The solar surface differential rotation from disk-integrated chromospheric fluxes

Disk-integrated solar chromospheric Caii K-line (3933.68 ) fluxes have been measured almost daily at Sacramento Peak Observatory since 1977. Using observing windows selected to mimic seasonal windows for chromospheric measurements of lower Main-Sequence stars such as those observed by Mount Wilson Observatory's HK Project, we have measured the solar rotation from the modulation of the Caii K-line flux. We track the change of rotation period from the decline of cycle 21 through the maximum of cycle 22. This variation in rotation period is shown to behave as expected from the migration of active regions in latitude according to Maunder's butterfly diagram, including an abrupt change in rotation period at the transition from cycle 21 to cycle 22. These results indicate the successful detection of solar surface differential rotation from disk-integrated observations. We argue that the success of our study compared to previous investigations of the solar surface differential rotation from disk-integrated fluxes lies primarily with the choice of the length of the time-series window. Our selection of 200 days is shorter than in previous studies whose windows are typically on the order of one year. The 200-day window is long enough to permit an accurate determination of the rotation period, yet short enough to avoid complications arising from active region evolution. Thus, measurements of the variation of rotation period in lower Main-Sequence stars, especially those that appear to be correlated with long-term changes in chromospheric activity (i.e., cycles), are probably evidence for stellar surface differential rotation.     

Spectrophotometry of a Galaxy with UV-excess

We present the results of a spectral study of Galaxy No. 47 of the list [1]. We determine the equivalent widths of the lines for the compact part of the galaxy and the relative intensities for both the compact part and the halo. We estimate the mass of the galaxy from the inclination of the H line. We obtain the electron density and the mass of the gas component of the compact part of the galaxy.Translated fromAstrofizika, Vol. 38, No. 2, 1995.     

TVZHR profile for the 1991 Perseid shower

Image intensified video detection systems were used to observe the 1991 Perseid meteor shower from two locations in eastern Canada. In 29.6 hours of total observing time a total of 668 meteors were detected, of which 403 were Perseids. We derived a profile of TVZHR (television zenithal hourly rate) values for the 1991 Perseid shower over the solar longitude (epoch 2000) interval 138°51 to 141°01. The apparent limiting stellar magnitudes of the observing systems were +9.4 and +8.8 (corresponding to limiting meteor magnitudes for our geometry ranging from +8.7 to +7.0). Within the observing period, the maximum TVZHR rate was approximately 1600, and occurred at solar longitude 139.9°. This is in good agreement with the second peak observed by visual observers. The data suggest that TVZHR values should be divided by a factor of approximately 5 to compare TVZHR and ZHR values.     

The British who are not British and the immigration policies that are not: the case of Hong Kong

"While 'closed-door' immigration policies are adopted by most countries, 'exceptionalist' legislation is often made to permit entry of special immigrant groups. An example is the British Nationality (Hong Kong) Act 1990, which was passed in the run-up to the change in sovereignty of Hong Kong in 1997. Britain's increasingly restrictive immigration policies prior to 1990 [have] resulted in the majority of Hong Kong citizens having British nationality (as British Dependent Territories citizens) but without the right of abode in the U.K. The 1990 Act conferred full British citizenship status on 50,000 heads of households in Hong Kong." The authors conclude that "in a world of marked global inequalities, immigration pressure will become even more extreme and is likely to produce an increasing number of cases of exceptionalist immigration legislation in countries with both ?open' and 'closed'-door policies.'     

Dynamics of Mars-orbiting dust: Effects of light pressure and planetary oblateness

This paper deals with dynamics of impact ejecta from Phobos and Deimos initially on near-circular equatorial orbits around Mars. For particles emitted in a wide size regime of 1 micron and greater, and taking into account the typical particle lifetimes to be less than 100 years, the motion is governed by two perturbing forces: solar radiation pressure and influence of Mars' oblateness. The equations of motion of particles in Lagrangian non-singular elements are deduced and solved, both analytically and numerically, for different-sized ejecta. We state that the coupled effect of both forces above is essential so that on no account can the oblateness of Mars are be neglected. The dynamics of grains prove to be quite different for the ejecta of Phobos and Deimos. For Deimos, the qualitative results are relatively simple and imply oscillations of eccentricity and long-term variations of orbital inclination, with amplitudes and periods both depending on grain size. For Phobos, the dynamics are shown to be much more complicated, and we discuss it in detail. We have found an intriguous peculiar behavior of debris near 300 µm in size. Another finding is that almost all the Phobos ejecta with radii less than 30 µm (against the values of 5 to 20 µm adopted earlier by many authors) should be rapidly lost by collisions with martian surface. The results of the paper may be the base for constructing an improved model of dust belts that presumably exist around Mars.     

The American whale oil industry: A look back to the future of the American petroleum industry?

