2001/10/24 by Hsien Shang, H. Shang, A. E. Glassgold +4 · 4 citations
Physics and Astronomy · #Ambipolar diffusion #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Computational physics #Diffusion #Ion #Ionization #Mechanics #Meteorology #Nuclear physics #Opacity #Optics #Physics #Plasma #Radiative transfer #Stellar, planetary, and galactic studies #Thermal #Thermal wind #Thermodynamics #Wind speed #astro-ph
paper · pdf · doi:10.1086/324197
48 pages, 5 figures, ApJ in press. For better figures, go to http://www.asiss.sinica.edu.tw/theory/prints.html
arxiv created 2001/10/24 · openalex publication_date 2002/01/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In order to compare the X -wind with observations, one needs to be able to calculate its thermal and ionization properties. We formulate the physical basis for the streamline-by-streamline integration of the ionization and heat equations of the steady X -wind. In addition to the well-known processes associated with the interaction of stellar and accretion funnel hot spot radiation with the wind, we include X-ray heating and ionization, mechanical heating, and a revised calculation of ambipolar diffusion heating. The mechanical heating arises from fluctuations produced by star-disk interactions of the time-dependent X -wind that are carried by the wind to large distances where they are dissipated in shocks, MHD waves, and turbulent cascades. We model the time-averaged heating by the scale-free volumetric heating rate, Γ mech = αρ v 3 s -1 , where ρ and v are the local mass density and wind speed, respectively, s is the distance from the origin, and α is a phenomenological constant. When we consider a partially revealed but active young stellar object, we find that choosing α ~ 10 -3 in our numerical calculations produces temperatures and electron fractions that are high enough for the X -wind jet to radiate in the optical forbidden lines at the level and on the spatial scales that are observed. We also discuss a variety of applications of our thermal-chemical calculations that can lead to further observational checks of X -wind theory.