bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibration of the Galileo/ISPM Dust Detectors with Iron Particles
Authors: Göller J.R. , Grün E. 
Published: July 2016

AbstractThe impact-ionization-detectors for the Galileo-/ISPM-Missions were calibrated using about 7000 iron particles with speeds between 1 km/s and 67 km/s and masses between 10−15 g and 2 × 10−10 g. These calibrations showed that the impact charge (Q) was proportional to the particle mass (m) at a fixed velocity. The speed dependent charge yield (Q/m) showed significant deviations (up to one magnitude) from a power law.There are three independent methods (risetimes of electron and ion pulses, amplitude ratio between channeltron and ion pulse) for measuring particle speed and two possibilities (charge yields of electron and ion pulses) for mass measurement. This calibration showed that the speed can be determined within a factor of 1.2 and the mass within a factor of 2.0.
An Empirical Penetration Equation for Thin Metallic Films Used in Capture Cell Techniques
Authors: Carey W.C. , McDonnell J.A.M. , Dixon D.G. 
Published: July 2016

AbstractThe problem in the determination of impact particle parameters from hypervelocity impact damage on a foil or multilayer structure is one which deserves close attention in the era of ready access to recovered space impact events. In the MFE experiment (McDonnell et al 1984), we chose metallic foils, and this paper addresses the decoding of perforations in metallic foils, primarily of aluminium of typical dimensions 5 μm (hard temper rolled). Data is examined to establish for the first time a penetration relationship which extends over:
1.marginal and thin sheet perforation;2.velocities varying from some 2 to 69 kms−13.particle densities varying from some 1 g cm−3 (ices?) to 7.8 g cm−3 (iron?)
A Method for Deriving the Mean Volume Scattering Phase Function for Zodiacal Dust
Authors: Hong S.S. 
Published: July 2016

AbstractA linear combination of 3 Henyey-Greenstein phase functions is substituted for the mean volume scattering phase function in the zodiacal light brightness integral. Results of the integral are then compared with the observed brightness to form residuals. Minimization of the residuals provides us with the best combination of Henyey-Greenstein functions for the scattering phase function of zodiacal dust particles.
Laboratory Results on Polarization Properties of Elongated Particles and Comparisons to Dust in the Tail of Comet Ikeya-Seki (1965 VIII)
Authors: Gustafson Bo.Å.S. 
Published: July 2016

AbstractData obtained through microwave analog measurements are used to compare optical polarization characteristics of silicate particles ranging in shape from spheroids and cylinders to chains of spheres. It is confirmed that the dependence of the degree of polarization on scattering angle is a powerful indicator of particle shape. The reversal and steep gradient in the degree of polarization found by Weinberg and Beeson (1976a,b) in the dust tail of comet Ikeya-Seki (1965 VIII) is suggestive of laboratory measurements corresponding to 1.6 μm long, 0.4 μm in diameter silicate cylinders.
Optical Models of the Three Dimensional Distribution of Interplanetary Dust
Authors: Giese R.H. , Kinateder G. , Kneissel B. , Rittich U. 
Published: July 2016

AbstractSeveral models of three dimensional distributions of the interplanetary dust number densities are compared with observational values. It is shown that a comparatively satisfying fit can be achieved by distributions similar to the “Sombrero-Model” of Dumont and that multilobe models as recently proposed by Buitrago et al. can be rejected due to discrepancies with rocket photometry of the inner zodiacal light.
Plans for Release of Simulated Interplanetary Materials into Low Earth Orbit
Authors: Strong I.B. , Brownlee R.R. , Farnum E.H. , Huebner W.F. , Kunkle T.D. , Stephens J.R. , Bode M.F. 
Published: July 2016

AbstractA number of experimental releases into low earth orbit of small, but detectable, quantities of very fine particulates are planned for the next several years. The principal materials are chemically and physically similar to those generally assumed to be the major constituents of interplanetary and circumstellar dusts (silicates, silicon carbide, graphitic materials). Later releases will include multi-phase releases of non-volatile particulates and volatile ices, simulating cometary material. Both ground-based and Space-Shuttle-based observations will be made in the visible and infra-red to study particle-plasma interactions, cometary physics and cloud dynamics in orbit.Since opportunities for observing the behavior of such well-characterized materials in space are likely to be rare, and the effective duration of significant concentrations will be very short, we wish to have early input from the scientific community so as to maximize the scientific return. We will be receptive to all suggestions including collaborations in making the observations.
On Two Mechanisms of X-Ray Generation in Comets
Authors: Ibadov S. 
Published: July 2016

