Are the outflows in FU Orionis systems driven by the stellar magnetic field

摘要: FU Orionis (FUOR) outbursts are major optical brightening episodes in low-mass protostars that evidently correspond to rapid mass-accretion events the innermost region of a protostellar disc. The accompanied by strong outflows, with inferred mass outflow rates reaching 10% inflow rates. Shu et al. proposed outflows represent accreted disc material is driven centrifugally from spun-up surface layers protostar stellar magnetic field. This model was critiqued Calvet al., who argued it cannot reproduce photospheric absorption-line shifts observed prototype object Ori. wind launched, instead, on scales few radii non-stellar In this paper we present results numerical simulations accretion slowly rotating star an aligned dipole moment gives rise kilogauss-strength We demonstrate that, for parameters appropriate Ori, such system can develop strong, collimated type previously identified Romanova low and moderate At high rate characterizes FUOR outburst phase, radius rm at which truncated field moves much closer surface, but basic properties outflow, launched vicinity along opened-up lines, remain same. These distinct those X-celerator (or closely related X-wind) mechanism ‐ particular, start pressuregradient force, not centrifugally, more strongly collimated. show simulated principle account main characteristics winds, including line measured A detailed radiative-transfer calculation is, however, required confirm latter result.