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We present a method for the computation of the variance of cosmic microwave background (CMB) temperature maps on azimuthally symmetric patches using a fast convolution approach. As an example of the application of the method, we show…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-15 P. Bielewicz , B. D. Wandelt , A. J. Banday

Debate over the planet occurrence rates around intermediate-mass stars has hinged on the accurate determination of masses of evolved stars, and has been exacerbated by a paucity of reliable, directly-measured fundamental properties for…

With FORS1 at the VLT we have tried for the first time to measure the magnetic field variation over the pulsation cycle in six roAp stars to begin the study of how the magnetic field and pulsation interact. For the star HD101065, which has…

Astrophysics · Physics 2009-11-10 S. Hubrig , D. W. Kurtz , S. Bagnulo , T. Szeifert , M. Schoeller , G. Mathys , W. A. Dziembowski

Asteroseismology, i.e. the study of the internal structures of stars via their global oscillations, is a valuable tool to obtain stellar parameters such as mass, radius, surface gravity and mean density. These parameters can be obtained…

Solar and Stellar Astrophysics · Physics 2015-06-16 S. Hekker , Y. Elsworth , S. Basu , A. Mazumdar , V. Silva Aguirre , W. J. Chaplin

We present the methodology and some preliminary results of our study of the relationship between a Mira's pulsating photosphere and its surrounding molecular layer(s) throughout several pulsation cycles, based on spatially resolved data.…

Solar and Stellar Astrophysics · Physics 2010-11-24 M. Hillen , T. Verhoelst , B. Acke , P. Degroote

Context. The dipole modes are the most common geometry of oscillations in roAp stars inferred from photometric measurements and are therefore of special interest for asteroseismic purposes. Aims. We present a theoretical and analytical…

Solar and Stellar Astrophysics · Physics 2011-10-06 L. Bigot , D. W. Kurtz

With the rapid development of asteroseismology thanks to space-based photometry missions such as CoRoT, Kepler, TESS, and in the future, PLATO, and the use of inversion techniques, quasi-model-independent constraints on the stellar…

Solar and Stellar Astrophysics · Physics 2022-07-20 J. Bétrisey , G. Buldgen

We have obtained a time series of 81 high-cadence circular polarization observations of the rapidly oscillating Ap star HD 24712 with the new ESPaDOnS spectropolarimeter at CFHT. We used the high-S/N, high-resolution Stokes I and V spectra…

Astrophysics · Physics 2009-11-13 O. Kochukhov , G. A. Wade

Astrometric detection of a stellar wobble on the plane of the sky will provide us a next breakthrough in searching extrasolar planets. The Space Interferometry Mission (SIM) is expected to achieve a high-precision astrometry as accurate as…

Astrophysics · Physics 2009-11-10 Taku Takeuchi , T. Velusamy , D. N. C. Lin

We present time-series radial velocities of the G8 subgiant star beta Aql obtained in 2022 and 2023 using SONG-Tenerife and, for the first time, SONG-Australia. We also analyse a sector of TESS photometry that overlapped with the 2022 SONG…

The searches for transiting exoplanets have produced a vast amount of time-resolved photometric data of many millions of stars. One of the leading ground-based surveys is the SuperWASP project. We present the initial results of a survey of…

Solar and Stellar Astrophysics · Physics 2015-06-17 Daniel L. Holdsworth , Barry Smalley

Understanding the physical process responsible for the transport of energy in the core of $\alpha$ Centauri A is of the utmost importance if this star is to be used in the calibration of stellar model physics. Adoption of different parallax…

Solar and Stellar Astrophysics · Physics 2018-06-06 B. Nsamba , M. J. P. F. G. Monteiro , T. L. Campante , M. S. Cunha , S. G. Sousa

Context: The main sequence binary star 61 Cyg (K5V+K7V) is our nearest stellar neighbour in the northern hemisphere. This proximity makes it a particularly well suited system for very high accuracy interferometric radius measurements. Aims:…

The Palomar Testbed Interferometer has observed several binary star systems whose separations fall between the interferometric coherence length (a few hundredths of an arcsecond) and the typical atmospheric seeing limit of one arcsecond.…

We present recent results from our radial velocity (RV) studies of rapidly oscillating Ap (roAp) stars. Our measurements reveal that the pulsational amplitude of these stars depends on the spectral region that is examined. For one star,…

Astrophysics · Physics 2007-05-23 A. P. Hatzes , A. Kanaan

We have used high-speed spectroscopy of the rapidly oscillating Ap (roAp) star HD99563 to study the pulsation amplitude and phase behaviour of elements in its stratified atmosphere over one 2.91-d rotation cycle. We identify spectral…

Solar and Stellar Astrophysics · Physics 2015-05-13 L. M. Freyhammer , D. W. Kurtz , V. G. Elkin , G. Mathys , I. Savanov , W. Zima , H. Shibahashi , K. Sekiguchi

We present optical interferometric polarimetry measurements of the Mira-like variables R Car and RR Sco, using the Sydney University Stellar Interferometer. By making visibility measurements in two perpendicular polarisations, the…

Astrophysics · Physics 2009-11-11 M. J. Ireland , P. G. Tuthill , J. Davis , W. Tango

We address the issue of relativistic stellar aberration requirements for the Space Interferometry Mission (SIM). Motivated by the importance of this issue for SIM, we have considered a problem of relative astrometric observations of two…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Slava G. Turyshev

We present the first on-sky demonstration of dual-field interferometry at the CHARA Array and the first direct resolution of the inner Ba--Bb subsystem in the bright hierarchical triple $\alpha$ Piscium. Using $H$-band fringe tracking on…

An interesting asteroseismic target is the G9.5 IV solar-like star beta Aql. This is an ideal target for asteroseismic investigations, because precise astrometric measurements are available from Hipparcos that greatly help in constraining…

Solar and Stellar Astrophysics · Physics 2015-05-30 E. Corsaro , F. Grundahl , S. Leccia , A. Bonanno , H. Kjeldsen , L. Paternò