2020/11/02 by Lewis G. Ireland, C. Zanni, Claudio Zanni +3
Physics and Astronomy · #Accretion (finance) #Angular momentum #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Field strength #Intermediate polar #Magnetic field #Physics #Solar wind #Star formation #Stars #Stellar magnetic field #Stellar mass #Stellar rotation #Stellar, planetary, and galactic studies #T Tauri star #White dwarf #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/abc828
26 pages, 14 figures
arxiv created 2020/11/02 · openalex publication_date 2020/12/29 · arxiv updated 2021/01/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The rotational evolution of an accreting pre-main-sequence star is influenced by its magnetic interaction with its surrounding circumstellar disk. Using the PLUTO code, we perform 2.5D magnetohydrodynamic, axisymmetric, time-dependent simulations of star–disk interaction—with an initial dipolar magnetic field structure, and a viscous and resistive accretion disk—in order to model the three mechanisms that contribute to the net stellar torque: accretion flow, stellar wind, and magnetospheric ejections (periodic inflation and reconnection events). We investigate how changes in the stellar magnetic field strength, rotation rate, and mass accretion rate (changing the initial disk density) affect the net stellar torque. All simulations are in a net spin-up regime. We fit semi-analytic functions for the three stellar torque contributions, allowing for the prediction of the net stellar torque for our parameter regime, as well as the possibility of investigating spin evolution using 1D stellar evolution codes. The presence of an accretion disk appears to increase the efficiency of stellar torques compared to isolated stars, for cases with outflow rates much smaller than accretion rates, because the star–disk interaction opens more of the stellar magnetic flux compared to that from isolated stars. In our parameter regime, a stellar wind with a mass-loss rate of ≈1% of the mass accretion rate is capable of extracting ≲50% of the accreting angular momentum. These simulations suggest that achieving spin equilibrium in a representative T Tauri case within our parameter regime, e.g., BP Tau, would require a wind mass-loss rate of ≈25% of the mass accretion rate.