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When a radio jet is partially optically thick in the launching region, its apparent compact core may display frequency-dependent positional shifts. High-precision astrometric measurements of core shifts enable astronomers to pinpoint the…

High Energy Astrophysical Phenomena · Physics 2026-04-24 Niu Liu , Jun Yang , Xiaopeng Cheng , Ai-Ling Zeng , Wen Chen , Xiao-Long Yang , Xiaoyu Hong , Xia-Xuan Zhang , Jia-Cheng Liu , Zi Zhu

In this work, we focus on the period-luminosity relation (PLR) of $\delta$ Sct stars, in which mode excitation and selection mechanisms are still poorly constrained, and whose structure and oscillations are affected by rotation. We review…

Solar and Stellar Astrophysics · Physics 2023-11-03 A. García Hernández , J. Pascual-Granado , M. Lares-Martiz , G. M. Mirouh , J. C. Suárez , S. Barceló Forteza , A. Moya

We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our…

Precise time-series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD 134214. We have fitted the observed frequencies with theoretical frequencies of…

Solar and Stellar Astrophysics · Physics 2015-05-30 H. Saio , M. Gruberbauer , W. W. Weiss , J. M. Matthews , T. Ryabchikova

Delta Scuti ($\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise…

Context. In asteroseismology the pulsation mode frequencies of a star are the fundamental data that are compared to theoretical predictions to determine a star's interior physics. Recent significant advances in the numerical, theoretical…

Solar and Stellar Astrophysics · Physics 2021-12-22 Dominic M. Bowman , Mathias Michielsen

Oscillation mode frequencies of stars are typically treated as static for a given stellar model. However, in reality they can be perturbed by time varying sources such as magnetic fields and flows. We calculate the sensitivities of radial…

Solar and Stellar Astrophysics · Physics 2020-07-01 René Kiefer , Anne-Marie Broomhall

Extensive photometric multisite campaigns of the Delta Scuti variable FG Vir are presented. For the years 2003 and 2004, 926 hours of photometry at the millimag precision level were obtained. The combinations with earlier campaigns lead to…

Context: Recent observations of HD49933 by the space-photometric mission CoRoT provide photometric evidence of solar type oscillations in a star other than our Sun. The first published reduction, analysis, and interpretation of the CoRoT…

Astrophysics · Physics 2015-05-13 T. Kallinger , M. Gruberbauer , D. B. Guenther , L. Fossati , W. W. Weiss

KIC8264293 is a fast rotating B-type pulsator observed by Kepler satellite. Its photometric variability is mainly due to pulsations in high-order g modes. Besides, we detected a weak H$\alpha$ emission. Thus, the second source of…

Solar and Stellar Astrophysics · Physics 2022-02-09 Wojciech Szewczuk , Przemysław Walczak , Jadwiga Daszyńska-Daszkiewicz , Dawid Moździerski

The lightcurves of variable DA stars are usually multi-periodic and non-sinusoidal, so that their Fourier transforms show peaks at eigenfrequencies of the pulsation modes and at sums and differences of these frequencies. These combination…

Astrophysics · Physics 2009-11-13 Celeste M. Yeates , J. Christopher Clemens , S. E. Thompson , F. Mullally

We discuss and characterise the power spectral density properties of a model aimed at describing pulsations in stars from the main-sequence to the asymptotic giant branch. We show that the predicted limit of the power spectral density for a…

Solar and Stellar Astrophysics · Physics 2020-09-30 Margarida S. Cunha , Pedro P. Avelino , William J. Chaplin

The light curves of 252 B-star candidates in the Kepler data base are analyzed in a similar fashion to that done by Balona et al. (2011) to further characterize B star variability, increase the sample of variable B stars for future study,…

Solar and Stellar Astrophysics · Physics 2012-03-19 Bernard J. McNamara , Jason Jackiewicz , Jean McKeever

Several studies have shown that a number of stars pulsating in p modes lie between the $\beta$ Cep and $\delta$ Sct instability strips in the Hertzsprung-Russell (HR) Diagram. At present, there is no certain understanding of how p~modes can…

Solar and Stellar Astrophysics · Physics 2023-03-29 D. W. Kurtz , R. Jayaraman , P. Sowicka , G. Handler , H. Saio , J. Labadie-Bartz , U. Lee

Comparing models and data of pulsating stars is a powerful way to understand the stellar structure better.\beta Hyi is an evolved solar-type pulsator with mixed modes in its frequency spectrum, making it very interesting for asteroseismic…

Solar and Stellar Astrophysics · Physics 2015-05-20 I. M. Brandão , G. Dogan , J. Christensen-Dalsgaard , M. S. Cunha , T. R. Bedding , T. S. Metcalfe , H. Kjeldsen , H. Bruntt , T. Arentoft

We present key sample results of a systematic survey of the pulsation properties of models of hot B subdwarfs. We use equilibrium structures taken from detailed evolutionary sequences of solar metallicity (Z = 0.02) supplemented by grids of…

Astrophysics · Physics 2009-10-28 Stephane Charpinet , Gilles Fontaine , Pierre Brassard , Ben Dorman

Context. OB stars are important building blocks of the Universe, but we have only a limited sample of them well understood enough from an asteroseismological point of view to provide feedback on the current evolutionary models. Our study…

In addition to revealing spherical harmonic degrees, $\ell$, of excited modes, pulsational amplitudes and phases from multicolour photometry and radial velocity data yield a valuable constraints on stellar atmospheric parameters and on…

Astrophysics · Physics 2009-11-10 J. Daszynska-Daszkiewicz , W. A. Dziembowski , A. A. Pamyatnykh , M. Breger , W. Zima

Effects of rotational mode coupling on photometric parameters of stellar oscillations are studied. At moderate rotation rates, a strong coupling between modes of spherical harmonic degree, $\ell$, differing by 2 and of the same azimuthal…

The line profile variations of the Delta Scuti star HD 2724=BB Phe were studied on the basis of new 189 high-resolution spectrograms covering 52 hours of observations on a baseline of 8.3 days. By combining these results with those of a…

Astrophysics · Physics 2009-10-31 Luciano Mantegazza , Ennio Poretti