Download or read book Analysis of Pre main sequence Delta Scuti Stars written by Michael Patrick Casey and published by . This book was released on 2011 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book VIBRATIONAL STABILITY OF PRE MAIN SEQUENCE STARS written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, vibrational properties and stability of delta-Scuti like pulsating pre-main sequence stars have been investigated. Studies were held in the mass range 2-4 Mo and limited to radial linear adiabatic pulsations. Numerical computations were performed by the oscillation program written by Kýrbýyýk & Al-Murad (1993). The models were selected to be at the latest phases of the pre-main sequence evolution where the luminosity starts to increase. We have limited our calculations upto the end of the radiative inner regions, since at the surface of the star, our adiabatic perturbation computation does not perfectly fit to the relatively thin non-adiabatic convective envelope of the star. The results of the stability analysis showed that the PMS models undergo an instability whose time period is a function of mass. Instability Strip of pulsating PMS stars was re-drawn with comparison to M. Marconi & F. Palla (1998). The effect of gravitational contraction on stability was also investigated.

Download or read book Delta Scuti and Related Stars written by Michel Breger and published by . This book was released on 2000 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Contains 35 papers presented as part of the August 1999 workshop. The opening papers review photometric techniques, spectroscopic techniques, and theoretical modeling of the pulsations. Shorter contributions discuss such topics as double-mode SX phoenicis variables in globular clusters, convective effects on p-mode stability in delta Scuti stars, problems encountered in the Hipparcos variable stars analysis, and a list of delta Scuti stars and their associated parameters. No subject index. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Download or read book Deriving the Structure of Pre supernovae and Delta Scuti Stars Using Nonradial Oscillations written by and published by . This book was released on 1998 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report of a three-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective is to learn more about the internal structure of two classes of variable stars, by using the observational data afforded by their pulsation properties. The authors updated the one-dimensional computer codes to calculate the evolution and pulsation frequencies of representative delta Scuti and LBV models. They compared the observed pulsation properties with model predictions in an iterative process to find a model (or models) with interior structures that matched the observational constraints for several delta Scuti stars. They carried out nonlinear hydrodynamic modeling of LBV envelopes and proposed a mechanism for their periodic outbursts. Finally, they began validation of a two-dimensional stellar evolution code that will be used to investigate the effects of rotation and hydrodynamic instabilities on the interior structure of these stars.

Download or read book Amplitude Modulation of Pulsation Modes in Delta Scuti Stars written by Dominic M. Bowman and published by Springer. This book was released on 2017-09-07 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: This outstanding thesis by Dominic Bowman provides a thorough investigation of long-standing questions as to whether amplitude modulation is astrophysical, whether it offers insights into pulsating stars, and whether simple beating of modes with stable amplitudes is unrecognised because of a lack of frequency resolution. In this thesis, the author studied a uniform sample of 983 delta Scuti stars—the most common type of main-sequence heat engine pulsator—that were observed nearly continuously for 4 years at stunning photometric precision of only a few parts per million by the Kepler space mission. With no mission planned to supersede the Kepler 4-year data set, this thesis will stand as the definitive study of these questions for many years. With revolutionary photometric data from the planet-hunting Kepler space mission, asteroseismic studies have been carried out on many hundreds of main-sequence solar-type stars and about 10,000 red giants. It is easy to understand why those stochastically driven stars have highly variable amplitudes. Over much of the rest of the Hertzsprung–Russell (HR) diagram, stellar pulsations are driven by heat mechanisms, which are much more regular than the stochastic driving in solar-like pulsators. Yet for decades, amplitude and frequency modulation of pulsation modes have been observed in almost all types of heat-driven pulsating stars. The author shows that the amplitude and frequency modulation are astrophysical, and he has investigated their implications and prospects to provide new insights into the delta Scuti stars and the many other types of heat-engine pulsators across the HR diagram.

Download or read book The Effects of Metallicity on delta Scuti Star Asteroseismology written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In [delta] Scuti star seismology, most researchers use evolution and pulsation models assuming a solar element mixture and Z = 0.02 for preliminary determinations of stellar masses or evolutionary state from observed frequencies. Here the authors investigate the consequences of this assumption by considering the effects of metallicity changes in the models on their inferences of the internal structure of [delta] Scuti stars. They use the main-sequence [delta] Scuti star FG Vir, and the more evolved shell hydrogen burning star [delta] Scuti to illustrate their results.

Download or read book Literature 1986 Part 1 written by Prof. Dr. Roland Wielen and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Asteroseismology written by C. Aerts and published by Springer Science & Business Media. This book was released on 2010-01-19 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the stars is the bedrock of modern astrophysics. Stars are the source of life. The chemical enrichment of our Milky Way and of the Universe withallelementsheavierthanlithiumoriginatesintheinteriorsofstars.Stars arethe tracersofthe dynamics ofthe Universe,gravitationallyimplying much more than meets the eye. Stars ionize the interstellar medium and re-ionized the early intergalactic medium. Understanding stellar structure and evolution is fundamental. While stellar structure and evolution are understood in general terms, we lack important physical ingredients, despite extensive research during recent decades.Classicalspectroscopy,photometry,astrometryandinterferometryof stars have traditionally been used as observational constraints to deduce the internal stellar physics. Unfortunately, these types of observations only allow the tuning of the basic common physics laws under stellar conditions with relatively poor precision. The situation is even more worrisome for unknown aspects of the physics and dynamics in stars. These are usually dealt with by using parameterised descriptions of, e.g., the treatments of convection, rotation,angularmomentumtransport,theequationofstate,atomicdi?usion andsettlingofelements,magneto-hydrodynamicalprocesses,andmore.There is a dearth of observational constraints on these processes, thus solar values areoftenassignedtothem.Yetitishardtoimaginethatonesetofparameters is appropriate for the vast range of stars.

