scholarly journals Introduction

1995 ◽  
Vol 10 ◽  
pp. 319-320
Author(s):  
W. Däppen
Keyword(s):  
Spherical Harmonics ◽  
Solar Rotation ◽  
Solar Neutrinos ◽  
The Sun ◽  
Solar Oscillations ◽  
Good Information ◽  
Solar Neutrino Problem ◽  
Oscillation Frequencies ◽  
Very High ◽  
Better Than

Since the early 1960s the surface of the Sun has been know to be in a regular pulsating motion with periods of about 5 minutes. While at the beginning various explanations were offered, only in the 1970s it was recognized that these so-called solar oscillations are manifestations of global motions of the Sun about its equilibrium. Helioseismology is the name of the branch of astrophysics that deals with deciphering these data, that cover the whole range of spherical harmonics from l = 0 (radial) to very high angular order (above l = 1000). Thanks to observational data of superb quality (each of the oscillation frequencies is measured accurately to better than one part in ten thousand), our knowledge of the Sun has leap-frogged in the last 20 years. For instance, we now know the run of temperature inside the Sun, or have good information about the internal solar rotation. In the solar neutrino problem the data from solar oscillations have become a compulsory testing stone for any model proposed to explain the discrepancy between observed and theoretically predicted solar neutrinos.

scholarly journals Solar Opacities Constrained by Solar Neutrinos and Solar Oscillations

1990 ◽  
Vol 121 ◽  
pp. 61-80
Author(s):  
Arthur N. Cox
Keyword(s):  
Electric Fields ◽  
Oscillation Frequency ◽  
Convection Zone ◽  
Solar Surface ◽  
Solar Neutrinos ◽  
Photon Absorption ◽  
Solar Oscillations ◽  
Percent Reduction ◽  
Neutrino Production ◽  
Oscillation Frequencies

AbstractThis review discusses the current situation for opacities at the solar center, the solar surface, and for the few million kelvin temperatures that occur below the convection zone. The solar center conditions are important because they are crucial for the neutrino production, which continues to be predicted about 4 times that observed. The main extinction effects there are free-free photon absorption in the electric fields of the hydrogen, helium and the CNO atoms, free electron scattering of photons, and the bound-free and bound-bound absorption of photons by iron atoms with two electrons in the 1s bound level. An assumption that the iron is condensed-out below the convection zone, and the opacity in the central regions is thereby reduced, results in about a 25 percent reduction in the central opacity but only a 5 percent reduction at the base of the convection zone. Furthermore, the p-mode solar oscillations are changed with this assumption, and do not fit the observed ones as well as for standard models. A discussion of the large effective opacity reduction by weakly interacting massive particles (WIMPs or Cosmions) also results in poor agreement with observed p-mode oscillation frequencies. The much larger opacities for the solar surface layers from the Los Alamos Astrophysical Opacity Library instead of the widely used Cox and Tabor values show small improvements in oscillation frequency predictions, but the largest effect is in the discussion of p-mode stability. Solar oscillation frequencies can serve as an opacity experiment for the temperatures and densities, respectively, of a few million kelvin and between 0.1 and 10 g/cm3. Current oscillation frequency calculations indicate that possibly the Opacity Library values need an increase of typically 15 percent just at the bottom of the convection zone at 3×106K. Opacities have uncertainties at the photosphere and deeper than the convection zone ranging from 10 to 25 percent. The equation of state that supplies data for the opacity calculations fortunately has pressure uncertainties of only about 1 percent, but opacity uncertainties will always be much larger. A discussion is given about opacity experiments that the stars provide. Opacities in the envelopes of the Hyades G stars, the Cepheids, δ Scuti variables, and the β Cephei variables indicate that significantly larger opacities, possibly caused by iron lines, seem to be required.

scholarly journals Interpretations of Solar Oscillations

1993 ◽  
Vol 139 ◽  
pp. 151-159
Author(s):  
Arthur N. Cox
Keyword(s):  
Material Properties ◽  
Convection Zone ◽  
Helium Abundance ◽  
Solar Oscillations ◽  
Solar Neutrino Problem ◽  
Helium Content ◽  
Structure Changes ◽  
Theoretical Status ◽  
Magnetic Layers ◽  
Oscillation Frequencies

AbstractThe current theoretical status of understanding solar oscillations is reviewed. Interpretation of the thousands of well-determined frequencies refines our knowledge of the composition and convection structure of the Sun, since its mass, radius, luminosity, and age are better known from other sources. Recent issues that have been discussed are the solar center structure, bearing on the missing solar neutrino problem, the convection zone helium content, validating helium settling by diffusion, the variations of the oscillation frequencies over the solar cycle, indicating cyclical structure changes in the very outer magnetic layers, and the fine structure splittings of mode frequencies, revealing the internal rotation. Our ability to match observed frequencies to now within only a few microhertz has been enhanced by the recently improved MHD equation of state and the new Livermore OPAL opacities. Thus solar oscillations not only reveal solar structure data, but also they guide improvements for stellar astrophysics material properties. A new discussion of current investigations of the convection zone helium abundance and its depth is presented.