AbstractThe intensity of solar X-radiation scattered by a comet is calculated and compared to the proper X-radiation of the comet due to impacts of cometary and interplanetary dust particles. Detection of X-radiation of dusty comets at small heliocentric distances (R ≤ 1 a.u.) is found to be an indicator of high-temperature plasma generation as result of grain collisions.
Dynamics and Spatial Distribution of Interplanetary Dust
Authors: Leinert Ch. 
Published: July 2016

AbstractThree attempts to explain the radial power law distribution n(r)~r−1.3 of interplanetary dust are reviewed, which include the influence of Poynting-Robertson effect, collisions and interplanetary magnetic fields. Electromagnetic forces are unlikely to affect appreciably the spatial distribution. The replenishment of the cloud of interplanetary dust by the disruption of larger meteoritic particles in catastrophic collisions appears to give the most natural explanation for the observed spatial distribution.
Possible Distributions of Some Orbital Elements of Interstellar Particles in the Solar System
Authors: Belkovich O.I. , Potapov I.N. 
Published: July 2016

AbstractDistribution of eccentricities, perihelion distances of interstellar particles and their concentrations in the Solar system have been computed in the assumption that their velocities are similar to ones of the nearby stars of late spectral classes. More than 75% of orbits have eccentricities not exceeding the value 1.1 and concentration of particles at the Earth’s orbit 3.5 times greater than in the interstellar space.
X-Ray Satellite Lines
Authors: Dubau J. 
Published: July 2016

Satellite lines are typical features of X-ray spectra. They correspond to radiative transitions involving an inner-shell vacancy. The most studied satellite lines are of the - type, i.e., (ls–2p) transition.With the advent of Space Astronomy, X-ray spectra emitted by very hot solar plasma have been obtained. By a simple comparison of different spectra, it appears that, for highly ionized atoms, some satellite lines have intensities as large as resonance lines intensities and, more particularly, this is the case for the ls2n. – ls 2pn satellite lines of the 1s2 – ls2p resonance lines.The analysis of the different population mechanisms responsible for the satellite lines and resonance lines emission has shown that different spectroscopic diagnostics could be derived from line ratios only if atomic data of great accuracy were available. There exists nowadays different atomic data programs adapted to X-ray satellite lines. They have in common to give a great amount of data simultaneously: wavelengths, autoionization and radiative transition probabilities. They take into account correlation and relativistic effects.After tackling the simple 3-electron system, the programs give now appropriate data for more complex systems but this required large computers because the lines become blended. It is therefore impossible to limit the calculation to the most intense lines.
Ultraviolet Spectroscopy of Cool Stars from IUE
Authors: Jordan C. , Judge P. , Johansson S. 
Published: July 2016

AbstractObservations of cool stars with the IUE satellite have shown that although main sequence stars have uv spectra similar to that of the sun, the spectra of the giants and supergiants are dominated by lines of neutral atoms and singly charged ions. The atmospheres of the low gravity stars are greatly extended and there is a large opacity in the stronger lines. This leads to multiple scattering and the appearance of many transitions through line ‘leakage’.A review is given of how high resolution IUE spectra have allowed line identifications to be established and some current problems are discussed.The spectroscopic diagnostic techniques for the low gravity, low density atmospheres are also briefly outlined.
Soft X-Ray Spectroscopy with Exosat
Authors: Mewe R. 
Published: July 2016

