The Spins of Astrophysical Systems and Extended Gravitational Theory

Recent data on the Tully–Fisher relation for spiral galaxies are compatible with the traditional correlation for astrophysical systems, where the angular momentum varies as the square of the mass. Such a correlation is consistent with standard gravitational theory, but is not explained by it. We here show that the noted relation follows from currently popular accounts of extended or higher-dimensional gravitational theory. The latter also predicts that the spins of spirals should decay as the universe expands, which can be tested by extending the Tully–Fisher data to higher redshifts.     

Observations of C2H6 and C2H2 in the stratosphere of Saturn

We have performed high-resolution spectral observations at mid-infrared wavelengths of C₂H₆ (12.16 μm), and C₂H₂ (13.45 μm) on Saturn. These emission features probe the stratosphere of the planet and provide information on the hydrocarbon photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer Celeste, in conjunction with the McMath-Pierce 1.5-m solar telescope in November and December 1994. We used Voyager IRIS CH₄ observations (7.67 μm) to derive a temperature profile on the saturnian atmosphere for the region of the stratosphere. This profile was then used in conjunction with height-dependent volume mixing ratios of each hydrocarbon to determine global abundances for ethane and acetylene. Our ground-based measurements indicate abundances of for C₂H₆ (1.0 mbar pressure level), and for C₂H₂ (1.6 mbar pressure level). We also derived new mixing ratios from the Voyager mid-latitude IRIS observations; 8.6±0.9×¹⁰⁻⁶ for C₂H₆ (0.1-3.0 mbar pressure level), and 1.6±0.2×¹⁰⁻⁷ for C₂H₂ (2.0 mbar pressure level).     

Ionospheric climatology derived from gps occultation observations made by the ionospheric occultation experiment

The ionospheric occultation experiment (IOX) is a GPS occultation sensor with an ionospheric mission focus. IOX measurements of GPS L1 and L2 carrier phase during Earth limb views of setting GPS satellites are used together with the Abel transform to determine vertical profiles of electron density from which F-region peak parameters are determined. Data from a four and a half month period beginning in November 2001 are statistically binned and compared with a climatological model. To account for potential errors in interpretation that could arise from violation of the Abel transform assertion of spherical symmetry, the data are compared to both the climatology and to statistics of simulated ionospheric inversions using the climatological model. General characteristics of the climatology are reproduced by the occultation data. However, several significant discrepancies between the model and the data are observed during this near-solar maximum time period. In particular, average mid-latitude daytime densities are shown to be higher than the climatological prediction and the height of F2 layer in the post-sunset equatorial region is underestimated by up to 150 km.

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A Maunder Minimum Scenario Based on Cross-Hemispheric Coupling and Intermittency

A novel scenario for Maunder minimum-like grand minima epochs of reduced solar activity is proposed, based on diffusive coupling between both solar hemispheres, each susceptible to stochastically-driven intermittent behavior. After introducing cross-hemispheric coupling into a well-validated reduced model of the solar cycle based on the Babcock–Leighton mechanism for poloidal field regeneration, simulations are presented demonstrating that even weak coupling can lead to a high degree of synchronicity between the two hemispheres. This is in qualitative agreement with the similar onset and recovery times of sunspot activity at and around the Maunder minimum. Moreover, even weak coupling manages to greatly reduce the frequency and duration of quiescent episodes, again in qualitative agreement with the relative paucity of grand minima in the sunspot and radioisotope records.     

Drift velocity at the wave breaking point

Wave-tank studies were conducted on the measurement of the drift velocity at the breaking point under different types of breaking waves on a rigid, plane beach. The drift velocity has onshore direction near the surface and close to the bottom; in the main flow column, the drift velocity is always offshore. The offshore drift velocity shows a more uniform vertical distribution than that in the offshore region. The experimental data are compared with theoretical values of three different second-order constant-depth wave theories. Comparisons with data from other sources are also made.     

A solar flare videometer

A new instrument, called a videometer, has been developed to measure solar flare area, peak intensity and integrated intensity in real time. The videometer uses a closed circuit television system to convert an optical H image into electrical signals for measurement. Observations of two Class I flares with the videometer are discussed.