Remarks on dynamical ellipticity at the Earth's

In this paper, two factors — the redistribution of the density and the variation in the angular velocity of the Earth rotation, that affect the adopted value of the flattening for equidensity surface within the Earth, are discussed. The computational results show that the contribution of the redistribution of the density in the Earth interior (especially in the core) on the change of the flattening at the core-mantle boundary (CMB) is marginal, and that the calculated value of the flattening at the CMB can be in good agreement with the VLBI observed value so long as the fact that the angular velocity of the Earth rotation has undergone the tidal evolution is taken into account. As a result, this paper presents a set of recommended values of the dynamical parameters of the Earth (see Table III) for computing Earth's forced nutation series.     

The electron pressure in the outer atmosphere of ε Eri (K2 V)

Observations of ε Eri (K2 V) have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope . The spectra obtained show a number of emission lines which can be used to determine, or place limits on, the electron density and pressure. Values of the electron pressure are required in order to make quantitative models of the transition region and inner corona from absolute line fluxes, and to constrain semi-empirical models of the chromosphere. Using line flux ratios in Si  iii and O  iv a mean electron pressure of P _e= N _e T _e=4.8×10¹⁵ cm⁻³ K is derived. This value is compatible with the lower and upper limits to P _e found from flux ratios in C  iii , O  v and Fe  xii . Some inconsistencies which may be because of small uncertainties in the atomic data used are discussed.     

Evidence of climatic warming in the southern Urals region derived from borehole temperatures and meteorological data

Thirty borehole temperature–depth profiles in the central and southern Urals, Russia were scrutinized for evidence of ground surface temperature histories. We explored two inversion schemes: a simple ramp inversion in which solutions are parameterized in terms of an onset time and magnitude of change and a more sophisticated functional space inverse algorithm in which the functional form of the solution is left unspecified. To enhance and potentially identify latitudinal differences in the ground surface temperature signal, we subdivided the data into three groups based on geographic proximity and simultaneously inverted the borehole temperature–depth logs. The simultaneous inversions highlighted 13 temperature–depth logs that could not both fit a common ground surface temperature history and a priori models within reasonable bounds. Our results confirm that this is an effective way to reduce site-specific noise from an ensemble of boreholes. Each inversion scheme gives comparable results indicating locally variable warming on the order of 1°C starting between 1800 and 1900 AD. Similarly surface air temperature records from 12 nearby meteorological stations exhibit locally variable warming also on the order of 1°C of warming during the 20th century. To explore the degree to which borehole temperatures and surface air temperature (SAT) time series are responding to the same signal, we average the SAT data into the same three groups and used these averages as a forcing function at the Earth's surface to generate synthetic transient temperature profiles. Root mean square (RMS) misfits between these synthetic temperature profiles and averaged temperature–depth profiles are low, suggesting that first-order curvature in borehole temperatures and variations in SAT records are correlated.     

A high speed near infrared photometer for lunar occultation studies

A recently developed near infrared high speed photometer intended for lunar oc-cultation studies is described. The primary scientific objective is to reach milli arc second levels of angular resolution so that circumstellar structure of the occulted sources can be resolved. Near infrared sky brightness close to the lunar limb is also studied. Angular diameter derived from the observed occultation of IRC +20169 is presented and system performance discussed.     

Trace-element contents and cathodoluminescence of “trapiche” rubies from Mong Hsu, Myanmar (Burma): geological significance

Summary ?Mong Hsu rubies of the “trapiche” type are sporadically seen in the gem market. However, they have never been described in the field. The study of the nature of solid inclusions, the variation of trace-element contents, as well as the cathodoluminescence behaviour of six “trapiche” rubies permit the conclusion that these rubies crystallised in the same geological environment (marble-type deposit) as the normal rubies from Mong Hsu: (1) Cr and V are the main chromophorous elements in both ruby types; they act, together with Ti, as activators or quenchers for cathodoluminescence; (2) calcite, dolomite, rutile, mica, diaspore, apatite, chlorite, and feldspar are solid inclusions found in both ruby types; (3) the presence of bastn?site in trapiche ruby and fluorite in non-trapiche ruby indicates the circulation of F-bearing fluids during ruby deposition; (4) the distribution of trace-element contents in the crystal is similar for both ruby types. In the Cr₂O₃ vs. Fe₂O₃ and Cr₂O₃ vs. Fe₂O₃/TiO₂ diagrams, the population fields of Mong Hsu “trapiche” and non-“trapiche” rubies overlap. They are distinct from those of rubies and sapphires hosted in basalts from South-east Asia. Received October 30, 2001; revised version accepted March 25, 2002     