Download or read book Observational Aspects of Pulsating B and A Stars written by Christiaan Sterken and published by . This book was released on 2002 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Papers from a July 2001 meeting report on the outcome of two decades of scientific collaboration between Flemish and South African researchers in the field of small-amplitude short-period variables and long-period pulsating stars. Some specific topics include global campaigns on Delta Scuti stars, photometric and spectroscopic reduction techniques, period changes in V 1162 Orionis, and autocorrelation analysis of Hipparcos photometry of short-period A and B stars. Other topics include oscillating blue stragglers in galactic globular clusters, and photometry of Delta Serpentis. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Download or read book Investigating the A Type Stars Using Kepler Data written by Simon J. Murphy and published by Springer. This book was released on 2014-09-20 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simon Murphy's thesis has significant impact on the wide use of the revolutionary Kepler Mission data, leading to a new understanding in stellar astrophysics. It first provides a deep characterisation and comparison of the Kepler long cadence and short cadence data, with particular insight into the Kepler reduction pipeline. It then brings together modern reviews of rotation and peculiarities in A-type stars, and their relationship with the pulsating delta Scuti stars. This is the first combined review of these subjects since the classic monograph by Sydney Wolff, "The A stars," was published three decades ago. The thesis presents a novel technique, Super-Nyquist Asteroseismology, that has opened up the asteroseismic study of thousands of Kepler stars. It shows case studies of delta Scuti stars examining amplitude growth, super-Nyquist pulsation, and pulsation in a high-amplitude, population II SX Phoenicis star in a 343-d binary. This work informs our understanding of the relation of rotation to peculiarity, hence has applications to atomic diffusion theory. This is a brilliant thesis written in an elegant and engaging style.

Download or read book Photometric Study of Pulsations In a Pre main Sequence Star V351 Ori written by Ayane Getinet and published by LAP Lambert Academic Publishing. This book was released on 2015-08-21 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much observational work has been done in recent years to increase the numbers of known PMS pulsating stars. However, no satisfactory asteroseismological solution exists specially for Delta Scuti stars. The unsolved problems constitute challenges for both stellar pulsation and stellar evolution. V351 Ori is a member of the Herbig Ae stars that are characterized by large infrared excess, emission in hydrogen lines and non periodic photometric and spectroscopic variability. V351 Ori has been found to pulsate in different frequencies of radial mode and possible existence of non-radial mode is also suggested. The main aim of this book is to carry out time series multicolour photometry of Herbig Ae star V351 Orionis (using 0.5 M telescope) in Johnson filters (UBVRI) to study pulsations in this star. The outcome has shown different pulsation frequencies in the star. Mode identification of the star is also presented. This book will be helpful for researchers who are interested in observing variable stars.

Download or read book Observational Constraints on Pre main Sequence Stellar Evolution from Time series Analysis of Open Cluster Stars written by J. M. Irwin and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Issues in Astronomy and Astrophysics 2012 Edition written by and published by ScholarlyEditions. This book was released on 2013-01-10 with total page 734 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Astronomy and Astrophysics / 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Planetary Science. The editors have built Issues in Astronomy and Astrophysics: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Planetary Science in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Astronomy and Astrophysics: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Literature 1983 Part 1 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 825 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 33 records literature published in 1983 and received before August 1, 1983. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organizations, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Mona El-Choura, Ms. Monika Kohl, and Ms. Sylvia Matyssek. Mr. Martin Schlotelburg and Mr. Ulrich Uberall supported our task by careful proofreading. It is a pleasure to thank them all for their encouragement. Heidelberg, September 1983 The Editors Contents Introduction . . . . . . . . . . . . 1 Concordance Relation: ICSU-AB-AAA 3 Abbreviations 10 Periodicals, Proceedings, Books, Activities 001 Periodicals . . . . . . . . . . . 15 002 Bibliographical Publications, Documentation, Catalogues, Atlases 47 003 Books ...... . 51 004 History of Astronomy 58 005 Biography . . 64 006 Personal Notes 65 007 Obituaries . . .

Download or read book Challenges of asteroseismology in the era of space missions written by Javier Pascual Granado and published by Frontiers Media SA. This book was released on 2023-01-17 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Astronomy and Astrophysics Abstracts written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 1180 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 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 #1

Download or read book Pulsation and Mass Loss in Stars written by R. Stalio and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stellar mass loss is an essential part of the cycling of material from the interstellar medium into stars and back, and must be understood if we are to model processes on galactic to cosmological scales. The study of stellar winds and the effects of stellar mass loss has reached a particularly exciting stage where observational capabilities are increasingly able to provide interesting constraints on models and theories. Recent resu1ts from theoretical and observational work for both hot and cool stars with substantial winds have led to the suggestion that a combination of pulsation with other mechanisms makes for particularly efficient mass loss from stars. This provided the original motivation for the organization of this workshop. The conference was organized along relatively conventional lines according to the types of objects being scrutinized. However the true unity of the proceedings comes from the interplay of the mechanisms involved. For example, for the cool, luminous Mira variables, pulsation leads to shock waves that extend the atmosphere, enhancing dust formation; radiation pressure on dust drives the wind, cooling the atmosphere and in some cases suppressing the shocks. Similarly for the Be stars, both pulsation (in this case, non-radial) and radiation pressure (due to UV resonance lines) are expected to be important, and this expectation is at least qualitatively borne out by the observations.