http://arxiv.org/abs/1604.03801
Using ALMA observations of the C$^{18}$O(2-1) line emission of the gas envelope of protostar L1527, we have reconstructed in space its morphology and kinematics under the assumption of axisymmetry about the west-east axis. We present evidence for rotation with a power law requiring an index increasing with decreasing distance from the star, as expected from a transition to Keplerian. The total velocity, interpreted as free-fall velocity, corresponds to a protostar mass of 0.2 solar masses. The very strong absorption slightly above systemic velocity prevents a reliable exploration at distances from the protostar smaller than $\sim$100 AU. The in-fall velocity, evaluated from the kinematics of the envelope without reference to this absorption, is found to be small and its variation over the explored range is poorly constrained. The accretion rate is evaluated at the scale of 2.5$\pm$1.0 10$^{-7}$ M$_{\odot}$. Deviations from a simple isothermal, stationary description are quantified. The overall morphology leaves room about the disk axis for a broad outflow and for a strong depression near the median plane. Finally, evidence is presented for the inclination of the median plane of the envelope to vary with distance from the star, requiring a non-trivial physical explanation.
P. Tuan-Anh, P. Nhung, D. Hoai, et. al.
Thu, 14 Apr 16
50/53
Comments: 10 pages, 12 figures, MNRAS submitted
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