Oblique Pulsation: New, Challenging Observations with TESS Data

Kurtz, D. W.; Holdsworth, Daniel Luke

doi:10.1007/978-3-030-55336-4_43

Cited by 6 publications

(9 citation statements)

References 23 publications

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“…This difference may suggest different pulsation axes for the two dipole modes (as suggested for KIC 10195926; Kurtz et al 2011). However, it is likely that we are seeing a depth dependence on the geometry which is being affected by different limb darkening weighting due to the stratified atmosphere of the star, as is proposed to be the case for HD 6532 (Kurtz & Holdsworth 2020), and previously observed with time-resolved spectroscopic studies that resolved the vertical structure of pulsations by studying lines with different formation heights (Kochukhov 2006;Freyhammer et al 2009). Another option is that the difference may result from the modes suffering different magnetic distortions in the atmosphere (Sousa & Cunha 2011; Quitral-Manosalva et al 2018), due to their slightly different frequencies.…”

Section: Tic 176516923mentioning

confidence: 82%

“…This provides a problem for the application of the oblique pulsator model where the stellar inclination angle, i, and the magnetic obliquity, β, can be derived or constrained. This, coupled with the difference in structure between observations made in different filters (e.g., TIC 326185137 -HD 6532; Kurtz & Holdsworth 2020), and spectral lines (e.g., TIC 280198016 -HD 83368 Kochukhov 2006), provides a significant challenge in understanding the results of the oblique pulsator model.…”

Section: Discussionmentioning

confidence: 99%

“…TESS observed this star in sector 3, with an initial analysis of the data being presented by Balona et al (2019) where it was noted that the multiplet structure was vastly different from previous B photometric data. Kurtz & Holdsworth (2020) explored this further, postulating two scenarios that could explain the striking difference between the two data sets: either the star has changed its pulsation axis or, more likely, we are seeing a depth dependence on the mode geometry revealed by the two wavelengths of observation.…”

Section: Tic 326185137mentioning

confidence: 99%

See 2 more Smart Citations

TESS cycle 1 observations of roAp stars with 2-min cadence data

Holdsworth

Cunha

Kurtz

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the results of a systematic search for new rapidly oscillating Ap (roAp) stars using the 2-min cadence data collected by the Transiting Exoplanet Survey Satellite (TESS) during its Cycle 1 observations. We identify 12 new roAp stars. Amongst these stars we discover the roAp star with the longest pulsation period, another with the shortest rotation period, and six with multiperiodic variability. In addition to these new roAp stars, we present an analysis of 44 known roAp stars observed by TESS during Cycle 1, providing the first high-precision and homogeneous sample of a significant fraction of the known roAp stars. The TESS observations have shown that almost 60 per cent (33) of our sample of stars are multiperiodic, providing excellent cases to test models of roAp pulsations, and from which the most rewarding asteroseismic results can be gleaned. We report four cases of the occurrence of rotationally split frequency multiplets that imply different mode geometries for the same degree modes in the same star. This provides a conundrum in applying the oblique pulsator model to the roAp stars. Finally, we report the discovery of non-linear mode interactions in α Cir (TIC 402546736, HD 128898) around the harmonic of the principal mode – this is only the second case of such a phenomenon.

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Section: Tic 176516923mentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Tic 326185137mentioning

confidence: 99%

See 1 more Smart Citation

TESS cycle 1 observations of roAp stars with 2-min cadence data

Holdsworth

Cunha

Kurtz

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…This difference may suggest different pulsation axes for the two dipole modes (as suggested for KIC 10195926; Kurtz et al 2011). However, it is likely that we are seeing a depth dependence on the geometry which is being affected by different limb darkening weighting due to the stratified atmosphere of the star, as is proposed to be the case for HD 6532 (Kurtz & Holdsworth 2020), and previously observed with time-resolved spectroscopic studies that resolved the vertical structure of pulsations by studying lines with different formation heights (Kochukhov 2006;Freyhammer et al 2009). Another option is that the difference may result from the modes suffering differ- ent magnetic distortions in the atmosphere (Sousa & Cunha 2011;Quitral-Manosalva et al 2018), due to their slightly different frequencies.…”

Section: Tic 176516923mentioning

confidence: 81%

TESS Cycle 1 observations of roAp stars with 2-min cadence data

Holdsworth,

Cunha,

Kurtz

et al. 2021

Preprint

Self Cite

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We present the results of a systematic search for new rapidly oscillating Ap (roAp) stars using the 2-min cadence data collected by the Transiting Exoplanet Survey Satellite (TESS) during its Cycle 1 observations. We identify 12 new roAp stars. Amongst these stars we discover the roAp star with the longest pulsation period, another with the shortest rotation period, and six with multiperiodic variability. In addition to these new roAp stars, we present an analysis of 44 known roAp stars observed by TESS during Cycle 1, providing the first high-precision and homogeneous sample of a significant fraction of the known roAp stars. The TESS observations have shown that almost 60 per cent (33) of our sample of stars are multiperiodic, providing excellent cases to test models of roAp pulsations, and from which the most rewarding asteroseismic results can be gleaned. We report four cases of the occurrence of rotationally split frequency multiplets that imply different mode geometries for the same degree modes in the same star. This provides a conundrum in applying the oblique pulsator model to the roAp stars. Finally, we report the discovery of non-linear mode interactions in Cir (TIC 402546736, HD 128898) around the harmonic of the principal mode -this is only the second case of such a phenomenon.

show abstract

“…Furthermore, in light of new results, we propose another interpretation of these different relative amplitudes. Recent observations by the TESS mission of HD 6532 show a distinctly different multiplet shape than the B-photometric observations presented by Kurtz et al (1996) [see Kurtz and Holdsworth (2020) for comparison plots]. New ground-based multicolor FIGURE 6 | (Top) Amplitude spectra of the two pulsation modes in KIC 10195926.…”

Section: Short Cadence Observationsmentioning

confidence: 99%

The roAp Stars Observed by the Kepler Space Telescope

Holdsworth

2021

Front. Astron. Space Sci.

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Before the launch of the Kepler Space Telescope, most studies of the rapidly oscillating Ap (roAp) stars were conducted with ground-based photometric B observations, supplemented with high-resolution time-resolved spectroscopy and some space observations with the WIRE, MOST, and BRITE satellites. These modes of observation often only provided information on a single star at a time, however, Kepler provided the opportunity to observe hundreds of thousands of stars simultaneously. Over the duration of the primary 4 year Kepler mission, and its 4 year reconfigured K2 mission, the telescope observed at least 14 new and known roAp stars. This paper provides a summary the results of these observations, including a first look at the entire data sets, and provides a look forward to NASA's TESS mission.

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Oblique Pulsation: New, Challenging Observations with TESS Data

Cited by 6 publications

References 23 publications

TESS cycle 1 observations of roAp stars with 2-min cadence data

TESS cycle 1 observations of roAp stars with 2-min cadence data

TESS Cycle 1 observations of roAp stars with 2-min cadence data

The roAp Stars Observed by the Kepler Space Telescope

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