, E. N.
1976ASIC...28..169P Altcode: 1976pntr.conf..169P
No abstract at ADS

---------------------------------------------------------
Title: University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin. Observatory reports.
Authors: Parker, E. N.; Hobbs, L. M.
1976BAAS....8...54P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The magnetic fields of planets
Authors: Parker, E. N.
1976pspe.proc..812P Altcode:
The magnetic fields of planets are considered, taking into account
the history of the geomagnetic field characteristics, the magnetic
field of Jupiter, the magnetic properties of Mars, the significance
of a failure to detect signs of a magnetic field during the passage
of Mariner 10 near Venus, the discovery of a magnetic field during
the passage of Mercury, the absence of a lunar magnetic field, and
the magnetic field of the sun. The causes of planetary magnetism are
discussed and attention is given to dynamic considerations.

---------------------------------------------------------
Title: The escape of magnetic flux from a turbulent body of gas.
Authors: Parker, E. N.
1975ApJ...202..523P Altcode:
Topological conditions on the surface of a turbulent body of highly
conductive fluid under which escape of magnetic force lines would
be impossible (Drobyshevski, Yuferev 1974) are studied with exact
calculation of intermediate field configurations as a possible
explanation of the decay of stellar magnetic fields via turbulent
mixing. It is shown that upward escape of magnetic force lines in the
regions between convective cells is possible through rapid reconnection
of the force lines (studied as neutral point annihilation) such as
occurs continually in rapidly evolving sunspot groups. It is concluded
that there exists no topological barrier to the escape of magnetic
flux from the sun or from the local galaxy.

---------------------------------------------------------
Title: X-ray bright spots on the sun and the nonequilibrium of a
twisted flux rope in a stratified atmosphere.
Authors: Parker, E. N.
1975ApJ...201..494P Altcode:
The calculations are concerned with the hydrostatic equilibrium of
a magnetic flux tube whose two ends are anchored at some level in a
stratified atmosphere. It is shown that no hydrostatic equilibrium
exists if the whole flux tube is twisted more than a modest amount,
equivalent to a 450 pitch over only one scale height. When the total
twisting exceeds this small amount, the tube is subject to negative
tension (compression) and buckles, spirals, and/or lengthens into
a contorted form which causes rapid dissipation and reconnection of
the magnetic field. The rapid dissipation continues until the excess
azimuthal field is consumed and equilibrium is again possible. We
suggest that the magnetic flux tubes in the Sun generally have more
than the allowed twisting, so that, when they rise up through the
surface, as a consequence of their buoyancy, they are subject to
rapid dissipation, causing the phenomenon observed as the X-ray bright
spot. Subject headings: hydromagnetics - Sun - X-rays, solar

---------------------------------------------------------
Title: Solar activity and the general absence of hydrostatic
equilibrium in an azimuthal magnetic field.
Authors: Parker, E. N.
1975ApJ...201..502P Altcode:
It is shown that any temperature variation along the axis of symmetry
of an azimuthal field causes continual convective activity. There is
no static equilibrium configuration except in very special, and hence
improbable, cases. It is suggested that this dynamic effect contributes
to the activity associated with the flux tubes extending through the
solar photosphere. The X-ray bright spots, evidently caused by the
emergence and expansion of small bipolar regions, may be produced in
part by the convective effect of an azimuthal field.

---------------------------------------------------------
Title: Comment on "The stabilizing effects of cloud reacceleration,
microturbulence, and rotation on Parker's instability".
Authors: Parker, E. N.
1975ApJ...201...74P Altcode:
It is pointed out that the calculations in the paper by Zweibel and
Kulsrud do not speak to the question of the instability and evolution of
the gaseous disk of the Galaxy. Rather, they seem to treat the question
of the statistical stability of the present turbulent dynamical
state. Subject headings: hydromagnetics - interstellar matter -
turbulence

---------------------------------------------------------
Title: The sun.
Authors: Parker, E. N.
1975SciAm.233c..42P Altcode: 1975SciAm.233...42P
The development of scientific knowledge of the sun is reviewed from
Emden's first theoretical solar model (early 19th century) to the
latest Skylab observations. Concepts dealt with include the solar
wind, solar activity, energetic processes, thermonuclear generation
of energy, and solar neutrinos. The carbon-nitrogen cycle and the
proton-proton chain are outlined, and attempts at neutrino detection
are discussed. Magnetohydrodynamic activity on the sun is described
together with the nature and behavior of sunspots. Possible effects
of sunspot activity on terrestrial weather are considered.

---------------------------------------------------------
Title: The Dynamo Mechanism for the Generation of Large-Scale
Magnetic Fields
Authors: Parker, E. N.
1975NYASA.257..141P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The generation of magnetic fields in astrophysical
bodies. X. Magnetic buoyancy and the solar dynamo.
Authors: Parker, E. N.
1975ApJ...198..205P Altcode:
The magnetic field appearing as bipolar magnetic regions at the surface
of the sun represents the lines of force from a general azimuthal
field of the order of 100 gauss somewhere beneath the surface. The
amplification time, as a consequence of the nonuniform rotation, is
of the order of 10 years. But magnetic buoyancy brings the azimuthal
field up through much of the convective zone in a time rather less
than 10 years, raising the question of where the azimuthal field can
be retained long enough to be amplified. We show that magnetic fields
can be retained for long periods of time in the stable radiative region
beneath the convective zone, but unfortunately the solar dynamo cannot
function there because turbulent diffusion is an essential part of its
operation. The only possible conclusion appears to be that the dynamo
operates principally in the very lowest levels of the convective zone
at depths of 150,000 km or more, where the gas density is 0.1 g/cu cm,
and the fields are limited to 50 gauss.

---------------------------------------------------------
Title: The Nature of the Sunspot Phenomenon. IV: The Intrinsic
Instability of the Magnetic Configuration
Authors: Parker, E. N.
1975SoPh...40..291P Altcode:
It is pointed out that the equilibrium configuration of a sunspot
magnetic field, confined to the cool umbra by the pressure of the
surrounding photospheric gas, is unstable to the familiar hydromagnetic
exchange instability. The characteristic time for dissolution of the
sunspot is of the order of one hour.

---------------------------------------------------------
Title: The Nature of the Sunspot Phenomenon. III: Energy Consumption
and Energy Transport
Authors: Parker, E. N.
1975SoPh...40..275P Altcode:
This paper points out the basic relation between the conversion of
thermal energy into convective fluid motion (Alfvén waves when a strong
vertical magnetic field is present) and the convective transport of
thermal energy. It is shown that heat transport necessarily accompanies
convective driving of fluid motion. Convective motions restricted to
a layer whose thickness is a small fraction of the local scale height
can divert no more than the same fraction of the energy into Alfvén
waves. But if the convecting layer extends over many scale heights,
then the convective forces may convert more energy into fluid motion
than they transport. Hence the creation of a cool sunspot requires
convection extending coherently over several scale heights, at least
500 km. This requirement is basically just the familiar thermodynamic
efficiency of an ideal heat engine. The calculations establish that
convection need not be much less efficient than the ideal.

---------------------------------------------------------
Title: Book Review: Cosmic gas dynamics. EVRY SCHATZMAN and LUDWIG
BIERMANN: John Wiley, New York, 1974. xv + 291 pp. £8.40
Authors: Parker, E. N.
1975P&SS...23..388P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The dynamo mechanism for the generation of large-scale
magnetic fields.
Authors: Parker, E. N.
1975NYASA.257Q.141P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin. Observatory reports.
Authors: Parker, E. N.; Hobbs, L. M.
1975BAAS....7...25P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The dynamo mechanism for the generation of larg-scale magnetic
fields.
Authors: Parker, E. N.
1975NYASA.257R.141P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Instability of Strong Magnetic Fields in Stellar Interiors
Authors: Parker, E. N.
1974Ap&SS..31..261P Altcode:
There has been discussion of the possibility of resolving the
solar neutrino dilemma with a sufficiently strong magnetic field
(5×108 G) in the solar interior to relieve the gas pressure
by some ten percent or more. We examine the time in which magnetic
buoyancy will bring a strong field to the surface and find it to be
less than 108 yr. We see no possibility for retaining a
suitably strong magnetic field in the solar interior.

---------------------------------------------------------
Title: The Nature of the Sunspot Phenomenon. II: Internal Overstable
Modes
Authors: Parker, E. N.
1974SoPh...37..127P Altcode:
The properties of Alfvén waves in a vertical column of field
are pointed out as a guide in treating the complicated problem of
overstability. There are internal Alfvén waves of arbitrary form
propagating along the magnetic field, without disturbing the fluid
outside the column. There are also surface waves which involve the
fluid both inside and outside the column of field. The surface waves
propagate at a speed less than the Alfvén speed.

---------------------------------------------------------
Title: The Dynamical Properties of Twisted Ropes of Magnetic Field
and the Vigor of New Active Regions on the Sun
Authors: Parker, E. N.
1974ApJ...191..245P Altcode:
The equilibrium configuration following expansion of all, or part,
of a force-free magnetic rope is worked out formally from the
hydromagnetic equilibrium equations. It is shown that expansion of a
portion of the length of a long magnetic rope beyond a certain radius
causes the expanded portion to be wrapped with an azimuthal field
composed of lines of force from the surface layer of the unexpanded
portion. This singular redistribution takes an extended period of time
to achieve. Further, it automatically causes the expanded portion to
become unstable to buckling. We suggest that the restless behavior of
the magnetic fields in new active regions in the solar photosphere is
largely a result (a) of the buckling brought about by the expansion
of the fields as they emerge through the photosphere, and (b) of the
long-term redistribution of the surface lines of force onto the expanded
portion of the rope. Subject headings: hydromagnetics - magnetic fields,
solar - solar activity

---------------------------------------------------------
Title: Hydraulic Concentration of Magnetic Fields in the Solar
Photosphere. II. Bernoulli Effect
Authors: Parker, E. N.
1974ApJ...190..429P Altcode:
The magnetic filaments in the solar photosphere are subject to vigorous
kneading and massaging by the convective turbulence at, and beneath,
the visible surface. It is shown that the Bernoulli effect of the
consequent surging of fluid up and down along the filaments is a
major factor in concentrating the magnetic pressure of the filament
(the mean square field). The mean field is also increased if the phase
velocity of the external massaging exceeds the Alfven speed within the
filament. The net observational magnetic result of the surging, then,
depends upon the response of the observing instrument, and whether
it essentially observes the mean field, the rms field, or whether
there are saturation effects. The hydraulic effects responsible for
the formation of the concentrated magnetic filaments are part of the
dynamical picture of spicules, pointed out a decade ago. Hence we
suggest that the chromospheric mottles (spicules) seen in Ha are in
fact the intense magnetic filaments that carry most of the magnetic flux
across the photospheric boundary of the Sun. Subject headings: granules
and supergranules, solar - hydromagnetics - magnetic fields, solar

---------------------------------------------------------
Title: The Nature of the Sunspot Phenomenon. I: Solutions of the
Heat Transport Equation
Authors: Parker, E. N.
1974SoPh...36..249P Altcode:
Heat transport in the Sun is describable by a Fokker-Planck, or
diffusion, transfer equation. A study of the general character of
the solutions of the transfer equation shows that the inhibition of
convective transport beneath the photosphere produces a photospheric
dark ring surrounded by a bright ring, or at best, a dark area
surrounded by a bright ring. The mean temperature beneath the `sunspot'
is unavoidably above normal, so that the enhanced gas pressure would
disperse, rather than concentrate, the magnetic field. Hence we conclude
that the inhibition of convection cannot be the cause of a sunspot.

---------------------------------------------------------
Title: Hydraulic Concentration of Magnetic Fields in the Solar
Photosphere. I. Turbulent Pumping
Authors: Parker, E. N.
1974ApJ...189..563P Altcode:
Observations suggest that most of the magnetic flux through the solar
photosphere is concentrated in vertical filaments in the supergranule
boundaries. Each filament appears to contain about 3 x 10' maxwells,
in the form of a field of 500 gauss or more, over a diameter of 700 km
or less. The magnetic energy density in the filaments is 100 times the
observed kinetic energy density of the observed supergranule motions,
but comparable to the kinetic energy density of the granules. Force-free
field configurations cannot duplicate the observational numbers, nor
can such cooling effects as are believed responsible for the intense
fields in sunspot umbrae. We point out a simple hydraulic mechanism-
turbulent pumping that appears to account for the observed concentration
of fields. The mechanism is treated by using the simple mixing-length
theory of convection and turbulence. Subject headings: atmospheres,
solar - granules and supergranules, solar hydromagnetics - turbulence

---------------------------------------------------------
Title: The University of Chicago: Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin 1972-1973. Observatory reports.
Authors: Parker, E. N.; van Altena, W. F.
1974BAAS....6R..15P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The University of Chicago, Department of Astronomy and
Astrophysics, Chicago, Illinois; The Yerkes Observatory, Williams Bay,
Wisconsin 1972-1973. Observatory reports.
Authors: Parker, E. N.; van Altena, W. F.
1974BAAS....6Q..15P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comment on "galactic Magnetic Fields: Cellular or Filamentary
STRUCTURE?"
Authors: Parker, E. N.
1974ApJ...187..191P Altcode:
The recent statistical studies of Michel and Yahil emphasize again the
difficulty in interpreting the observed Faraday rotation measure in
terms of an unambiguous model of the galactic magnetic field. We have
difficulty in understanding their specific suggestion that the magnetic
fields expelled from stars have anything to do with the model. Subject
headings: interstellar matter magnetic fields - solar wind

---------------------------------------------------------
Title: Convection and Magnetic Fields in an Atmosphere with Constant
Temperature Gradient. II. The Supergranules and Magnetic Fields
Authors: Parker, E. N.
1973ApJ...186..665P Altcode:
The hydrodynamic properties of convective motions in a stratified
atmosphere suggest that e supergranules in the solar photosphere extend
to depths in excess of their horizontal diameters. The calculations
presented here show that the weak fields which appear at the photosphere
are as strong as, or stronger than, the horizontal fields anywhere in
the supergranules below the surface. Hence the general gauss azimuthal
field of the Sun, whose presence is indicated by the emerging bipolar
magnetic regions, must lie below the base of the supergranules, i.e.,
below a depth probably of the order of 2-5 x i0 km. Presumably then
the azimuthal field is generated by nonuniform rotation below the
supergranule convection and does not appear in the supergranule
layer because of the high rate of turbulent diffusion loss from
that layer. Subject headings: atmospheres, solar - granules, solar -
hydromagnetics

---------------------------------------------------------
Title: Convection and Magnetic Fields in an Atmosphere with Constant
Temperature Gradient. I. Hydrodynamic Flows
Authors: Parker, E. N.
1973ApJ...186..643P Altcode:
In order to deduce the fluid and field conditions deep in the
supergranules from the fluid motions and magnetic fields observed
in the solar photosphere, it is necessary to have some idea of the
depth to which the supergranules extend and the form of their internal
fluid velocities. Toward this end a number of analytic solutions of
the Navier-Stokes equations are given for circumstances possessing
various facets of the supergranule environment in the Sun. These
solutions, together with the earlier work by others, shows that the
granules extend to depths in excess of their mean diameters, that the
convective velocities probably do not diminish much, if any, with depth,
and that across the tops of the supergranules at the photosphere the
horizontal velocity is more or less independent of depth. Subject
headings: atmospheres, solar - granules, solar - hydrodynamics

---------------------------------------------------------
Title: Extragalactic Cosmic Rays and the Galactic Magnetic Field
Authors: Parker, E. N.
1973Ap&SS..24..279P Altcode:
The origin and behavior of cosmic rays in the Galaxy depends crucially
upon whether the galactic magnetic field has a closed topology, as
does the field of Earth, or whether a major fraction of the lines of
force connect into extragalactic space. If the latter, then cosmic rays
could be of extragalactic origin, or they could be of galactic origin,
detained in the Galaxy by the scattering offered by hydromagnetic waves,
etc. If, on the other hand, the field is largely closed, then cosmic
rays cannot be of extragalactic origin (at least below 1016
eV). They must be of galactic origin and escape because their collective
pressure inflates the galactic field and they push their way out. This
paper examines the structure of a galactic field that opens initially
into intergalactic space and, with the inclusion of turbulent diffusion,
finds no possibility for maintaining a significant magnetic connection
with an extragalactic field. Unless some mechanism can be found, we
are forced to the conclusion that the field is closed, that cosmic
rays are of galactic origin, and that cosmic rays escape from the
Galaxy only by pushing their way out.

---------------------------------------------------------
Title: The Generation and Dissipation of Solar and Galactic Magnetic
Fields
Authors: Parker, E. N.
1973Ap&SS..22..279P Altcode:
Turbulent diffusion of magnetic field plays an essential role in
the generation of magnetic field in most astrophysical bodies. This
paper reviews what can be proved, and what can be believed, about
the turbulent diffusion of magnetic field. Observations indicate the
dissipation of magnetic field at rates that can be understood only
in terms of turbulent diffusion. Theory shows that a largescale weak
magnetic field diffuses in a turbulent flow in the same way that smoke
is mixed throughout the fluid by the turbulence. The small-scale fields
(produced from the large-scale field by the turbulence) are limited
in their growth by reconnection of field lines at neutral points,
so that the turbulent mixing of field and fluid is not halted by
them. Altogether, it appears that the mixing of field and fluid
in the observed turbulent motions in the Sun and in the Galaxy is
unavoidable. Turbulent diffusion causes decay of the general solar
fields in a decade or so, and of the galactic field in 108
109 yr. We conclude that continual dynamo action is implied
by the observed existence of the fields.

---------------------------------------------------------
Title: Cosmic Rays in the Outer Solar System (Article published
in the Space Science Reviews special issue on 'Outer Solar System
Exploration - An Overview', ed. by J. E. Long and D. G. Rea.)
Authors: Parker, E. N.
1973SSRv...14..576P Altcode:
A space mission to Jupiter and Saturn, and beyond, provides an
opportunity to explore the low energy galactic cosmic rays, which
are largely excluded from the inner solar system by the outward sweep
of the magnetic fields in the solar wind. The low energy cosmic rays
are believed to be responsible for much of the heating of the gaseous
disk of the galaxy, so a measurement of their intensity will have far
reaching effects on theories of the interstellar gas and the evolution
of the galaxy. The nuclear abundances, and in particular the presence
or absence of high Z nuclei, will give critical information on the
proximity of cosmic ray sources.

---------------------------------------------------------
Title: The Reconnection Rate of Magnetic Fields
Authors: Parker, E. N.
1973ApJ...180..247P Altcode:
Solar flares, and the absence of intense small-scale magnetic fields
in the turbulent solar photosphere, suggest that the reconnection
rate, or merging speed, of two oppositely directed magnetic fields
is of the general order of the Alfve'n speed. The fluid between
the opposite fields escapes via the well-known interchange and kink
instabilities, permitting rapid close approach of the fields, and
merging rates probably of the order of 0.1 VA, or faster, in most
cases. Hence reconnection is sufficiently rapid, with or without
microinstabilities, that it plays a major role in solar flares and
in the reduction of small-scale turbulent fields. Subject headings:
flares, solar - hydromagnetics - magnetic fields, solar - turbulence

---------------------------------------------------------
Title: Comments on the reconnexion rate of magnetic fields
Authors: Parker, E. N.
1973JPlPh...9...49P Altcode:
The reconnexion rate of magnetic fields is crucial in understanding
the fields found in turbulent flows in the solar photosphere and
in the galaxy, and in flare phenomena. This paper examines the
behaviour of magnetic fields in the neighbourhood of an X-type neutral
point. The treatment is kinematical, specifying the velocity field v
and constructing solutions to the hydromagnetic equation for B. The
calculations demonstrate that the reconnexion rate is controlled by
the diffusion in the near neighbourhood of the neutral point, and is
not arbitrarily large, as has been suggested by similarity solutions
of the complete field and fluid equations for vanishing diffusion

---------------------------------------------------------
Title: A strategy for investigation of the outer solar system. Outer
planets, their satellites, and particles and fields at great distances
from the sun.
Authors: Münch, G.; Hunten, D. M.; Kliore, A. J.; Lewis, J. S.;
McElroy, M. B.; Spencer, N. W.; Stone, P. H.; Wetherill, G. W.;
Cameron, A. G. W.; Hubbard, W. B.; Murray, B. C.; Peale, S. J.; van
Allen, J. A.; Axford, W. I.; Gulkis, S.; Kennel, C. F.; Montgomery,
M. D.; Parker, E. N.; Sonett, C. P.; Stone, R. G.; Trainor, J. H.;
Rea, D. G.; Long, J. E.; Padrick, B. D.
1973SSRv...14..347M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: (Inaugural Lecture) What We Think We Know and Do Not Know
About Solar Flares
Authors: Parker, E. N.
1973str..conf....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical Bodies.IX. a
Solar Dynamo Based on Horizontal Shear
Authors: Lerche, I.; Parker, E. N.
1972ApJ...176..213L Altcode:
In view of the uncertainty in the angular velocity (r, 0) in the solar
interior, we have worked out the general behavior of the solar dynamo
for horizontal shear (() /aO) for comparison with the earlier models
based on vertical shear (a /ar). The horizontal shear produces greater
complexity, with the fields at the surface migrating toward the equator
(for a uniform distribution of shear and cyclonic convection) and a
layer of counter migrating fields at the bottom of the dynamo. More
important, perhaps, the horizontal shear excites the even and odd
modes equally, whereas vertical shear excites the odd mode before the
even mode.

---------------------------------------------------------
Title: Topological Dissipation and the Small-Scale Fields in
Turbulent Gases
Authors: Parker, E. N.
1972ApJ...174..499P Altcode:
It is shown that a large-scale magnetic field possesses a hydrostatic
equilibrium only if the pattern of small-scale variations is uniform
along the large-scale field. Thus equilibrium obtains only if the
variations in the field consist of simple twisting of the lines,
with the twists extending uniformly the full length of the field. Any
more complicated topology, such as two or more flux tubes wrapped
around each other to form a rope, or braided or knotted flux tubes,
is without equilibrium, no matter what fluid pressures are applied
along the individual lines of force. The result is rapid dissipation
and field-line merging, which quickly reduces the topology to the
simple equilibrium form. It follows from this general theorem that
line merging has important consequences in turbulent fields. In
spite of large magnetic Reynolds numbers of the individual eddies,
the line merging reduces the small-scale fields in the turbulence
below the value for equipartition with the turbulence. The effect has
important astrophysical implications. It explains the absence of strong
small-scale fields in the solar photosphere and in interstellar space
in spite of the vigorous turbulence.

---------------------------------------------------------
Title: Present Developments in Theory of the Solar Wind
Authors: Parker, E. N.
1972NASSP.308..161P Altcode: 1972sowi.conf..161P
No abstract at ADS

---------------------------------------------------------
Title: The dynamical behavior of the interstellar gas, field, and
cosmic rays
Authors: Parker, E. N.
1972cpp..conf..195P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. VII. The Internal Small-Scale Fields
Authors: Lerche, I.; Parker, E. N.
1971ApJ...168..231L Altcode:
The paper investigates the small-scale magnetic fields B generated,
along with the large-scale magnetic fields B, by cyclonic turbulence
and large-scale shear. The results are directly applicable to the
problem of the generation of magnetic fields in the Galaxy,for
which the observations show only the complexity of the small- and
large-scale fields together, making it difficult to discover the actual
configuration of the large-scale galactic field. The calculations
show that the fluctuations in the generaijon of field in the Galaxy
contribute a (( B)1) comparable to (B1).

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. VIII. Dynamical Considerations
Authors: Parker, E. N.
1971ApJ...168..239P Altcode:
It is pointed out that the kinetic energy of the differential rotation
of the Galaxy is sufficient to maintain generation of the galactic
magnetic field for a period of time in excess of 10's years. In the
Sun, on the other hand, the nonuniform rotation must be driven by
thermal convective forces, etc. Magnetic buoyancy of the azimuthal
field B is an important energy source in the Sun, nd contributes to
the generation of the poloidal of the solar field. In the Galaxy
the magnetic buoyancy of B contributes to the generation of the
poloidal field, but if present observational estimates are correct,
the inflation of the gaseous disk of the Galaxy by cosmic rays is a
major source of the energy generating the poloidal component of the
galactic poloidal field. The dynamical-dynamo equations are solved
in the linear approximation to illustrate the direct generation of
poloidal field from magnetic buoyancy and from cosmic-ray inflation.

---------------------------------------------------------
Title: Recent Developments in Theory of Solar Wind
Authors: Parker, E. N.
1971RvGSP...9..825P Altcode: 1971RvGeo...9..825P
No abstract at ADS

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies.VI. Periodic Modes of the Galactic Field
Authors: Parker, E. N.
1971ApJ...166..295P Altcode:
It is shown from the dynamo equations that the cyclonic turbulence
and nonuniform rotation of the gaseous disk of the Galaxy generate
magnetic field in both periodic and nonperiodic modes. Order-ofmagmtude
estimates of the dynamo number suggest that the large-scale galactic
field is generated in the lowest even periodic and/or nonperiodic
modes. The characteristic period of the periodic mode is estimated at
108 years. The large amplitude of the small-scale (lO pc) fluctuations
in the internal field of the Galaxy make it difficult to compare the
local field observations with theory to designate the mode of the
large-scale field extending throughout the disk.

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. V. Behavior at Large Dynamo Numbers
Authors: Parker, E. N.
1971ApJ...165..139P Altcode:
There is the theoretical possibility that some astrophysical objects may
have large dynamo numbers, generating fields in high modes. The effect
of the boundaries is diminished, and it is profitable to consider the
fields in terms of the four basic wave modes of the dynamo. Normal
incidence and reflection of dynamo waves from boundaries are worked
out. Dynamo wave packets are discussed briefly, and a pseudoillustration
of the solar dynamo is presented. The purpose of the calculations is
to illustrate some of the behavior at large dynamo numbers, to aid in
observational recognition.

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies.IV. The Solar and Terrestrial Dynamos
Authors: Parker, E. N.
1971ApJ...164..491P Altcode:
This paper explores the question of why the magnetic field of
Earth is quasi-stationary in time while the field of the Sun is
quasi-periodic. Both fields are believed to be produced by a combination
of nonuniform rotation and cyclonic turbulence, or Rossby waves. The
calculations show that small dynamo numbers lead to stationary states,
producing a dipole when the dynamo number is negative in the northern
hemisphere, as in Earth. The dynamo number in the northern hemisphere
of the Sun is positive, but fails to produce the stationary quadrupole
field because of the high dissipation associated with the thinness of
the convective region. The lowest mode available in the Sun is periodic
in time, with the fields an odd function of latitude, as observed. The
calculations show that a modest increase in the dynamo number in the
Sun excites the quadrupole mode. In view of the observed north-south
asymmetry of the solar magnetic fields, the periodic quadrupole mode
may be excited much of the time. The important consequences of magnetic
variation of the Sun for the space environment of Earth suggest that
a more general theoretical exploration of the dynamo equations in
spherical coordinates should be carried out.

---------------------------------------------------------
Title: The Dynamical Effects of Cosmic Rays in the Galaxy and the
Generation of the Galactic Magnetic Field.
Authors: Parker, E. N.
1971ICRC....8...95P Altcode: 1971ICRC........95P; 1971ICRC...12h..95P
No abstract at ADS

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. III. Turbulent Diffusion of Fields and Efficient Dynamos
Authors: Parker, E. N.
1971ApJ...163..279P Altcode:
It is shown v formal calculation that the probability distribution of
magnetic field carried in a turbulent fluid varies with the time in a
manner identical with the probability distribution of a scalar field
carried in the same turbulence. Then if Kraichnan's results are used
for the diffusion of scalar fields, the effective turbulent-diffusion
coefficient is 0.15 `u/k5, where u is the rms velocity of the turbulence
and k0 is the wavenumber of the large eddies. In the gaseous disk of the
Galaxy this gives 3 X I0 cm2 . It follows from this large value of that
the galactic field cannot be primordial, but is automatically generated
by the nonuniform rotation and turbulence throughout the gaseous disk.

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. II. The Galactic Field
Authors: Parker, E. N.
1971ApJ...163..255P Altcode:
The gaseous disk of the Galaxy is subject to nonuniform rotation
and internal turbulence. The rotation causes the turbulence to be
cyclonic. Formal solution of the dynamo equations in a slab of gas,
representing the galactic disk, produces regenerative modes, in which
the aximutal field is an even function of the distance a from the
central plane of the slab. Inclusion of the ` eddy diffusivity" of
the turbulence in the dissipation terms of the dynamo equations gives
growth times of 108 years. Hence we suggest that the magnetic field of
the Galaxy is generated by the combination of nonuniform rotation and
turbulence in the gaseous disk. The dynamo principle responsible for
the magnetic field of Earth and of tlie Sun appears to be operative
on a galactic scale, too.

---------------------------------------------------------
Title: Magnetic fields in astrophysics.
Authors: Parker, E. N.
1971JAP....42.1464P Altcode:
Magnetic fields appear in association with most astrophysical objects
and spaces. Their general effect is to promote fast-particle and
enhanced-temperature activity. It appears that the magnetic fields are
generated by the combined nonuniform rotation and cyclonic turbulence of
the objects. The nonuniform rotation shears the fields, producing strong
fields in the azimuthal direction. The cyclonic turbulence interacts
with the azimuthal field Bφ generating azimuthal vector
potential Aφ at a rate described by the dynamo equation
(∂/∂t-η▿2) Aφ = ΓBφ, where
Γ is essentially the cyclonic velocity of the turbulence. The fields
of Earth, the Sun, and the galaxy appear to be generated in this way.

---------------------------------------------------------
Title: Theoretical aspects of the worldwide magnetic storm phenomenon.
Authors: Parker, E. N.; Ferraro, V. C. A.
1971HDP....49..131P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Universal magnetic fields.
Authors: Parker, E. N.
1971AmSci..59..578P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Generation of Magnetic Fields in Astrophysical
Bodies. I. The Dynamo Equations
Authors: Parker, E. N.
1970ApJ...162..665P Altcode:
The paper presents a formal derivation of the dynamo equations
describing the generation of largescale magnetic fields by small-scale
cyclonic turbulence (or convection) in a rotating fluid body. The
derivation is based on the simple approximation that the individual
turbulent cells are small and shortlived. The dynamo equations show
that large-scale magnetic fields are generated at a very high rate,
in periods comparable to the time of nonuniform rotation. The dynamo
equations describe the generation of the quasi-steady field of Earth
and the migratory field of the Sun, in characteristic times of 10 and
10 years, respectively.

---------------------------------------------------------
Title: Comments on `Steady state charge neutral models of the
magnetosphere'
Authors: Lerche, I.; Parker, E. N.
1970Ap&SS...8..140L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Origin of Magnetic Fields
Authors: Parker, E. N.
1970CoASP...2..127P Altcode: 1970ComAp...2..127P
No abstract at ADS

---------------------------------------------------------
Title: The Origin of Magnetic Fields
Authors: Parker, E. N.
1970ApJ...160..383P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: on the Convection, Diffusion, and Adiabatic Deceleration of
Cosmic Rays in the Solar Wind
Authors: Jokipii, J. R.; Parker, E. N.
1970ApJ...160..735J Altcode:
We present a generalization and clarification of work on the transport
of cosmic rays in the solar system. The general equations for the
cosmic-ray density and flux, in the anisotropic-diffusion approximation,
are derived in the frame of reference moving with the solar wind,
and the transformation to the fixed frame is discussed. Only if
the particle density varies smoothly with energy does one obtain a
straightforward generalization of equations derived previously for
isotropic diffusion. In this approximation we write down, for the first
time, the correct differential equations for the particle density and
flux for anisotropic diffusion. If the density varies sharply with
energy, more complex integro-differential equations arise. We conclude
that existing alternative derivations, based on the Boltzmann equation,
are in general not adequate for either anisotropic-diffusion or energy
transformations.

