TY - JOUR
T1 - An 'analytic dynamical magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars
AU - Owocki, Stanley P.
AU - ud-Doula, Asif
AU - Sundqvist, Jon O.
AU - Petit, Veronique
AU - Cohen, David H.
AU - Townsend, Richard H.D.
N1 - Funding Information:
This work was supported in part by SAO Chandra grant TM3-14001A and NASA Astrophysics Theory Program grant NNX11AC40G, awarded to the University of Delaware. AuD acknowledges support by NASA through Chandra Award number TM4-15001A and 16200111 issued by the Chandra X-ray Observatory Center which is operated by the Smithsonian Astrophysical Observatory for and behalf of NASA under contract NAS8-03060. AuD also acknowledges support for programme number HST-GO-13629.008-A provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. JOS acknowledges funding from the European Unions Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 656725. DHC acknowledges support of Chandra grant TM4-15001B to Swarthmore College. RHDT acknowledges NASA ATP Grant NNX08AT36H to the University of Wisconsin. VP acknowledges partial support of NNX15AG33G from NASA's XMM-Newton Guest Observer Facility, and NASA Chandra grants TM4-15001C and GO3-14017A. We thank D. Kee and G. Wade for many fruitful discussions. We thank the anonymous referee for many constructive criticisms and comments that helped to improve the final version of this paper.
Publisher Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2016/11/11
Y1 - 2016/11/11
N2 - Slowly rotating magnetic massive stars develop 'dynamical magnetospheres' (DMs), characterized by trapping of stellar wind outflow in closed magnetic loops, shock heating from collision of the upflow from opposite loop footpoints, and subsequent gravitational infall of radiatively cooled material. In 2D and 3D magnetohydrodynamic (MHD) simulations, the interplay among these three components is spatially complex and temporally variable, making it difficult to derive observational signatures and discern their overall scaling trends. Within a simplified, steady-state analysis based on overall conservation principles, we present here an 'analytic dynamical magnetosphere' (ADM) model that provides explicit formulae for density, temperature, and flow speed in each of these three components - wind outflow, hot post-shock gas, and cooled inflow - as a function of colatitude and radius within the closed (presumed dipole) field lines of the magnetosphere. We compare these scalings with time-averaged results from MHD simulations, and provide initial examples of application of this ADM model for deriving two key observational diagnostics, namely hydrogen Hα emission line profiles from the cooled infall, and X-ray emission from the hot post-shock gas. We conclude with a discussion of key issues and advantages in applying this ADM formalism towards derivation of a broader set of observational diagnostics and scaling trends for massive stars with such dynamical magnetospheres.
AB - Slowly rotating magnetic massive stars develop 'dynamical magnetospheres' (DMs), characterized by trapping of stellar wind outflow in closed magnetic loops, shock heating from collision of the upflow from opposite loop footpoints, and subsequent gravitational infall of radiatively cooled material. In 2D and 3D magnetohydrodynamic (MHD) simulations, the interplay among these three components is spatially complex and temporally variable, making it difficult to derive observational signatures and discern their overall scaling trends. Within a simplified, steady-state analysis based on overall conservation principles, we present here an 'analytic dynamical magnetosphere' (ADM) model that provides explicit formulae for density, temperature, and flow speed in each of these three components - wind outflow, hot post-shock gas, and cooled inflow - as a function of colatitude and radius within the closed (presumed dipole) field lines of the magnetosphere. We compare these scalings with time-averaged results from MHD simulations, and provide initial examples of application of this ADM model for deriving two key observational diagnostics, namely hydrogen Hα emission line profiles from the cooled infall, and X-ray emission from the hot post-shock gas. We conclude with a discussion of key issues and advantages in applying this ADM formalism towards derivation of a broader set of observational diagnostics and scaling trends for massive stars with such dynamical magnetospheres.
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U2 - 10.1093/mnras/stw1894
DO - 10.1093/mnras/stw1894
M3 - Article
AN - SCOPUS:84994499324
SN - 0035-8711
VL - 462
SP - 3830
EP - 3844
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -