Download or read book Convective Overshoot in the Atmosphere of White Dwarf Stars written by T. J. Cunningham and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Convective Overshoot in the Atmosphere of White Dwarf Stars written by Timothy Jack Cunningham and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrodynamical models of stellar convection written by Bernd Freytag and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book White Dwarfs in Open Clusters written by Kurtis A. Williams and published by . This book was released on 2002 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stellar Astrophysics written by Roger John Tayler and published by Taylor & Francis Group. This book was released on 1992 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stellar Astrophysics contains a selection of high-quality papers that illustrate the progress made in research into the structure and evolution of stars. Senior undergraduates, graduates, and researchers can now be brought thoroughly up to date in this exciting and ever-developing branch of astronomy.
Download or read book On the Spectral Evolution of Cool Helium Atmosphere White Dwarfs Detailed Spectroscopic and Photometric Analysis of DZ Stars written by and published by . This book was released on 2007 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a detailed analysis of a large spectroscopic and photometric sample of DZ white dwarfs based on our latest model atmosphere calculations. We revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz (12 stars) and analyze 147 new DZ white dwarfs discovered in the SDSS. The inclusion of metals and hydrogen in our model atmosphere calculations leads to different atmospheric parameters than those derived from pure helium models. Calcium abundances are found in the range from log (Ca/He) = -12 to -8. We also find that fits of the coolest objects show peculiarities, suggesting that our physical models may not correctly describe the conditions of high atmospheric pressure encountered in the coolest DZ stars. We find that the mean mass of the 11 DZ stars with trigonometric parallaxes is significantly lower than that obtained from pure helium models and in much better agreement with the mean mass of other types of white dwarfs. We determine hydrogen abundances for 27% of the DZ stars in our sample, while only upper limits are obtained for objects with low-S/N spectroscopic data. We confirm with a high level of confidence that the accretion rate of hydrogen is at least 2 orders of magnitude smaller than that of metals (and up to 5 in some cases) to be compatible with the observations. We find a correlation between the hydrogen abundance and the effective temperature, suggesting for the first time empirical evidence of a lower temperature boundary for the hydrogen screening mechanism. Finally, we speculate on the possibility that the DZA white dwarfs could be the result of the convective mixing of thin hydrogen rich atmospheres with the underlying helium convection zone.
Download or read book Exoplanets Compositions Mineralogy Evolution written by Natalie R. Hinkel and published by Walter de Gruyter GmbH & Co KG. This book was released on 2024-09-02 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus for RiMG volume 90 is on rocky exoplanets because the search for truly Earth-like planets is of special interest. The goal is to motivate communication between the disciplines so as to make the best use possible of existing data and data yet to be collected by the James Webb and the Nancy Grace Roman Space Telescopes, since the astronomy community is gathering data on stars and exoplanets at an accelerating rate. Such data now include exoplanet size and mass (i.e., density) as well as their atmospheric compositions, which are collectively telltale of mineralogy and evolution. Much of what is published may still fall in the realm of educated speculation, but our conjectures are metamorphosing into testable hypotheses. There is now a remarkably large amount of astronomical data (with even more on the way) that geochemists and petrologists can make much use of. But just as astronomers may benefit from geologic insights, geologists need our colleagues in astronomy to help interpret their data and their underlying implications to better understand its astronomical context. Our hopes for this volume will be fulfilled if readers initiate their own analyses of what at present may seem like novel or unusual data, and if new collaborations between academic departments and subfields are forged.
Download or read book Stellar Astrophysics written by K.S. Cheng and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pacific Rim Conference originally started with one research concentration only - binary star research. The first Conference was held in Beijing, China, 1985, the second one in Seoul and Taejon, South Korea, 1990 and the third one in Chiang Mai, Thailand, 1995. In recent years, the conference series evolved into a much broader area of stellar astrophysics. The first such conference was held in Hong Kong in 1997. Kwong-Sang Cheng, a. k. a. one of the three Musketeers, documented the "accidental" development in writing in the Proceedings of the 1997 Pacific Rim Conference on Stellar Astrophysics (Volume 138 of the ASP Conference Series)! The meeting at Hong Kong University of Science and Technology covered three major topics: binary stars, compact stars and solar type stars. The conference was extremely successful. There was a general feeling among the participants that the conference on stellar astrophysics provided a good means to share ideas between such closely related disciplines. Unfortunately after the very successful meeting at HKST, Kwing L. Chan (another Musketeer) thought that he had already served and would not like to chair for another LOC for at least five years! After a few drinks at one of the watering holes in Wan Chai district of Hong Kong, Kwong-Sang Cheng was in very hiRh spirit and volunteered to taking on the responsibility of hosting the 51 Pacific Rim Conference at Hong Kong University in 1999.