With the 500 and 1000 l/mm transmission gratings aboard the European x-ray Observatory SATellite (EXOSAT) we have measured medium-resolution (Δλ 5 A at 100 A) spectra of some ten objects of various categories such as isolated white dwarfs, cool stars with convective mantles, cataclysmic variables (e.g. AM Her) and a high-luminosity X-ray source (Sco X-1).The Instrument configuration was mostly such that one low-energy telescope was used as a photometer, while the other telescope was used as a spectrometer with the 500 l/mm grating inserted.The white dwarf spectra were measured between about 60 and 300 A. They show a continuum with no clear evidence of aborption and emission lines except for the He II absorption edge at 227 A in the spectrum of Feige 24. For the cooler (28 000 K) white dwarf Sirius B the emission is peaked between about 100 and 160 A and limited to about 200 A. which can be expected from atmospheric model spectra of DA white dwarfs. The soft X-ray emission of the hotter (> 60 000 K) DA white dwarfs (HZ43. Feige 24) is also interpreted in terms of photospheric emission. In the HZ43 spectrum the absorption edge is apparently absent which sets a stringent upper limit to the abundance ratio He/H of about 10−5. On the other hand the spectrum of Feige 24 shows a dominant absorption edge, implying He/H > 10−3. Moreover, here the shape of the continuum may be indicative of a stratification of element abundances in the outer atmosphere.
X-Ray Spectroscopic Measurements of Non-Equilibrium Ionization in Supernova Remnants
Authors: Markert T.H. , Canizares C.R. , Pfafman T. , Vedder P. , Winkler P.F. , Pradhan A. 
Published: July 2016

When a cool plasma is shock-heated to X-ray temperatures, the ionization structure does not attain its final, equilibrium value immmediately, but proceeds toward it through electron-ion collisions with a timescale τ ≡ net of order 1012 cm−3 sec. For supernova remnants (SNRs), where 0.1 ≤ ne ≤ 10 cm−3 typically, the time required to achieve collisional ionization equilibrium (CIE) can be greater than the age of the remnant. Even if the SNR is quite old, that part of the remnant which is emitting most of the X-rays may have been shocked relatively recently, so that the assumption of CIE may be inappropriate (see below).The question of ionization equilibrium is of great astrophysical importance in the study of SNRs because it affects the deduced values of their masses and elemental abundances (e.g. Shull 1982). Mass determinations are affected because underionized plasma generally has a much higher emissivity in soft X-rays than equilibrium plasma. Unless this is accounted for, the deduced value of the density and therefore of the mass, will be considerably overestimated.
The Measurement of Branching Ratios of Spontaneous Radiative Transition Probabilities for Be-Like Ions N IV and O V
Authors: Lang J. , Hardcastle R.A. , Spurrett P.H. 
Published: July 2016

In an experiment to measure emission line intensities from the Belike ion Ne VII (Lang 1983), the intensity ratio I(2s3s3S−2s3p3P)/I(2p23P−2s3p3P) was found to be a factor six larger than predicted from the ratio of the theoretical spontaneous radiative transition probabilities (A values). Indeed, to reconcile the Ne VII experiment and theory in several respects it was suggested also that in Be-like C III the theoretical ratios I(2s3s1 S−2s3p1P)/I(2p21D−2s3p1P) was about a factor three too low.The same apparatus was used to measure A value ratios in Be-like N IV and 0 V. Briefly the 40 kJ θ-pinch plasma source was viewed radially using a m Ebert and a l m grazing incidence photoelectric spectrometer. The m Ebert was intensity calibrated from 7300 Å to 3600 Å using a tungsten filament lamp, and from 3800 Å to 2500 Å using a deuterium lamp, both lamps having been calibrated by NPL. As described fully by Lang (1983), the branching-ratios method was used to calibrate the front exit slit of the grazing incidence instrument in the wavelength range 88 Å to 500 Å. Only Li-like line pairs of those listed in that paper were used with the addition of the C IV doublets 2s2S−3p2P (312.4 Å) and 3s2S−3p2P (5801.33 Å, 5811.98 Å). The H-like ion He II 1–4 transition (243.0 Å) and 3–4 transition (4685.7 Å) were used to cross-check the calibration. As shown in the figure, the He II result agrees excellently with the calibration as defined from the Li-like lines.
Study of Electron Capture in the N5+-He, H2 Collisions by UV Spectroscopy
Authors: Druetta M. , Cotte P.H. 
Published: July 2016

