Energy Technology Data Exchange (ETDEWEB)

The Active Magnetospheric Particle Tracer Explorers (AMPTE) program provided important information on the behavior of clouds of plasma artificially injected into the solar wind and the earth's magnetosphere. Now that the releases are over, data from the satellites are being analyzed to investigate the processes by which the ambient solar wind mass, momentum, and energy are transferred to the magnetosphere. Work in progress at APL indicates that the solar wind is much more inhomogeneous than previously believed, that the solar wind constantly buffets the magnetosphere, and that ground observers may remotely sense these interactions as geomagnetic pulsations. 8 refs.

Energy Technology Data Exchange (ETDEWEB)

With the improvements accomplished during the past 15 years in detection techniques and instrumentation and with the opening of space exploration, molecular spectroscopy has become a very efficient way to probe planetary atmospheres.

Science.gov (United States)

During the Mars Exploration Rovers (MER) landings, the Descent Image Motion Estimation System

Science.gov (United States)

Nov 14, 2009 ... Ring Current electrons from the Fok Ring Current Model are computed using plasma and magnetic field values from the SWMF magnetosphere ...

International Nuclear Information System (INIS)

An approximate expression for whistler-mode group velocity is obtained, taking into account the effects of electron temperature and anisotropy, density and ion effects, effects of oblique propagation and a non-dipolarity of the dayside magnetospheric magnetic field. This expression is applied to the propagation of whistlers between one hemisphere and the other. It is pointed out that at frequencies close to the upper cut-off of whistler spectra, perturbations to whistler group delay times due to temperature effects can be of the same order of magnitude as, or even higher than, the corresponding perturbations due to finite electron density and ion effects. A method of magnetospheric electron temperature diagnostics is proposed and applied to two whistlers recorded at Halley (L = 4.3). It is pointed out that the values of temperature obtained from the analysis of whistler spectra depend on the choice of model of electron density and temperature ...

Science.gov (United States)

Aug 26, 2011 ... The main article on the back of the poster explains star evolution in very simple terms (including the fate of our own Sun), and how a planetary ...

Science.gov (United States)

... California where he is currently working on an AS in. Data Communication & Network Management as well as Microsoft. MCSE and Cisco CCNA certifications.

Science.gov (United States)

Mar 1, 2011 ... Currently there is no compact, portable and real time neutron detector instrumentation available for use inside spacecraft or on planetary ...

Energy Technology Data Exchange (ETDEWEB)

The results of Sandia National Laboratories' participation in the NASA Planetary Definition and Design Program are summarized. Areas reported include the characterization of large area cadmium zinc telluride spectrometers and the application of simulation techniques to the prediction of device performance. Also investigated was the response of mercuric iodide devices in the region from 1 to 100 KeV. A literature study to determine the status or radiation damage measurements in room temperature semiconductor devices is also reported.

International Nuclear Information System (INIS)

This paper focuses on potential effects of solar phenomena on communication systems used by the electric utility industry. It begins with a discussion of solar phenomena fundamentals and discussion of the interaction between solar emissions and the earth's ionosphere and magnetosphere. It continues with a discussion of the resulting impacts on communication systems including radio, satellite, wireline, fiber optic, and powerline systems and concludes with a discussion of mitigation techniques and a call for observers to report suspected solar impact experiencexperiences.

British Library Electronic Table of Contents (United Kingdom)

The 6n-dimensional phase space of the planetary (1+n)-body problem (after the classical reduction of the total linear momentum) is shown to be foliated by symplectic leaves of dimension (6n?2) invariant for the planetary Hamiltonian Formula Not Shown . Such foliation is described by means of a new global set of Darboux coordinates related to a symplectic (partial) reduction of rotations. On each symplectic leaf Formula Not Shown has the same form and it is shown to preserve classical symmetries. Further sets of Darboux coordinates may be introduced on the symplectic leaves so as to achieve a complete (total) reduction of rotations. Next, by explicit computations, it is shown that, in the reduced settings, certain degeneracies are removed. In particular, full torsion is checked both in the ...