Some New Observed Properties of Elliptical Galaxies

We suggest that elliptical galaxies, as stellar systems in a stage of quasi-equilibrium, may have a specific entropy. We use the Sérsic law to describe the light profile. The specific entropy (the Boltzmann–Gibbs definition) is then calculated assuming that the galaxy behaves as a spherical, isotropic, one-component system. We predict a relation between the three parameters of the Sérsic law linked to the specific entropy, defining a surface in the parameter space, an ‘entropic plane’. We have analysed a sample of simulated merging elliptical galaxies (virtual) and a sample of galaxies belonging to the Coma Cluster (real). Both virtual and realgalaxies are: 1) located in their own ‘entropic plane‘ and 2) in this plane, they are located on a straight line, indicating constant entropy: another physical property A careful examination of the value of the specific entropy indicates a very small increase in the specific entropy with the generation after merging (virtual sample). Although one cannot distinguish between various generations for real galaxies, the distribution of specific entropy in this sample is very similar to that in the virtual sample. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rapid Measurements of Solar Wind Ions with the Triana PlasMag Faraday Cup

The Triana PlasMag Faraday Cup (FC) will be able to determine speed, flow angles, temperature, and density of the main solar wind ion species with a time resolution of better than one second. Thus, the Triana PlasMag FC will enable resolution of spatial structures as small as a few hundred kilometers as the structures convect past the spacecraft. Under typical solar wind conditions, that size is comparable to a few proton gyroradii. This revised version was published online in July 2006 with corrections to the Cover Date.     

Prediction in Real Time of the 2000 July 14 Heliospheric Shock Wave and its Companions During the `Bastille' Epoch*

Prediction of solar-generated disturbances and their three-dimensional propagation through interplanetary space continues to present a vitally important operational space weather forecasting objective. This paper presents the first successful real-time prediction of a series of major heliospheric shock waves at Earth, including the one from the 14 July 2000 (`Bastille Day') flare. An ensemble of three models and their predictions were distributed to a world-wide group of interested scientists as part of an informal Internet space weather forecast research program. Two of the models, STOA (Shock Time of Arrival) and ISPM (Interplanetary Shock Propagation Model), presently in operation by the US Air Force Weather Agency, provided predictions of shock arrival time (SAT) that were, respectively, 0.5 hours after and 3.7 hours before the observed arrival. The third model, HAFv.2 (Hakamada–Akasofu–Fry version 2.0) predicted a time 0.3 hours after the observed shock arrival time (14:37 UT, 15 July 2000). Of primary interest to this study is the third model, firstly in terms of its capability of propagating shocks through non-uniform solar wind conditions, and secondly, in terms of its ability to integrate multiple solar events and display them graphically along with the background solar wind. This latter capability was brought to bear on ten real-time-reported flares, some with CMEs (coronal mass ejections) that took place as companions to the Bastille flare during the period 7–15 July 2000. Some limited statistics are given regarding the three models' shock arrival prediction capability at Earth, as an extension of our earlier studies with this three model ensemble in the prediction of SAT. HAFv.2, however, was able to describe not only the ten events and their interaction as measured at Earth, but also at the spacecraft NEAR (orbiting the asteroid, Eros, at 1.8 AU), and CASSINI (en route, at 4.0 AU, to Saturn). Several important points are noted: (1) this epoch represents a small statistical sample that should be expanded; and (2) the three models, based on theory, empiricism, and simulations represent the state of the art that should presage a similar community process. This paper was presented earlier as an Invited Talk at the American Geophysical Union Fall Meeting, December 14–19, 2000, in San Francisco, CA, U.S.A.toward space weather objectives in the Sun-Earth domain. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014200719867