---------------------------------------------------------
Title: The Origin of Solar Magnetic Fields
Authors: Parker, E. N.
1970ARA&A...8....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Origin and Dynamical Effects of the Magnetic Fields and
Cosmic Rays in the Disk of the Galaxy
Authors: Parker, E. N.
1970IAUS...39..168P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Report on quasi-stationary modulation papers.
Authors: Parker, E. N.
1970ICRC....5..341P Altcode: 1970ICRC...11e.341P; 1969ICRC.......341P
No abstract at ADS

---------------------------------------------------------
Title: Interstellar Gas and Field
Authors: Parker, E. N.; Lerche, I.
1969CoASP...1..215P Altcode: 1969ComAp...1..215P
No abstract at ADS

---------------------------------------------------------
Title: The Occasional Reversal of the Geomagnetic Field
Authors: Parker, E. N.
1969ApJ...158..815P Altcode:
It is presently believed that the geomagnetic field is generated by the
combined effects of the cyclonic convective motions and the nonuniform
rotation of the liquid core of Earth. Fossil magnetism shows that
the fie'd remains steady for periods of the order of 1O6~1O7 years,
and then, at apparently random times, reverses abruptly, thereafter
remaining steady for another 1O~-1O~ years, etc. We do not believe
that the reversal of the field is caused by a temporary change in
the sign of the cyclonic or nonuniform rotations, since the signs of
both are determined by the Coriolis forces of the rotating Earth. We
demonstrate that a statistical fluctuation in the distribution of the
fifteen to twenty cyclonic con~ vective cells in the core produces an
abrupt reversal of the geomagnetic field. The simplest fluctuation
lead- ing to reversal is a general absence of cyclones below about
300 latitude for a time comparable to the life (`-%`1O~ years) of the
individual cell. Assuming that the convective cells are statistically
independent of each other, we estimate that such a fluctuation might
occur once in 1O~ years. The simplicity of the mechanism recommends
it as the explanation for the reversal of the field at random intervals

---------------------------------------------------------
Title: Amplification of Weak Magnetic Fields in Turbulent Flow
Authors: Parker, E. N.
1969ApJ...157.1119P Altcode:
The problem of a weak magnetic field carried in a turbulent-velocity
field is considered under the circumstance that the velocity field is
a prescribed random function of space and time. It is assumed that the
time over which the velocity field is correlated with itself is very
short. In this approximation the theory of random functions is used
to show that the velocity field amplifies the magnetic field at all
wave- numbers. Thus the calculation establishes that the large-scale
components of a magnetic field in a turbu- lent-velocity field grow
without limit as long as the velocity field is maintained. The unlimited
amplifica- tion is of interest in astrophysical problems

---------------------------------------------------------
Title: Origin of the Magnetic Field of the Galaxy
Authors: Parker, E. N.
1969ApJ...157.1129P Altcode:
A recent formal calculation demonstrates that the individual Fourier
components of a magnetic field are stochastic variables when the
field is carried in a random turbulent velocity V~(r,t). The indi-
vidual Fourier components random-walk, with the result that their
mean squares increase with time. The calculation is applicable to
the Galaxy when the magnetic field is sufficiently weak (B &lt; 1O~
gauss). Application to the gaseous disk of the Galaxy indicates that a
field of 1O~ gauss would be created in less than 1O~ years. The present
orientation and large scale of the field along the galactic arm are
presumably the result of the nonuniform rotation of the Galaxy. We
conclude that turbulence is the most powerful source of magnetic field
in the Galaxy, and that the present galactic magnetic field is the
result of such turbulence. I. INTRODUCTIO

---------------------------------------------------------
Title: Galactic Effects of the Cosmic-Ray Gas
Authors: Parker, E. N.
1969SSRv....9..651P Altcode:
On an astronomical scale cosmic rays must be considered a tenuous and
extremely hot (relativistic) gas. The pressure of the cosmic-ray gas
is comparable to the other gas and field pressures in interstellar
space, so that the cosmic-ray pressure must be taken into account
in treating the dynamical properties of the gaseous disk of the
galaxy. This review begins with a survey of present knowledge of the
cosmic-ray gas. Then the kinetic properties of the gas are developed,
followed by an exposition of the dynamical effects of the cosmic-ray
gas on a large-scale magnetic field embedded in a thermal gas. The
propagation of low-frequency hydromagnetic waves is worked out in the
fluid approximation. The dynamical properties of the gaseous disk of
the galaxy are next considered. The equations for the equilibrium
distribution in the direction perpendicular to the disk are worked
out. It is shown that a self-consistent equilibrium can be constructed
within the range of the observational estimates of the gas density,
scale height, turbulent velocity, field strength, cosmic-ray pressure,
and galactic gravitational acceleration. Perturbation calculations then
show that the equilibrium is unstable, on scales of a few hundred pc
and in times of the order 2 × 107 years. The instability is
driven about equally by the magnetic field and the cosmic-ray gas and
dominates self-gravitation. Hence the instability dominates the dynamics
of the interstellar gas and is the major effect in forming interstellar
gas clouds. Star formation is the end result of condensation of the
interstellar gas into clouds, indicating, then, that cosmic rays play
a major role in initiating star formation in the galaxy. The cosmic
rays are trapped in the unstable gaseous disk and escape from the disk
only in so far as their pressure is able to inflate the magnetic field
of the disk. The observed scale height of the galactic disk, the short
life (106 years) of cosmic-ray particles in the disk of the
galaxy, and their observed quiescent state in the disk, indicate that
the galactic magnetic field acts as a safety valve on the cosmic ray
pressure P so that P≅B 2/8π. We infer from the observed
life and quiescence of the cosmic rays that the mean field strength
in the disk of the galaxy is 3 5 × 10-6 gauss.

---------------------------------------------------------
Title: Theoretical Studies of the Solar Wind Phenomenon
Authors: Parker, E. N.
1969SSRv....9..325P Altcode:
This paper is a review of current theoretical topics concerning the
solar wind. Broadly speaking the questions outstanding at the present
time concern the loss of angular momentum to the sun, the origin of the
fluctuations observed in the wind at the orbit of earth, conditions in
the wind in regions yet unvisited by spacecraft (inside the orbit of
Venus, beyond the orbit of Mars, and out of the plane of the ecliptic),
conditions at the terminus of the wind, etc. The question of angular
momentum loss is important in understanding the evolution of the sun
to its present form with a slowly rotating surface. Evidence from both
comet and spacecraft observations of the wind indicate that the rate
at which angular momentum is being carried away by the solar wind is
very large, of the order of 1031 dyne/cm in the gas flow
and half as much by the interplanetary magnetic field. But theory
cannot account for more than about 1030 dynes/cm in the
gas without special assumptions. The fluctuations presently observed
in the wind at the orbit of earth have scales ranging upward from
102 km. Their presence is puzzling because fluctuations with
scales less than about 106 km are not expected to survive
from the sun. Presumably, therefore, the fluctuations are generated
by the velocity differences of more than 100 km/sec in the wind from
different regions in the solar corona and by instabilities produced
by the anisotropy of the electrons of the wind plasma. Conditions in
the wind at places far removed from the orbit of earth can be inferred
from the behavior of cosmic rays. The evidence is that the wind becomes
relatively placid beyond about 5 AU, extending from there out to 30 300
AU without much small-scale turbulence. There are also some suggestions
that the wind may perhaps be less turbulent toward the sun from 1 AU,
and that the wind may be faster and more turbulent at higher solar
latitudes. But the ambiguity of the situation does not permit a firm
conclusion on this yet.

---------------------------------------------------------
Title: Stochastic Aspects of Magnetic Lines of Force with Application
to Cosmic-Ray Propagation
Authors: Jokipii, J. R.; Parker, E. N.
1969ApJ...155..777J Altcode:
It is pointed out that magnetic lines of force in nature are generally
stochastic and ergodic. Owing to unavoidable fluctuations in the field,
adjacent lines of force random-walk away from each other. The stochastic
properties of the lines of force in the astrophysical universe are
related to the stochastic prop- erties of the (turbulent) velocity
fields in which they are imbedded. The consequent random walk of the
field lines is shown to contribute appreciably to K1, the coefficient
for particle diffusion normal to the average field, with the result
that the particles are spread across the average magnetic field
much more rapidly than expected from the usual resonant scattering
by small-scale irregularities. The Sun's extended magnetic field,
traversed by both energetic solar particles and galactic cosmic rays,
serves as an excellent illustration of these concepts. Application of
the theory to the interplanetary magnetic fields shows that the random
walk of the field lines is determined by the observed power spec-
trum of the fluctuations in the magnetic field at zero frequency. The
observed turbulent velocity field in the solar photosphere yields a
random walk equal to that obtained from the observed power spectrum
of the magnetic field. These two determinations of the random walk of
the field lines, in turn, agree with the observed spread in solar
longitude of promptly arriving solar cosmic rays. The observed
shear planes and flux tubes of the "wet spaghetti" model of the
interplanetary magnetic field are evidently a direct manifestation
of the photospheric supergranulation. We also discuss the diffusion
of cosmic rays in the interplanetary magnetic field observed near
solar minimum. For protons with energies of 10 MeV and below, the
ratio KL/KII at the orbit of the Earth becomes comparable to unity,
instead of nearly zero as would be expected on the basis of resonant
scat- tering alone. The contribution of the random walk to K~ is also
significant at relativistic energies. Applica- tion to the theory of
the diurnal variation of galactic cosmic rays agrees with observation
both at `-~.-`1O MeV and at relativistic particle energies

---------------------------------------------------------
Title: Cosmic-Ray Life and the Stochastic Nature of the Galactic
Magnetic Field
Authors: Jokipii, J. R.; Parker, E. N.
1969ApJ...155..799J Altcode:
We point out that the observed mean life for cosmic rays of ~ yrs
is difficult to account for in conventional models of the galactic
magnetic field. A stochastic model of the interstellar magnetic field
is proposed, and is shown to provide a natural explanation of the
cosmic-ray lifetimes. The random walk of magnetic lines of force,
deduced from the observed turbulent motions of the gas and also from
observa- tions of the polarization of starlight, leads to rapid motion
of the cosmic-ray particles normal to the plane of the galactic disk

---------------------------------------------------------
Title: Energetic solar particles.
Authors: Parker, E. N.
1969AIQSY...4...57P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar wind interaction with the geomagnetic field.
Authors: Parker, E. N.
1969RvGSP...7....3P Altcode: 1969RvGeo...7....3P
No abstract at ADS

---------------------------------------------------------
Title: Summary of symposium
Authors: Parker, E. N.
1969sfsr.conf..412P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Physical model of hydrodynamic turbulence.
Authors: Parker, E. N.
1969PhFl...12.1592P Altcode:
A model for statistically isotropic homogeneous turbulence in an
incompressible fluid is constructed, representing the turbulence as a
superposition of individual vortex sheets. Each vortex sheet moves in
the velocity field of the other sheets which have larger scale. Each
sheet is stretched out, and intensified, until obliterated by viscosity
at high wavenumber. The rate of stretching is related to the symmetric
part of the strain tensor ∂νi/∂κj, which
is postulated to be statistically independent of the antisymmetric
part. Representing the turbulence by the usual energy spectrum function
F(k) leads to a set of integrodifferential equations. Solution of
the equations gives a spectrum which is in close agreement with
experimental spectra of turbulence over both the inertial and
viscous subranges, suggesting that the model may be of some real
physical interest. The model is sufficiently explicit so as to give
information on the correlation between different Fourier components
of the turbulence. The calculations give the probability of finding
a particular value of the vorticity or velocity at a given position
and time in the turbulent field.

---------------------------------------------------------
Title: Dynamical properties and effects of cosmic rays in the galaxy
Authors: Parker, E. N.
1969pia..conf..237P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical Behaviour of the Gaseous Disk of the Galaxy
Authors: Parker, E. N.
1969crsr.conf..202P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Fields. VII. Disruptive Forces
Authors: Parker, E. N.
1968ApJ...154..875P Altcode:
The important role played by disruptive forces in regulating the
conversion of interstellar gas into stars is pointed out in the context
of the present dynamical theory of the interstellar gas and fields

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Field.VI. Instability and Enhanced Diffusion in a Twisted Field
Authors: Lerche, I.; Parker, E. N.
1968ApJ...154..515L Altcode:
The general instability of a magnetic field confined by the weight
of thermal gas (through which the field threads) is investigated for
a twisted field (v X B II B). The purpose is to see whether the asso-
ciated enhanced ambipolar diffusion is seriously affected by the twist
in the field. It was pointed out earlier that the enhanced diffusion
(computed for an untwisted field) may contribute (a) to the escape of
the interstellar magnetic field from the gas forming a star and (b)
to the evolution of the gaseous disk of the Galaxy The calculations
given in the present paper suggest that the twist in the field should
in- crease the instability and the associated large wavenumbers,
thereby increasing the enhanced ambipolar diffusion. We conclude that
our earlier estimates of the enhanced ambipolar diffusion rate in the
Galaxy may be on the conservative side

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Field.IV. Evolution of the Disk of Interstellar Gas
Authors: Parker, E. N.
1968ApJ...154...49P Altcode:
It is shown that ambipolar diffusion, enhanced by the dynamical
instability of the interstellar gas-field system, may permit the escape
of a significant portion of the interstellar magnetic field from the
disk of the Galaxy during the 1O'°-year life of the Galaxy. The result
is a decrease in the scale height or thickness of the gaseous disk

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Field. V. Reduced Dynamical Equations
Authors: Parker, E. N.
1968ApJ...154...57P Altcode:
The dynamical equations for a gas suspended on a horizontal magnetic
field are simplified and re- duced by supposing that the Alfvén speed
is large compared with the thermal velocity and that the scales are
small compared with the scale height. The simplification renders the
equations tractable in more complicated physical situations than the
complete set of hydromagnetic equations used in some of the earlier
investigations. A number of results for hydrostatic equilibrium,
and for small perturbations of an equilibrium, are worked out to
illustrate the properties of the approximate system of equations. Com-
parison with the special cases treated from the complete equations
indicates that most of the essential features of the dynamics appear
to be retained by the simplified equations. The simplified equations
are to be applied to more complicated cases in future papers

---------------------------------------------------------
Title: Random Walk of Magnetic Lines of Force in Astrophysics
Authors: Jokipii, J. R.; Parker, E. N.
1968PhRvL..21...44J Altcode:
We point out the importance of the random fluctuations in astrophysical
magnetic fields, which lead among other things to rapid diffusion of
energetic particles across the average magnetic field. Application
to the interplanetary magnetic field leads to a theory in which the
field-line random walk, measured by the observed power spectrum of
field fluctuations, is in agreement with that deduced from the observed
turbulent motions in the solar photosphere. The two determinations
agree well with the recently observed spread in longitude of low-energy
particles released at the sun.

---------------------------------------------------------
Title: Dynamical Properties of Cosmic Rays
Authors: Parker, E. N.
1968nim..book..707P Altcode: 1968S&SS....7..707P
No abstract at ADS

---------------------------------------------------------
Title: Dynamical Properties of the Magnetosphere
Authors: Parker, E. N.
1968ASSL...10....3P Altcode: 1968phma.conf....3P
No abstract at ADS

---------------------------------------------------------
Title: Considerations of Solar Wind-Magnetosphere Interactions
Authors: Parker, Eugene N.
1968epf..conf..357P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The role of stochastic fields in admitting low-energy galactic
cosmic rays to the solar system
Authors: Parker, E. N.
1968JGR....73.6842P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Non-Equilibrium and Enhanced Mixing at a Plasma-Field Interface
Authors: Lerche, I.; Parker, E. N.
1967ApJ...150..731L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Cosmic ray diffusion, energy loss, and the diurnal variation
Authors: Parker, E. N.
1967P&SS...15.1723P Altcode:
The purpose of this paper is to consider a number of points pertaining
to the origin of the observed mean diurnal variation of the cosmic
ray intensity, which were not treated in the earlier papers on the
subject. Following a brief review of the basic nature of the diurnal
variation, the necessary diffusion across the lines of force is
investigated. It is found that the values κ ⊥/κ
‖ ≅ 10 -2 deduced from the observed
fluctuations inside the orbit of Earth give about the right amount of
diffusion to account for the fact that the amplitude of the diurnal
variation is approximately half the theoretical upper limit, which
would apply if κ⊥ were much larger. The calculations show
that the geometry of the spiral form of the field beyond the orbit
of Earth plays an essential role in providing sufficient diffusion
across the lines of force. The calculations also show that variation
in outer radius R and in κ ⊥/κ ‖ due to
changing wind conditions may contribute to some of the observed changes
in the amplitude of the diurnal variation. The diurnal variation is
rederived for steady uniform wind conditions in order to include the
effect of adiabatic deceleration. The effect is the addition of a
small diurnal component with an amplitude proportional to the radial
cosmic ray gradient in space. The effect is only a few per cent of the
total diurnal variation above 1 GeV, and so may be neglected there. The
effect is large at low energies, but is not subject to observation. The
principal observable steady diurnal variation is, then, the rotation
of the cosmic rays with the Sun. Appendix II gives a summary of the
motion of a particle in an idealized smooth spiral interplanetary field,
with a discussion of the energy loss from adiabatic expansion.