CERN Document Server

Simulations of planetary microlensing at high magnification that were carried out on a cluster computer are presented. It was found that the perturbations due to two-thirds of all planets occur in the time interval [-0.5t_FWHM, 0.5t_ FWHM] with respect to the peak of the microlensing light curve, where t_FWHM is typically about 14 hours. This implies that only this restricted portion of the light curve need be intensively monitored for planets, a very significant practical advantage. Nearly all planetary detections in high magnification events will not involve caustic crossings. The position angle, mass and projected orbital radius of a planet may be systematically determined from the planetary deviation. Earth mass planets may be detected with 1-m class telescopes if their projected orbital radii lie within about 1.5 - 2.5 AU. Giant planets are detectable over a much larger region. For multi-planet systems the ...

Science.gov (United States)

Aug 25, 2004 ... Current Developments in Future Planetary Probe Sensors: .... Data: Outgoing and incoming EIA RS-422 interface for serial data transmission (for electrical purposes only, .... Milos, et. al, Journal of Spacecraft & Rockets 1999 ...

CERN Document Server

A proposal is made to test Newton's inverse-square law using the perihelion shift of test masses (planets) in free fall within a spacecraft located at the Earth-Sun L2 point. Such an Artificial Planetary System In Space (APSIS) will operate in a drag-free environment with controlled experimental conditions and minimal interference from terrestrial sources of contamination. We demonstrate that such a space experiment can probe the presence of a "hidden" fifth dimension on the scale of a micron, if the perihelion shift of a "planet" can be measured to sub-arc-second accuracy. Some suggestions for spacecraft design are made.

CERN Document Server

All of the solar system gas giants produce electron cyclotron masers, driven by the solar wind impinging on their magnetospheres. Extrapolating to the planet orbiting tau Boo, various authors have predicted that it may be within the detection limits of the 4-meter wavelength (74 MHz) system on the Very Large Array. This paper reports three epochs of observations of tau Boo. In no epoch do we detect the planet; various means of determining the upper limit to the emission yield single-epoch limits ranging from 135 to 300 mJy. We develop a likelihood method for multi-epoch observations and use it to constrain various radiation properties of the planet. Assuming that the planet does radiate at our observation wavelength, its typical luminosity must be less than about 10^{16} W, unless its radiation is highly beamed into a solid angle Omega << 1 sr. While within the range of luminosities predicted by various authors for this planet, this value is lower than recent ...

CERN Document Server

Aims. We attempt to detect starlight reflected from the hot Jupiter orbiting the main-sequence star Tau Boo, in order to determine the albedo of the planetary atmosphere, the orbital inclination of the planetary system and the exact mass of the planetary companion. Methods. We analyze high-precision, high-resolution spectra, collected over two half nights using UVES at the VLT/UT2, by way of data synthesis. We interpret our data using two different atmospheric models for hot Jupiters. Results. Although a weak candidate signal appears near the most probable radial velocity amplitude, its statistical significance is insufficient for us to claim a detection. However, this feature agrees very well with a completely independently obtained result by another research group, which searched for reflected light from Tau Boo b. As a consequence of the non-detection of reflected light, we place upper limits to the planet-to-star flux ...

Science.gov (United States)

We present here a study based on the migration of protoplanets in an accretion disc of a forming star, as the mainly proposed scenario for the formation of planetary systems. Attention is here focused on the mutual interactions between two protoplanets, both embedded in the accretion disc, as a function of the protoplanets masses, their relative positions, the dynamic properties of the accretion disc particles. The study is performed through a 2D SPH code and preliminary results show an oscillation of the distance between the two protoplanets, together with a slow migration of the two planets towards the central star when two Jupiter-like planets are considered. Less correlated behaviour is observed when at least one of the two protoplanets has an Earth-like mass. The role played by the disc particles initial angular momentum is discussed.

