A face-on accretion system in high-mass star formation: possible dusty infall streams within 100 AU

K Motogi, T Hirota, K Sorai, Y Yonekura… - The Astrophysical …, 2017 - iopscience.iop.org
K Motogi, T Hirota, K Sorai, Y Yonekura, K Sugiyama, M Honma, K Niinuma, K Hachisuka…
The Astrophysical Journal, 2017iopscience.iop.org
We report on interferometric observations of a face-on accretion system around the high-
mass young stellar object, G353. 273+ 0.641. The innermost accretion system of 100 au
radius was resolved in a 45 GHz continuum image taken with the Jansky-Very Large Array.
Our spectral energy distribution analysis indicated that the continuum could be explained by
optically thick dust emission. The total mass of the dusty system is∼ 0.2 M☉ at minimum
and up to a few M☉ depending on the dust parameters. 6.7 GHz CH 3 OH masers …
Abstract
We report on interferometric observations of a face-on accretion system around the high-mass young stellar object, G353. 273+ 0.641. The innermost accretion system of 100 au radius was resolved in a 45 GHz continuum image taken with the Jansky-Very Large Array. Our spectral energy distribution analysis indicated that the continuum could be explained by optically thick dust emission. The total mass of the dusty system is∼ 0.2 M☉ at minimum and up to a few M☉ depending on the dust parameters. 6.7 GHz CH 3 OH masers associated with the same system were also observed with the Australia Telescope Compact Array. The masers showed a spiral-like, non-axisymmetric distribution with a systematic velocity gradient. The line-of-sight velocity field is explained by an infall motion along a parabolic streamline that falls onto the equatorial plane of the face-on system. The streamline is quasi-radial and reaches the equatorial plane at a radius of 16 au. This is clearly smaller than that of typical accretion disks in high-mass star formation, indicating that the initial angular momentum was very small, or the CH 3 OH masers selectively trace accreting material that has small angular momentum. In the former case, the initial specific angular momentum is estimated to be 8× 10 20 (
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