The discovery of high-amplitude 10.9-minute oscillations in the cool magnetic Ap star HD 115226

Abstract

We present the discovery of pulsational variations in the cool magnetic Ap star HD 115226 -- the first high-amplitude rapidly oscillating Ap star discovered with time-series spectroscopy. Using high-resolution spectra obtained with the HARPS instrument at the ESO 3.6-m telescope, we detect radial velocity variations with a period of 10.86 min in Pr III, Nd III, Dy III lines and in the narrow cores of hydrogen lines. Pulsational amplitudes exceed 1 km/s in individual lines of Nd III. The presence of running waves in the stellar atmosphere is inferred from a phase shift between the radial velocity maxima of rare-earth and hydrogen lines. Our abundance analysis demonstrates that HD 115226 exhibits typical roAp spectroscopic signature, notably ionization anomaly of Pr, Nd and Dy. We discuss the discovery of pulsations in HD 115226 in the context of recent spectroscopic studies of roAp stars and point to the existence of correlation between spectroscopic pulsational amplitude and the stellar rotation rate.

arXiv comment4 pages, 3 figures; accepted for publication in Astronomy & Astrophysics

References in corpus (10)

• Evolutionary state of magnetic chemically peculiar stars
• Rare-earth elements in the atmosphere of the magnetic chemically peculiar star HD 144897. New classification of the Nd III spectrum
• Radial Velocity Variations in Pulsating Ap Stars. II. 33 Librae
• Pulsation tomography of rapidly oscillating Ap stars. Resolving the third dimension in peculiar pulsating stellar atmospheres
• Radial Velocity Variations in Pulsating Ap Stars III. The Discovery of 16.21 min Oscillations in Beta CrB
• Pulsational line profile variation of the roAp star HR 3831
• Indirect imaging of nonradial pulsations in a rapidly oscillating Ap star
• Line profile variations in rapidly oscillating Ap stars: resolution of the enigma
• Asteroseismic Signatures of Helium gradients in Main-Sequence A Stars ; Application to the roAp Star HD60435
• Observations of pulsations in roAp stars

Cited by in corpus (9)

• New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive
• The Nainital-Cape Survey-III : A Search for Pulsational Variability in Chemically Peculiar Stars
• The Nainital-Cape Survey-IV
• TESS Cycle 1 observations of roAp stars with 2-min cadence data
• Statistical analysis of roAp, He-weak and He-rich stars
• Discovery of very low amplitude 9-minute multiperiodic pulsations in the magnetic Ap star HD 75445
• A theoretical tool for the study of radial velocities in the atmospheres of roAp stars
• USuRPER: Unit-Sphere Representation PERiodogram for full spectra
• Numerical simulations of line-profile variation beyond a single-surface approximation for oscillations in roAp stars