ON THE COHERENCE CONDITION FOR RESONANT SPIN-FLAVOR PRECESSION OF MAJORANA SOLAR NEUTRINOS

1992 ◽  
Vol 07 (06) ◽  
pp. 1309-1314
Author(s):  
RAUL HORVAT
Keyword(s):  
Solar Neutrino ◽  
Neutrino Flux ◽  
Majorana Neutrino ◽  
Solar Neutrinos ◽  
Sunspot Activity ◽  
The Sun ◽  
Solar Neutrino Problem ◽  
Mass Eigenstates ◽  
Flavor Changing ◽  
Solar Neutrino Flux

One of the most attractive solutions to the solar-neutrino problem (including an anticorrelation of the solar-neutrino flux with sunspot activity) incorporates a Majorana neutrino having a flavor-changing transition moment as large as (0.1–1)×10−10 Bohr magnetons. This solution is compatible with all known laboratory, astrophysical and cosmological bounds. Here we show the consistency of the solution with the coherence condition for effective-mass eigenstates inside the sun.

Solar neutrinos and solar oscillations

1994 ◽  
Vol 346 (1678) ◽  
pp. 37-49 ◽  
Keyword(s):  
Solar Neutrino ◽  
Particle Physics ◽  
Sound Speed ◽  
Solar Neutrinos ◽  
Diagnostic Information ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermonuclear Reactions ◽  
Neutrino Production ◽  
Classical Models

For solar neutrino measurements to contribute directly to particle physics it is essential that we know the structure of the Sun. Only then can we be sure both of the conditions under which the neutrinos are produced and of the state of the material through which they must pass before arriving at the detectors on Earth. Solar oscillations play at least one, and possibly two important roles: firstly, as passive carriers of information about density and sound speed, they provide important diagnostic information which has been used to set quite stringent constraints on the structure of the Sun’s interior; secondly, as active participants in the dynamics of the solar core, it is not out of the question that they induce motion that influences substantially the rates of the various thermonuclear reactions that em it the neutrinos. The basic processes of seismic inference will be discussed briefly, followed by a summary of those inferences that have a bearing on neutrino production. Finally, some of the uncertainties in our understanding of the Sun’s interior will be aired, to restrain the temptation to accept too hastily the details of the simple hydrostatic classical models of the Sun.

scholarly journals Brief Review of Solar Models and Solar Neutrino Experiments

1993 ◽  
Vol 137 ◽  
pp. 100-107
Author(s):  
Douglas R.O. Morrison
Keyword(s):  
Solar Neutrino ◽  
Input Data ◽  
New Physics ◽  
Solar Neutrinos ◽  
High Variability ◽  
Neutrino Masses ◽  
The Sun ◽  
Evolutionary Models ◽  
Solar Neutrino Problem ◽  
Neutrino Experiments

AbstractSolar Evolutionary Models are briefly reviewed and while the models are robust, there are uncertainties in the input data which justify rather larger errors. The 1992 experimental results from GALLEX, SAGE II and Kamiokande are shown to be consistent with calculated fluxes of solar neutrinos whereas the Chlorine results continue to be significantly low though this experiment has a problem with the high variability with time of its results in contradiction to Kamiokande. It is concluded that the evidence for a solar neutrino problem is not compelling and New Physics are not demanded. Further experiments are essential to search for neutrino masses and to study the Sun.

scholarly journals The Internal Structure of the Sun and Solar Type Stars

1976 ◽  
Vol 71 ◽  
pp. 453-466 ◽  
Author(s):  
IAN W. Roxburgh
Keyword(s):  
Internal Structure ◽  
Solar Neutrino ◽  
Convective Zone ◽  
The Sun ◽  
Solar Oscillations ◽  
Solar Constant ◽  
Solar Neutrino Problem ◽  
Solar Type

Our understanding of the internal structure of the Sun and solar type stars has been undermined by recent observations. In this paper we consider some of the puzzles and possible resolutions; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone. The picture that emerges is one of confusion, and so it should be since we have no idea of what is going on inside the Sun and a fortiori of what is going on inside other stars.

