New light on the driving mechanism in roAp stars

Théado, S.; Dupret, Marc‐Antoine; Noels, A.; Ferguson, Jason W.

doi:10.1051/0004-6361:200810494

Cited by 18 publications

(18 citation statements)

References 69 publications

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“…A possible explanation for why that mode is preferentially excited was proposed by Balmforth et al (2001) who argued that the strong magnetic field present in roAp stars is likely to suppress convection around the magnetic poles. Since the absence of convection is believed to help the excitation of the high‐radial‐order oscillations observed in roAp stars (Balmforth et al 2001; Cunha 2002; Saio 2005; Théado et al 2009), the modes of highest amplitude near the magnetic poles will be preferentially excited. If the magnetic field effect on the oscillations dominates over the rotation effect, then the interpretation suggested by these authors remains possible.…”

Section: Introductionmentioning

confidence: 99%

Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

Balona

Cunha

Gruberbauer

et al. 2011

Monthly Notices of the Royal Astronomical Society

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Photometry of KIC 10483436 was obtained continuously with 1‐min exposures over a 27‐d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 ± 0.002 d, an amplitude of about 6 mmag and eight pulsation frequencies typical of roAp stars. The high‐frequency pattern consists of a quintuplet of equally spaced peaks where the frequency of the dominant central peak (68 μmag amplitude) is 1353.00 μHz (P= 12.32 min). A second set of three peaks of lower amplitude are also visible. These appear to form part of a quintuplet centred on 1511.6 μHz with the central peak and one side peak missing. The equidistant frequency spacing is 2.69 μHz, which corresponds to the 4.303 d rotation period. However, the amplitudes (12 μmag) of these peaks are too close to the detection level to allow definite identification of the multiplets. Although no spectrum is available, the character of the pulsations shows that this is a roAp star with two high‐frequency modes modulated in amplitude in accordance with the oblique pulsator model. The 4.303‐d variation in the light curve, which is interpreted as rotational modulation, shows harmonics as high as the 26th. These harmonics are probably a result of many patches of varying surface brightness associated with surface abundance variations characteristic of Ap stars.

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Section: Introductionmentioning

confidence: 99%

Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

Balona

Cunha

Gruberbauer

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…They also determined an effective temperature of 7700 K for HD75445, while Kochukhov & Bagnulo (2006) determined log (L/L sun ) = 1.17 and (M /M sun ) = 1.81 for HD75445. These numbers imply that HD75445 just falls within the hotter half of detected roAp stars (see, for example, Théado et al (2009)) and is expected to display pulsation frequencies at the higher end of the range of pulsation frequencies seen in roAp stars (see, for example, Dupret et al (2008)). We detect only one high-frequency roAp mode (and this is only a marginal detection), accompanied by a set of much stronger lower-frequency modes extending all the way into the Delta Scuti domain.…”

Section: Introductionmentioning

confidence: 95%

Multi-season photometry of the newly-discovered roAp star HD75445

et al. 2010

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Abstract. HD75445 was recently announced by Kochukhov et al. (2009) to be a low-amplitude roAp star, based on spectroscopic measurements. We present putative pulsation frequencies of HD75445 determined from 22 hours of Johnson B photometry obtained in 2008, 2009 and 2010. We present the first photometric periodicities detected in this star. We make a marginal detection of one of Kochukhov et al. (2009)'s spectroscopic periods, along with a range of confidently detected periodicities covering the low-frequency end of the roAp instability spectrum and the high-frequency end of the Delta Scuti instability spectrum.

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“…There are many papers in which stellar pulsations of various objects were used as a test of opacity data, e.g., Dziembowski & Pamyatnykh (2008) for β Cep stars, Jeffery & Saio (2006) for pulsating subdwarf B stars, Lenz et al (2008) for δ Sct stars or Théado et al (2008) for roAp stars. The role of input from opacity data in pulsation computations was recently summed up by Montalbán & Miglio (2008).…”

Section: Theoretical Challengesmentioning

confidence: 99%

Challanges for stellar pulsation and evolution theory

Daszyńska‐Daszkiewicz

2009

cia

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During the last few decades, great effort has been made towards understanding hydrodynamical processes which determine the structure and evolution of stars. Up to now, the most stringent constraints have been provided by helioseismology and stellar cluster studies. However, the contribution of asteroseismology becomes more and more important, giving us an opportunity to probe the interiors and atmospheres of very different stellar objects. A variety of pulsating variables allows us to test various parameters of micro-and macrophysics by means of oscillation data. I will review the most outstanding key problems, both observational and theoretical, of which our knowledge can be improved by means of asteroseismology.

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New light on the driving mechanism in roAp stars

Cited by 18 publications

References 69 publications

Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

Multi-season photometry of the newly-discovered roAp star HD75445

Challanges for stellar pulsation and evolution theory

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