CERN Document Server

The interaction of accretion disks with the magnetospheres of young stars can produce X-winds and funnel flows. With the assumption of axial symmetry and steady state flow, the problem can be formulated in terms of quantities that are conserved along streamlines, such as the Bernoulli integral (BI), plus a partial differential equation (PDE), called the Grad-Shafranov equation (GSE), that governs the distribution of streamlines in the meridional plane. The GSE plus BI yields a PDE of mixed type, elliptic before critical surfaces where the flow speed equals certain characteristic wave speeds are crossed and hyperbolic afterward. The computational difficulties are exacerbated by the locations of the critical surfaces not being known in advance. To overcome these obstacles, we consider a variational principle by which the GSE can be attacked by extremizing an action integral, with all other conserved quantities of the problem explicitly included as part of the overall ...

Science.gov (United States)

The transport of magnetospheric particles in the outer cusp region is examined by means of three-dimensional single particle codes. It is shown that, at high altitudes, particles can experience nonadiabatic motions leading to significant magnetic moment changes. It is demonstrated that this nonadiabatic behavior can be interpreted, at least partly, by the action of an impulsive centrifugal force perturbing the particle gyromotion. Systematic trajectory calculations reveal that plasma sheet ions which ExB convert toward the magnetopause from low L-shells in the dayside sector are subjected to such nonadiabatic motions. As a result of magnetic moment damping, a number of them are injected into the loss cone and subsequently precipitate near the cusp equatorward edge.

CERN Document Server

The available data of single X-ray pulsars, their wind nebulae, and the SNRs which are connected to some of these sources are analysed. It is shown that electric field intensity of neutron stars tears off charged particles from the surface of neutron star and triggers the acceleration of particles. The charged particles are accelerated mainly in the field of magnetodipole radiation wave. Power and energy spectra of the charged particles depend on the strength of the magnetodipole radiation. Therefore, the X-ray radiation is strongly dependent on the rate of rotational energy loss and weakly dependent on the electric field intensity. Coulomb interaction between the charged particles is the main factor for the energy loss and the X-ray spectra of the charged particles.

Energy Technology Data Exchange (ETDEWEB)

Interactions between spacecraft systems and the space charged particle environment are reviewed and recommendations are presented for both near-term and far-term research considerations. Transient environment models, large space structures, solar and nuclear power systems/environment interactions, single event upsets, material degradation, and planetary missions are addressed.

CERN Document Server

We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early type galaxies. This empirical law assumes that the surface brightness profile is a combination of two power laws with different slopes gamma and beta for the inner and outer regions. Conventional structural parameters such as core radius and central surface brightness are replaced by break radius r_b, where the transition between power-law slopes takes place, and surface brightness mu_b at that radius. An additional parameter alpha describes the sharpness of the break. The structural parameters are derived using a chi-squared minimization process applied to the mean surface brightness profiles. The resulting model profiles generally give very good agreement to the observed profiles out to the radius of 10 ...

CERN Document Server

Emission-line abundances have been uncertain for more than a decade due to unexplained discrepancies in the relative intensities of the forbidden lines and weak permitted recombination lines in planetary nebulae (PNe) and H II regions. The observed intensities of forbidden and recombination lines originating from the same parent ion differ from their theoretical values by factors of more than an order of magnitude in some of these nebulae. In this study we observe UV resonance line absorption in the central stars of PNe produced by the nebular gas, and from the same ions that emit optical forbidden lines. We then compare the derived absorption column densities with the emission measures determined from ground-based observations of the nebular forbidden lines. We find for our sample of PNe that the collisionally excited forbidden lines yield column densities that are in basic agreement with the column densities derived for the same ions from the UV absorption lines. ...

CERN Document Server

A decreasing gravitational constant, G, coupled with angular momentum conservation is expected to increrase a planetary semimajor axis, a, as \\dot a/a=-\\dot G/G. Analysis of lunar laser ranging data strongly limits such temporal variations and constrains a local (~1 AU) scale expansion of the solar system as \\dot a/a=-\\dot G/G =-(4\\pm9)\\times10^{-13} yr^{-1}, including that due to cosmological effects.

