roAp stars

Kurtz, D. W.; Martinez, Peter

doi:10.1017/s1539299600011461

Cited by 35 publications

(42 citation statements)

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“…If it would prove to be a magnetic Ap star (showing magnetic variations along with spectral variations modulated by the rotational period), it would be an exceptional case, together with HD 75425, a weak Ap Sr(CrEu) star (Martinez & Medupe 1998) and HD 188136, a ρ Pup star (Kurtz 1980). Such cases suggest that the presence of a global magnetic field does not inhibit δ Scuti pulsation in all cases (in contradiction with the actual knowledge of the diffusion theory, see Kurtz & Martinez 2000) …”

Section: Hd 68725 -Hip 40361mentioning

confidence: 87%

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

Frémat

Lampens

Cauteren

et al. 2007

A&A

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Context. In the H-R diagram, the intersection of the main sequence and the classical Cepheid instability strip corresponds to a domain where a rich variety of atmospheric phenomena are at play (including pulsation, radiative diffusion, convection). Main-sequence A-type stars are among the best candidates to study the complex interplay between these various phenomena. Aims. We have explored a sample of suspected A-type binaries in a systematic way, both spectroscopically and photometrically. The sample consists of main-sequence A-type stars for which the few existing radial velocity measurements may show variability, but for which other essential information is lacking. Due to their location in the H-R diagram, indications of pulsation and/or chemical peculiarities among these suspected binary (or multiple) systems may be found. Methods. High-resolution spectroscopy obtained with the ELODIE and MUSICOS spectrographs was used in combination with a few nights of differential CCD photometry in order to search for pulsation(s). In order to search as well for chemical peculiarities or for possible hidden component(s), we derived the atmospheric stellar parameters by fitting the observed spectra with LTE synthetic ones. Results. Of the 32 investigated targets, eight are spectroscopic binaries, one of which is a close binary also showing eclipses, and three have been identified as δ Scuti pulsators with rapid line-profile variations. Conclusions. Among the latter stars, HD 217860 reveals interesting multiperiodic photometric and spectroscopic variations, with up to eight frequencies common to two large photometric data sets. We suggest that at least one radial overtone mode is excited among the two most dominant frequencies, on the basis of the computation of the pulsation constants as well as of the predicted frequencies and the expected behaviour of the amplitude ratio and the phase difference in two passbands using adequate theoretical modelling. We furthermore found evidence for a strong modulation of the amplitude(s) and/or the (radial) frequency content of this intriguing δ Scuti star.

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Section: Hd 68725 -Hip 40361mentioning

confidence: 87%

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

Frémat

Lampens

Cauteren

et al. 2007

A&A

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“…There are 34 such stars currently known. Detailed reviews of the photometric results for roAp stars have been published by Kurtz (1990), Matthews (1991), and Kurtz & Martinez (2000). The radial velocity studies have not yet been reviewed; see Mkrtichian & Hatzes (2005), Kurtz et al (2005), Kochukhov (2004), Kochukhov & Ryabchikova (2001) for some examples of the rich results coming from the radial velocity studies.…”

Section: Observations and Magnetic Field Measurementsmentioning

confidence: 99%

Detection of an extraordinarily large magnetic field in the unique ultra-cool Ap star HD 154708

Hubrig¹,

Nesvacil

Schöller³

et al. 2005

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Abstract.We have discovered an extraordinarily large mean longitudinal magnetic field of 7.5 kG in the ultra-cool low mass Ap star HD 154708 using FORS 1 in spectropolarimetric mode. From UVES spectra, we have measured a mean magnetic field modulus of 24.5 kG. This is the second-largest mean magnetic field modulus ever measured in an Ap star. Furthermore, it is very likely that this star is one of the coolest and least massive among the Ap stars and is located in the H-R diagram in the same region in which rapidly oscillating Ap stars have been detected. We note that all known roAp stars have much smaller magnetic fields, by at least a factor of three.

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“…we refer to Kurtz & Martinez (2000) and Kochukhov (2007), and for the theoretical aspects, to Shibahashi (2003) and Cunha (2005).…”

Section: Introductionmentioning

confidence: 99%

MOST observations of the roAp stars HD 9289, HD 99563, and HD 134214

Gruberbauer

Huber²,

Kuschnig³

et al. 2011

A&A

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We report on the analysis of high-precision space-based photometry of the roAp (rapidly oscillating Ap) stars HD 9289, HD 99563, and HD 134214. All three stars were observed by the MOST satellite for more than 25 days, allowing unprecedented views of their pulsation. We find previously unknown candidate frequencies in all three stars. We establish the rotation period of HD 9289 (8.5 d) for the first time and show that the star is pulsating in two modes that show different mode geometries. We present a detailed analysis of HD 99563's mode multiplet and find a new candidate frequency that appears to be independent of the previously known mode. Finally, we report on 11 detected pulsation frequencies in HD 134214, nine of which have never before been detected in photometry, and three of which are completely new detections. Thanks to the unprecedentedly small frequency uncertainties, the p-mode spectrum of HD 134214 can be seen to have a well-defined large frequency spacing similar to the well-studied roAp star HD 24712 (HR 1217).

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roAp stars

Cited by 35 publications

References 0 publications

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

Search for pulsation among suspected A-type binaries and the new multiperiodic δ Scuti star HD 217860

Detection of an extraordinarily large magnetic field in the unique ultra-cool Ap star HD 154708

MOST observations of the roAp stars HD 9289, HD 99563, and HD 134214

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