---------------------------------------------------------
Title: An Initial-Value Problem for Oscillations of the Interstellar
Gas
Authors: Lerche, I.; Parker, E. N.
1967ApJ...149..559L Altcode:
For a simple model of the interstellar-gas-magnetic-field system, in
which the disk population of stars provides most of the gravity, it
is demonstrated that a dispersion relation approach to the problem of
small perturbations of the equilibrium state leads to unstable modes
which possess a constant energy density at an infinite distance from
the disk. Since one normally treats perturbations in which the energy
density vanishes at infinity, rather than merely being bounded, we
investigate an initial-value problem in which the energy density does
vanish at infinity. It is shown, with one simple case, that an unstable
situation still develops but that the perturbed quantities grow linearly
with time rather than exponentially, as a normal mode analysis would
indicate. It is further shown that one can still characterize the time
scale for instability by the free-fall time so that conclusions drawn
elsewhere by Parker remain valid.

---------------------------------------------------------
Title: Energy changes of cosmic rays in the solar system
Authors: Jokipii, J. R.; Parker, E. N.
1967P&SS...15.1375J Altcode:
The energy (in the fixed frame of reference) of a cosmic-ray particle
with velocity w in the frame of the solar wind fluctuates between
1/2M(w + v) 2 and 1/2M(w - v) 2 as the particle
random walks in the magnetic field, where v is the wind velocity. This
energy change cannot be treated as a simple Markov process, together
with the random walk and adiabatic deceleration, in a fixed frame
of reference. To describe the particle motion by a Fokker-Planck
differential equation, the energy variable must be the particle
energy in a frame of reference moving with the wind. The appropriate
transformations of both the solutions and boundary conditions are
presented to order v/ w. The corrections due to this effect are
∼10% for 1 MeV particles and correspondingly less for higher energy
particles. The energy balance between the solar wind and cosmic rays
is examined and is shown to depend in a fundamental manner on these
energy transformations. Although the solar wind does net work on the
cosmic-ray gas, no particle gains more than 2 Mvw kinetic energy and
the few particles which penetrate deeply into the solar system suffer
a net energy loss because of adiabatic deceleration.

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Field. II. Non-Linear Growth of Clouds and Forces in Three Dimensions
Authors: Parker, E. N.
1967ApJ...149..517P Altcode:
The growth of the two-dimensional instability of a gas in a
gravitational field g confining a horizontal magnetic field B is
followed into the non-linear regime to provide an illustration of the
formation of discrete gas clouds from a more uniform medium. A shock
forms as the gas falls together, dissipating the energy and making
the process irreversible. The effective force field of an element of
gas (suspended on the lines of force of a horizontal magnetic field)
is calculated in three dimensions. The force field is made up of
an attractive force of the same form as gravity but stronger by the
factor g2/GB2, and a force which extends undiminished along the lines of
force passing near the element of gas. The latter dominates the former
at large distances and is attractive on the lines of force through,
and above and below, the element of gas, and repulsive along the lines
of force passing beside the element of gas. The over-all effect is a
strong attraction, accompanied by vigorous streaming of gas both toward
and away from an established cloud. Clouds are expected to accumulate
gas in such a way as to increase their vertical dimension relative to
the transverse dimension g X B.

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and
Field. III. Turbulence and Enhanced Diffusion
Authors: Parker, E. N.
1967ApJ...149..535P Altcode:
The dynamical instability of the interstellar gas, caused by the
galactic cosmic rays and magnetic field, is examined for the purpose
of gaining a more detailed understanding of the phenomenon. It is shown
that a tissue of field, formed by superposing alternate layers of field
at right angles to each other, fails to produce stability. It is shown
that the instability develops very short wavelengths in the direction
perpendicular to the galactic gravitational field g and magnetic field
B. The result is that the interstellar gas must be in a continual
state of turbulence and fragmentation down to scales of 1 pc or less,
terminating only when the clouds become so dense that self-gravitation
becomes dominant The turbulence and fragmentation enhance ambipolar
diffusion to such an extent that the field escapes from the gas rapidly
compared to the usual ambipolar rates It is suggested that this may
contribute to the escape of the magnetic fields from the interstellar
gas which forms stars

---------------------------------------------------------
Title: Phenomena in Interplanetary Space. (Book Reviews: The Solar
Wind. Proceedings of a conference held in Pasadena, California,
in April 1964)
Authors: Parker, Eugene N.
1967Sci...155..681P Altcode: 1967Sci...155..681M
No abstract at ADS

---------------------------------------------------------
Title: Sun and Earth
Authors: Parker, E. N.
1967easp.book...46P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Disturbance of the Geomagnetic Field by the Solar Wind
Authors: Parker, E. N.
1967pgp..conf.1154P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical State of the Interstellar Gas and Field
Authors: Parker, E. N.
1966ApJ...145..811P Altcode:
There is now enough observational information available to show that
the interstellar magnetic field in the general neighborhood of the
Sun is, on the average, parallel to the plane of the Galaxy, with an
average strength somewhere between 10-6 and tO-' gauss. This paper
points out certain dynamical requirements for the existence of such
a field. The paper is based on the assumption that the intergalactic
medium, whatever it may be, exerts pressures on the Galaxy that
are small compared to 10-12 dyne/cm'. It can then be shown that the
galactic, or interstellar, magnetic field must be to the Galaxy by the
weight of the gas threaded by the field and distributed throughout the
disk of the Galaxy. It is then shown that the interstellar gas-field
system is subject to a universal Rayleigh-Taylor instability of such
a nature that the interstellar gas tends to concentrate into pockets
suspended in the field. The cause of the instability may he thought
of as a hydromagnetic self-attraction in the interstellar gas, which
may be ten times larger than the gravitational self-attraction of
the gas. It is this hydromagnetic self-attraction which produces the
observed tendency of the interstellar gas to be confined in discrete
clouds. The calculations and arguments do not restrict the over-all
topology or the strength of the galactic field, which apparently must
still be determined from observation.

---------------------------------------------------------
Title: Non-Relativistic Equations of Bulk Motion of a Relativistic Gas
Authors: Lerche, I.; Parker, E. N.
1966ApJ...145..106L Altcode:
The linearized equations of bulk motion of a gas, in which the
pressure cannot be neglected compared to the rest energy of the gas,
are deduced by taking moments of the collisionless Boltzmann equation
in the absence of external forces. The problem is of interest because
of its application to the cosmic-ray gas in the Galaxy.

---------------------------------------------------------
Title: The Kinetic Properties of the Galactic Cosmic-Ray Gas
Authors: Parker, E. N.
1966ApJ...144..916P Altcode:
The elementary formulae for the pressure and the speed of sound in
a statistically isotropic homogeneous cosmic-ray gas are worked
out. Cosmic-ray observations near Earth give a cosmic-ray energy
density of 1.29 X 10- erg/cm3, a pressure of 0.45 x 1O dyne/cm2, and
a compressibility P/ N = 0.66&gt;&lt; 10-li erg/cm3. There is reason
to believe that the interstellar values are not significantly higher
than near Earth.

---------------------------------------------------------
Title: The effect of adiabatic deceleration on the cosmic ray spectrum
in the solar system
Authors: Parker, E. N.
1966P&SS...14..371P Altcode:
Cosmic rays in the magnetic fields carried in the solar wind are
continually expanded and decelerated, in addition to being convected
out of the solar system. The effect of the deceleration on the cosmic
ray spectrum is calculated for the case that the outward convection
of cosmic rays is small and for the case that the cosmic ray spectrum
is a simple power law and the diffusion coefficient is independent of
energy. The calculations are carried out for both particle momentum
and energy. It is shown that a power law spectrum is preserved by the
deceleration. It is shown that the deceleration contributes a decrease
at high energies of about one third of the total modulation. Where the
spectrum flattens out at lower energies, the deceleration produces an
increase which partially cancels the reduction by convection.

---------------------------------------------------------
Title: Dynamical Properties of Stellar Coronas and Stellar
Winds. V. Stability and Wave Propagation
Authors: Parker, E. N.
1966ApJ...143...32P Altcode:
The stability of an expanding corona against radial compressional
waves is considered. It is shown that the linearized equations of
motion are hyperbolic and the expanding corona is stable to the same
general degree as a static atmosphere. Examples of wave propagation
are worked out to illustrate the variation of amplitude of the waves
with radial distance from the Sun.

---------------------------------------------------------
Title: The Penetration of Galactic Cosmic Rays into the Solar System
Authors: Parker, E. N.
1966sowi.conf..185P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Particle Effects in the Geomagnetic Field
Authors: Parker, E. N.
1966ASSL....5..302P Altcode: 1966rtem.conf..302P
No abstract at ADS

---------------------------------------------------------
Title: Superthermal Hydromagnetic Waves.
Authors: Parker, E. N.
1965ApJ...142.1086P Altcode:
The linearized of motion of a thermal gas and some very hot suprathermal
gas, such as interstellar cosmic rays, in a uniform magnetic field are
wntten down for plane waves in the low-frequency limit. The dispersion
relation shows that there are three modes altogether: The conventional
slow and fast hydromagnetic waves in the thermal gas are unaffected,
except that there is a "hole" in the fast mode in the direction
perpendicular to the magnetic field. The third mode is the suprathermal
mode, representing waves in the suprathermal gas with essentially the
velocity of sound in the suprathermal gas alone. The suprathermal
mode fills the "hole" in the fast mode and is obviously the first
disturbance to reach distant points following a supernova explosion.

---------------------------------------------------------
Title: Dynamical Theory of the Solar Wind
Authors: Parker, E. N.
1965SSRv....4..666P Altcode:
This paper is a review of the basic theoretical dynamical properties
of an atmosphere with an extended temperature strongly bound by
gravity. The review begins with the historical developments leading up
to the realization that the only dynamical equilibrium of an atmosphere
with extended temperature is supersonic expansion. It is shown that
sufficient conditions for supersonic expansion are T(r) declining
asymptotically less rapidly than 1/r, or the density at the base of
the corona being less than N b given by (40) if no energy
is available except through thermal conductivity, or the temperature
falling within the limits given by (18) if T ∝ N α-1
throughout the corona. Less extended temperatures lead to equilibria
which are subsonic or static. The hypothetical case of a corona with no
energy supply other than thermal conduction from its base is considered
at some length because the equations may be solved by analytical
methods and illustrate the transition from subsonic to supersonic
equilibrium as the temperature becomes more extended. Comparison with
the actual corona shows that the solar corona is actively heated for
some distance into space by wave dissipation. The dynamical stability
of the expanding atmosphere is demonstrated, and in a later section the
radial propagation of acoustic and Alfvén waves through the atmosphere
and wind is worked out. The calculations show that the magnetometer
will probably detect waves more easily than the plasma instrument,
but that both are needed to determine the mode and direction of the
wave. An observer in the wind at the orbit of Earth can “listen”
to disturbances generated in the corona near the sun and in turbulent
regions in interplanetary space. The possibility that the solar corona
is composed of small-scale filaments near the sun is considered. It is
shown that such filamentary structure would not be seen at the orbit
of Earth. It is pointed out that the expansion of a non-filamentary
corona seems to lead to too high a calculated wind density at the
orbit of Earth to agree with the present observations, unless T(r)
is constant or increases with r. A filamentary corona, on the other
hand, would give the observed wind density for declining T(r). It
is shown that viscosity plays no important role in the expansion
of an atmosphere either with or without a weak magnetic field. The
termination of the solar wind, presumably between 10 103
AU, is discussed briefly. The interesting development here is the
interplanetary L αrecently observed, which may come from the
interstellar neutral hydrogen drifting into the outer regions of the
solar wind. Theory is at the present time concerned with the general
dynamical principles which pertain to the expansion equilibrium of an
atmosphere. It is to be expected that the rapid progress of direct
observations of the corona and wind will soon permit more detailed
studies to be carried out. It is important that the distinction between
detailed empirical models and models intended to illustrate general
principles be kept clearly in mind at all times.

---------------------------------------------------------
Title: Cosmic Rays and Their Formation of a Galactic Halo.
Authors: Parker, E. N.
1965ApJ...142..584P Altcode:
It is demonstrated that a magnetic gas cloud confined by gravity has
no equilibrium configuration if cosmic rays are generated within it. By
application of the theorem to the Galaxy, it is shown that cosmic rays
lead to inflation of the galactic magnetic fields, producing a halo of
cosmic rays and field around the Galaxy. Present observational estimates
of cosmic-ray life, magnetic-field strength, etc.,indicate an outward
inflation rate of the order of 102 km/sec, although this number may
be revised with improved observations. This cosmic-ray halo extends
far out from the disk and nucleus of the Galaxy, presumably limited
by instabilities which eventually free the cosmic rays and fields at
a great distance. The field inflation acts as a pressure regulator on
the cosmic rays generated in the galactic disk and nucleus, so that
the life of a cosmic-ray particle in the disk of the is determined
mainly by the rate of generation of cosmic rays. Present estimates of
the cosmic-ray life are based on the rather uncertain value of the
density of interstellar gas. The gas is intimately associated both
with the dynamics of the galactic fields and the calculated rate of
cosmic-ray production.

---------------------------------------------------------
Title: Dynamical Properties of Stellar Coronas and Stellar Winds,
IV. The Separate Existence of Subsonic and Supersonic Solutions.
Authors: Parker, E. N.
1965ApJ...141.1463P Altcode:
The dynamical equations are considered for a stationary stellar corona
whose energy is supplied only by thermal conduction from its base and
which is surrounded by a cold vaccuum. The density and temperature
at the base of the corona are denoted by N0 and T0, respectively. It
is shown that subsonic and supersonic expansion of such a minimum
stellar corona are separated by a density N (To): If N0 &lt; NB(To),
the expansion is supersonic; if N0&gt; NB(To), the expansion is
subsonic. Observations suggest that T0 1 X 100 K for the quiet solar
corona, so that NB(To) 3 X 1010/ cm3. The observed densities are
108-109/cm3, requiring supersonic expansion. Detailed comparison of
this theoretical corona of minimum heating with the observed solar
temperatures, densities, and expansion velocity suggests that the
solar corona is, in fact, heated in depth.

---------------------------------------------------------
Title: General dynamical effects of cosmic rays in the Galaxy.
Authors: Parker, E. N.
1965ICRC....1..126P Altcode: 1965ICRC....9..126P
No abstract at ADS

---------------------------------------------------------
Title: The passage of energetic charged particles through
interplanetary space
Authors: Parker, E. N.
1965P&SS...13....9P Altcode:
The passage of cosmic ray particles and energetic solar particles
through interplanetary space is illustrated with a number of
idealized examples. The formal examples are worked out from the
condition that energetic particles in interplanetary space random
walk in the irregularities in the large-scale interplanetary magnetic
field. The irregularities move with approximately the velocity of the
solar wind. The classical probability distribution is describable
by a Fokker-Planck equation. A general expression for the particle
diffusion coefficient kij is worked out, including
both scattering in magnetic irregularities and systematic pressure
drifts. Magnetometer data from Explorer XVIII is presented to show
the close average adherence of the quiet-day interplanetary magnetic
field to the theoretical spiral angle, and to show the tendency
for particles to move more freely along the field than across,
k∥ &gt; k⊥. The observed fields show that
the diffusion coefficient is of the order of 10 21-10
22 cm 2/sec, as had been estimated from
earlier cosmic ray studies. A middle value of 3 × 10 21
cm 2/sec suggests a cosmic ray density gradient of about 10
per cent per a.u. across the orbit of Earth. Direct observations of the
interplanetary magnetic field afford the possibility for quantitative
estimate of Kij as a function of particle energy. The
first example to be considered is isotropic diffusion in a spherical
region r &lt; R with uniform radial wind velocity v for the purpose
of illustrating the general nature and duration of the passage of a
cosmic ray particle through the solar system. It is shown that the
cosmic ray density reduction is of the order of exp (- vR/ k), and,
hence, that during the years of solar activity vR/ k is not less than
about 1 for protons of one BeV or so. It follows from this that the
galactic cosmic ray particles will generally have spent several days
in the solar system by the time they are observed. During this time
they are in the expanding magnetic fields carried in the solar wind
and are adiabatically decelerated, losing 15 per cent or more of their
energy by the time they are observed. The energy distribution is shown
for particles starting all with the same energy T0 from
interstellar space. The incoming probability wave of a single particle
is computed as a function of time, showing how the particle is swept
back by the wind. The converse problem of energetic solar particles
is illustrated. The solar particles may typically lose half their
initial energy before escaping into interstellar space. The outward
motion of the wind displaces their probability distribution outward so
that ultimately the maximum solar particle intensity may lie beyond the
orbit of Earth. The outward motion of the wind steepens the decline of
the solar particle intensity. The steady-state cosmic ray intensity is
calculated throughout the spherical region r &lt; R supposing a uniform
cosmic ray density N0 to obtain in interstellar space. The
calculation is carried out for isotropic Kij, which would
obtain if the magnetic irregularities were of large amplitude and
of a scale not exceeding the radius of gyration of the cosmic ray
particles, and for anisotropic kij with k∥
≫ k⊥, which obtains when the field is relatively
smooth. (The observations at sunspot minimum suggest k∥ ≫
k⊥ at the orbit of Earth.) The particles diffuse only along
the spiral lines of force when k∥ ≫ k⊥,
so their path in and out of the solar system is much longer than when
Kij is isotropic. The result is a much greater reduction
of the cosmic ray intensity for a given vR/| Kij|. There
is no direct observational information on Kij beyond the
orbit of Earth, where the intensity reduction takes place. Indirect
information is available, however. There is the fact that the intensity
of energetic solar particles at Earth often decays as t- g
with g = 1·5-2·0. It is shown that in order for this to follow, it is
necessary that | Kij| ∞ rs with s = 0·0-0·5 if
kij is isotropic, and s = 2·0-2·5 if k∥ ≫
k⊥. That is to say, if Kij should continue to
be as anisotropic beyond Earth as it is observed to be near Earth, then
the diffusion must increase rapidly with distance from the Sun. These
qualitative features should be easily detectable with particle, field,
and plasma observations beyond the orbit of Earth.

