Spectroscopic and photometric variability of the O9.5Vp star HD93521

Abstract

The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Fourier techniques are used to characterize the modulations of the He I 5876, 6678 and H-alpha lines in several spectroscopic time series and to search for variations in a photometric time series. Our spectroscopic data confirm the existence of two periods of 1.75 and 2.89 hr. The line profiles, especially those affected by emission wings, exhibit also modulations on longer time scales, but these are epoch-dependent and change from line to line. Unlike previous claims, we find no unambiguous signature of the rotational period in our data, nor of a third pulsation period (corresponding to a frequency of 2.66 day${}^{-1}$). HD 93521 very likely exhibits non-radial pulsations with periods of 1.75 and 2.89 hr with $l\simeq 8\pm 1$ and $l\simeq 4\pm 1$ respectively. No significant signal is found in the first harmonics of these two periods. The 2.89 hr mode is seen at all epochs and in all lines investigated, while the visibility of the 1.75 hr mode is clearly epoch dependent. Whilst light variations are detected, their connection to these periodicities is not straightforward.

13 pages, 11 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (4)

• Fourier method in the determination of rotational velocities in OB stars
• A new method for the spectroscopic identification of stellar non-radial pulsation modes. I. The method and numerical tests
• delta Ceti is not monoperiodic: seismic modeling of a beta Cephei star from MOST spacebased photometry
• Radial Velocities of Six OB Stars

Cited by in corpus (17)

• The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
• Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150 and HD 46966
• On the photometric detection of Internal Gravity Waves in upper main-sequence stars I. Methodology and application to CoRoT targets
• An asteroseismic study of the O9V star HD 46202 from CoRoT space-based photometry
• Detection of frequency spacings in the young O-type binary HD 46149 from CoRoT photometry
• MOST detects corotating bright spots on the mid-O type giant ξ Persei
• Simultaneous X-ray and optical spectroscopy of the Oef supergiant lambda Cep
• Kepler's first view of O-star variability: K2 data of five O stars in Campaign 0 as a proof-of-concept for O-star asteroseismology
• Exploring the origin of magnetic fields in massive stars: II. New magnetic field measurements in cluster and field stars
• Plaskett's Star: Analysis of the CoRoT photometric data
• Chemical abundances of fast-rotating massive stars. II. Interpretation and comparison with evolutionary models
• The nature of the high Galactic latitude O-star HD93521: new results from X-ray and optical spectroscopy
• Similar but different: the varied landscape of Onfp/Oef stars variability
• The nature of the line profile variability in the spectrum of the massive binary HD 152219
• The Transformative Journey of HD 93521
• Spectroscopic study of the O-type runaway supergiant HD 195592
• Short-term spectroscopic variability of Plaskett's star