An 'analytic dynamical magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars

Stanley P. Owocki, Asif Ud-Doula, Jon O. Sundqvist, Veronique Petit, David H. Cohen, Richard H.D. Townsend

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
Pages (from-to)3830-3844
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume462
Issue number4
DOIs
StatePublished - Nov 11 2016

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magnetic stars
massive stars
magnetospheres
magnetosphere
light emission
formalism
magnetohydrodynamic simulation
x rays
magnetohydrodynamics
scaling
outflow
shock
shock heating
trends
complex variables
stellar winds
gases
gas
simulation
trapping

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Owocki, Stanley P. ; Ud-Doula, Asif ; Sundqvist, Jon O. ; Petit, Veronique ; Cohen, David H. ; Townsend, Richard H.D. / An 'analytic dynamical magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 462, No. 4. pp. 3830-3844.
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An 'analytic dynamical magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars. / Owocki, Stanley P.; Ud-Doula, Asif; Sundqvist, Jon O.; Petit, Veronique; Cohen, David H.; Townsend, Richard H.D.

In: Monthly Notices of the Royal Astronomical Society, Vol. 462, No. 4, 11.11.2016, p. 3830-3844.

Research output: Contribution to journalArticle

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