International Nuclear Information System (INIS)

Attention is given to the folowing topics: population I and II variable stars; LP variables, the sun, and mass determination; and predegenerate and degenerate variables. Particular papers are presented on alternative evolutionary approaches to the absolute magnitude of the RR Lyrae variables; the evolution of the Cepheid stars; nonradial pulsations in rapidly rotating Delta Scuti stars; dynamical models of dust shells around Mira variables; and pulsations of central stars of planetary nebulae.

International Nuclear Information System (INIS)

Electrostatic wave measurements from the Active Magnetospheric Particle Tracer Explorer Ion Release Module have been used to investigate the wave modes and their possible generation mechanisms in the Earth's bow shock and magnetosheath. It is demonstrated that electrostatic waves are present in the bow shock and magnetosheath with frequencies above the maximum frequency for Doppler-shifted ion acoustic waves, yet below the plasma frequency. Waves in this frequency range are tentatively identified as electron beam mode waves. Data from 45 bow shock crossings are then used to investigate possible correlations between the electrostatic wave properties and the near-shock plasma parameters. The most significant relationships found are anticorrelations with Alfven Mach number and electron beta. Mechanisms which might produce electron beams in the shock and magnetosheath are discussed in terms of the correlation study results. These mechanisms include acceleration by the ...

CERN Document Server

This remodeled form of Einstein's relativity theories retains and incorporates only experimentally proven principles. It is based on a generalized law for spinning and rotational motions, which is in fact the conservation law of momentum vector direction, and can be successfully used for the precision computation of planetary and lunar orbits. The most fundamental principles of the remodeled relativity theory are the conservation laws of energy and momentum. Based on experience of relativity experiments, we adopted the principles that energy level is the underlying cause for relativistic effects, and that mass is expressed by the relativistic energy equation from Einstein. From space age ephemeris generation experience and following nature's way to conserve energy and momentum, we found reason to replace the concept of "relativity of all frames" with that of "nature's preferred frame", which helped us to escape Einstein's dilemma till 1912, when he concluded that ...

Energy Technology Data Exchange (ETDEWEB)

Today TBP and TBAs are the compounds which have the highest potential to replace the hydrides arsine and phosphine in the MOVPE process. The authors have demonstrated the entire material system Ga-In-As-P can be grown without any loss of quality using TBP and TBAs not only in one reactor, but in a complete family of reactors. These reactors range from small-scale single wafer R and D reactors to multiwafer Planetary Reactor systems. Both InP based and GaAs based materials could be grown with an excellent quality. Thus all growth processes for III-V devices--long and short wavelength lasers, LEDs, high speed transistors, etc.--can be switched to TBP and TBAs. This will drastically reduce safety hazards and lead to processes that have advantages both from the ecological and economical point of view.

British Library Electronic Table of Contents (United Kingdom)

New photometric observations of the variable star FG Sge, a rapidly evolving planetary nebula nucleus, were performed in 2003?2008. On 230 nights, we obtained 86 UBV and 155 BV RI (or R c , I c ) magnitude estimates. The maximum amplitude of the V-band light variations was >8 m . Six deep minima and four high maxima were observed. Analysis of the light curve has shown that the pulsation period of the star remained constant since 1991 and was P = 115 days. We have studied the wavelength dependence of the extinction at various phases of the light curve. The blueing of the B-V color at deep minima is interpreted as the result of light scattering in the circumstellar dust shell of the star formed by preceding dust ejections since 1992. Our spectroscopic observations performed on nine nights in...

Science.gov (United States)

Current theories on planetary formation establish that massive objects accrete gaseous envelopes, becoming gaseous planets if the accretion process proceeds before the accretion disc dissolution. One of the unsolved problems is that the planet formation is contextual to their quick migration towards the central star, due to the protoplanets-disc interaction, on a timescale lower by an order of magnitude than that of gas accretion onto the protoplanet. These arguments have been recently broached using N-body and/or Eulerian fluid-dynamics codes, mainly in 2D, or a mixing of them. In this work, 2D simulations with a SPH code are performed, to study the migration of one protoplanet. The goal is to scrutinise the protoplanet dragging as a function of planet's mass.