Download or read book Asymptotic Giant Branch Stars written by Harm J. Habing and published by Springer Science & Business Media. This book was released on 2004 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with stars during a short episode before they undergo a ma jor, and fatal, transition. Soon the star will stop releasing nudear energy, it will become a planetary nebula for abrief but poetic moment, and then it will turn into a white dwarf and slowly fade out of sight. Just before this dramatic change begins the star has reached the highest luminosity and the largest diameter in its existence, and while it is a star detectable in galaxies beyond the Local Group, its structure contains already the inconspicuous white dwarf it will become. It is called an "asymptotic giant branch star" or "AGB star". Over the last 30 odd years AGB stars have become a topic of their own although individual members of this dass had already been studied for cen turies without realizing what they were. In the early evolution, so called "E-AGB"-phase, the stars are a bit bluer than, but otherwise very similar to, what are now called red giant branch stars (RGB stars). It is only in the sec ond half of their anyhow brief existence that AGB stars differ fundamentally from RGB stars.
Download or read book Convection in Astrophysics IAU S239 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007-06-07 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: Convection is ubiquitous throughout the Universe, and during the last three decades it has become the largest factor of uncertainty in theoretical models of stars and in the interpretation of observations on the basis of such models. Recently, numerical simulations of convection have dramatically improved in their potential to take into account both the large scale properties of the flow itself and the microphysical properties of the fluid. Observations have become accurate enough to provide stringent tests for both numerical simulations and models of convection. IAU S239 was held to further understanding of convection, bringing together leading researchers in solar and stellar physics, the physics of planets, and of accretion disks. With reviews, research contributions, and detailed recordings of plenary discussions, this book is a valuable resource for professional astronomers and graduate students interested in the interdisciplinary study of one of the key physical processes in astrophysics.
Download or read book Flow Equations for Composite Gases written by Johannes Martinus Burgers and published by . This book was released on 1969 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 1212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stellar Structure and Evolution written by Rudolf Kippenhahn and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete and comprehensive treatment of the physics of the stellar interior and the underlying fundamental processes and parameters. The text presents an overview of the models developed to explain the stability, dynamics and evolution of the stars, and great care is taken to detail the various stages in a star's life. The authors have succeeded in producing a unique text based on their own pioneering work in stellar modeling. Since its publication, this textbook has come to be considered a classic by both readers and teachers in astrophysics. This study edition is intended for students in astronomy and physics alike.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Convective Overshooting in Stars written by and published by . This book was released on 2015 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Numerous observations provide evidence that the standard picture, in which convective mixing is limited to the unstable layers of a star, is incomplete. The mixing layers in real stars are significantly more extended than what the standard models predict. Some of the observations require changing the thermal structure of the stellar model, e.g. the poorly-fitting evolutionary tracks of intermediate-mass and massive stars, or the "inflated" cores of OB stars seen by asteroseismic techniques. On the other hand, there are effects that can be explained by some form of weak mixing with no influence the structure of the star, e.g. the Li and Be depletion in low-mass stars, or the abundance anomalies observed in red giants. Both kinds of mixing have traditionally been covered be the umbrella term "convective overshooting," although the physics involved is clearly different. There is a need to look at the overshooting problem from a more fundamental perspective. In this thesis, we investigate two mixing process, which could explain the Li and Be depletion in low-mass stars ("convective settling," Chapters 2 and 3) and contribute to slow mixing at the boundaries of internal convection zones in a whole range of different stars ("differential heating," Chapter 4)."--Samenvatting auteur.
Download or read book Literature 1988 Part 1 written by U. Esser and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ...The abstracts are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews#1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine#2
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
