Gold

Kurtz, Wolfgang; Vanecek, Hans

doi:10.1007/978-3-662-08690-2_28

Cited by 9 publications

(15 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The frequency septuplet of ν 1 of KIC 10195926 is very similar to that of HR 3831 (Kurtz et al 1990, 1997), which is interpreted as arising from a distorted dipole mode. Kurtz (1992) showed that the mode in HR 3831 is primarily an oblique dipole mode from a spherical harmonic decomposition of its frequency septuplet. Kochukhov (2004) found that both dipole and octupole components are needed to describe the radial velocity variations in HR 3831.…”

Section: The Pulsation Frequenciesmentioning

confidence: 99%

The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

Kurtz¹,

Cunha

Saio

et al. 2011

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We have discovered a new rapidly oscillating Ap (roAp) star among the Kepler mission target stars, KIC 10195926. This star shows two pulsation modes with periods that are amongst the longest known for roAp stars at 17.1 and 18.1 min, indicating that the star is near the terminal‐age main sequence. The principal pulsation mode is an oblique dipole mode that shows a rotationally split frequency septuplet that provides information on the geometry of the mode. The secondary mode also appears to be a dipole mode with a rotationally split triplet, but we are able to show within the improved oblique pulsator model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 μHz, which we model as the large separation. The star is an α2 CVn spotted magnetic variable that shows a complex rotational light variation with a period of Prot= 5.684 59 d. For the first time for any spotted magnetic star of the upper main sequence, we find clear evidence of light variation with a period of twice the rotation period, that is, a subharmonic frequency of νrot/2. We propose that this and other subharmonics are the first observed manifestation of torsional modes in an roAp star. From high‐resolution spectra, we determine Teff= 7400 K, log g= 3.6 and v sin i= 21 km s−1. We have found a magnetic pulsation model with fundamental parameters close to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance patches.

show abstract

Section: The Pulsation Frequenciesmentioning

confidence: 99%

The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

Kurtz¹,

Cunha

Saio

et al. 2011

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Note that the phase θ (as in cos (ωt − θ)) has been transformed to φ (as in sin (ωt + φ)) for comparison to Handler et al (2006). pulsator through, e.g., the technique of Kurtz (1992). In particular, one needs to take into account how uncertainties and instrumental properties affect the results.…”

Section: The Pulsation Of Hd 99563 -A New Candidate Frequencymentioning

confidence: 99%

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

Gruberbauer

Huber²,

Kuschnig³

et al. 2011

A&A

View full text Add to dashboard Cite

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).

show abstract

“…Kurtz et al 1989); caution is warranted. Such nonintrinsic peaks can change the amplitudes of rotational sidelobes and can therefore influence inferences about the geometry of distorted modes (Kurtz 1992).…”

Section: Roap Starsmentioning

confidence: 99%

Methodological Aspects of Delta Scuti Star Seismology

Handler¹

1998

Open Astronomy

View full text Add to dashboard Cite

Abstract. I present a personally biased view of the present status of seismology of δ Scuti stars. While much thought has been given to develop new tools for mode identification, the required crosscalibrations between them are difficult. I suggest to pay more attention to target selection, since the objects which have the best chances to be successfully modeled -unevolved, slowly rotating δ Scuti stars -are poorly observed.In the light of an upcoming large multi-site campaign on the only well investigated representative of this class, WET 0856 = CD-24°7599 = XX Pyx, I estimate the size of some spurious results which can affect data analysis, in particular those caused by passband mismatches of inhomogeneous equipment used in worldwide observing campaigns. I find that they hardly influence the results for δ Scuti and roAp stars, but they can become dangerous for high-amplitude DA pulsators.

show abstract

Gold

Cited by 9 publications

References 45 publications

The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

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

Methodological Aspects of Delta Scuti Star Seismology

Contact Info

Product

Resources

About