The physics of multicharged ions has considerably developped during the last few years. Aside from its fundamental interest and its motivation for fusion research with Tokamak devices where charge exchange involving highly charged impurities are important, this new effort in this direction is due to the development of new sources of highly charged ions.We report results concerning spectroscopic study of radiative transitions observed during the collision between multicharged N5+ ions with a helium or molecular hydrogen target. Nx+ ions are produced with the E.C.R. ion source in Grenoble (Geller and Jacquot 1981). The N5+ ions are then selected with two 168° bending magnets and finally sent into the target chamber where they collide either with He or H2 gas. Spectra are observed with a grazing incidence (82°) spectrometer equipped with photon detection.
Population of Excited States of Al10+ in a Plasma by a Time-Dependent Model
Authors: Guennou H. , Sureau A. 
Published: July 2016

The present model is the time-dependent version of a previous model (Sureau et al. 1983) in which the population distribution was assumed in steady state. A finite set of levels is partitioned in four subsets: the Z-ion ground-level and, contingently, the first near-degenerated levels (subset 1); all the successive excited Z-ion levels up to n=5 (subset 2); a finite number of higher Rydberg levels (because of the limitation of the series in the plasmas) which are assumed in LTE with the Z+l−ion ground-level (subset 3, called the thermal band); and the Z+l ion ground-level (subset 4).The physical processes explicitly considered are the radiative cascades and the transitions between the Z-ion bound levels induced by electron-ion collisions. The radiative-transition probabilities are given by ab-initio calculations using a modified Hartree-Fock method including the spin-orbit interaction (Sureau et al., 1984). The collision rates are derived by the Van Regemorter formula multiplied by an adjustable parameter Fc.
Curriculum for the Training of Astronomers: Comments
Authors: Caton Daniel B. 
Published: July 2016

In this first international meeting on the teaching of astronomy, we should not only look at many specific techniques and approaches but also examine the overall process. In doing so, several general problems come to light and need to be commented upon:1.Introductory astronomy course lab exercises are often lacking in rigor, compared to labs in other physical sciences. Students are often asked to do simple, qualitative exercises like drawing the moon or constellations – projects that bear more resemblance to 19th-century astronomy than to the work of modern science. Lab programs should be modernized, taking advantage of modern telescopes and ancillary instrumentation.2.A survey taken of U.S. astronomy department chairs, in preparation for an American Astronomical Society roundtable discussion, revealed a wide spectrum of approaches to undergraduate astronomy instruction. The one single obvious result of the survey was the recognition of a need for an international survey, with the results distributed and discussed by the participants. The dispersion of programs may also suggest another need ....3.The astronomy instructional community lacks a central journal for the publication of pedagogical articles. The physicists have the American Journal of Physics and the Physics Teacher for advanced and lower-level articles, respectively. While astronomical articles appear in these from time to time (as well as in other publications), there is no single publication that educators can depend upon to contain important articles. While there is probably too little material available to form a new journal or newsletter, perhaps educational sections could be started in the Publications of the Astronomical Society of the Pacific, Mercury, or Sky & Telescope.4.Astronomy students (majors) are often told to “get a physics (undergraduate) degree” in preparation for becoming an astronomer, yet strongly desire to take astronomy courses. This dual-program requirement results in either larger course loads (to include the astronomy), or the possibility of losing them to other disciplines. Students can perhaps be kept interested by involving them in astronomy research while they are learning their basic math and physics.
The Thrill of Discovery
Authors: Verschuur Gerrit L. 
Published: July 2016

In the process of communicating to the student or the lay person, we often forget to point out why it is that scientists are involved in their esoteric explorations of the universe. As a result, the scientific endeavor is painted as being somewhat removed from “real life.” This unfortunate misconception can be remedied by discussing the thrill of discovery.Scientists love to “boldly go where no man has gone before.” The act of discovery produces a heady sensation akin to the thrill of victory for an athlete. The thrill may come as a surprise, as the result of a serendipitous turn of events, or may be experienced at the conclusion of a dedicated piece of research whose end-point was always understood. In either case the joy is associated with the revelation of what was previously unknown or not understood. It is this joy that is the reward for the researcher.
Starting Out: The Dilemma of the Beginning College Astronomy Teacher
Authors: Shipman Harry L. 
Published: July 2016

