Download or read book Pulsations of Delta Scuti Stars written by and published by . This book was released on 1989 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A general review of the pulsating [delta] Scuti variables is given including the observed light curves and positions of the stars in the Hertzsprung-Russell diagram. Theoretical interpretations from evolution and pulsation calculations give their masses, radii, luminosities, and even their approximate internal compositions. Three models of these stars are discussed and used to study the nonlinear hydrodynamic behavior of these stars. The hydrodynamic equations and the Stellingwerf method for obtaining strictly periodic solutions are outlined. Problems of allowing for time-dependent convection and its great sensitivity to temperature and density are presented. Tentative results to date do not show any tendency for amplitudes to grow to large unobserved amplitudes, in disagreement with an earlier suggestion by Stellingwerf. It is found that the very small growth rates of the pulsations may even be too small to be useful in seeking a periodic solution. 15 refs., 8 figs., 3 tabs.
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 Nonradial Pulsations of Delta Scuti Stars written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An improved stellar model with a detailed composition structure is used to look at the nonradial behavior of a star near the region in the H-R diagram where the delta Scuti variables are found. Satisfactory solutions are obtained to the linear nonadiabatic equations. The newly calculated evolution models will be used in the future to study the pulsational stability of this class of stars. 4 refs., 2 figs., 1 tab.
Download or read book The Pulsation of Delta Scuti Stars written by Helen Milligan and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonradial Pulsations of Rapidly Rotating delta Scuti Stars written by Edward James Kennelly and published by . This book was released on 1990 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Observing and Modeling Delta Scuti Pulsating Variable Stars written by Jonathan H. McBee and published by . This book was released on 2004 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 A Study of the Multifrequency Pulsation of the Delta Scuti Star V369 Scuti written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stellar Pulsation and Evolution written by Michael D. Hiland and published by . This book was released on 2010 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amplitude Modulation and Energy Conservation of Pulsation Modes in Delta Scuti Stars written by Dominic Matthew Bowman and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pulsating Stars written by Márcio Catelan and published by John Wiley & Sons. This book was released on 2015-03-23 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys our understanding of stars which change in brightness because they pulsate. Pulsating variable stars are keys to distance scales inside and beyond the Milky Way galaxy. They test our understanding not only of stellar pulsation theory but also of stellar structure and evolution theory. Moreover, pulsating stars are important probes of the formation and evolution of our own and neighboring galaxies. Our understanding of pulsating stars has greatly increased in recent years as large-scale surveys of pulsating stars in the Milky Way and other Local Group galaxies have provided a wealth of new observations and as space-based instruments have studied particular pulsating stars in unprecedented detail.
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 The MACHO Project Sample of Galactic Bulge High Amplitude Scuti Stars written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have detected 90 objects with periods and lightcurve structure similar to those of field [delta] Scuti stars, using the Massive Compact Halo Object (MACHO) Project database of Galactic bulge photometry. If we assume similar extinction values for all candidates and absolute magnitudes similar to those of other field high-amplitude [delta] Scuti stars (HADS), the majority of these objects lie in or near the Galactic bulge. At least two of these objects are likely foreground [delta] Scuti stars, one of which may be an evolved nonradial pulsator, similar to other evolved, disk-population [delta] Scuti stars. We have analyzed the light curves of these objects and find that they are similar to the light curves of field [delta] Scuti stars and the [delta] Scuti stars found by the Optical Gravitational Lens Experiment (OGLE). However, the amplitude distribution of these sources lies between those of low- and high-amplitude [delta] Scuti stars, which suggests that they may be an intermediate population. We have found nine double-mode HADS with frequency ratios ranging from 0.75 to 0.79, four probable double- and multiple-mode objects, and another four objects with marginal detections of secondary modes. The low frequencies (5-14 cycles d−1) and the observed period ratios of ≈0.77 suggest that the majority of these objects are evolved stars pulsating in fundamental or first overtone radial modes.
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 1979 Part 1 written by Siegfried Böhme and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Understanding Variable Stars written by John R. Percy and published by Cambridge University Press. This book was released on 2007-05-24 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was first published in 2007. Variable stars are those that change brightness. Their variability may be due to geometric processes such as rotation, or eclipse by a companion star, or physical processes such as vibration, flares, or cataclysmic explosions. In each case, variable stars provide unique information about the properties of stars, and the processes that go on within them. This book provides a concise overview of variable stars, including a historical perspective, an introduction to stars in general, the techniques for discovering and studying variable stars, and a description of the main types of variable stars. It ends with short reflections about the connection between the study of variable stars, and research, education, amateur astronomy, and public interest in astronomy. This book is intended for anyone with some background knowledge of astronomy, but is especially suitable for undergraduate students and experienced amateur astronomers who can contribute to our understanding of these important stars.
