K2 photometry and HERMES spectroscopy of the blue supergiant rho Leo: rotational wind modulation and low-frequency waves

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    C. Aerts, Radboud Univ Nijmegen, Radboud University Nijmegen, IMAPP, Dept Astrophys, D. M. Bowman, Katholieke Univ Leuven, KU Leuven, Inst Sterrenkunde, S. Simon-Diaz, Univ La Laguna, Universidad de la Laguna, Dept Astrofis, B. Buysschaert, Univ Paris Diderot, Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, Universite Sorbonne Paris Cite-USPC (ComUE), University of Paris Diderot, PSL Research University Paris (ComUE), Sorbonne Universite, UPMC Univ Paris 06, Sorbonne Univ, LESIA,Observ Paris,PSL Res Univ,CNRS,Sorbonne Par, C. Johnston, Katholieke Univ Leuven, KU Leuven, Inst Sterrenkunde, E. Moravveji, Katholieke Univ Leuven, KU Leuven, Inst Sterrenkunde, P. G. Beck, Instituto de Astrofísica de Canarias, Univ La Laguna, Universidad de la Laguna, Dept Astrofis, P. De Cat, Royal Observ Belgium, S. Triana, Royal Observ Belgium, S. Aigrain, Univ Oxford, University of Oxford, Dept Phys Astrophys, DWB, N. Castro, Univ Michigan, University of Michigan, University of Michigan System, Dept Astron, D. Huber, Univ Hawaii, University of Hawaii System, Inst Astron, Univ Sydney, University of Sydney, SIfA, Sch Phys, SETI Inst,
  • T. White

We present an 80-d long uninterrupted high-cadence K2 light curve of the B1Iab supergiant rho Leo (HD91316), deduced with the method of halo photometry. This light curve reveals a dominant frequency of f(rot) = 0.0373 d(-1) and its harmonics. This dominant frequency corresponds with a rotation period of 26.8 d and is subject to amplitude and phase modulation. The K2 photometry additionally reveals multiperiodic low-frequency variability (<1.5 d(-1)) and is in full agreement with low-cadence high-resolution spectroscopy assembled during 1800 d. The spectroscopy reveals rotational modulation by a dynamic aspherical wind with an amplitude of about 20 km s(-1) in the H alpha line, as well as photospheric velocity variations of a few kms(-1) at frequencies in the range 0.2-0.6 d(-1) in the Si III 4567 angstrom line. Given the large macroturbulence needed to explain the spectral line broadening of the star, we interpret the detected photospheric velocity as due to travelling superinertial low-degree large-scale gravity waves with dominant tangential amplitudes and discuss why. Leo is an excellent target to study how the observed photospheric variability propagates into the wind.

Original languageEnglish
JournalRoyal Astronomical Society. Monthly Notices
Issue number1
Pages (from-to)1234-1241
Number of pages8
StatePublished - May 2018

    Research areas

  • asteroseismology - techniques, photometric - techniques, spectroscopic - stars, massive - stars, oscillations - stars, rotation, LINE-PROFILE VARIATIONS, EARLY-TYPE STARS, PRESUPERNOVA EVOLUTION, MASSIVE STARS, VARIABILITY, OSCILLATIONS, KEPLER, MODE, VARIABLES, AMPLITUDE

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