Most beginning college professors in the United States receive little if any help in the important task of learning how to teach well. Occasionally, a colleague or department chairman can provide some guidance, but in general most American college faculty are taught how to teach by the “sink or swim” method. There are many resources that can help the new professor swim, rather than sink, but in my case at least, I found out about them many years after I needed them the most. This paper will identify some of the literature, journals, and on-campus facilities that can help both new and experienced faculty members develop and hone teaching skills.The literature on teaching and learning is vast. Fortunately, the new teacher need not spend years becoming an expert on this literature; much of it is like the astronomical research literature in that it is full of jargon and it requires some expertise to distill useful, easily implementable ideas from it. Fortunately, there are a few (too few!) books that distill this vast literature into practical advice from it.
Microcomputers in an Introductory College Astronomy Laboratory: A Software Development Project
Authors: Meisel David D. , Kinsey Kenneth F. , Recchia Charles H. 
Published: July 2016

We have developed software for the Apple IIe series of microcomputers for use in labs in an introductory astronomy course. This software emphasizes a toolkit approach to data analysis; it has been class tested with over 170 students and was a resounding success as a replacement for previously used graphical approximations. A unique feature of this software is the incorporation of image-processing techniques into a course designed for non-science majors.The five software packages are:(a)Datasheet - A six-column spreadsheet with columnwise operations, statistical functions, and double-high-resolution graphics.(b)Image-Processor Program - Allows 37 × 27 pixel × 8 bit video captured images to be manipulated using standard image-processing techniques such as low pass/high pass filtering and histogram equalization.(c)Picture-Processor Program - Allows 256 × 192 bilevel pictures to be manipulated and measured with functions that include calipers, odometer, planimeter, and protractor.(d)Orrery Program - Simulates planet configurations along the ecliptic. A movable cursor allows selection of specific configurations. Since both relative times and angular positions are given, students can deduce the scale of the solar system using simple trigonometry.(e)Plot Program - Allows orbital positions as observed from above the pole to be plotted on the screen. By entering trial values of elliptical orbit parameters, students obtain and the program plots the best fitting ellipse to the data. The sum of the squares of the residuals in the radial coordinate is given after each trial so that students can discover convergence more easily than by simple visual examination of a plot comparing the trial theoretical points with the raw data points.
Clea: Aims and Activities
Authors: Gouguenheim L. , Bottinelli L. , Dupré J. , Gerbaldi M. 
Published: July 2016

The Liaison Committee between School-Teachers and Astronomers (in French, “Comité de Liaison Enseignants Astronomes” or CLEA) was officially created about ten years ago under its present form, but its story began in 1970. In that time, there was no astronomy at all in French school programs, neither in elementary nor in secondary schools.A discussion was beginning about introducing physics earlier in the curriculum, with a specific purpose, the main ideas being (i) to avoid too much formalism (and formalism is a strong general characteristic of French science teaching) and (ii) to concentrate on experimentation and on the various representations of natural phenomena.
An Example of Clea Activities in the Training of School Teachers
Authors: Bottinelli L. , Dupré J. , Gerbaldi M. , Gouguenheim L. 
Published: July 2016

Various simple activities are being developed by the French Comité de Liaison Enseignants Astronomes (CLEA) in the training of school teachers. We give in the following one example of a very simple instrument which we call “Alphonse’s box,” after Alphonse Delavergne who invented it. It is also called a heliograph. This very simple and inexpensive instrument enables (1) the plotting of the daily apparent path of the sun, (2) the determination of the duration of sunlight, and (3) the determination of the declination of the sun. The following description is due to Maryse Jonas:1. photosensitive paper (used by architects) that can be handled in semi-darkness; its sensitive face is yellow and it is developed by the vapor of an ordinary ammonia solution in about ten minutes;2. a simple can, with a cover that will shut tight; approximate dimensions: diameter 10 cm, height 15 cm, with a hole about 0.5 mm in diameter on one side;3. two pieces of wood, 15 x 15 cm and 15 x 20 cm; one butt hinge; one threaded rod with two nuts and two washers.