scholarly journals Helioseismic Investigation of Solar Internal Structure

1990 ◽  
Vol 121 ◽  
pp. 305-326
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Internal Structure ◽  
The Sun ◽  
Solar Oscillation ◽  
Solar Oscillations ◽  
Oscillation Frequencies

AbstractThe solar oscillation frequencies provide our only means of obtaining detailed information about conditions inside the Sun. Here I give a brief overview of the relevant properties of solar models and solar oscillations, and present examples of the dependence of the oscillation frequencies on the structure of the model. Furthermore I discuss some results obtained so far from analysis of observed frequencies.

scholarly journals Solar structure and evolution

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Solar Surface ◽  
Solar Neutrinos ◽  
Solar Interior ◽  
Stellar Structure ◽  
The Sun ◽  
Physical Processes ◽  
Solar Evolution ◽  
Internal Properties ◽  
Atmospheric Phenomena

AbstractThe Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

SOLAR NEUTRINOS WITH EXOTIC SCATTERING

1993 ◽  
Vol 08 (14) ◽  
pp. 1273-1284 ◽  
Author(s):  
JOÃO PULIDO
Keyword(s):  
Elastic Scattering ◽  
Solar Neutrino ◽  
Solar Neutrinos ◽  
The Sun ◽  
Neutral Currents ◽  
Neutrino Scattering ◽  
Flavor Changing ◽  
Lepton Decays ◽  
Neutrino Experiments ◽  
Vacuum Mixing

The possibility of unconventional neutrino scattering in the Sun via flavor changing neutral currents as a possible source of the solar neutrino deficit is investigated. If the effect is really significant, a resonant process will occur. Taking into account the neutrino deficit reported by the solar neutrino experiments (Kamiokande II, SAGE Gallex), one finds Δ2m21 = (0.6–1.4) × 10−5 eV 2 with no vacuum mixing and 0.16 ≤ fex ≤ 0.34 where fex is the lepton violating coupling. Our understanding of the neutrino phenomenon in the Sun may be improved through accuracy improvements in experiments measuring νee− elastic scattering or others searching for exotic lepton decays.

FUNGI IN AIR MASSES OVER MONTREAL DURING 1950 AND 1951

1956 ◽  
Vol 34 (1) ◽  
pp. 1-15 ◽  
Author(s):  
S. M. Pady ◽  
L. Kapica
Keyword(s):  
Seasonal Variation ◽  
Pollen Grains ◽  
Average Concentration ◽  
Yeast Cells ◽  
The Sun ◽  
Air Masses ◽  
Air Sampler ◽  
Agricultural Areas ◽  
Very High ◽  
Made In

Numbers and kinds of fungi were determined from nutrient plate and silicone slide studies from the roof of the Sun Life Building, Montreal, between September 1950 and December 1951. Exposures of plates were made in the General Electric Bacterial Air Sampler, and plates and silicone slides in the Bourdillon Slit Sampler. A total of 978 exposures was made on 113 sampling days during 16 months; 507 plates in the G. E. Sampler, 344 plates and 127 slides in the Slit Sampler. Of 40,359 colonies examined, Cladosporium, Penicillium, yeasts, Aspergillus, Alternaria, and Actinomycetes were commonest, constituting 47.7, 15.8, 10.4, 4.6, 4.2, and 2.2% of the total. The next commonest fungi were Pullularia, Oöspora, Fusarium, Stemphylium, Verticillium, Rhizopus, Spicaria, Scopulariopsis, Phoma, Mucor, Botrytis, Cephalosporium, Trichoderma, Helmin-thosporium, Neurospora, Papularia, Cephalothecium, Pyrenochaeta, Zythia, and Nigrospora. In addition 12 genera were infrequently found. Unidentified colonies numbered 174 and nonsporulating 3371 (8.3%). On a cubic foot basis numbers in the plates varied from 17.7 per cu. ft. in August to 0.4 per cu. ft in February.Fungus spores showed a seasonal variation with summer highs averaging 244 per cu. ft. in July to a low of 0.8 per cu. ft. in December. The most abundant spores were Cladosporium, yeasts, smuts, Fusarium, Alternaria, Venturia-like, Stemphylium, rusts, Septoria, and Helminthosporium. Hyphal fragments and pollen grains were present also. On eight occasions during the summer, readings of over 200 spores per cu. ft. were recorded, the maximum being 445 per cu. ft. on September 6, 1951. Cladosporium in August reached a peak of 74.1 per cu. ft. and yeast cells in July had an average concentration of 100 per cu. ft.An analysis of the air masses indicated that pure polar air carried low numbers of fungi, whereas tropical air had very high numbers. Most of the air masses were modified polar air and their fungus content varied considerably. The fungi in the air over Montreal are believed to have had their origin in agricultural areas.

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