Science.gov (United States)

In 1999, RECONS (Research Consortium on Nearby Stars) began gathering astrometric data using the CTIO 0.9m under the auspices of the NOAO Surveys Program. In 2003, SMARTS began operating the 0.9m and the program continued, with an enhanced ability to acquire long-term astrometric series on the nearest stars. With over a decade of milli-arcsecond astrometry for hundreds of red dwarfs within 25 pc, we now have a rich dataset in which to search for previously unknown stellar, substellar, and planetary companions. We can also use our data to better constrain the orbits of known binaries to reduce their mass errors to less than a few percent, and consequently test astrophysical models as never before. Here we present our orbit fitting analysis of M dwarfs that show clear evidence of gravitational perturbations due to unseen companions, after solving for their proper motion and parallax signals. We show discoveries such as LHS 3738AB, found for the first time to have a ...

Science.gov (United States)

1. Contest rules The European Space Agency (ESA) is launching a public competition to find the most suitable names for its four Cluster II space weather satellites. The quartet, which are currently known as flight models 5, 6, 7 and 8, are scheduled for launch from Baikonur Space Centre in Kazakhstan in June and July 2000. Professor Roger Bonnet, ESA Director of Science Programme, announced the competition for the first time to the European Delegations on the occasion of the Science Programme Committee (SPC) meeting held in Paris on 21-22 February 2000. The competition is open to people of all the ESA member states (*). Each entry should include a set of FOUR names (places, people, or things from history, mythology, or fiction, but NOT living persons). Contestants should also describe in a few sentences why their chosen names would be appropriate for the four Cluster II satellites. The winners will be those which are considered most suitable and relevant for the Cluster II mission. ...

Energy Technology Data Exchange (ETDEWEB)

The Argonne Boundary Layer Experiments (ABLE) facility, located in south central Kansas, east of Wichita, is devoted primarily to investigations of and within the planetary boundary layer (PBL), including the dynamics of the mixed layer during both day and night; effects of varying land use and land form; the interactive role of precipitation, runoff, and soil moisture; storm development; and energy budgets on scales of 10 to 100 km. Located entirely within the Walnut River watershed, ABLE provides intense measurements within the northeast quadrant (Fig. 1) of the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) of the Atmospheric Radiation Measurement (ARM) Program (Stokes and Schwarz, 1994). By combining the continuous measurements of ABLE with ancillary continuous measurements of, for example, the ARM and the Global Energy Water cycle Experiment (GEWEX) (Kinster and Shukla, 1990) programs, ABLE provides a platform within which shorter, more ...

CERN Document Server

A debris disk is a constituent of any planetary system surrounding a main sequence star. We study whether close stellar encounters can disrupt and strip a debris disk of its planetesimals in the expanding open cluster of its birth. Such stripping would affect the dust production and hence detectability of the disk. We tabulated the fractions of planetesimals stripped off during stellar flybys of miss distances between 100 and 1000 AU and for several mass ratios of the central to passing stars. We then estimated the numbers of close stellar encounters over the lifetime of several expanding open clusters characterized by their initial star densities. We found that a standard disk, with inner and outer radii of 40 and 100 AU, suffers no loss of planetesimals around a star born in a common embedded cluster with star density 20 000 pc^-3. In this environment, a disk loses >97% of its planetesimals around an M-dwarf, >63% around a solar-type star, and >42% ...