---------------------------------------------------------
Title: On the Existence of Slow Solutions in Coronal Hydrodynamics.
Authors: Parker, E. N.
1965ApJ...141..322P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Some remarks on the influence of the granulation on the
magnetic field
Authors: Parker, E. N.
1965IAUS...22..232P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A brief outline of the development of cosmic ray modulation
theory
Authors: Parker, E. N.
1965ICRC....1...26P Altcode: 1965ICRC....9...26P
No abstract at ADS

---------------------------------------------------------
Title: Coronal Expansion and Solar Corpuscular Radiation
Authors: Parker, E. N.
1965ASSL....3...99P Altcode: 1965pss..conf...99P
No abstract at ADS

---------------------------------------------------------
Title: A Mechanism for Magnetic Enhancement of Sound-Wave Generation
and the Dynamical Origin of Spicules.
Authors: Parker, E. N.
1964ApJ...140.1170P Altcode:
It is pointed out that a vertical magnetic field through an atmosphere
with a small scale height greatly tahances the generation of sound
(fast-mode) waves in the fluid motions in the atmosphere. The fluid
motions become a monopole, rather than the usual quadrupole, source of
radiation. The sound waves ropagate principally in the upward direction
along the field. It is suggested that this mechanism, apart from its
other applications, operates in the plage areas on the Sun and is
responsible for the spicules.

---------------------------------------------------------
Title: Review of Publications- Interplanetary Dynamical Processes
Authors: Parker, E. N.
1964JRASC..58..235P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Discussion of Paper by E. J. Stegelmann and C. H. von
Kenschitzki `On the Interpretation of the Sudden Commencement of
Geomagnetic Storms'
Authors: Parker, E. N.; Dessler, A. J.
1964JGR....69.3745P Altcode:
It was pointed out some years ago [Dessler et al. 1960] that a major
part of the rise time of a sudden commencement can be accounted for
as the period of time in which the enhanced solar wind sweeps over
the outer boundary of the geomagnetic field, plus the difference in
propagation time from different points on the boundary. The dimensions
of the outer boundary of the geomagnetic field are of the order of
105 km, so that an enhanced wind of 103 km/sec
characteristically takes about 102 seconds to engulf the
field and enhance the compression of the field. Typical propagation
times within the field differ by 102 seconds. The basic idea
was simply that the compression of the geomagnetic field at the surface
of the earth results from the algebraic sum of all the compressive
forces exerted by the wind on the outer boundary of the field [Parker,
1958]. Any changes in the compressive forces on the outer boundary are
communicated inward at about the Alfvén velocity [Francis et al.,
1959]. Enhanced compression of the boundary starts somewhere on the
solar side, at which time a slight increase in compression begins to
propagate through the geomagnetic field as a hydromagnetic wave. With
the passage of time more and more of the boundary is compressed as the
enhanced wind sweeps by in space. The rising compression communicates
throughout the field with the Alfvén speed, and levels off only after
the enhanced wind fully encloses the geomagnetic field.

---------------------------------------------------------
Title: Theory of streaming of cosmic rays and the diurnal variation
Authors: Parker, E. N.
1964P&SS...12..735P Altcode:
The motion of charged particles in magnetic fields is reviewed
for the purpose of understanding the observed net streaming of
cosmic rays through interplanetary space. It is shown that the
large-scale fields (which often reverse) give no steady streaming by
themselves. Small-scale irregularities in the large-scale fields can
give steady radial streaming which in the vicinity of Earth is some
small fraction of the solar wind velocity. A large-scale field at
the orbit of Earth with sufficient magnetic irregularity beyond gives
an azimuthal streaming with the velocity of rigid rotation with the
Sun. It is suggested that this rigid rotation is the origin of the
observed diurnal variation.

---------------------------------------------------------
Title: Formation of Massive Quasi-Stellar Objects.
Authors: Miller, R. H.; Parker, E. N.
1964ApJ...140...50M Altcode:
Enhancement of evaporation from a star cluster through the operation
of co-operative phenomena is suggested as a possible mechanism for
the formation of compact massive objects from star clusters in times
of the order of 1016 years.

---------------------------------------------------------
Title: Coronal expansion and solar corpuscular radiation
Authors: Parker, E. N.
1964P&SS...12..451P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Scattering of Charged Particles by Magnetic Irregularities
Authors: Parker, E. N.
1964JGR....69.1755P Altcode:
The equations of motion of a charged particle are integrated through
an irregularity in a large-scale magnetic field. The scattering of
the particle is shown to diminish as the cyclotron radius of the
particle becomes either large or small compared to the scale of the
irregularity and to have a maximum when the radius is comparable to
the scale. When the cyclotron radius is large, the order of magnitude
of the scattering depends on the number of sequential reverse bends in
the lines of force through the magnetic irregularity. It is important
for the understanding of modulation of the cosmic-ray intensity by
the solar wind to determine the degree of correlation between adjacent
bends in the irregularities in the interplanetary magnetic field.

---------------------------------------------------------
Title: The Perturbation of Interplanetary Dust Grains by the Solar
Wind.
Authors: Parker, E. N.
1964ApJ...139..951P Altcode:
It is expected that photoelectric emission from the interplanetary
dust grains leads to a positive charge the order of 10 volts on each
grain. The Lorentz forces exerted on this charge by the magnetic
fields . ied in the solar wind produce large perturbations in the
Kepler orbits of the grains. On the assumpn that the sign of the
interplanetary magnetic field reverses every few days, it is shown
that the orbital lination of particles with radii equal to or smaller
than about 1 X 10- cm at the orbit of Earth is atly increased by the
Lorentz forces The importance of the Lorentz perturbation increases
with the tance from the Sun.

---------------------------------------------------------
Title: Dynamical Properties of Stellar Coronas and Stellar
Winds. III. The Dynamics of Coronal Streamers.
Authors: Parker, E. N.
1964ApJ...139..690P Altcode:
Observations suggest that the solar corona may perhaps consist of
thin radial filaments and streamers, rather than bring an amoiphous
atmosphere. The filaments and streamers presumably are confined by the
magnetic field, along whose lines 9f force they lie. To investigate the
consequences of a filamentary corona for the solar wind, the dynamics
of an idealized cona composed of gaseous streamers, with vacuum between
the streamers, is worked out neglecting solar rotation, etc. The pnndpal
conclusions are that the streamers occupy most of space at large radial
distance from the Sun, no matter how small a fraction they may occupy
at the Sun; the velocity of the solar wind is not greatly affected by
filamentary structure for a given coronal temperature distribution; the
mean-wind density is not affected by more than a factor of 2. Mtogether,
then, except for the presence of some thin interstreamer regions, there
is no great effect of a filamentary structure on the mean values of the
solar-wind velocity and density at large distance from the Sun. The
possibility of instability of coronal streamers is looked into, and
it is shown that, if the corona is composed principally of streamers,
the Helmholtz instability may be expected to disorder and mix up the
streamer and interstreamer regions beyond some distance 0 (1 a.u.) from
the Sun, which might perhaps be the origin of some of the disorder
observed by Mariner. More quantitative observational information of
the solar corona and/or of the structure of the solar wind close to
the Sun will have to be available before quantitative statements can
be made concerning the role of streamers in the solar wind.

---------------------------------------------------------
Title: Dynamical Properties of Stellar Coronas and Stellar
Winds. I. Integration of the Momentum Equation.
Authors: Parker, E. N.
1964ApJ...139...72P Altcode:
The hydrodvnamic momentum and mass flow equations are integrated
for a stellar corona with spherical symmetry about the center of
the star. The coronal temperature is taken to be a known function
T(r) of radial distance. The general properties of the equations are
discussed, and it is shown that if the corona is tightly bound by the
solar gravitational field, so that the thermal elodty is small compared
to the gravitational escape velocity, and if the coronal temperature
declines outward more slowly than 1/r, then the corona is quasi-static
at its base and expands to supersonic velocity in space. No alternative
is available. The stellar mass loss resulting from the expansion is
determined by the coronal temperature between the base of the corona
and the point at which the flow becomes supersonic. The amount by
which the velocity of the resulting stellar wind exceeds the thermal
velocity in the corona depends principally upon the temperature beyond
the point where the flow becomes supersonic.

---------------------------------------------------------
Title: Dynamical Properties of Stellar Coronas and Stellar
Winds. II. Integration of the Heat-Flow Equation.
Authors: Parker, E. N.
1964ApJ...139...93P Altcode:
The temperature T(r) in a stellar corona is computed under the
circumstances that energy is supplied outward from the base of the
corona only by thermal conduction. The heat-flow equation is solved
analytically under a variety of circumstances. It is shown that the
energy flow to infinity is non-vanishing for finite coronal density
and thermal conductivity. The temperature declines less rapidly than
1/r, and a supersonic stellar wind is the only available solution of
the equations compatible with negligible pressure at r = A variety of
asymptotic cases are worked out to illustrate some of the temperature
proffles T(r) to be expected under various circumstances. For instance,
in a corona of very low density the energy consumed by expansion of
the corona can be neglected and T(r) , as in Chapman's original static
coronal model. The result is a supersonic stellar wind with a velocity
v( ) of the same order as the gravitational escape velocity 21!2w. In
a corona with medium density and sufficiently low temperature that
v('0) is small compared to w, a near region, in which T(r) extends
for some distance outward from the star before the far region, T(r)
, takes over. The result is a supersonic stellar wind velocity v(
) of the same order as the characteristic thermal velocity C0 at
the base of the corona. In a corona which is exceedingly dense, an
intermediate region in which T(r) appears between the near and the
far regions, which has the result of extending to large distance the
point at which the coronal expansion becomes supersonic. In a corona
which is exceedingly hot (cc w) the expansion becomes so violent that
thermal conduction becomes negligible and the behavior of the corona
is approximately adiabatic. It is shown that any effect which tends to
reduce the thermal conductivity of the coronal gases at large distance
from the star has the effect of enhancing the velocity of the stellar
wind. Comparison with Chamberlain's earlier discussion of the solution
of the momentum and heat-flow equations in his "solar-breeze" model
shows that he made two self-consistent errors in his assumption that
the energy flux in the solar wind is identically zero and that the
gas motion is adiabatic at large radial distances from the sun. It
is shown that neither assumption is correct in a corona of finite
density. It is shown, however, that the analytical form T(r) 1/r
suggested by Chamberlain is obtained in the limit as the density of
the corona is made large without limit, in which case all motion in the
corona approaches zero. Application of the solutions of the heat-flow
equation to the sun-assuming that the solar corona is heated solely
by thermal conduction-show that at least under present conditions the
solar corona and wind lie in the middle ground between high and low
density and temperature. Assuming that they have coronas heated solely
by conduction it is suggested that some of the giant stars with the low
gravitational escape velocities, may fall into the high-density case,
and certain dwarfs into the low-density case. Some of the very active
stars may fall into the high-temperature quasi-adiabatic case.

---------------------------------------------------------
Title: Coronal Expansion and Solar Corpuscular Radiation
Authors: Parker, E. N.
1964rege....1...99P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comments on Understanding the Solar Flare
Authors: Parker, E. N.
1964NASSP..50..417P Altcode: 1964psf..conf..417P
No abstract at ADS

---------------------------------------------------------
Title: Kinematical Hydromagnetic Theory and its Application to the
Low Solar Photosphere.
Authors: Parker, E. N.
1963ApJ...138..552P Altcode:
The magnetic field B is computed from the hydromagnetic equations for a
variety of given velocity fields';. The velocity fields are classified
as turbulent if their time correlation extends no more than their scale
a divided by their characteristic velocity v. The velocity fields are
classified as persistent if their time correlation extends beyond a/v
but is short compared with the magnetic diffusion time a2/X (X = c2/4ir
, and as stationary if their time correlation extends beyond a2/X. It
is shown that turbulent fluid motions in the solar photosphere generate
r.m.s. fields which are a few times the large-scale field strength B0 in
the photosphere. Where B0&gt; 20 gauss, this leads to equipartition of
energy between the turbulent magnetic and velocity fields. It is &amp;
njectured that, since plages occupy the areas on the solar surface where
B0&gt; 20 gauss, there may be some connection between equipartition and
plage formation. It is shown that motions tend to draw the field into
concentrated sheets and filaments. The observed supergranulation in the
solar atmosphere tends to concentrate vertical magnetic fields around
the edges of the cells, where the field density may become 102 times
larger than in the interior of the cell. It is shown that stationary
motions tend to exclude the magnetic field from the region of fluid
motion. A number of examples are given to show the distortion of the
field by the forces exerted by the fluid diffusing through it. It is
to be hoped that observations will yield simultaneous velocity and
magnetic-field maps so that quantitative comparison can be made with
the expected theoretical results.

---------------------------------------------------------
Title: A Kinematical Theory of Turbulent Hydromagnetic Fields.
Authors: Parker, E. N.
1963ApJ...138..226P Altcode:
A kinematical theory is developed for the r.m.s. magnetic fields
produced by the interaction of turbulent eddies, of scale a and
velocity v, with a large-scale weak magnetic field B0. The principal
interest lies in the small-scale magnetic field generated by the
observed photospheric granules in the observed large-scale photospheric
magnetic fields. The theory considers how a rope of magnetic flux is
both lengthened and widened by the velocity gradients in statistically
stationary, isotropic, homogeneous turbulence in which the velocity
fields are given. Both the amplification and diffusion of the magnetic
field are then computed from the proportions of the rope of flux,
employing the usual statistical assumption that moments of order 2n can
be expressed in terms of the product of n factors of second moments. The
conclusion is that a weak field B0 can be amplified by a factor of the
order of R1/4/ln R, where R is the magnetic Reynolds number. in the
solar photospheric granules this amounts to amplification by a factor
less than 10, so that the small-scale r m 5. fields resulting in quiet
regions where B0 __ 1 gauss are far below the value for equipartition
of energy with the velocity field.

---------------------------------------------------------
Title: The Solar-Flare Phenomenon and the Theory of Reconnection
and Annihiliation of Magnetic Fields.
Authors: Parker, E. N.
1963ApJS....8..177P Altcode:
The paper presents a study of the observations and theory which are
relevant to the presently popular belief that the solar-flare phenomenon
is a direct consequence of the annihilation of magnetic fields on the
sun. There is very little in the observations to support such views. A
systematic study of the known theoretical mechanisms for the diffusion,
reconnection, and annihilation of magnetic fields is presented. The
mechanisms discussed are Joule dissipation, ambipolar diffusion,
and various forms of Sweet's mechanism. It is shown that Sweet's
mechanism is much more effective in a highly compressible medium if
the merging magnetic fields are exacily antiparallel. None of the known
mechanisms are sufficiently rapid to account for the solar flare from
the annihilation of magnetic fields. Errors and omissions in earlier
discussions of the problem are cited. Since no possible energy source
other than magnetic fields has yet been developed, the question of
field annihilation remains both open and pressing. The possibilities of
runaway electrons and hydrodynamic instability, as means for hastening
magneticfield annihilation, are considered. It is shown that there is no
reason to expect runaway electrons and no effective instability unless
the fields are exactly antiparallel. The observational and theoretical
difficulties with the hypothesis of magnetic-field annihilation suggest
that other alternatives for the flare must be explored.

