K2 photometry on oscillation mode variability: the new pulsating hot B subdwarf star EPIC 220422705

Abstract

We present an analysis of oscillation mode variability in the hot B subdwarf star EPIC~220422705, a new pulsator discovered from $\sim 78$~days of {\em K}2 photometry. The high-quality light curves provide a detection of 66 significant independent frequencies, from which we identified 9 incomplete potential triplets and 3 quintuplets. Those {\sl g-} and {\sl p-}multiplets give rotation periods of $\sim$ 36 and 29 days in the core and at the surface, respectively, potentially suggesting a slightly differential rotation. We derived a period spacing of 268.5\,s and 159.4\,s for the sequence of dipole and quadruple modes, respectively. We characterized the precise patterns of amplitude and frequency modulations (AM and FM) of 22 frequencies with high enough amplitude for our science. Many of them exhibit intrinsic and periodic patterns of AM and FM, with periods on a timescale of months as derived by the best fitting and \texttt{MCMC} test. The nonlinear resonant mode interactions could be a natural interpretation for such AMs and FMs after other mechanisms are ruled out. Our results are the first step to build a bridge between mode variability from {\em K}2 photometry and nonlinear perturbation theory of stellar oscillation.

arXiv comment18 pages,9 figures, 2 tables, accepted in APJ

References in corpus (35)

• emcee: The MCMC Hammer
• The Transiting Exoplanet Survey Satellite
• The K2 Mission: Characterization and Early results
• Hot subluminous stars
• The Potential of Asteroseismology for Hot, Subdwarf B Stars: A New Class of Pulsating Stars?
• First Kepler results on compact pulsators I. Survey target selection and the first pulsators
• An update to the EVEREST K2 pipeline: Short cadence, saturated stars, and Kepler-like photometry down to Kp = 15
• Radial velocity measurements of Subdwarf B stars
• HS0702+6043: A star showing both short-period p-mode and long-period g-mode oscillations
• Amplitude and frequency variations of oscillation modes in the pulsating DB white dwarf star KIC~08626021: The likely signature of nonlinear resonant mode coupling
• First Kepler results on compact pulsators VI. Targets in the final half of the survey phase
• First Kepler results on compact pulsators VIII: Mode identifications via period spacings in $g-$mode pulsating Subdwarf B stars
• A pulsation zoo in the hot subdwarf B star KIC 10139564 observed by Kepler
• Seismic sensitivity to sub-surface solar activity from 18 years of GOLF/SoHO observations
• Asteroseismology revealing trapped modes in KIC 10553698A
• Internal rotation of subdwarf B stars: limiting cases and asteroseismological consequences
• Signatures of nonlinear mode interactions in the pulsating hot B subdwarf star KIC 10139564
• Deriving the orbital properties of pulsators in binary systems through their light arrival time delays
• Exploring B4: A Pulsating sdB star, in a Binary, in the Open Cluster NGC 6791
• The discovery of differential radial rotation in the pulsating subdwarf B star KIC 3527751
• TESS first look at evolved compact pulsators : Discovery and asteroseismic probing of the g-mode hot B subdwarf pulsator EC 21494-7018
• Detection of nonlinear resonances among gravity modes of slowly pulsating B stars: results from five iterative prewhitening strategies
• A Radial Velocity Study of Composite-Spectra Hot Subdwarf Stars with the Hobby-Eberly Telescope
• The magnetic fields of hot subdwarf stars
• Asteroseismic analysis of variable hot subdwarf stars observed with TESS I. The mean g-mode period spacings in hot subdwarf B stars
• The effects of near-core convective shells on the gravity modes of the subdwarf B pulsator KIC 10553698A
• Limits on Mode Coherence in Pulsating DA White Dwarfs Due to a Non-static Convection Zone
• Mode identification in three pulsating hot subdwarfs observed with TESS satellite
• KIC 10001893: A pulsating sdB star with multiple trapped modes
• The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data
• High-degree gravity modes in the single sdB star HD4539
• Looking into the cradle of the grave: J22564-5910, a young post-merger hot subdwarf?
• Pulsating subdwarf B stars observed with K2 during Campaign 7 and an examination of seismic group-properties
• EPIC 216747137: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion
• Asteroseismology across the HR diagram

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