CERN Document Server

We present very sensitive polarimetry of 55 Cnc and tau Boo in an attempt to detect the partially polarised reflected light from the planets orbiting these two stars. 55 Cnc is orbited by a hot Neptune planet (55 Cnc e) at 0.038 AU, a hot Jupiter planet (55 Cnc b) at 0.11 AU, and at least 3 more distant planets. The fractional polarisation of this star is very stable, with a standard deviation in the nightly averaged Stokes Q/I and U/I parameters of 2.2x10^{-6}. We derive upper limits on the geometric albedo, A_G and planetary radius using Monte Carlo multiple scattering simulations of a simple model atmosphere. We assume Rayleigh-like scattering and polarisation behaviour (scaled by the maximum polarisation, p_m at 90 degrees) and pressure insensitive extinction. Atmospheres in which multiple scattering plays only a small role have an almost linear relation between polarisation and A_G. In this case, the 4 sigma upper limits are A_G<0.13(R/1.2 ...

British Library Electronic Table of Contents (United Kingdom)

Ultra fine tungsten carbide and cobalt powders were milled by high energy planetary ball mill at different ball to powder weight ratios (BPR) to produce particles of WC-10wt%Co hard metal in nanometer scale size. Microstructural characterizations by TEM show that the particle size of tungsten carbide was achieved to 32nm after milling at 15 BPR during 10h. In order to reduce the WC grain growth during the sintering process, tantalum carbide was added to the hard metal as a WC grain growth inhibitor. The nano hard metal powders were compacted at 200MPa pressure and sintered at 1370-1450degreeC temperatures in a high purity hydrogen atmosphere. The results show that the addition of 0.6wt% of TaC improves the hardness and fracture toughness from 1493 HV30 and 11.8MPam (for TaC free sample) to...

CERN Document Server

We present results from Spitzer Space Telescope observations of the mid-infrared phase variations of three short-period extrasolar planetary systems: HD 209458, HD 179949 and 51 Peg. We gathered IRAC images in multiple wavebands at eight phases of each planet's orbit. We find the uncertainty in relative photometry from one epoch to the next to be significantly larger than the photon counting error at 3.6 micron and 4.5 micron. We are able to place 2-sigma upper limits of only 2% on the phase variations at these wavelengths. At 8 micron the epoch-to-epoch systematic uncertainty is comparable to the photon counting noise and we detect a phase function for HD 179949 which is in phase with the planet's orbit and with a relative peak-to-trough amplitude of 0.00141(33). Assuming that HD 179949b has a radius R_J < R_p < 1.2R_J and a small Bond albedo, it must recirculate less than 30% of incident stellar energy to its night side at the 1-sigma level (where 50% ...

British Library Electronic Table of Contents (United Kingdom)

The nanocomposite WC-Co powders were prepared through planetary ball milling method. Effects of grain growth inhibitor addition and the vacuum sintering parameters on the microstructure and properties of ultrafine WC-10Co cemented carbides were investigated using X-ray diffractometer, scanning electron microscope and mechanical property tester. The results show that VC and NbC additions can refine the WC grains, decrease the volume fraction of Co3W3C phase in ultrafine WC-10Co cemented carbides, and increase the hardness and fracture toughness of the base alloys. After sintering for 60 min at 1400 degreeC, the average grain size and hardness of ultrafine-grained WC-10Co-1VC cemented carbide are 470 nm and HRA 91.5, respectively. The fracture toughness of cemented carbide WC-10Co-1NbC alloy...

CERN Document Server

Nine extrasolar planets with masses between 110 and 430M are known to transit their star. The knowledge of their masses and radii allows an estimate of their composition, but uncertainties on equations of state, opacities and possible missing energy sources imply that only inaccurate constraints can be derived when considering each planet separately. Aims: We seek to better understand the composition of transiting extrasolar planets by considering them as an ensemble, and by comparing the obtained planetary properties to that of the parent stars. Methods: We use evolution models and constraints on the stellar ages to derive the mass of heavy elements present in the planets. Possible additional energy sources like tidal dissipation due to an inclined orbit or to downward kinetic energy transport are considered. Results: We show that the nine transiting planets discovered so far belong to a quite homogeneous ensemble that is characterized by a mass of heavy elements ...

