Interplanetary sector structure near the maximum of the sunspot cycle
Interplanetary magnetic sector structure near sunspot maximum
Colburn, D. S.↗
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The birth and growth of sunspot regions
Sunspot region birth and growth, noting arch filament systems with H alpha time lapse movies
Weart, S. R.↗
A discussion of solar cosmic ray activity near sunspot maximum
Solar cosmic ray activity near sunspot maximum, discussing events of 18 November 1968 and 11 April 1969
Masley, A. J.↗
The molecular spectrum of sunspots
Sunspot molecular lines and rotational temperatures of MgH, CaH and TiO using model umbral atmospheres and photographic spectrograms
Webber, J. C.↗
A new empirical model of a sunspot umbra
Sunspot umbra empirical model, deriving temperature and optical depth relationship from IR continuous limb darkening
Sik Yun, H.↗
A magnetostatic sunspot model with 'twisted' field
Magnetostatic sunspot model with twisted field showing radial dependence of azimuthal component
Yun, H. S.↗
Cosmic ray atmospheric neutron measurements at high elevations over a sunspot cycle
Atmospheric neutron production by cosmic radiation over sunspot cycle, measuring energy spectrum with airplanes and balloon-borne instruments
Korff, S. A.↗
Polarized solar radio emission at mm wavelengths associated with sunspot magnetic fields
Polarized solar millimeter emission associated with sunspot magnetic field compatible with multiple sources from chromosphere
Edelson, S.↗
Two-dimensional observations of the velocity field in and around sunspots
Two dimensional velocity field observations in and around sunspots from Doppler spectroheliograms
Bhatnagar, A.↗
Sunspot analysis and prediction
Evaluation of several procedures that apply rarely used and exotic mathematical functions yields a unique method of application of common trigonometric functions. These functions appear to produce results in the development of a mathematical model capable of describing all available sunspot data.
Source record↗
Faculae and east-west asymmetry of sunspot area.
Asymmetry of sunspot area with respect to the central meridian is found to depend strongly on the location of the spot group in its chromospheric facula or plage. The usual area excess for spots in the eastern half of the disk is reversed for the relatively rare spot groups situated in the following part of the plage. Qualitatively, the observed asymmetries can be explained by supposing that the apparent area of the spot is decreased by overlying bright facula, especially west of central meridian where the spot (in the usual preceding position) is viewed through the relatively bright and extensive follower part of the plage. Since both facula and spot effects are seen along the same line of sight, optical depth must change slowly with geometric depth, that is, in the active region the atmosphere is relatively transparent.
Sawyer, C.↗
High resolution power spectra of daily Zurich sunspot numbers
High resolution power spectra of 77 years of Zurich daily sunspot numbers were computed using various lags and data point intervals. Major harmonic peaks of the approximately 124-month period showed up strongly as well as the 27-day solar rotational period.
Euler, H. C., Jr.↗
Structural and spectral studies of sunspots
The work is reported in the multicolor photometry of umbral cores, and the residual intensity midway between the Na D1 and D2 lines. The photelectric magnetometer observations, the generation of umbral flashes and penumbral running waves, and the work on sunspot interior modes with Alfen wave emission are discussed.
Wyller, A. A.↗
The auroral green line in Perseid spectra near sunspot maximum
Thirty-one spectra photographed during the Perseid showers of 1969 and 1970 are found to exhibit greater ionization and stronger, more frequent appearance of the forbidden oxygen line at 5577 A than Perseid spectra obtained with the same instrument in 1961. Data from 13 Perseid showers indicate a relationship between the frequency of occurrence of the oxygen line and solar activity. In 1969-70, near sunspot maximum, the strength of this auroral green line is greatest near shower maximum, as though the nature of the meteoroids were a function of their distance from the core of the stream, or, alternatively, the strength of the green line were a function of the altitude of the radiant.
Russell, J. A.↗
Structural and spectral studies of sunspots
Observations of umbral cores, both by multicolor photometry and by narrow band photometry in the vicinity of the sodium D lines, are described, and evidence is given which supports the validity of many umbral models, each of which describes different aspects of the observed umbral cores. Theoretical studies carried on at the observatory include the following: (1) Zeeman profiles of the sodium D sub 2 line and other lines; (2) turbulent heat conduction, sound waves, and the missing flux in sunspots; (3) chromospheric heating above spots by Alfven waves; (4) magnetic convection in the sun and solar neutrinos; (5) models of starspots on flare stars; (5) starspots on the primaries of contact binary systems; and (6) implications of starspots on red dwarfs.
Wyller, A. A.↗
Correction of sunspot intensities for scattered light
Correction of sunspot intensities for scattered light usually involves fitting theoretical curves to observed aureoles (Zwaan, 1965; Staveland, 1970, 1972). In this paper we examine the inaccuracies in the determination of scattered light by this method. Earlier analyses are extended to examine uncertainties due to the choice of the expression for limb darkening. For the spread function, we consider Lorentzians and Gaussians for which analytic expressions for the aureole can be written down. Lorentzians lead to divergence and normalization difficulties, and should not be used in scattered light determinations. Gaussian functions are more suitable.
Mullan, D. J.↗
Sunspot models with Alfven wave emission
Sunspot models have been computed on the assumption that the missing flux is transported by undissipated Alfven waves. In order to estimate the flux of these waves, we propose an extension of Opik's cellular model of convection to include the effects of a vertical magnetic field on horizontal gas flow. Horizontal motions, not vertical motions, are impeded more or less severely depending on the electrical conductivity, and this reduces the convective flux. These motions, however, shake the field lines; this is assumed to be a source of Alfven waves, compensating for the reduction in the convective flux. The free parameter D/H (ratio of cell diameter to cell depth) is adjusted such that the total sum of radiative, convective, and Alfven wave fluxes remains constant at all depths and equals the undisturbed solar flux entering the spot from below. Our treatment is speculative to some extent, but it leads to a unique spot model for a given field strength.
Mullan, D. J.↗
Are climatological correlations with the Hale double sunspot cycle meaningful?
A sunspot cycle which may have been subject to a predicted phase reversal between 1800 and 1880 A. D is discussed. Several climatological parameters normally correlated with this cycle are examined and do not exhibit a corresponding phase reversal during this period. It is proposed that this apparent discrepancy can be resolved by suitable observations during the upcoming half decade.
Goldberg, R. A.↗