Multiple variability time-scales of the early nitrogen-rich Wolf-Rayet star WR7

Abstract

We present the analysis of the optical variability of the early, nitrogen-rich Wolf-Rayet (WR) star WR7. The analysis of multi-sector Transiting Exoplanet Survey Satellite (TESS) light curves and high-resolution spectroscopic observations confirm multi-periodic variability that is modulated on time-scales of years. We detect a dominant period of $2.6433\pm 0.0005$ d in the TESS sectors 33 and 34 light curves in addition to the previously reported high-frequency features from sector 7. We discuss the plausible mechanisms that may be responsible for such variability in WR7, including pulsations, binarity, co-rotating interacting regions (CIRs) and clumpy winds. Given the lack of strong evidence for the presence of a stellar or compact companion, we suggest that WR7 may pulsate in quasi-coherent modes in addition to wind variability likely caused by CIRs on top of stochastic low-frequency variability. WR7 is certainly a worthy target for future monitoring in both spectroscopy and photometry to sample both the short ($\lesssim 1$ d) and long ($\gtrsim 1000$ d) variability time scales.

9 pages, 5 Figures, 1 Table; Accepted to MNRAS

References in corpus (23)

• The Transiting Exoplanet Survey Satellite
• Binary interaction dominates the evolution of massive stars
• Physical Properties of Wolf-Rayet Stars
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• The Galactic WN stars: Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation
• Cross-Correlation and Maximum Likelihood Analysis: A New Approach to Combine Cross-Correlation Functions
• Spatial distribution of Galactic Wolf-Rayet stars and implications for the global population
• Wolf-Rayet stars in the Small Magellanic Cloud: I. Analysis of the single WN stars
• The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters
• Why binary interaction does not necessarily dominate the formation of Wolf-Rayet stars at low metallicity
• Massive heartbeat stars from TESS. I. TESS sectors 1-16
• Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227
• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars. I. The northern WC sequence
• The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33
• X-ray emission from BH+O star binaries expected to descend from the observed galactic WR+O binaries
• Excitation of g modes in Wolf-Rayet stars by a deep opacity bump
• Red noise and pulsations in evolved massive stars
• On the diffuse X-ray emission from the Wolf-Rayet Bubble NGC 2359
• The nature of the companion in the Wolf-Rayet system EZ Canis Majoris
• The Wolf-Rayet Stellar Response To The Iron Opacity Bump: Envelope Inflation, Winds, and Microturbulence
• X-rays from wind-blown bubbles: an XMM-Newton detection of NGC 2359
• The coupling between pulsation and mass loss in massive stars
• Classifying Be star variability with TESS I: the southern ecliptic

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