The energy of waves in the photosphere and lower chromosphere

It is appropriate at a solar session during a radio astronomy conference to report on an analysis of optical observations to infer the properties of a non-spherically-symmetric chromosphere. For the first detailed model of such a non-symmetric chromosphere was that presented by Giovanelli (1949) [1] in an attempt to reconcile apparent contradictions between radio and optical data. Here we summarize some investigations based only on optical data, obtained by the High Altitude Observatory at the 1952 eclipse. Our observations of this eclipse were obtained as part of a joint programme with the Naval Research Laboratory, which conducted radio observations. Dr Hagen reports on the radio material (papers 46 and 47). The optical data in the present paper come from hydrogen and helium alone, the metallic data being still in reduction.

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Turbulence in the Atmospheres of Eclipsing Binary Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100075308 ◽

1980 ◽

Vol 51 ◽

pp. 144-156

Author(s):

K.O. Wright

Keyword(s):

Binary Stars ◽

Large Scale ◽

Giant Component ◽

Line Profiles ◽

Eclipsing Binary ◽

Multiple Structure ◽

Eclipsing Binary Stars ◽

Ultraviolet Observations ◽

Chromospheric Structure ◽

Lower Chromosphere

Abstract:A review of the orbits and dimensions of the ζ Aurigae systems is given, based on photometric and spectrographic observations. The Ca II K-line has been studied intensively to determine the extent and uneven structure of the chromospheres of these stars; the multiple structure of this line observed at several eclipses confirms the presence of large-scale clouds in the atmospheres. Measurements of line profiles and equivalent widths show that macroturbulent velocities up to 10 km/sec in the upper chromosphere, and up to 20 km/sec. in the lower chromosphere are present. Microturbulent velocities in the lower chromosphere are about 10 km/sec. Recent ultraviolet observations indicate that the B star in the 32 Cygni system may be within the outer chromosphere of the giant component and its radiation may affect the chromospheric structure more than had previously been suggested.

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Physical Processes in the Lower Chromosphere of the Sun

Plasma Physics Reports ◽

10.1134/s1063780x20070089 ◽

2020 ◽

Vol 46 (7) ◽

pp. 709-714

Author(s):

I. A. Molotkov ◽

N. A. Ryabova

Keyword(s):

The Sun ◽

Physical Processes ◽

Lower Chromosphere

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Hydrogen Atmospheres in the Absence of Thermodynamic Equilibrium. IV. The Solar Chromosphere

Australian Journal of Chemistry ◽

10.1071/ch9480360 ◽

1948 ◽

Vol 1 (4) ◽

pp. 360

Author(s):

RG Giovanelli

Keyword(s):

Observational Data ◽

Density Gradient ◽

Electron Concentration ◽

Hydrostatic Equilibrium ◽

Profile Measurement ◽

Solar Chromosphere ◽

Hydrogen Atoms ◽

Lower Accuracy ◽

Good Agreement ◽

Lower Chromosphere

A discussion of the observational data shows that in the range 0<z<2.5 x 108 cm. the electron concentration in the lower chromosphere may be expressed as Ne=5x 1011 exp(-6 x 10-9z) per cc., where z cm. is the height measured from a level 500 km. above the base of the chromosphere. It is shown that above the 500-km. level hydrogen atoms are almost completely ionized, and that with hydrostatic equilibrium the observed density gradient corresponds to a temperature of 2.7 X 104 �K . This is in good agreement with the temperature derived by Redman from line profile measurement, so that the lower chromosphere appears to be effectively in thermal and hydrostatic equilibrium. Estimates of lower accuracy are given for the electron concentrations at some higher levels in the chromosphere. A discussion is given of the mechanism of absorption of Hα radiation by a chromosphere whose temperature is well above that of the photosphere.

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SPATIAL AND TEMPORAL VARIATIONS OF K Ca II LINE PROFILE SHAPES IN DIFFERENT STRUCTURES OF THE SOLAR CHROMOSPHERE. II. DETERMINATION TECHNIQUE AND CORRELATION RELATIONSHIPS BETWEEN THE K CA II LINE PARAMETERS FOR K1 AND K2 FEATURES

Solar-Terrestrial Physics ◽

10.12737/stp-64202002 ◽

2020 ◽

Vol 6 (4) ◽

pp. 10-16

Author(s):

Irina Turova ◽

Sofiya Grigoryeva ◽

Olga Ozhogina

Keyword(s):

Magnetic Field ◽

Line Profile ◽

Direct Determination ◽

Temporal Variations ◽

Solar Chromosphere ◽

Considerable Contribution ◽

Opposite Behavior ◽

Scatter Plots ◽

Different Levels ◽

Lower Chromosphere

We have studied two regions located at the base of a coronal hole. For the K₁ intensity minima and K₂ peaks, which form between the upper photosphere and the lower chromosphere and in the lower chromosphere respectively, a number of Ca II line parameters have been computed. We have improved the determination technique for ∆λᴋ₁ᵥ and ∆λᴋ₁ᵣ, ∆λᴋ₂ᵥ and ∆λᴋ₂ᵣ line profile shifts, including certain cases when their direct determination was complicated. We have determined Iᴋ₁ᵥ, Iᴋ₁ᵣ, Iᴋ₂ᵥ, Iᴋ₂ᵣ intensities, K₁ minima and K₂ peaks separations SEPᴋ₁ = ∆λᴋ₁ᵣ – ∆λᴋ₁ᵥ, SEPᴋ₂ = ∆λᴋ₂ᵣ – ∆λᴋ₂ᵥ, respectively. We have constructed scatter plots and have computed correlation relationships between parameters relating to different levels of atmosphere. We have obtained the following results. The intensities observed in the lower and middle chromosphere are connected closer than intensities related to the upper photosphere and middle chromosphere. The structures with a stronger magnetic field are brighter at the upper photosphere and lower chromosphere levels as compared to the structures with a weaker magnetic field. K₁ minima separations are of greater value for the structures with a stronger magnetic field relative to the structures with a weaker magnetic field, whereas K₂ peaks separations demonstrate the opposite behavior. They are lower for the structures with a stronger magnetic field. It is true not only for the chosen structures belonging to quiet regions but also for the plage, though we need additional statistics for plages. The relation between shifts of K₁ minima and K₂ peak intensities for violet and red wings appeared to be weak. This may be due to the considerable contribution of random movements to the velocity field at the upper photosphere and lower chromosphere levels or due to different forming levels for the profile violet and red wings.

