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The Ap star HD3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated…

Astrophysics · Physics 2009-11-13 V. G. Elkin , D. W. Kurtz , L. M. Freyhammer , S. Hubrig , G. Mathys

We report the detection of short period variations in the stars HD69013 and HD96237. These stars possess large overabundances of rare earth elements and global magnetic fields, thus belong to the class of chemically peculiar Ap stars of the…

Solar and Stellar Astrophysics · Physics 2015-05-20 V. G. Elkin , D. W. Kurtz , H. L. Worters , G. Mathys , B. Smalley , F. van Wyk , A. M. S. Smith

We have investigated the structure of the pulsating atmosphere of one of the best studied rapidly oscillating Ap stars, HD 24712. For this purpose we analyzed spectra collected during 2001-2004. An extensive data set was obtained in 2004…

We present the discovery of pulsational variations in the cool magnetic Ap star HD 115226 -- the first high-amplitude rapidly oscillating Ap star discovered with time-series spectroscopy. Using high-resolution spectra obtained with the…

Astrophysics · Physics 2009-11-13 O. Kochukhov , T. Ryabchikova , S. Bagnulo , G. Lo Curto

We present our discovery of pulsational radial-velocity variations in the cool Ap star HD 75445, an object spectroscopically similar to the bright, rapidly-oscillating Ap (roAp) star gamma Equ. Based on high-resolution time-series…

Astrophysics · Physics 2009-11-13 O. Kochukhov , S. Bagnulo , G. Lo Curto , T. Ryabchikova

We present results of the radial velocity (RV) analysis of spectroscopic time-series observations of the roAp star HD24712 (HR1217) which were carried out simultaneously with the Canadian MOST mini-satellite photometry. Only lines of the…

We present the discovery of a long-period, rapidly oscillating Ap star, HD177765. Using high-resolution time-series observations obtained with UVES at the ESO VLT telescope, we found radial velocity variations with amplitudes 7-150 m/s and…

Solar and Stellar Astrophysics · Physics 2015-06-03 D. Alentiev , O. Kochukhov , T. Ryabchikova , M. Cunha , V. Tsymbal , W. Weiss

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

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant…

Solar and Stellar Astrophysics · Physics 2015-06-05 S. Joshi , E. Semenko , P. Martinez , M. Sachkov , Y. C. Joshi , S. Seetha , N. K. Chakradhari , D. L. Mary , V. Girish , B. N. Ashoka

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

We have carried out a survey of short-period pulsations among a sample of carefully chosen cool Ap stars using time-resolved observations with the UVES spectrometer at the ESO 8-m VLT telescope. Here we report the discovery of pulsations…

Solar and Stellar Astrophysics · Physics 2015-06-15 O. Kochukhov , D. Alentiev , T. Ryabchikova , S. Boyko , M. Cunha , V. Tsymbal , W. Weiss

We present detailed analysis of the vertical pulsation mode cross-section in ten rapidly oscillating Ap (roAp) stars based on spectroscopic time-series observations. The aim of this analysis is to derive from observations a complete picture…

Astrophysics · Physics 2009-11-13 T. Ryabchikova , M. Sachkov , O. Kochukhov , D. Lyashko

Recently, Tiwari, Chaubey, & Pandey (2007) detected the bright component of the visual binary HD151878 to exhibit rapid photometric oscillations through a Johnson B filter with a period of 6 min (2.78 mHz) and a high, modulated amplitude up…

Astrophysics · Physics 2009-11-13 L. M. Freyhammer , V. G. Elkin , D. W. Kurtz

We report the identification of 61.45 d^-1 (711.2 mu Hz) oscillations, with amplitudes of 62.6-mu mag, in KIC 4768731 (HD 225914) using Kepler photometry. This relatively bright (V=9.17) chemically peculiar star with spectral type A5 Vp…

Asteroseismology has the potential to provide new insights into the physics of stellar interiors. We have obtained UVES high time resolution observations of the delta Scuti star HD21190 and of the Ap Sr star HD218994 to search for…

Astrophysics · Physics 2009-11-13 J. F. Gonzalez , S. Hubrig , D. W. Kurtz , V. Elkin , I. Savanov

I review recent results of the observations of magnetoacoustic p-mode oscillations in roAp stars with the focus on time-resolved spectroscopic studies. Time-series spectroscopy of roAp stars reveals unexpected and diverse pulsational…

Astrophysics · Physics 2009-11-13 O. Kochukhov

We present precise relative radial velocity (RV) measurements for the rapidly oscillating Ap (roAp) star 33 Librae measured from high resolution data spanning the wavelength interval 5000--6200 A. We find that pulsational radial velocity…

Astrophysics · Physics 2009-11-10 David E. Mkrtichian , Artie P. Hatzes , Antonio Kanaan

In some delta Scuti stars, only one or two radial modes are excited (usually the fundamental mode and/or first overtone mode) and the observed peak-to-peak amplitudes exceed 0.3 mag (V). These stars are known as High Amplitude Delta Scuti…

We report the first comprehensive investigation of the line profile variation caused by non-radial pulsation in a magnetic oscillating chemically peculiar star. Spectrum variation of the well-known roAp star HR 3831 is detected using very…

Astrophysics · Physics 2009-11-11 O. Kochukhov

We present the analysis of spectroscopic time-series observations of the roAp star 10 Aql. Observations were carried out in July 2006 with the UVES and SARG spectrographs simultaneously with the MOST mini-satellite photometry. All these…

Astrophysics · Physics 2010-11-26 M. Sachkov , O. Kochukhov , T. Ryabchikova , F. Leone , S. Bagnulo , W. W. Weiss
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