http://earthscience.rice.edu/wp-content/uploads/2015/09/AndersGrevesse.pdf

Abundances of the elements: Meteoritic and solar

This is a comprehensive and richly illustrated textbook on the astrophysics of the interstellar and intergalactic medium--the gas and dust, as well as the electromagnetic radiation, cosmic rays, and magnetic and gravitational fields, present between the stars in a galaxy and also between galaxies themselves. Topics include radiative processes across the electromagnetic spectrum; radiative transfer; ionization; heating and cooling; astrochemistry; interstellar dust; fluid dynamics, including ionization fronts and shock waves; cosmic rays; distribution and evolution of the interstellar medium; and star formation. While it is assumed that the reader has a background in undergraduate-level physics, including some prior exposure to atomic and molecular physics, statistical mechanics, and electromagnetism, the first six chapters of the book include a review of the basic physics that is used in later chapters. This graduate-level textbook includes references for further reading, and serves as an invaluable resource for working astrophysicists. * Essential textbook on the physics of the interstellar and intergalactic medium * Based on a course taught by the author for more than twenty years at Princeton University * Covers radiative processes, fluid dynamics, cosmic rays, astrochemistry, interstellar dust, and more * Discusses the physical state and distribution of the ionized, atomic, and molecular phases of the interstellar medium * Reviews diagnostics using emission and absorption lines * Features color illustrations and detailed reference materials in appendices * Instructor's manual with problems and solutions (available only to teachers)

Physics of the Interstellar and Intergalactic Medium

Helium and heavy-element diffusion are both included in precise calculations of solar models. In addition, improvements in the input data for solar interior models are described for nuclear reaction rates, the solar luminosity, the solar age, heavy-element abundances, radiative opacities, helium and metal diffusion rates, and neutrino interaction cross sections. The effects on the neutrino fluxes of each change in the input physics are evaluated separately by constructing a series of solar models with one additional improvement added at each stage. The effective 1 σ uncertainties in the individual input quantities are estimated and used to evaluate the uncertainties in the calculated neutrino fluxes and the calculated event rates for solar neutrino experiments. The calculated neutrino event rates, including all of the improvements, are 9.3-1.4+1.2 SNU for the 37Cl experiment and 137-7+8 SNU for the 71Ga experiments. The calculated flux of 7Be neutrinos is 5.1 (1.00-0.07+0.06)×10^9 cm^-2 s^-1 and the flux of 8B neutrinos is 6.6(1.00-0.17+0.14)×10^6 cm^-2 s^-1. The primordial helium abundance found for this model is Y=0.278. The present-day surface abundance of the model is Ys=0.247, in agreement with the helioseismological measurement of Ys=0.242±0.003 determined by Hernandez and Christensen-Dalsgaard (1994). The computed depth of the convective zone is R=0.712R⊙, in agreement with the observed value determined from p-mode oscillation data of R=0.713±0.003R⊙ found by Christensen-Dalsgaard et al. (1991). Although the present results increase the predicted event rate in the four operating solar neutrino experiments by almost 1 σ (theoretical uncertainty), they only slightly increase the difficulty of explaining the existing experiments with standard physics (i.e., by assuming that nothing happens to the neutrinos after they are created in the center of the sun). For an extreme model in which all diffusion (helium and heavy-element diffusion) is neglected, the event rates are 7.0-1.0+0.9 SNU for the 37Cl experiment and 126-6+6 SNU for the 71Ga experiments, while the 7Be and 8B neutrino fluxes are, respectively, 4.5(1.00-0.07+0.06)×10^9 cm^-2 s^-1 and 4.9(1.00-0.17+0.14)×10^6 cm^-2 s^-1. For the no-diffusion model, the computed value of the depth of the convective zone is R=0.726R⊙, which disagrees with the observed helioseismological value. The calculated surface abundance of helium, Ys=0.268, is also in disagreement with the p-mode measurement. The authors conclude that helioseismology provides strong evidence for element diffusion and therefore for the somewhat larger solar neutrino event rates calculated in this paper.

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Solar models with helium and heavy-element diffusion

Binary stars are the main source of fundamental data on stellar masses and radii (M, R). Considerable progress has been made in recent years in the quality and quantity of such data, and stellar masses and radii of high accuracy have led to a number of qualitatively new and interesting results on the properties and evolution of normal stars. This paper reviews the current status of fundamentalM andR determinations which (i) have errors ⩽ 2%, the limit for non-trivial results in many applications, and (ii) can be presumed valid for single stars. These two conditions limit the discussion to data fromdetached, doublelined eclipsing binary systems. After a brief discussion (Sect. 2) of the main tests for accuracy and consistency which must be met for observational data to be included in the sample, data for 45 binary systems (90 single stars) are presented in Sect. 3 (Table 1 and Figs. 2–5). Spectral types are O8-M1 on the main sequence, with only two stars clearly in the red-giant region. From the review by Popper (1980), data for only 6 systems survive unchanged in the present list, while improved data are given for 18 systems; 21 systems are new additions. Broadband colours, effective temperatures, and luminosities are also given, but are scale-dependent and considerably less reliably determined thanM andR. The observed ranges inM andR for a given colour far exceed the observational errors, primarily due to evolutionary effects within the main sequence. For this reason, single-parameter relations used to predictM andR for single stars are limited to an accuracy of some ±15% inM and ±50% inR, basically independent of the number and accuracy of the data used to establish the relations. Two-parameter calibrations are discussed (Sect. 4) which can eventually reduce these errors to & 5% in bothM andR. At this level, abundance effects become significant and presumably account for the residual scatter. Comparison of the data with stellar evolution models is the topic of Sect. 5. Characteristic features of the data which are crucial in such work are emphasized, rather than attempts to “prove” the validity of any particular set of models. Already fromM andR alone, some significant constraints can be derived (Fig. 4). When bothM, R, andT
e are known, the initial helium abundanceY can be estimated if the metal-abundance parameter Z is assumed or determined. Studies in which binaries with accurate values ofM, R, and Z are fit by models calculated for the precise observed masses, and withY and mixing length constrained to solar values, provide the most stringent tests of the models. Probing further model refinements such as convective overshooting requires full use of the potential of the data. For example, models may yield general main-sequence limits which are consistent with the observations, but still be unable to fit any single system to the precision of the data. Conditions for critical, informative tests are discussed. Tidal effects in binaries are briefly discussed in Sect. 6. As tidal forces are extremely sensitive to the dimensions and internal structure of the stars, the present sample is well suited for such studies. Recent success in matching computed and observed apsidal-motion parameters for early-type binaries is mentioned. Finally, main priorities for future work are outlined.

