HD 42659: The only known roAp star in a spectroscopic binary observed with B photometry, TESS and SALT

Abstract

We present a multi-instrument analysis of the rapidly oscillating Ap (roAp) star HD 42659. We have obtained $B$ photometric data for this star and use these data, in conjunction with TESS observations, to analyse the high-frequency pulsation in detail. We find a triplet which is split by the rotation frequency of the star (${\nu }_{\mathrm{rot}}=0.3756$ d${}^{-1}$; $P_{\mathrm{rot}}=2.66$ d) and present both distorted dipole and distorted quadrupole mode models. We show that the pulsation frequency, $150.9898$ d${}^{-1}$ ($P_{\mathrm{puls}}=9.54$ min) is greater than the acoustic cutoff frequency. We utilise 27 high-resolution ($R\simeq 65000$), high signal-to-noise ($\sim 120$) spectra to provide new orbital parameters for this, the only known roAp star to be in a short period binary ($P_{\mathrm{orb}}=93.266$ d). We find the system to be more eccentric than previously thought, with $e=0.317$, and suggest the companion is a mid-F to early-K star. We find no significant trend in the average pulsation mode amplitude with time, as measured by TESS, implying that the companion does not have an affect on the pulsation in this roAp star. We suggest further photometric observations of this star, and further studies to find more roAp stars in close binaries to characterise how binarity may affect the detection of roAp pulsations.

9 pages, 11 figures, 6 tables. Accepted for publication in MNRAS

References in corpus (22)

• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Modern stellar spectroscopy caveats
• Evolutionary state of magnetic chemically peculiar stars
• The dependence of dark halo clustering on the formation epoch and the concentration parameter
• Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I
• Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments
• Lensing Constraints on the Mass Profile Shape and the Splashback Radius of Galaxy Clusters
• 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
• Evolution of magnetic fields in stars across the upper main sequence: I. Catalogue of magnetic field measurements with FORS1 at the VLT
• Cosmological constraints from Subaru weak lensing cluster counts
• On mode conversion and wave reflection in magnetic Ap stars
• To the center of cold spot with Planck
• The imprint of $f(R)$ gravity on weak gravitational lensing II : Information content in cosmic shear statistics
• HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode
• HD 99458: First time ever Ap-type star as a $\delta$ Scuti pulsator in a short period eclipsing binary?
• Prime Focus Spectrograph - Subaru's future -
• The metrology cameras for Subaru PFS and FMOS
• Six new rapidly oscillating Ap stars in the Kepler long-cadence data using super-Nyquist asteroseismology
• Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star
• SALT spectroscopy of evolved massive stars

Cited by in corpus (5)

• The DES view of the Eridanus supervoid and the CMB Cold Spot
• Shapley Supercluster Survey: mapping the dark matter distribution
• Subaru Hyper Suprime-Cam excavates colossal over- and under-dense structures over 360 deg2 out to z=1
• Cosmic voids and induced hyperbolicity. II. Sensitivity to void/wall scales
• Cosmic voids and induced hyperbolicity