Energy Technology Data Exchange (ETDEWEB)

The role played by planetary boundary layer (PBL) in the development and evolution of a severe convective storm is studied by means of meso-scale modeling and surface and upper air observations. The severe convective precipitation event that occurred on 14 September 1999 in the northeast of the Iberian Peninsula was simulated by means of the mesoscale model MM5 (version 3) using three different PBL schemes. The numerical results show a large impact of the PBL schemes on the precipitation fields associated to the convective storm. The schemes are based on different physical assumptions: the nonlocal first order medium-range forecast (MRF) and blackadar (BLA) scheme and the local, one-and-a-half order ETA scheme. Surface and radar observations are used to validate the model results. The comparison focuses on three aspects: the evolution, the spatial distribution and the 24-h accumulated precipitation. The comparison with rain gauge observations shows that the MRF, ...

Science.gov (United States)

We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. For the hypothetical systems, we restrict our exploration to systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 giant planets. We verify that these systems are stable for 108 years with N-body simulations. We then calculate the obliquity variations induced by the orbital architecture on the Earth-mass planets. We find that in some cases the spin axes can rotate through 360 degrees in as little as 10,000 years (John is that right? Can you look through the systems and find the most extreme case of obliquity variation?) Next, we run energy balance models (EBM) on the terrestrial planets to assess surface temperature and ice coverage on the planets' oceans. Finally, we explore differences in the outer edge of the habitable zone for planets with rapid obliquity variations. We run EBM simulations for a range of ...

International Nuclear Information System (INIS)

New stellar models which track the production and destruction of "3He (and D) have been evolved for a range of stellar masses (0.65#<=#M/M_c_i_r_c_l_e_-_d_o_t#<=#100), metallicities (0.01#<=#Z/Z_c_i_r_c_l_e_-_d_o_t#<=#1), and initial (main-sequence) "3He mass fractions (10"-"5#<=#X_3_,_M_S#<=#10"-"3). Armed with the "3He yields from these stellar models we have followed the evolution of D and "3He using a variety of chemical evolution models with and without infall of primordial or processed material. Production of new "3He by the lower mass stars overwhelms any reasonable primordial contributions and leads to predicted abundances in the presolar nebula and/or the present interstellar medium in excess of the observationally inferred values. This result, which obtains even for zero primordial D and "3He, and was anticipated by Rood, Steigman, ampersand Tinsley is insensitive to the choice of chemical evolution model; it is driven by the large "3He yields from low-mass ...

Energy Technology Data Exchange (ETDEWEB)

The environment - external or internal degrees of freedom coupled to the object of interest - can, in effect, monitor some of its observables. As a result, the eigenstates of these observables decohere and behave like classical states. Continuous destruction of superpositions leads to the effective environment-induced superselection (einselection), which is beginning to be recognized as a key step in the transition from quantum to classical. We investigate it here in the context of quantum chaos. I show that the evolution of a chaotic macroscopic system is not just difficult to predict (requiring accuracy exponentially increasing with time) but quickly ceases to be deterministic in principle as a result of the Heisenberg uncertainty (which limits the available resolution). This happens after a time t{sub {Dirac_h}} which is only logarithmic in the Planck constant. For example, various components of the solar system are chaotic, with the Lyapunov timescales ranging from a bit more then ...

International Nuclear Information System (INIS)

We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy's sphere of influence based on the predicted value of the black hole mass from the M-#sigma# relation. We find masses for the following galaxies: NGC 3585, M _B_H = 3.4"+"1"."5 _-_0_._6 x 10"8 M _s_u_n; NGC 3607, M _B_H = 1.2"+"0"."4 _-_0_._4 x 10"8 M _s_u_n; NGC 4026, M _B_H = 2.1"+"0"."7 _-_0_._4 x 10"8 M _s_u_n; and NGC 5576, M _B_H = 1.8"+"0"."3 _-_0_._4 x 10"8 M _s_u_n, all significantly excluding M _B_H = 0. For NGC 3945, M _B_H = 9"+"1"7 _-_2_1 x 10"6 M ...