Poster abstract
Radiation Pressure Problem in the Massive Star Formation: Shielding by the Dust-Free Disk
Abstract
In the formation of the massive stars, the radiation pressure acting the dust grains exceeds the gravitational force. The strong radiation pressure would disturb the mass accretion, and may limit the stellar masses. The radiation pressure force is thought to act strongest at first absorbed region, i.e. behind the dust sublimation front. To overcome the direct stellar radiation feedback, it is argued that the ram pressure with high accretion rates (Wolfire & Cassinelly 1987, in spherical accretion) or gravity force with sufficient radial surface density (Tanaka & Nakamoto 2010, Kuiper et al. 2010, in disk accretion) is needed. However, previous works assumed that the dust-free region (>2000K) is optically thin and neglected the gas opacity. Since the gas opacity is not equal to completely zero, it seems necessary to take into account the gas opacity to investigate the dense disk structure.
In this work, we semi-analytically calculate the structures of the dust-free disks, taking into account the gas opacity. In the result, we show that the dust-free disk is optically thick for a wide range of parameters. Thus, the dust sublimation front would be shielded by the optically thick dust-free disk from direct stellar feedback, and accretion flow is not halted there. In this poster, we present structures of the innermost accretion disks and the condition for disk shielding.
In this work, we semi-analytically calculate the structures of the dust-free disks, taking into account the gas opacity. In the result, we show that the dust-free disk is optically thick for a wide range of parameters. Thus, the dust sublimation front would be shielded by the optically thick dust-free disk from direct stellar feedback, and accretion flow is not halted there. In this poster, we present structures of the innermost accretion disks and the condition for disk shielding.