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Motions of Chromospheric Fine Structures

Symposium - International Astronomical Union ◽

10.1017/s007418090006900x ◽

1974 ◽

Vol 56 ◽

pp. 97-135 ◽

Cited By ~ 2

Author(s):

Edward N. Frazier

Keyword(s):

Line Profile ◽

Profile Analysis ◽

Broad Band ◽

Empirical Models ◽

Line Profile Analysis ◽

The Core ◽

Different Types ◽

Fine Structures ◽

Observational Techniques ◽

Lower Chromosphere

This review concerns itself with the measurement of the effects of chromospheric motions and the diagnosis of those motions themselves over approximately the last ten years. The different types of observational techniques are described. The different size regimes of motions are reviewed and their possible effects on observable quantities are discussed. The different types of motion in the lower chromosphere are reviewed, including microturbulence, ‘layered’ motions, and observations and interpretation of asymmetries in the core of the CaII K line. The observation of motions in Hα mottles on the disk and spicules on the limb are reviewed, from the standpoint of both line profile analysis and broad-band measurements. The interpretation of these motions and attempts to construct empirical models of chromospheric fine structures are discussed.

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Electric Conductivity of Lower Solar Atmosphere

International Astronomical Union Colloquium ◽

10.1017/s025292110002964x ◽

1993 ◽

Vol 141 ◽

pp. 465-468 ◽

Cited By ~ 1

Author(s):

Jingxiu Wang

Keyword(s):

Electric Conductivity ◽

Solar Atmosphere ◽

Conductivity Tensor ◽

Lower Atmosphere ◽

Temperature Minimum ◽

Atmospheric Models ◽

Minimum Value ◽

Minimum Zone ◽

Lower Solar Atmosphere ◽

Lower Chromosphere

AbstractElectric conductivity tensor of partly-ionized plasma is deduced. Four atmospheric models are used then to estimate the conductivity in the lower atmosphere. The parallel conductivity reaches its minimum value in the temperature minimum zone, which is 1 to 2 orders smaller than the conductivity of fully-ionized plasmas of the same condition; the effective perpendicular conductivity, or Cowling conductivity, becomes 5 to 6 orders smaller than the fully-ionized value in the lower chromosphere.

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The Upper Photosphere and Lower Chromosphere of Small-Scale Magnetic Features

Solar Surface Magnetism ◽

10.1007/978-94-011-1188-1_8 ◽

1994 ◽

pp. 91-98 ◽

Cited By ~ 3

Author(s):

S. K. Solanki ◽

J. H. M. J. Bruls ◽

O. Steiner ◽

T. Ayres ◽

W. Livingston ◽

...

Keyword(s):

Small Scale ◽

Magnetic Features ◽

Lower Chromosphere

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A Discussion on solar studies with special reference to space observations - Abundance of iron in the photosphere

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1971.0056 ◽

1971 ◽

Vol 270 (1202) ◽

pp. 23-28 ◽

Cited By ~ 7

Keyword(s):

Temperature Distribution ◽

Absorption Coefficient ◽

Thermodynamic Equilibrium ◽

Local Thermodynamic Equilibrium ◽

Thermal Excitation ◽

Solar Photosphere ◽

Continuous Absorption ◽

Non Local ◽

Atomic States ◽

Lower Chromosphere

About ten years ago astrophysics was haunted by a nightmare called non-local thermodynamic equilibrium (n.l.t.e.). Some astrophysicists, notably Pecker (1959) and R .N . Thomas, began to doubt whether the well-known formulae for thermal excitation and ionization could be applied with sufficient accuracy to, for example, the solar photosphere. If that contention had been true, it would have meant that all solar abundance determinations were affected by large errors. On the other hand, it would have been a hopeless enterprise to develop a purely statistical theory for the distribution of the atomic states, for example, of neutral iron under the influence of the complicated field of radiation in the photosphere together with all sorts of collisions. After preliminary studies (Unsold 1962) had made it probable that in reality deviations from local thermodynamic equilibrium (l.t.e) were quite negligible in the photosphere and the lower chromosphere (but probably not so in the higher chromosphere and certainly not in the corona), Holweger (1967) proceeded to construct an empirical model of the solar photosphere (and lower chromosphere) in l.t.e. Since it was known (Pagel 1959; Unsold 1962; Lambert & Pagel 1968) that the negative hydrogen ion in any case conformed to the laws of l.t.e., the continuous spectrum and its centre limb variation could be used for obtaining the temperature distribution T(r0) for about 0.05 < t0 < 2. Just extrapolating this temperature distribution towards smaller r 0—as many authors have done would lead to very serious errors. So T ( t0) out to t0 10-6 was obtained using the observed intensities within strong lines, where the line absorption coefficient is much larger than the continuous absorption coefficient.

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