Six new rapidly oscillating Ap stars in the Kepler long-cadence data using super-Nyquist asteroseismology

Abstract

We perform a search for rapidly oscillating Ap stars in the Kepler long-cadence data, where true oscillations above the Nyquist limit of 283.21 μHz can be reliably distinguished from aliases as a consequence of the barycentric time corrections applied to the Kepler data. We find evidence for rapid oscillations in six stars: KIC 6631188, KIC 7018170, KIC 10685175, KIC 11031749, KIC 11296437 and KIC 11409673, and identify each star as chemically peculiar through either pre-existing classifications or spectroscopic measurements. For each star, we identify the principal pulsation mode, and are able to observe several additional pulsation modes in KIC 7018170. We find that KIC 7018170 and KIC 11409673 both oscillate above their theoretical acoustic cutoff frequency, whilst KIC 11031749 oscillates at the cutoff frequency within uncertainty. All but KIC 11031749 exhibit strong amplitude modulation consistent with the oblique pulsator model, confirming their mode geometry and periods of rotation.

20 pages, 14 figures, accepted for publication in MNRAS

References in corpus (14)

• The Transiting Exoplanet Survey Satellite
• Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
• {\em Gaia}-derived luminosities of {\em Kepler} A/F stars and the pulsator fraction across the δ Scuti instability strip
• Finding binaries among Kepler pulsating stars from phase modulation of their pulsations
• SpectRes: A Fast Spectral Resampling Tool in Python
• Pulsation tomography of rapidly oscillating Ap stars. Resolving the third dimension in peculiar pulsating stellar atmospheres
• Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2
• Super-Nyquist asteroseismology of solar-like oscillators with Kepler and K2 - expanding the asteroseismic cohort at the base of the red-giant branch
• Asteroseismology of 1523 misclassified red giants using $\text{Kepler}$ data
• On mode conversion and wave reflection in magnetic Ap stars
• KIC 7582608: A new Kepler roAp star with frequency variability
• HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode
• Destroying Aliases from the Ground and Space: Super-Nyquist ZZ Cetis in K2 Long Cadence Data
• Large amplitude change in spot-induced rotational modulation of the Kepler Ap star KIC 2569073

Cited by in corpus (13)

• Gaia Data Release 3: All-sky classification of 12.4 million variable sources into 25 classes
• Gaia Data Release 3: Cross-match of Gaia sources with variable objects from the literature
• On the first $\delta$ Sct--roAp hybrid pulsator and the stability of p and g modes in chemically peculiar A/F stars
• TESS Cycle 1 observations of roAp stars with 2-min cadence data
• Confronting sparse Gaia DR3 photometry with TESS for a sample of around 60,000 OBAF-type pulsators
• The Discovery of lambda Bootis Stars -- The Southern Survey II
• Long-period Ap stars discovered with TESS data: The northern ecliptic hemisphere
• The roAp stars observed by the Kepler Space Telescope
• HD 213258: a new rapidly oscillating, super-slowly rotating, strongly magnetic Ap star in a spectroscopic binary
• Discovery of multiple p-mode pulsation frequencies in the roAp star, HD 86181
• Distinguishing super-Nyquist frequencies via their temporal variation in $\gamma$ Doradus stars from continuous photometry
• SALT HRS capabilities for time resolved pulsation analysis: a test with the roAp star $\alpha$ Circini
• A search for transits among the δ Scuti variables in Kepler