---------------------------------------------------------
Title: Discussion of Paper by L. M. Noble and F. L. Scarf,
`Hydrodynamic Models of the Solar Corona'
Authors: Parker, E. N.
1963JGR....68.1769P Altcode:
In a recent paper entitled `Hydrodynamic models of the solar corona'
Noble and Scarf [1962] discuss the many theoretical models of the
solar corona that have been worked out over the past few years. Some of
the calculations they present are of interest, but unfortunately the
value of the calculations is obscured by the extraordinary physical
interpretations the authors associate with them. For instance, Noble
and Scarf remark that `the models with conductive [heat] flow and no
inner heat source lead to density distributions in fair agreement with
zodiacal light observations, but no solar wind is obtained'. They seem
to be unaware that Chamberlain [1961], whose paper on conductive flow
they quote, had arbitrarily to inhibit the thermal conductivity by a
factor of 8 to obtain agreement with the zodiacal light. Uninhibited
thermal conduction in a 2×106 deg K corona supplies energy
in the amount that seems to be required for the observed solar wind
[Bridge et al., 1962].

---------------------------------------------------------
Title: Theory of Solar Wind
Authors: Parker, E. N.
1963ICRC....1..175P Altcode: 1963ICRC....8a.175P
No abstract at ADS

---------------------------------------------------------
Title: Plasma Dynamics in Astrophysics and Geophysics (Notes by
M. Turoff and A. Skalafuris)
Authors: Parker, E. N.
1963ambp.book....1P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comments on Coronal Heating.
Authors: Parker, E. N.
1963IAUS...16...11P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Interplanetary dynamical processes.
Authors: Parker, Eugene Newman
1963idp..book.....P Altcode: 1963QB505.P3.......
No abstract at ADS

---------------------------------------------------------
Title: Kinetic properties of interplanetary matter
Authors: Parker, E. N.
1962P&SS....9..461P Altcode:
The paper is a review of present estimates of the kinetic and transport
properties of the interplanetary medium. It is pointed out that the
effective mean free paths of interplanetary ions and electrons are
effectively small compared to the scale of the system either because
of Coulomb collisions or because of dynamical instability of the
gas. Numerical expressions are given for the mean free path for Coulomb
collisions, the electrical conductivity, the thermal conductivity, the
viscosity, electromagnetic emission rates, recombination and ionization
times and the charge exchange cross-sections. The magnetic Reynolds
number of the solar wind proves to be large, the Reynolds number is
not very large and the Prandtl number is small. All stationary atoms
and ions are swept out of the solar system by the solar wind. It is
pointed out that the quiet day cosmic ray density in interplanetary
space increases the speed of sound beyond the orbit of Earth, reaching
10 2 km/sec at 50 a.u. if the solar wind should extend
that far. Energetic particles from the sun have an effect which may
be much larger. The abundance of heavy ions in the solar wind may be
significantly below the solar abundance because of diffusion in the
solar corona.

---------------------------------------------------------
Title: Interplanetary Dynamical Processes; The Solar Wind and
Interplanetary Fields
Authors: Parker, E. N.
1962pss..conf...23P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dynamics of the Geomagnetic Storm
Authors: Parker, E. N.
1962SSRv....1...62P Altcode:
This paper is intended as a critical review of current ideas concerning
the mechanisms responsible for the geomagnetic storm. The dynamical
theory of the geomagnetic storm phenomenon is formulated as a problem
in elasticity. The observed variations in the field are the strains
produced by particle stresses exerted by gases in interplanetary space,
by gases enmeshed in the field, and by the gases in the ionosphere. The
stresses exerted by interplanetary gases are principally inward,
resulting in the initial phase increase of the horizontal component. The
stresses exerted by gases enmeshed in the field are principally outward,
resulting in the main phase decrease of the horizontal component. The
transient sudden commencement is a hydromagnetic wave phenomenon. The
main phase is most simply explained by the shock heating of the ions
to kev energies at 3 5 R E during the active phase of the
storm. The recovery follows then from charge exchange with the ambient
neutral hydrogen. The predicted more rapid recovery at sunspot minimum
has been verified observationally.

---------------------------------------------------------
Title: A Mechanism to Establish the Magnetic Storm Ring Current
Authors: Dessler, A. J.; Hanson, W. B.; Parker, E. N.
1962JPSJS..17A.178D Altcode: 1962PSJaP..17A.178D; 1962ICRC....7A.178D; 1962JPSJ...17A.178D
No abstract at ADS

---------------------------------------------------------
Title: Interplanetary Dynamics and Cosmic Ray Modulation
Authors: Parker, E. N.
1962JPSJS..17B.563P Altcode: 1962PSJaP..17B.563P; 1962JPSJ...17B.563P; 1962ICRC....7B.563P
No abstract at ADS

---------------------------------------------------------
Title: Theory of Magnetic Storms
Authors: Parker, E. N.
1962JPSJS..17A.199P Altcode: 1962ICRC....7A.199P; 1962JPSJ...17A.199P; 1962PSJaP..17A.199P
No abstract at ADS

---------------------------------------------------------
Title: Formation of the Geomagnetic Storm Main-Phase Ring Current
Authors: Dessler, A. J.; Hanson, W. B.; Parker, E. N.
1961JGR....66.3631D Altcode:
It is suggested that hydromagnetic waves generated by the impact
of solar plasma on the geomagnetic field may form shock waves in
the magnetosphere, thus providing a mechanism for establishing
the diamagnetic main-phase ring current. These shock waves should
develop on the night side of the earth and heat the ambient protons
(which constitute the normal protonosphere) to approximately
the hydromagnetic-wave velocity (of the order of 500 km/sec). The
transfer of hydromagnetic-wave energy to the protons stresses the
geomagnetic field and produces the geomagnetic-storm main phase; i.e.,
the kilovolt-energy protons form a diamagnetic current. The bombardment
of the upper atmosphere by energetic hydrogen atoms from the decaying
ring current and the possible change in the decay time-constant of
the ring current through the sunspot cycle are discussed.

---------------------------------------------------------
Title: Transresonant Electron Acceleration
Authors: Parker, E. N.
1961JGR....66.2673P Altcode:
Helliwell and Bell have suggested synchronous acceleration of electrons
by electromagnetic waves in the whistler range in the geomagnetic
field. The acceleration of trapped electrons by electromagnetic
waves is here generalized to include nonsynchronous or transresonant
acceleration. It is shown that whistlers will scatter the electron
velocity, by an amount inversely proportional to the square root of
the time rate of change of the whistler frequency, during the time that
the whistler frequency is passing over the electron gyrofrequency. Only
electrons with initial energy above about 102 ev can see the
Doppler-shifted whistler frequency at the gyrofrequency and be affected
by this transresonant acceleration. Thermal electrons experience no
effect. Current observation of whistlers in the outer geomagnetic field
is too sketchy to allow a determination of transresonant acceleration
rates, so that the relative importance, as compared, for example, with
the strong-whistler synchronous acceleration of Helliwell and Bell,
cannot be assessed. The importance of whistler acceleration can be
established when the whistler frequency spectrum and recurrence rate
are known throughout the geomagnetic field.

---------------------------------------------------------
Title: The Distribution of Trapped Particles in a Changing Magnetic
Field
Authors: Parker, E. N.
1961JGR....66.2641P Altcode:
The redistribution of charged particles in the mirror field B(s, t) =
B0T(t){1 + [s/a(t)]v (t)}is worked out for slow
changes in T(t), a(t), and v(t). It is found that increasing T(t)
gives a relatively greater particle density increase in the center
of the field than deep in the mirrors s≫a(t). The mirror distance
retracts like 1/T1/(v+2). Decreasing a(t) has the opposite
effect. Field variations constrained to preserve T(t) a2(t)
and v(t) leave the form of the particle distribution unchanged,
increasing the density everywhere by the same factor.

---------------------------------------------------------
Title: The Stellar-Wind Regions.
Authors: Parker, E. N.
1961ApJ...134...20P Altcode:
From the observations of the solar wind and of the M giant a Herculis
the gross dynamical features of the stellar-wind regions associated
with class G main-sequence and M giant stars are given for various
interstellar environments. The supersonic wind from a class G star
undergoes a shock transition to subsonic flow at a radial distance of
1O-1O a u. This subsonic flow will be subject to turbulence and other
instabilities in many cases. The wind from an M giant may extend many
parsecs if the M-giant phase of evolution lasts as long as 1O years; the
resultant interstellar contamination and heating are important. A rough
calculation of the cavity formed by a stellar wind in a large-scale
interstellar magnetic field shows that the cavity shape and dimensions
for stationary flow depend on the pressure at infinity. As the pressure
increases, the cavity changes from a circular cylinder of infinite
radius, through an increasingly bulbous shape of finite radius, to
a sphere of infinite radius with one finite cylindrical channel from
each pole.

---------------------------------------------------------
Title: Sudden Expansion of the Corona Following a Large Solar Flare
and the Attendant Magnetic Field and Cosmic-Ray Effects.
Authors: Parker, E. N.
1961ApJ...133.1014P Altcode:
We show from the hydrodynamic equations that the 4 X 106 K temperatures
observed in the solar corona after a large solar flare can produce a
hydrodynamic blast wave, moving out through interplanetary space with
velocities of 1500 km/sec and densities from a few times 105/cm3 to
105/cm3 at the orbit of earth. We suggest that it is this hydrodynamic
explosion of the enhanced corona that is the "accelerating mechanism"
for the "plasma clouds" or "enhanced solar corpuscular emission"
responsible for the geomagnetic storm, the cosmic-ray decrease, the
low4atitude aurorae, etc, observed at earth a day or two following
large solar flares on the visible hemisphere of the sun. We compute the
interplanetary magnetic field in the blast wave, assuming an initial
quiet-day solar wind of a few hundred km/sec ahead of the wave. The
spiral field of the quiet-day wind is sheared by the blast wave, and its
density, of the order of 2 X 10- gauss at the orbit of earth, may be
increased to 5 X 10- gauss or more for a period of several hours. The
effect of the outward-sweeping magnetic shear in the blast wave is
to decrease the cosmic-ray intensity, occasionally perhaps by as much
as 40 per cent, in the inner solar system behind the blast wave. The
onset of the decrease has a characteristic time of several hours,
and the relaxation many hours or days. The energy dependence of the
decrease may go inversely with particle rigidity, or it may be flatter,
depending on the details of the magnetic configuration in and around
the blast wave. Thus the cosmic-ray decrease produced by the blast
wave is identical with the Forbush-type cosmic-ray decrease observed
in association with "enhanced solar corpuscular radiation." Thus,
besides producing the observed 1500 km/sec ejection of matter from the
sun responsible for the geomagnetic storm, the hydrodynamic expansion
of the enhanced corona produces the observed Forbush decrease. We
suggest, therefore, that the simple dynamical model of the enhanced
corona developed in this paper is not unlike what actually occurs
following a large solar flare.

---------------------------------------------------------
Title: Effect of Hydromagnetic Waves in a Dipole Field on the
Longitudinal Invariant
Authors: Parker, E. N.
1961JGR....66..693P Altcode:
Hydromagnetic wave violation of the longitudinal invariant of a particle
trapped in a mirror magnetic field is investigated quantitatively. It
is shown that the passage of hydromagnetic waves across the region
of mirroring leads to a diffusion of the individual-particle mirror
points. If the relative wave amplitude ΔB/B is maintained throughout
the mirror field, particles released in the field will soon diffuse
out through the mirror and be lost. Application to thermonuclear
devices is obvious. Confining our attention principally to the charged
particles trapped in the geomagnetic field, it is shown that high-energy
(105-ev) electrons in the outer Van Allen radiation zone
are caused to diffuse along the lines of force with a characteristic
time of 4 months by hydromagnetic waves of 1 cps and an amplitude of
10-4 gauss. Hydromagnetic diffusion appears to be more
important than collisions in determining the electron lifetime and
distribution in the outer Van Allen radiation zone. Different wave
distributions along the lines of force can give radically different
particle distributions. It is shown that, if the hydromagnetic
disturbances extend throughout the geomagnetic field, then, rather than
yielding particle acceleration, they result in a net loss of particle
energy. But if we assume a region of hydromagnetic disturbance localized
inside the geomagnetic field, limited particle acceleration may result.

---------------------------------------------------------
Title: The Interplanetary Gas and Magnetic Fields
Authors: Parker, E. N.
1961sis..book..229P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Solar Wind
Authors: Parker, E. N.
1961spas.book..157P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Hydrodynamic Theory of Solar Corpuscular Radiation and
Stellar Winds.
Authors: Parker, E. N.
1960ApJ...132..821P Altcode:
We show from the conventional application of the static barometric law
to the density of the solar corona, observed out to 20 RO at sunspot
minimum, that the corona would be so hot at 20 RO that it could
not be static but must expand. Thus one cannot correctly deduce the
temperature in the outer corona from the density distribution by using
the static barometric law. Allowing for the possibility of expansion,
we find that the solution of the stationary, spherically symmetric,
hydrodynamic equation for a uniform coronal temperature of 1.22 X 106
0K fits the observed coronal density predsely out to 14 R O,indicating
an expansion velocity of the order of 300 km/sec at large radial
distances. We conclude that at sunspot minimum the coronal temperature
is 1.22 X 106 0K. We carry out an extensive investigation of the
singular mathematical properties of the solutions of the stationary,
spherically symmetric, non-linear hydrodynamic equation for the
polytrope law P a N0. We show that there exist continuous solutions 4,
[(4,o) , a, X; which go from low velocity in a strong gravitational
field at the base of the corona out to infinity with the necessary
boundary condition that p( ) = 0. These solutions yield supersonic
velocities of expansion. In terms of the polytrope index, a, and the
gravitational parameter, X GMOM/ROk T0, we show that these solutions
exist for a strong gravitational field (X »1), provided only that a
&lt; T3 and X &lt; 2a/(a - 1). Since observations of the solar corona
show that these conditions are satisfied, we demonstrate formally the
expansive nature of the solar corona. The mathematical theory allows
us to work out the upper and lower bounds on the velocity of expansion
of the solar corona-the solar wind-into interplanetary space. We find
that at solar minimum the velocity of expansion may be only 300 km/sec,
with densities as low as 20/cm2 at the orbit of earth. The quiet-day
solar wind during the years of solar activity is evidently more than
500 km/sec. The solar wind is obviously what has heretofore been termed
the ccsolar corpuscular radiation," to which quiet-day velocities and
densities of 500 km/sec and 102/cm3 have been assigned on the basis
of a number of independent observational analyses. We show that we
expect at least all main-sequence stars later than class F to possess
stellar winds, in analogy with the solar wind, so that the phenomenon
is of widespread importance in the mass balance of the Galaxy, as well
as in the early evolution of most stars. In the appendix we give an
outline of the theory of hydromagnetic heating of the solar corona,
pointing out that the ion thermal velocity in a stellar atmosphere, in
which hydromagnetic heating is dominant, should be of the same order
as the bydromagnetic wave velocity. This prediction is in agreement
with the observed solar coronal temperatures.

---------------------------------------------------------
Title: Geomagnetic Fluctuations and the Form of the Outer Zone of
the Van Allen Radiation Belt
Authors: Parker, E. N.
1960JGR....65.3117P Altcode:
It is demonstrated by formal calculation that the large-scale
geomagnetic fluctuations observed at ground stations result in a rapid
and somewhat remarkable kind of diffusion of the electrons in the
outer zone of the Van Allen radiation belt. An initial thin ring of
electrons will give an immediate finite particle flux at infinity, at
the same time that the group of the particles remaining moves radially
inward as a `wave'. We predict a decline of particle counting rate
beyond about 4 earth radii of the order of 1/rβ, where
β≅12 to 16, depending upon the kind of counter, in agreement with
the many observations.

---------------------------------------------------------
Title: Geomagnetic Storm Sudden-Commencement Rise Times
Authors: Dessler, A. J.; Francis, W. E.; Parker, E. N.
1960JGR....65.2715D Altcode:
Adopting the view that the sudden commencement of a geomagnetic
storm (SC) is the result of the impact on the geomagnetic field of an
abrupt solar-plasma front, the form of the SC observed on the surface
of the earth is investigated. A model is constructed to represent
the shape of the geomagnetic field boundary as perturbed by the
solar plasma. Calculations (carried out in the equatorial plane for
simplicity) show that, regardless of how abrupt may be the impact
of a solar-plasma front on the geomagnetic field, the variation in
hydromagnetic transit times from different positions on the boundary,
down to a point on the surface of the earth, yields SC rise times of
several minutes at ground level. These times are in agreement with
the observed SC rise times.

