Download or read book Properties of Delta Scuti Stars written by Michael Viskum and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Automated Variable Star Classification and the Pulsation Properties of Eclipsing delta Symbol Scuti Stars written by Douglas Irving Hoffman and published by . This book was released on 2009 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 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 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 Multiple Mode in Delta Scuti Stars written by Gregory Lee Loumos and published by . This book was released on 1980 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Delta Scuti Stars written by Michael A. Seeds and published by . This book was released on 1971 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Asteroseismology in the Kepler Era written by Andrzej S. Baran and published by Frontiers Media SA. This book was released on 2021-10-13 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Binary and Multiple Stars as Tracers of Stellar Evolution written by Zdenek Kopal and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 69th Colloquium of the International Astronomical Union held in Bamberg, F.R.G., August 31-September 3, 1981
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismological Modeling of the Delta Scuti Star written by and published by . This book was released on 1996 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major goal of asteroseismology is a better understanding of stellar evolution via ''snapshots'' of many stars of different masses in different evolutionary states. For stars of about 2M{sub {circle_dot}} near the sequence, b Scuti stars are the usual suspects. There is an ongoing renaissance in theoretical modeling of 6 Scuti stars brought on by improvements in constitutive physics and by a dramatic increase in the number of modes observed. FG Virginis and CD-24' 7599 are two of the best studied objects, and they have 19 and 13 known frequencies, respectively. . We create models using an updated and modified version of the Iben code described by Guzik & Cox that includes either of the two versions of the OPAL opacities . We use the star's observed location on the H-R diagram as a starting point for our seismological modeling. Because there is no evidence for observed t = 3 modes, we only consider l = 0, 1, and 2 modes in our analysis. We take into account rotational splitting (about 5 - 10 [mu]Hz) in our frequency matching. Several observed modes must be rotationally split members of a given mode. CD-24' 7599 is less than halfway through core hydrogen burning, and the modes appear to be a set of consecutive 3rd through 5th overtones of {ital l} = 0 through 2 modes. With only 13 modes, we find satisfactory fits with models between 1.9 and 2.0 M{sub {circle_dot}} that fall within the observed luminosity and effective temperature range. By contrast, Guzik & Bradley suggest that FG Virginis is over halfway through core hydrogen burning and the best fitting models lie near 1.80 or 2.00 M{sub {circle_dot}}. We see persistent discrepancies in some low frequency modes, which suggests we may need a small amount of core overshoot or a slight change in metallicity to duplicate FG Virginis.
Download or read book Asteroseismology Across the HR Diagram written by Michael J. Thompson and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: We stand at the threshold of an exciting era of Asteroseismology. In a few months' time, the Canadian small-satellite asteroseismology mission MOST will be laun ched. Danish and French missions MONS and COROT should follow, with the ESA mission Eddington following in 2007/8. Helioseismology has proved spec tacularly successful in imaging the internal structure and dynamics of the Sun and probing the physics of the solar interior. Ground-based observations have detected solar-like oscillations on alpha Centauri A and other Sun-like stars, and diagnostics similar to those used in helioseismology are now being used to test and constrain the physics and evolutionary state of these stars. Multi-mode oscillations are being observed in an abundance of other stars, including slowly pulsating B stars (SPB stars), delta Scuti stars, Ap stars and the pulsating white dwarfs. New classes of pulsators continue to be discovered across the Hertzsprung-Russell diagram. For good reason it was decided to entitle our conference 'Asteroseismology Across the HR Diagram' . Yet the challenges still to be faced to make asteroseismology across the HR diagram a reality are formidable. Observation, data analysis and theory all pose hard problems to be overcome. In conceiving this meeting, the aim of the organisers was to facilitate a cross-fertilization of ideas and approaches between researchers working on different pulsators and with different areas of expertise. We venture to suggest that in this the conference was a great success.
Download or read book The Future of Asteroseismology written by Joyce Ann Guzik and published by Frontiers Media SA. This book was released on 2021-08-17 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for lnformation and Numerica/ Data Analysis and Synthesis (C/NDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficia! to the academic and general scientific and technical community. After fi ve years of this joint undertaking we had concluded that it was in the interest of ali concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and App/ied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. Ali back issues can also be ordered from Plenum. We have reported in Volume 21 (thesis year 1976) a total of 10,586 theses titles from 25 Canadian and 219 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work.
Download or read book An Investigation of the Delta Scuti Stars written by Robert L. Millis and published by . This book was released on 1968 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