Accurate masses and radii of normal stars

A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio H II regions, and about 13% enclose known star clusters. It appears that B4-B9 stars (too cool to produce detectable radio H II regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young O-B3 stars that produce detectable radio H II regions. Some of the bubbles may be the outer edges of H II regions where PAH spectral features are excited and may not be dynamically formed by stellar winds. Only three of the bubbles are identified as known SNRs. No bubbles coincide with known planetary nebulae or W-R stars in the GLIMPSE survey area. The bubbles are small. The distribution of angular diameters peaks between 1' and 3' with over 98% having angular diameters less than 10' and 88% less than 4'. Almost 90% have shell thicknesses between 0.2 and 0.4 of their outer radii. Bubble shell thickness increases approximately linearly with shell radius. The eccentricities are rather large, peaking between 0.6 and 0.7; about 65% have eccentricities between 0.55 and 0.85.

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The Bubbling Galactic Disk

Our galaxy is composed of billions of stars concentrated in the galactic plane, surrounded by interstellar gas, which is mainly composed of hydrogen. About half of the hydrogen is distributed uniformly in the galaxy; the other half is concentrated in interstellar clouds. We find atomic hydrogen in diffuse clouds (with a particle number density n = 10 cm−3); we find molecular hydrogen (H2) in dark clouds (n = 103 cm−3). Finally we have interstellar molecular clouds (n = 106 cm−3) which also contain more complex molecules.

The Formation of Stars

The mutual consistency between standard solar models is studied based on the recent Los Alamos opacity tables. Satisfactory agreement is found among these models concerning the helium content and the neutrino capture rates. The reference model leads to a solar helium content of 0.276 + or - 0.012 by mass fraction. 75 references.

Revisiting the Standard Solar Model

The evolution of mass-losing stars that have M(ZAMS)/solar-M in the 50-100 range is examined. The stellar models used in this study include: (1) mass loss formalism for O, Of, and W-R stars; (2) the Roxburgh criterion for the convective core; and (3) a nuclear reaction network of 28 nuclides from H to Si-30 for analysis of energy production and chemical evolution during the H- and He-burning phases. The internal evolution of stars with solar masses of 50, 60, 80, and 100 is described by observing time variations of the stellar and convective core masses, and central temperature and density fluctuation during the H- and He-burning phases; the evolution of the models in the Hertzsprung-Russell diagram is studied. The formation of the chemical abundances in the convective core and surface of the stars is investigated. The composition of the stellar ejecta of the W-R stars is discussed. The data reveal that the computed evolutionary tracks and core and surface abundances correlate well with the observational data. 93 references.

Nucleosynthesis and Evolution of Massive Stars with Mass Loss and Overshooting

Purpose – The purpose of this paper is to examine the critical success factors of ERP implementations in Belgian SMEs and to identify those success factors that are specific to a SME environment.Design/methodology/approach – The authors survey the literature to discover and classify critical success factors that are potentially applicable to small and medium‐sized enterprises. Through a survey and a multiple case study within four Belgian companies, the authors investigate which of these critical success factors apply to SMEs.Findings – The results show that most of the success factors found in the literature apply to SMEs. Nevertheless, distinct differences were found as well. Some factors, such as a clear scope definition and a standardised infrastructure, are not regarded as critical success factors for SMEs. Moreover, SMEs tend to rely relatively heavily on the input of consultants, who they use as a source of knowledge and experience. Moreover, SMEs need to be able to adjust their businesses quickly ...

Critical success factors for ERP implementations in Belgian SMEs

E-learning systems, also known as a virtual learning environments (VLE’s), are systems that use modern information and communication technology to support education and training efforts. In this paper we present the evaluation of a newly developed Compendium Platform (CP) that can be used to create educational applications that support effective learning of statistics and related analytical skills. Using the web-enabled CP, students are empowered to easily archive, exchange and reproduce statistical computations. The CP was applied in three statistics courses. Based on behavioral concepts from the Technology Acceptance Model (usefulness, ease of use and future usage intention) and object-based beliefs about the e-learning environment (information and system qualities), we tested an integrated and predictive e-learning acceptance model. Using a sample of 200 students, we report that the CP was well accepted and that the majority of our hypotheses are confirmed. System quality has a considerable impact on ease of use and does directly influence the students’ intention to use the CP in the future. The effect of information quality on intention is fully mediated by relative advantage. Relative advantage was used as an alternative to usefulness and is clearly a better predictor of usage intention. A detailed analysis indicates that the attractiveness of the user interface, the presence of appropriate search options and the availability of sufficient relevant information are critical success factors of the CP’s acceptance.

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Claude Doom

Papers

The Formation of Stars

Revisiting the Standard Solar Model

Nucleosynthesis and Evolution of Massive Stars with Mass Loss and Overshooting

Critical success factors for ERP implementations in Belgian SMEs

Usability and acceptance of e-learning in statistics education, based on the compendium platform