The American whaling industry rose from humble beginnings off Long island to become an international giant. In its peak year, 1846, 735 ships and 70,000 people served the industry. As whale stocks and reserves decreased, whalers were forced to go farther and farther from their New England home ports. Voyages became longer, and risks on required return-on-investment became higher. The easy money of Atlantic and Pacific whaling was no more: the only remaining profitable ventures were to Arctic and Antarctic waters. Many ships returned empty, if at all. in 1871, most of the Arctic whaling fleet was crushed by early winter ice and lost. This calamity, in conjunction with the long-term diminishing whale stocks, the diversion of investment capital to more profitable ventures, and the discovery, development, and refinement of abundant petroleum crude oil, struck the death blow to the American whaling industry. By 1890, only 200 whaling vessels were at work, and by 1971, no American commercial whaling ship sailed the world's oceans.It is apparent that no single event caused the final, rapid decline. However, a single calamity, in an already stressed industry, that was self-insured and commercially interlinked, precipitated the end. Today's American petroleum industry, although adopting some principles of the American whaling industry, also has embraced other activities such as work process reengineering and customer alliances, which may preempt, or postpone, a similar catastrophic demise.     

The orion-IRc2 outflow observed in COJ=4-3

A CO J=4-3 map of the Orion-IRc2 region (size 80, beam 15) is presented. The outflow has a bipolar structure observed nearly pole-on. We interpret our observations in terms of an hierarchy of tubes where the fastest gas proceeds through the narrowest, innermost cone. The gas has an inhomogeneous temperature distribution and must be highly clumped. Most of the properties derived comply with the picture developed for the few known extreme high velocity outflows; however, this outflow contains exceptionally dense gas ( > 10⁶ cm^–3).     

Interstellar neutral hydrogen filaments at high galactic latitudes and the bennett pinch

Observed properties of interstellar neutral hydrogen filaments suggest the presence of the Bennett pinch as described by the Carlqvist relationship with rotation around the filament axes included. A brief summary is first given of three ways in which a filament model for interstellar cloud structure was tested. Preliminary results from highresolution HI mapping of gas and dust in an apparent HI cloud indicate that the neutral gas and dust within and around its boundary is itself highly filamentary. An attempt to detect magnetic fields in this and similar features using the Zeeman effect technique at the 21-cm wavelength of interstellar neutral hydrogen set upper limits of a fewµG. In contrast, the strength of the toroidal magnetic field expected from the examination of the Carlqvist relationship is of order 5µG, which would be produced by a current of 1.4 · 10¹³ A. Zeeman effect technology is at present not able to detect toroidal magnetic fields of this order at the edge of barely resolved HI filaments. Nevertheless, currently available high-resolution HI data suggest that interstellar filament physics should take into account the role of currents and pinches for creating and stabilizing the structures.     

Effects of hall current on the hydromagnetic free convection with mass transfer in a rotating fluid

An exact analysis of Hall current on hydromagnetic free convection with mass transfer in a conducting liquid past an infinite vertical porous plate in a rotating fluid has been presented. Exact solution for the velocity field has been obtained and the effects ofm (Hall parameter),E (Ekman number), andS _c (Schmidt number) on the velocity field have been discussed.Nomenclature C species concentration - C _w concentration at the porous plate - C species concentration at infinity - C _p specific heat at constant pressure - D chemical molecular diffusivity - g acceleration due to gravity - E Ekman number - G Grashof number - H ₀ applied magnetic field - j _x, j_y, j_z components of the current densityJ - k thermal conductivity - M Hartman number - m Hall parameter - P Prandtl number - Q heat flux per unit area - S _c Sehmidt number - T temperature of the fluid near the plate - T _w temperature of the plate - T temperature of the fluid in the free-stream - u, v, w components of the velocity fieldq, - U uniform free stream velocity - w ₀ suction velocity - x, y, z Cartesian coordinates - Z dimensionless coordinate normal to the plate. Greek symbols coefficient of volume expansion - ^* coefficient of expansion with concentration - _e cyclotron frequency - dimensionless temperature - ^* dimensionless concentration - v kinematic viscosity - density of the fluid in the boundary layer - coefficient of viscosity - _e magnetic permeability - angular velocity - electrical conductivity of the fluid - _e electron collision time - _u skin-friction in the direction ofu - _v skin-friction in the direction ofv     

Phenomenological theory of gravitational vacuum

An idea is developed that the vacuum in the gravitational field acquires properties of an elastic medium described by a definite tension _ik . The vacuum is stated to also participate in the formation of the space-time metric, together with the usual matter. So, the matter, vacuum and metric form a complex unity determined by the solution of the field equations. The vacuum may prove to play an essential role in the extremely strong fields existing in superdense celestial bodies. The tensor _ik is not to be identified with the pseudo-tensor of the energy-momentum of the gravitational field the idea of which is preserved.The problem of vacuum is investigated in the case of the central symmetry static field. A number of properties of the tensor _ik is found using the symmetry of the field and comparison with the post-Newton limit. The external and internal problems, as well as the procedure of joining the solutions on the surface of a celestial body, have been formulated. The stellar surface is determined in the usual way:P(r) = 0 whereP is the matter pressure. The theory includes three dimensionless parametersa=p/,b=p / (,p, p are the density of the vacuum energy and of its pressures in the radial and transverse directions) and determining the vacuum elastic properties. Generally speaking, they depend on the valueP/c² in the stellar centre where is the mass density. From general physical considerations it is shown that 0 1 + lim _P (l/q). The field equations are solved for the simple version of the theoryb=–a. There are solutions corresponding to superdense celestial bodies with masses considerably exceeding that of the Sun.