@Article{LundWFVSBJK:2019:RaHySi,
               author = "Lund, Kristin and Wood, K. and Falceta-Gon{\c{c}}alves, Diego and 
                         Vandenbroucke, Bert and Sartorio, Nina Sanches and Bonnell, I. A. 
                         and Johnston, K. G. and Keto, E.",
          affiliation = "{University of St Andrews} and {University of St Andrews} and 
                         {University of St Andrews} and {University of St Andrews} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {University 
                         of St Andrews} and {The University of Leeds} and 
                         {Harvard-Smithsonian Center for Astrophysics}",
                title = "Radiation hydrodynamic simulations of massive star formation via 
                         gravitationally trapped H II regions – spherically symmetric 
                         ionized accretion flows",
              journal = "Monthly Notices of the Royal Astronomical Society",
                 year = "2019",
               volume = "485",
               number = "3",
                pages = "3761--3770",
                month = "May",
             keywords = "hydrodynamics, radiative transfer, stars: formation, stars: 
                         massive, H II regions.",
             abstract = "This paper investigates the gravitational trapping of H II regions 
                         predicted by steady-state analysis using radiation hydrodynamical 
                         simulations. We present idealized spherically symmetric radiation 
                         hydrodynamical simulations of the early evolution of H II regions 
                         including the gravity of the central source. As with analytic 
                         steady-state solutions of spherically symmetric ionized Bondi 
                         accretion flows, we find gravitationally trapped H II regions with 
                         accretion through the ionization front on to the source. We found 
                         that, for a constant ionizing luminosity, fluctuations in the 
                         ionization front are unstable. This instability only occurs in 
                         this spherically symmetric accretion geometry. In the context of 
                         massive star formation, the ionizing luminosity increases with 
                         time as the source accretes mass. The maximum radius of the 
                         recurring H II region increases on the accretion time-scale until 
                         it reaches the sonic radius, where the infall velocity equals the 
                         sound speed of the ionized gas, after which it enters a 
                         pressure-driven expansion phase. This expansion prevents accretion 
                         of gas through the ionization front, the accretion rate on to the 
                         star decreases to zero, and it stops growing from accretion. 
                         Because of the time required for any significant change in stellar 
                         mass and luminosity through accretion our simulations keep both 
                         mass and luminosity constant and follow the evolution from trapped 
                         to expanding in a piecewise manner. Implications of this evolution 
                         of H II regions include a continuation of accretion of material on 
                         to forming stars for a period after the star starts to emit 
                         ionizing radiation, and an extension of the lifetime of 
                         ultracompact H II regions.",
                  doi = "10.1093/mnras/stz621",
                  url = "http://dx.doi.org/10.1093/mnras/stz621",
                 issn = "0035-8711 and 1365-2966",
             language = "en",
           targetfile = "lund_radiation.pdf",
        urlaccessdate = "27 abr. 2024"
}