---------------------------------------------------------
Title: The Hydrodynamic Treatment of the Expanding Solar Corona.
Authors: Parker, E. N.
1960ApJ...132..175P Altcode:
It has been argued elsewhere that our earlier hydrodynamic treatment
of the solar corona, which predicted a steady 500-km/sec expansion,
is incorrect and that the appropriate treatment of the mass loss to
the solar corona is with the classical evaporation theory of Jeans
et at. In the first part of this paper we investigate the singular
properties of the solutions of the hydrodynamic equations and show
that the only stationary solution appropriate to the solar corona
is the critical solution, which passes straight across the critical
point and yields supersonic (500-km/sec) expansion at infinity. In
the second part of the paper we show that the evaporative solutions
are incompatible with the hydrodynamic equation and hence incompatible
with the Boltzmann equation.

---------------------------------------------------------
Title: Statement of Agreement regarding the Ring-Current Effect
Authors: Hines, C. O.; Parker, E. N.
1960JGR....65.1299H Altcode:
In an earlier communication [Hines and Parker, 1958], we recorded
discrepant views regarding the possible magnetic effects at the ground
caused by a hypothetical ring current in the earth's exosphere. This
followed upon earlier statements by Parker [1956, 1958a and b] to the
effect that only an increase of geomagnetic field could be produced
in a reasonably short time by such a current, as a consequence of
exospheric shielding, and conflicting statements by Hines [1957] and
Hines and Storey [1958] to the effect that geomagnetic field changes
of either sense could be propagated rapidly through the exosphere by
hydromagnetic waves. In view of the interest that this controversy
appears to have raised, and because of the basic importance of the
consequences in geomagnetic storm theory, we wish now to record a
reconciliation of views, to the effect that circulating charge high in
the exosphere can indeed be associated with a decrease of geomagnetic
field at ground level in a reasonably short time and, therefore, may
indeed be responsible for the main phase of a geomagnetic storm. In
order to clarify the basic features of the controversy most readily,
the original discrepant views will be restated briefly in application to
very extreme models where each in turn undoubtedly applies. It should
be noted, however, that each view can in turn be justified for other
models which bear a much closer resemblance to the circumstances of
nature, and the separate conclusions were originally formulated with
these other models in mind.

---------------------------------------------------------
Title: Extension of the Solar Corona into Interplanetary Space
Authors: Parker, Eugene
1960exsp.conf...28P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Extension of the Solar Corona into Interplanetary Space
Authors: Parker, Eugene
1959JGR....64.1675P Altcode:
I shall first write down a number of observational facts, and then in
another column compare them with the results of the theoretical program
we have been carrying out at Chicago over the past few years. The
purpose of this comparison will be to suggest experiments, some of
which are already in progress, and which will perhaps resolve a few
of the difficulties in our present knowledge of the dynamics of the
interplanetary medium. I shall start with the sun, since we believe,
as Gold and others have pointed out, that it is the source of energy for
all phenomena observed in the earth, in particular magnetic storms and
auroras, and the source of energy for all the churning that apparently
occurs in interplanetary space. Let me list a few basic facts about
the sun that seem most pertinent to the problem.

---------------------------------------------------------
Title: Plasma Dynamical Determination of Shock Thickness in an
Ionized Gas (a Correction).
Authors: Parker, E. N.
1959ApJ...129..860P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Plasma Dynamic Determination of Shock Thickness in an
Ionized Gas.
Authors: Parker, E. N.
1959ApJ...129..217P Altcode:
It is shown that the principal interaction in a shock front in a
tenuous ionized gas is a plasma interaction in which the ions transfer
their translational energy to the plasma oscillations. The effect
is, of course, of interest in auroral theories and in solar radio
noise. It turns out to be the dominant effect in determining shock
thicknesses nearly everywhere that the gas density is less than the
solar photospheric value of 1016 atoms/cm3. We estimate that shock
thicknesses in interstellar H ii regions and in interplanetary space
will be 1 km or less, even though the mean free paths may be 108 km
or more and the ion Larmor radius 100 km.

---------------------------------------------------------
Title: Inadequacy of Ring-Current Theory for the Main Phase of a
Geomagnetic Storm
Authors: Parker, E. N.
1958JGR....63..683P Altcode:
It is demonstrated that there is apparently not enough dissipation to
allow significant diffusion, during a magnetic storm, of the magnetic
fields in the vicinity of the earth. It is then demonstrated that
a ring-current field can only increase the horizontal component of
the geomagnetic field, and so cannot account for the main phase of a
geomagnetic storm. Thus, other storm mechanisms must be sought.

---------------------------------------------------------
Title: Statement of Differences Regarding the Ring-Current Effect
Authors: Hines, C. O.; Parker, E. N.
1958JGR....63..691H Altcode:
The two preceding articles have expressed different views concerning
the possible effects of ring currents, and have supported those views
at some length by quite distinct analyses. It is probable that the
essential points of difference which still remain require clarification,
and the purpose of this note is to provide that clarification. The
statements made here are based on views expressed in a lengthy private
correspondence between the present authors, who, unfortunately, were
unable to reconcile their differences. In Parker's view, a magnetic
field such as that pictured in Figure 1 would be distorted for an
extremely long time into the form given in Figure 2, following the
introduction of a line-current source such as that indicated. The
shaded areas are intended to represent the region filled by a highly
conducting fluid, before and after the establishment of the current;
the unshaded areas represent the space swept clear of fluid by the
newly created ring-current field. This picture is based on the fact
that the equations describing electromagnetic effects in a conducting
fluid can be written in the usual hydromagnetic form ? which implies
that the lines of force and the fluid move exactly together. From this,
Parker deduces that the field of a newly created ring current cannot
immediately penetrate the surrounding gas, and so will push back the
gas and the pre-existent field lines, as in Figure 2.

---------------------------------------------------------
Title: Suprathermal Particles. III. Electrons
Authors: Parker, E. N.
1958PhRv..112.1429P Altcode:
Certain phenomena in nature, such as the 50- to 100-kev electrons of
the aurora, suggest that there are plasma-dynamical processes which
can quickly transfer the translational energy of the ions in a plasma
stream to the electrons (some 20 kev/ion for a 2000-km/sec solar
wind). It is shown that two interpenetrating streams of noncolliding
and initially neutral plasma can achieve this energy transfer with a
characteristic time comparable to (Mm)12 times the plasma
period. The process is closely analogous to the excitation of plasma
oscillations by two interpenetrating electron streams, but of course
proceeds to much greater electron energies because the ion components
of the streams carry so much more kinetic energy than do the electron
components. Hence, besides the auroral electrons, it is probably
responsible for solar radio emission, rather than the electron streams
implied in current theories. Further, the process is probably the
dominant interaction in shock fronts, particularly in astrophysical
cases where neither direct collisions nor the existing weak magnetic
fields can give sharp fronts. The characteristic thickness of a shock
front in the solar wind is of the order of 104 cm due to
the above plasma excitation whereas the Larmor radius of the ions,
which would otherwise determine the shock thickness in the absence of
collisions, is 100 km or more.

---------------------------------------------------------
Title: Suprathermal Particle Generation in the Solar Corona.
Authors: Parker, E. N.
1958ApJ...128..677P Altcode:
It is shown that hydromagnetic waves propagating outward through the
solar corona will convert all but a small portion of their energy into
suprathermal particles It is suggested that this is the source, of the
3 X 1028 ergs/sec necessary to maintain the 2 X 108 0K solar corona
with its continued expansion into the solar wind The temperature of
the solar corona will then correspond to an ion thermal velocity of
the same order of magnitude as the hydromagnetic wave velocity.

---------------------------------------------------------
Title: Dynamics of the Interplanetary Gas and Magnetic Fields.
Authors: Parker, E. N.
1958ApJ...128..664P Altcode:
We consider the dynamical consequences of Biermann's suggestion that
gas is often streaming outward in all directions from the sun with
velocities of the order of 500-1500 km/sec. These velocities of 500
km/sec and more and the interplanetary densities of 500 ions/cm3
(1014 gm/sec mass loss from the sun) follow from the hydrodynamic
equations for a 3 X 1060 K solar corona. It is suggested that the
outward-streaming gas draws out the lines of force of the solar magnetic
fields so that near the sun the field is very nearly in a radial
direction. Plasma instabilities are expected to result in the thick
shell of disordered field (10- gauss) inclosing the inner solar system,
whose presence has already been inferred from cosmic-ray observations.

---------------------------------------------------------
Title: Suprathermal Particles
Authors: Parker, E. N.; Tidman, D. A.
1958PhRv..111.1206P Altcode:
The production of suprathermal particles in agitated plasmas bearing
magnetic fields is discussed. This is done by setting up a Fokker-Planck
equation to describe the phenomenon. The role of such particles in
astrophysics and in the problem of the production of thermonuclear
power is considered.

---------------------------------------------------------
Title: Gross Dynamics of the Interstellar Medium
Authors: Parker, E. N.
1958RvMP...30..955P Altcode: 1958IAUS....8..955P
No abstract at ADS

---------------------------------------------------------
Title: Cosmic-Ray Modulation by Solar Wind
Authors: Parker, E. N.
1958PhRv..110.1445P Altcode:
It is shown that the hydrodynamic outflow of gas from the sun observed
by Biermann results in a reduction of the cosmic-ray intensity in the
inner solar system during the years of solar activity. The computed
cosmic-ray energy spectrum so closely resembles the observed spectrum
at earth that we suggest the outflow of gas to be the explanation for
the 11-year variation of the cosmic-ray intensity. It is also suggested
that perhaps the Forbush-type decrease, which is a local geocentric
phenomenon, is the result of disordering of the outer geomagnetic
field by the outflowing gas from the sun.

---------------------------------------------------------
Title: Electrical Conductivity in the Geomagnetic Storm Effect
Authors: Parker, E. N.
1958JGR....63..437P Altcode:
Hines1 has recently argued that it is possible for
the magnetic field of a ring current to penetrate rapidly through
the electrically conducting gas surrounding the earth because the
geomagnetic field greatly reduces the conductivity perpendicular
to the lines of force. In this way, he argues that a ring current
can very quickly cancel (dissipate) part of the geomagnetic field
at the surface of the earth to yield the main phase of a geomagnetic
storm. Now it was first pointed out by Schlüter,2 and has
since been discussed by Bungey,3 and by Cowling,4
that the decay or dissipation of a magnetic field is not enhanced by
the reduction of conductivity perpendicular to B. As Cowling puts it,
one is justified in discussing the conductivity only if at the same
time he considers the effective electric field.

---------------------------------------------------------
Title: Interaction of the Solar Wind with the Geomagnetic Field
Authors: Parker, E. N.
1958PhFl....1..171P Altcode:
The dynamical properties of the solar wind blowing past the geomagnetic
field are investigated by considering the effective viscosity and the
resulting transition layer thickness. The collision of ions in the solar
wind produces a negligible viscosity in the flow past the geomagnetic
field, but such an inviscid flow is shown to be unstable. The resulting
disordered interface between the field and the wind yields Fermi
acceleration of ions and consequently a not insignificant effective
viscosity. The Fermi acceleration results in suprathermal ions which
may have an energy spectrum like that observed for primary auroral
protons. The auroral zones and the agitated nature of the polar
geomagnetic field are shown to follow from the depth of penetration of
the solar wind into the geomagnetic field. The injection of gas into the
geomagnetic field is studied. The effect at Earth of the distortion of
the outer boundary of the geomagnetic field is computed; no matter how
unevenly and anisotropically the outer field is distorted, the effect at
Earth is a nearly uniform perturbation field which is closely parallel
to the geomagnetic axis. Pushing in on the outer field increases the
horizontal component at Earth, and pulling out decreases it; the total
increase of the horizontal component is the algebraic sum of all the
pushing and pulling. The simultaneous world-wide onset and the main
phase of a geomagnetic storm follow. The common tendency of large
and/or violent bodies of plasma to produce suprathermal particles is
noted and suggested to be a general dynamical property.

---------------------------------------------------------
Title: Dynamical Instability in an Anisotropic Ionized Gas of
Low Density
Authors: Parker, E. N.
1958PhRv..109.1874P Altcode:
It is shown that when the thermal motions of a tenuous ionized gas are
sufficiently anisotropic, the gas, and the initially uniform magnetic
field which the gas is assumed to contain, become unstable. One mode
of instability occurs when the gas pressure is greater parallel to
the field than perpendicular, and another mode when the pressure
is greater perpendicular than parallel. It is suggested that such
instabilities may be of astrophysical interest, particularly with
regard to the configuration of the solar dipole field as it is drawn
out into interplanetary space by ionized gas from the sun.

---------------------------------------------------------
Title: Origin and Dynamics of Cosmic Rays
Authors: Parker, E. N.
1958PhRv..109.1328P Altcode:
As a consequence of our inability to observe directly the origin of
a cosmic-ray particle, we begin the development with a discussion of
the limitations within which we can construct a cosmic-ray accelerator
mechanism. We find that we are allowed only the betatron effect and
the Fermi mechanism. We review some of the many variations of these
mechanisms which are to be found in the literature. Then it is shown
that trains of oppositely moving hydromagnetic waves of large amplitude
and with sharp crests can accomplish large and continued particle
accelerations which are adequate to maintain the observed galactic
cosmic-ray field. The large acceleration arises as a consequence
of the simple fact that each wave tends to sweep up the cosmic-ray
particles before it, so that head-on collisions of particles with
waves are much more common than overtaking collisions. It is pointed
out that the sharp crests of the waves are a natural consequence of
the observed supersonic mass motions. Therefore, the acceleration by
oppositely moving waves does not depend upon any special wave form, and
we suggest that it is the naturally occuring acceleration process. By
treating the cosmic rays as a gas with relativistic thermal motions,
it is shown that the cosmic-ray gas is effectively coupled to the
motions of the ordinary matter both parallel and perpendicular to the
magnetic field. Thus the effective speed of sound must be computed in
the composite cosmic-ray and ordinary gas. It is noted that with this
composite speed of sound the irregular mass motions in the galactic
disk and halo are approximately Mach one. It is suggested that this
represents a general dynamic balance to be found in all sufficiently
active regions of space, and explains how it is that we often observe
prolonged mass motions in the galaxy and in stellar atmospheres which
would otherwise be computed to be highly supersonic and dissipative. The
dynamic balance comes about from the fact that increased cosmic-ray
density would reduce the effective Mach number below one, allowing
the sharp crests of the hydromagnetic waves to degenerate, and thereby
halting the production of comsic-ray particles.

---------------------------------------------------------
Title: On the Variations of the Primary Cosmic Ray Intensity
Authors: Parker, E. N.
1958IAUS....6..420P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sweet's Mechanism for Merging Magnetic Fields in Conducting
Fluids
Authors: Parker, E. N.
1957JGR....62..509P Altcode:
Sweet's mechanism for the merging of two oppositely directed
magnetic fields in a highly conducting fluid is investigated in a
semi-quantitative manner. It is shown that two oppositely directed
sunspot fields with scales of 104 km could be merged by
Sweet's mechanism, if shoved firmly together, in about two weeks; their
normal interdiffusion time would be of the order of 600 years. It is
suggested that Sweet's mechanism may be of considerable astrophysical
importance: It gives a means of altering quickly the configuration of
magnetic fields in ionized gases, allowing a stable field to go over
into an unstable configuration, subsequently converting much of the
magnetic energy into kinetic energy of the fluid.

---------------------------------------------------------
Title: Acceleration of Cosmic Rays in Solar Flares
Authors: Parker, E. N.
1957PhRv..107..830P Altcode:
It is shown that the white-light cosmic-ray solar flare of February
23, 1956 expended of the order of 2×1032 ergs of energy,
or 104 ergs/cm3. The energy apparently came from
a 500-gauss force-free magnetic field initially occupying the site of
the flare. It is shown that the 500-gauss field, besides supplying
the flare energy, will produce fluid motions of sufficient velocity
to accelerate ions from thermal to relativistic energies by Fermi's
mechanism in about 2 minutes. The theoretical energy spectrum of the
model is in agreement with the observed spectrum. About one percent
of the total flare energy is converted to relativistic particles and
the remainder is dissipated through thermal processes to produce the
observed optical radiation.

