A remarkable change of the spectrum of the magnetic Of?p star HD 148937 reveals evidence of an eccentric, high-mass binary

Abstract

We report new spectroscopic observations of the magnetic Of?p star HD 148937 obtained since 2015 that differ qualitatively from its extensive historical record of weak, periodic spectral variations. This remarkable behaviour represents clear evidence for an unprecedented change in the character of variability of the star. In this paper we describe the new spectral properties and compare them to the previous line profiles. Based on measurements of the radial velocities of the C iii/N iii} emission lines near 4640 Å and the C iv absorption lines near 5800 Å, we infer that HD 148937 is likely a high-mass, double-lined spectroscopic binary. Combining the spectroscopic orbit with an archival interferometric measurement of the apparent separation of the equal-brightness components, we tentatively conclude that HD 148937 consists of two O-type stars with masses of approximately 34 and $49M_{\odot }$, orbiting in an eccentric ($e=0.75$), long-period ($P_{\mathrm{orb}}\sim 26$ y) orbit. We discuss the potential relationship of the binary system to the peculiar properties of HD 148937, and propose future observations to refine the orbital and stellar properties.

arXiv comment12 pages, accepted by MNRAS

References in corpus (26)

• Gaia Data Release 2: The astrometric solution
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Pre-Supernova Evolution of Massive Single and Binary Stars
• Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• Early Results from the Galactic O-Star Spectroscopic Survey: C III Emission Lines in Of Spectra
• Magnetic massive stars as progenitors of "heavy" stellar-mass black holes
• Kinematics of OB-associations and the new reduction of the Hipparcos data
• X-ray emission from magnetic massive stars
• Stokes IQUV Magnetic Doppler Imaging of Ap stars I. ESPaDOnS and NARVAL Observations
• New findings on the prototypical Of?p stars
• X-ray emission from interacting massive binaries: a review of 15 years of progress
• Possible pair-instability supernovae at solar metallicity from magnetic stellar progenitors
• The ESO Diffuse Interstellar Bands Large Exploration Survey: EDIBLES I. Project description, survey sample and quality assessment
• The spectral variability and magnetic field characteristics of the Of?p star HD 148937
• Exploring the origin of magnetic fields in massive stars: A survey of O-type stars in clusters and in the field
• Early-type stars observed in the ESO UVES Paranal Observatory Project: I -- Interstellar Na I UV, Ti II and Ca II K observations
• HD148937: a multiwavelength study of the third Galactic member of the Of?p class
• The 2.35 year itch of Cyg OB2 #9 - I. Optical and X-ray monitoring
• A Period and a Prediction for the Of?p Spectrum Alternator HD 191612
• High-resolution X-ray spectroscopy of the magnetic Of?p star HD148937
• The large- and small-scale CaII K structure of the Milky Way from observations of Galactic and Magellanic sightlines
• Evolutionary status of the Of?p star HD148937 and of its surrounding nebula NGC6164/5
• Review: Magnetic fields of O stars

Cited by in corpus (7)

• The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography
• A magnetic massive star has experienced a stellar merger
• Modelling of the B-type binaries CW Cep and U Oph: A critical view on dynamical masses, core boundary mixing, and core mass
• The very slow rotation of the magnetic O9.7V star HD54879
• Discovery and Characterization of a Rare Magnetic Hybrid $\beta$ Cephei Slowly Pulsating B-type Star in an Eclipsing Binary in the Young Open Cluster NGC 6193
• Diving into the magnetosphere of the Of?p star HD108
• Two Nested Shells around the Blue Supergiant ALS 19653