Hollis R. Johnson

Daily, monthly, and yearly tidal cycles within laminated siltstones of the Mansfield Formation (Pennsylvanian) of Indiana

Whetstones (laminated siltstones) within the Mansfield Formation of Orange County, Indiana, are Lower Pennsylvanian (Morrowan) tidal deposits characterized by rhythmic laminations. Laminae thicknesses vary systematically in a vertical sequence and reflect tidal events of a mixed tidal regime. So complete is the record of tidal deposition that daily and monthly tidal cycles can be delineated. Neap-spring tides (related to the phases of the moon) and equatorial-tropical tides (related to the declination of the moon) are recognizable within the sequence.

Analysis of modern tides and implications for ancient tidalites

Abstract Recently, stacked successions of ancient tidal rhythmites have been found to preserve long records of tidal cycles. These include semidaily, daily, semimonthly, monthly, semiannual, annual and multiyear periods. Though such deposits reveal much about ancient tidal dynamics, the tidal signatures within the rhythmites can be masked or modified by basinal or nontidal effects. This paper discusses the results of an analysis of data from several different modern tidal stations. We show how actual tidal data can be abstracted to a form similar to what might ideally be preserved in the rock record, and then power spectra are calculated to yield estimates of the astronomical periods which can be compared to the current values. In this study, data from four modern tidal stations, ranging from diurnal to semidiurnal, are analyzed as both time- and event-series. A series of tests, which involve selective removal of parts of the tidal signal, are made using the modern tidal-station data. These tests were performed in order to determine to what extent the tidal signal can be degraded and still be recognized. Finally, we discuss some implications of the similarities of the modern and ancient tidal data and suggest how ancient data may be used to constrain basinal paleography and make inferences regarding ancient lunar orbital geometries.

Ca II resonance lines in non-homogeneous chromospheres

Profiles of the K line of Caii are computed for a two component solar chromosphere, chosen to simulate with a simple geometry the chromospheric supergranular network. Each component rises above the BCA photosphere, the boundary component representing the bright network with a sharp temperature rise and the cell component representing the darker region with an extended temperature minimum. Theoretical intensity profiles of the Can K core, calculated as weighted averages over the projected areas of the components, are produced for μ = 0.6 and 0.3. The line source function and the optical depth are obtained from a self-consistent treatment of the steady state and radiative transfer equations, with complete redistribution assumed for scattering in the line. The atomic model consists of two bound levels and a continuum. It is found that a 4600 K minimum can lead to the successful theoretical prediction of the observed limb darkening and 4300 K radiation temperature of the K1 feature only when very large values of turbulent velocity are assumed to exist in the cell region.

New molecular constants for the Phillips system of C2

Abstract New rotational, vibrational and equilibrium constants for the Phillips system of C2 were obtained by re-analyzing the data of Ballik and Ramsay. The agreement, even to high J values, between observed and computed wavenumbers is about 0.02 cm-1 when using the new rotational constants and about 0.03 cm-1 when using the new equilibrium constants.

Radiative opacity due to the red system of CN

Abstract Recent observational and theoretical work has indicated that CN may play a major role in forming the spectrum and in fixing the thermal structure in a wide variety of cool stellar atmospheres. As the first step in investigating that role, we have calculated straight mean absorption coefficients over intervals of 100 cm -1 for the red system ( A 2 П − X 2 Σ ) of CN for the entire spectrum (0−25,000 cm -1 ) by summing the integrated absorption coefficient for every line within the chosen interval. Over 100,000 lines from all bands with -3≤Δ v ≤12 and 0≤ v ″≤18 are included. The accuracy of this smoothing in the opacity is investigated. Complete calculations are made for four temperatures (1000, 2000, 3500 and 5000 K), and the resulting mean absorption coefficients ( α ) are fitted by the equation log α = A 1 + A 2 θ + A 3 θ 2 , where θ is the reciprocal temperature (θ = 5040/ T ). The coefficients A 1 , A 2 and A 3 are given for each wavenumber interval for both C 12 N 14 and C 13 N 14 .

A method for empirical determination of stellar atmospheric structure

A technique for obtaining information on the temperature structure of a stellar atmosphere from spectral line data where only flux observations are available is discussed. The direct inversion of the flux integral to obtain the line source function can be circumvented by making the physically plausible assumptions of (1) source function equality in a multiplet and (2) the dominance of line absorption over continuum absorption at line center. Consistency of the technique is demonstrated by treating a synthetic spectrum as input data and attempting to recover the temperature structure of the input atmosphere. Using high quality solar spectrum scans obtained from K.P.N.O. we demonstrate the accuracy of source function equality for several Fe i multiplets and use one of these multiplets to obtain an empirical outer atmosphere for the Sun. Our empirical atmosphere agrees well with current solar models.