---------------------------------------------------------
Title: The Gross Dynamics of a Hydromagnetic Gas Cloud.
Authors: Parker, Eugene N.
1957ApJS....3...51P Altcode:
The tensor virial equations are applied to the dynamics of magnetic gas
clouds in which self-gravitation is negligible, such as are presumed to
be ejected from the sun into interplanetary space. To avoid the immense
mathematical difficulties of a general treatment, we constrain the cloud
to homogeneous, though not necessarily isotropic, dilatation. It is
shown that, in the absence of an external magnetic - field surrounding
the cloud, no static equilibrium is possible without non-vanishing
external gas pressure. The unsymmetric expansion of a cloud along
one axis is considered. In the presence of an external large-scale
magnetic field surrounding the cloud, it is necessary, in order that
we may compute the external field, to pad- the cloud surface so that
the over-all shape will be ellipsoidal. Cloud equilibrium conditions
are given in the presence of the external fiel 1. The force exerted on
a cloud by a gradient in the external field is given; it is shown that
a cloud expelled, like a melon seed, from a large-scale field may have
a velocity as great the speed of sound or the Alfve'n wave velocity,
whichever is greater. It is shown that a field-free cloud of gas be
contained between constrictions in a large-scale field; but we do not
expect to find permanent field-free clouds in nature because such a
cloud will repeatedly split lengthwise or otherwise decrease one of its
limit, until the field-free gas diffuses into the external field. -
It is pointed out that, except -in special cases where the cloud is
held together by constrictions in an external field, the existence of
a static equilibrium requires that the lines of force of the internal
cloud field be tangled.

---------------------------------------------------------
Title: The Solar Hydromagnetic Dynamo
Authors: Parker, E. N.
1957PNAS...43....8P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: On the Geomagnetic Storm Effect
Authors: Parker, E. N.
1956JGR....61..625P Altcode:
The high electrical conductivity of the region surrounding Earth,
inferred from the observations of atmospheric whistlers and the
zodiacal light, requires abandoning the customary models for producing
a geomagnetic storm field with impressed current system. It becomes
necessary to adopt a purely hydromagnetic approach wherein one
focuses his attention only on the magnetic lines of force of the
geomagnetic field and their displacement with the conducting gas
surrounding Earth. From the hydromagnetic point of view, a decrease
of the horizontal component is brought about by lifting the lines of
force in the region above the observer. It is suggested that heating
in the upper atmosphere may produce the necessary lifting; this model,
along with another, is developed quantitatively to show that lifting
the lines of force a distance of only 5 km will produce a decrease in
the horizontal component of 0.2 per cent at the equator.

---------------------------------------------------------
Title: Solar Cosmic Rays of February, 1956 and Their Propagation
through Interplanetary Space
Authors: Meyer, P.; Parker, E. N.; Simpson, J. A.
1956PhRv..104..768M Altcode:
The data from six neutron-intensity monitors distributed over a wide
range of geomagnetic latitudes have been used to study the large and
temporary increase of cosmic-ray intensity which occurred on February
23, 1956, in association with a solar flare. During the period of
enhanced intensity a balloon-borne neutron detector measured the
absorption mean free path and intensity of the flare particles at
high altitudes. From these experiments the primary particle intensity
spectrum as a function of particle rigidity, over the range &lt;2
to&gt; 15-30 Bv rigidity, has been deduced for different times during
the period of enhanced intensity. It is shown that the region between
the sun and the earth should be free of magnetic fields greater than
~10-6 gauss and that the incoming radiation was practically
isotropic for more than 16 hours following maximum flare particle
intensity. The decline of particle intensity as a function of time t
depends upon the power law t-32, except for high-energy
particles and late times, where the time dependence approaches an
exponential. The experiments lead to a model for the inner solar system
which requires a field-free cavity of radius greater than the sun-earth
distance enclosed by a continuous barrier region of irregular magnetic
fields [B(rms)~10-5 gauss] through which the cosmic-ray
particles must diffuse to reach interstellar space. This barrier
is also invoked to scatter flare particles back into the field-free
cavity and to determine the rate of declining intensity observed at the
earth. The diffusion mechanism is strongly supported by the fact that
the time dependence t-32 represents a special solution of
the diffusion equation under initial and boundary conditions required
by experimental evidence. The coefficient of diffusion, the magnitude
of the magnetic field regions, the dimensions of the barrier and cavity,
and the total kinetic energy of the high-energy solar injected particles
have been estimated for this model. Recent studies of interplanetary
space indicate that the conditions suggested by the experiments may
be established from time to time in the solar system. The extension of
the model to the explanation of earlier cosmic-ray flare observations
appears to be satisfactory. The solar flare event was superposed
by chance upon a large but typical intensity decrease of nonsolar
cosmic rays which began several days prior to February 23. Hence,
the flare particles have been used as probes to explore the intensity
modulation mechanism responsible for this decrease of background
cosmic-ray intensity.

---------------------------------------------------------
Title: Modulation of Primary Cosmic-Ray Intensity
Authors: Parker, Eugene N.
1956PhRv..103.1518P Altcode:
It is assumed that the cosmic-ray particles observed at the earth
are of galactic origin, except for the occasional bursts from
solar flares. With this interpretation the 11-year variation of the
cosmic-ray intensity and the Forbush decreases represent depressions
of the steady galactic intensity. The observed rigidity dependence
of the depression indicates that magnetic fields are responsible. A
quantitative investigation of the possible motion and configuration of
magnetic fields capable of producing the observed effects is carried
out. It is shown that, within the limitations imposed by what we think
we know today of the galactic magnetic field, of solar activity, and
of interplanetary fields, serious difficulties are encountered by any
mechanism, such as Morrison's interplanetary cloud model, modulating
the galactic cosmic-ray intensity throughout the solar system. It is
proposed that the modulation of the intensity is produced locally,
within a few earth's radii, by interplanetary magnetic gas clouds
captured by the terrestrial gravitational field. Such a model seems
to produce the observed effects on the basis of the known facts about
solar activity. The most straightforward test of this geocentric
model, independent of inferences from cosmic-ray effects, is the
question of whether the absorption of the captured magnetic hydrogen
gas can be detected as a narrow line in the center of the broad solar
Lα emission line.

---------------------------------------------------------
Title: Diffusion and Severing of Magnetic Lines of Force.
Authors: Parker, E. N.; Krook, M.
1956ApJ...124..214P Altcode:
The general asymptotic form for the magnetic field in a diffusing flux
tube is developed and applied to the problem of severing magnetic lines
of force in a medium with finite electrical conductivity Calculations
of the details of the severing and reconnection of lines of force are
given for the formation of an idealized free meridional magnetic ring
in a hydromagnetic dynamo, for the merging of idealized neighboring
rings, and for the straightening of the lines in a twisted tube, in
order to illustrate the general qualitative features of these processes
as they would presumably occur in the core of the earth. The problem
of two nearly intersecting slender flux tubes is considered in order
to demonstrate how the lines of force of the lesser tube are diverted
into the denser tube.

---------------------------------------------------------
Title: Hydromagnetic and Plasma Problems
Authors: Parker, Eugene N.
1956SCoA....1...59P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Hydromagnetic Dynamo Models.
Authors: Parker, Eugene N.
1955ApJ...122..293P Altcode:
The purpose of this paper is to investigate the steady-state
amplification of magnetic fields in a fluid It is shown that a rotating
sphere of conducting fluid can regenerate a dipole magnetic field. It is
sufficient for the angular velocity of rotation to vary with distance
from the axis of rotation and for cyclonic fluid motions to be present
The nonuniform rotation generates a toroidal field from the dipole
field; the cyclones generate, from the toroidal field, loops of flux
in the meridional plane which coalesce to amplify the dipole field The
rotating sphere is discussed in relation to the liquid core of the earth
and the geomagnetic dipole field. If, instead of a rotating sphere, one
has a prismatic volume of fluid, it is possible to construct migratory
dynamo waves The dynamo waves are discussed in relation to the solar
convective zone; it is shown that such waves can account for many of
the principal features of the observed solar magnetic activity

---------------------------------------------------------
Title: Hydromagnetic Waves and the Acceleration of Cosmic Rays
Authors: Parker, Eugene N.
1955PhRv...99..241P Altcode:
The large amounts of energy necessary for the acceleration of
cosmic rays throughout the galaxy introduces a serious transport
problem. The hydrodynamic and hydromagnetic equations are investigated
from the viewpoint of energy propagation. It is shown that, with the
galactic model of Fermi and Chandrasekhar, the observed motions of the
interstellar gas reduce to hydromagnetic waves, which are, as it turns
out, the most effective means of energy transport. A consideration of
the interaction of charged particles with hydromagnetic waves shows that
it is the fluid velocity, and not the wave velocity, that is responsible
for the acceleration of cosmic rays by Fermi's mechanism. We calculate
the the dissipation of hydromagnetic waves in the interstellar medium,
and the variation of amplitude and wavelength of such waves with changes
in density and large-scale field intensity. It is then shown that the
galaxy is no more than one percent efficient in the acceleration of
cosmic rays because of the tremendous viscous losses in the interstellar
medium, and that there is no hydromagnetic mechanism that can convert
the observed large-scale low-velocity fluctuations in the interstellar
medium to the required small-scale high-velocity motions.

---------------------------------------------------------
Title: The Formation of Sunspots from the Solar Toroidal Field.
Authors: Parker, Eugene N.
1955ApJ...121..491P Altcode:
It is shown that a horizontal magnetic flux tube in an electrically
conducting atmosphere is buoyant and will tend to rise. This magnetic
buoyancy is large enough to bring an occasional strand of flux from
the general solar toroidal field up into the photosphere, if we assume
general field densities of a few hundred gauss farther down. Identifying
the intersection of such ropes with the photosphere as the source
of sunspots, we may deduce several general characteristics of the
spots, e.g., east-west orientation, bipolarity, appearance only in low
latitudes, migration, reversal of polarity, etc. The linearized static
equilibrium equations for a flux tube are developed. With a cooling
mechanism, such as that suggested by Biermann (1941), we find from the
equilibrium equations that a sunspot group should consist of a diffuse
flux tube of 10-100 gauss and 10 km extent in the photosphere, forming
eventually a number of cool intense cores of several thousand gauss.

---------------------------------------------------------
Title: Instability of Thermal Fields.
Authors: Parker, Eugene N.
1953ApJ...117..431P Altcode:
The field equation for the kinetic temperature, Te, is considered in the
case of a gas composed of hydrogen-like atoms. If the atoms are largely
ionized and free-free emission does not predominate, the thermal field
is unstable unless stabilized by a strongly temperature-dependent supply
of energy. The possibility of interpreting much of the thermal activity
in the solar atmosphere as due to such instability is discussed.

---------------------------------------------------------
Title: On the instability of gaseous media.
Authors: Parker, Eugene N.
1953AJ.....58Q..46P Altcode:
Introducing the assumption that all large scale astrophysical
structures, e.g., gas clouds, galaxies, etc. have formed by collapse
of regions of an initially more homogeneous distribution of matter
according to Jeans' gravitational instability criterion, it is possible
to work backwards from existing conditions to the initial conditions. It
is found that gravitational instability produces a collapse in which
the scale of the final structure is approximately one-sixth of its
original dimensions. This agrees with observations of the interstellar
gas clouds which show that the clouds are separated by approximately
twice the diameter of their extremities. Given the relative velocity of
neighboring clouds, it is possible from the diameter of the clouds to
determine the average density of the interstellar medium. The relative
velocity 3 km/sec gives roughly 10 hydrogen atoms per cm1. This agrees
with the average density computed by smearing out the estimated mass
of the galaxy over the estimated dimensions of the galaxy. The collapse
time in such a medium is of the order of I0~ years. On the other hand,
galaxies are separated by distances of the order of 100 or more times
their diameters, implying that they have separated greatly since
their formation. Observations imply masses of the order of 1011 Mo
and internal velocities 300 km/sec for the brighter galaxies. From
these is predicted a relative velocity 50 km/sec for galaxies not in
clusters. The observed motions and dimensions of both spheroidal and
spiral galaxies yield an initial mean density of the order of 5 X 10-26
gm/cm3 at the time the collapse of the primordial homogeneous medium
began. That both types give the same initial density suggests that
regions not occupied by relatively active eddies have collapsed over
smaller dimensions to form spheroidal galaxies, i.e., galaxies of low
mass, whereas active regions, if they collapse at all, form the more
massive galaxies. Finally, the collapse time for forming a galaxy is
found to be of the order of 3 X 108 years. Department of Mathematics
and Astronomy, University of Utah, Salt Lake City, Utah.

---------------------------------------------------------
Title: The Interstellar Structures. I. Gas Clouds.
Authors: Parker, Eugene N.
1953ApJ...117..169P Altcode:
In an effort to arrive at a dynamical model for the interstellar
medium, its mechanical properties are discussed. Using a polytrope
relation between the temperature and density within a gas cloud, the
mechanical and then the statistical properties of an idealized model of
the interstellar clouds are developed. One finds that the collision rate
of clouds, computed in an elementary fashion from their diameters and
random translational velocities, leads to several difficulties. First,
the very inelastic nature of head-on collisions would rapidly reduce
the translational velocities, and it would be difficult to explain the
observed radial velocities. Second, there would be a strong tendency
toward statistical equilibrium of the internal state of the clouds. The
equilibrium is investigated, and the cloud is found to be either in
a collapsed condition or completely dispersed, again contrary to
observation. Ordering of the translational velocities is proposed
as one means of circumventing these difficulties. In any case, the
tendency of clouds to collapse, possibly to form clusters of stars,
is shown to be intrinsic in their nature.

---------------------------------------------------------
Title: An analytical investigation of turbulence and acoustics in
the solar ionization zone.
Authors: Parker, Eugene N.
1952AJ.....57Q..22P Altcode:
An investigation of the turbulence field to be expected in the solar
ionization zone requires an extension of the existing turbulence
theories to cover the case of an inhomogeneous field where convective
forces are producing the turbulence. Heisenberg's development of
isotropfc homogeneous turbulence was used because it affords a simple
physical picture of turbulence and is therefore readily generalized to
the inhomogeneous field. Isotropy was assumed for the solar convection
turbulence field. A convective driving and a diffusion term were worked
out on this basis and inserted in Heisenberg's field equation. Thus
it is possible to compute the velocity field in the ionization zone as
well as the diffusion of this turbulent velocity field up into the solar
atmosphere. Second, in order to compute the acoustical radiation which
the velocity field of the ionization zone produces, it was necessary to
reformulate radiation theory since many misconceptions are associated
with the conventional viewpoint. An inhomogeneous wave equation was
obtained giving rigorously the velocities of radiation particles in
terms of the velocity field producing the turbulence. Because of the
complexity of the velocity of a turbulent field, the inhomogeneous
term in the wave equation can be computed only approximately from the
turbulence field. As a result of the above analysis the turbulence
velocity field is found to have velocities 0.6 km$sec in agreement
with observations on the solar granules.' Further, the turbulence
diffuses only ~oo km into the atmosphere above the convection zone. The
acoustical radiation for the entire velocity field is found to be
completely inadequate to heat the corona. The differences between
this and previous results by Mr. Schwarzschild2 are readil tracked
down in the theory. Finally, from the reformulation of radiation
theory it follows that supersonic turbulence in the chromosphere is
an impossibility unless the entire energy of such a velocity field is
replenished, say, every 50 seconds, a truly fantastic energy source
being required. I.R. S. Richardson and M. Schwarzschild, Ap. J. iii,
351, 1950. 2.Ap. J. 107, 1, 1947. University of Utah, Salt Lake City,
Utah.

---------------------------------------------------------
Title: The interstellar dust and gas structures
Authors: Parker, Eugene Newman
1951PhDT........36P Altcode:
An investigation of the statistical properties of the mechanics of the
dust and gas structures making up the interstellar medium is carried
out. The aim is to get a comprehensive picture of the general nature
of the motions and structure of the interstellar material that would
follow from certain simple assumptions. Comparison with observation
then shows to what extent the behavior of the interstellar material can
be accounted for on such a basis and to what extent further factors,
such as for example magnetic fields, will have to be studied in the
hope of finding more satisfactory agreement.In I the interstellar gas
is considered. It is shown that the observed radial motions of the gas
clouds, if unordered, give too high a kinetic temperature for one to
account for the observed clumping of the gas into clouds. The stability
of a clump of gas was investigated using a modification of the ideas
commonly employed in the virial theorem. It is further shown that given
discrete gas clouds, the unordered component of their proper motions
must be even lower to prevent them from collapsing into extremely dense
structures, possibly clusters of stars, after repeated low velocity
collisions.In II the observed dust structures are considered and their
general evolution under the influence of the velocity field of the gas
and the radiation field is worked out. It is shown that for a continuous
distribution of dust sizes, certain types of finely striated structures
cannot be formed.From the inadequacies of this non-magnetic theory,
one concludes that magnetic fields must play a very significant role in
the dynamics of the interstellar medium.Finally, in III the collapse
of a nonturbulent nonrotating dust cloud under its own gravitational
field is very briefly considered yielding remarkably short collapse
times of the order of only [...] years.