Temperature, Mass and Turbulence: A Spatially Resolved Multi-Band Non-LTE Analysis of CS in TW~Hya

Abstract : Observations of multiple rotational transitions from a single molecule allow for unparalleled constraints on the physical conditions of the emitting region. We present an analysis of CS in TW~Hya using the $J=7-6$, $5-4$ and $3-2$ transitions imaged at $\sim 0.5^{\prime\prime}$ spatial resolution, resulting in a temperature and column density profile of the CS emission region extending out to 230~au, far beyond previous measurements. In addition, the 15~kHz resolution of the observations and the ability to directly estimate the temperature of the CS emitting gas, allow for one of the most sensitive searches for turbulent broadening in a disk to date. Limits of $v_{\rm turb} \lesssim 0.1 c_s$ can be placed across the entire radius of the disk. We are able to place strict limits of the local H$_2$ density due to the collisional excitations of the observed transitions. From these we find that a minimum disk mass of $3 \times 10^{-4}~M_{\rm sun}$ is required to be consistent with the CS excitation conditions and can uniquely constrain the gas surface density profile in the outer disk.
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Astrophysical Journal, American Astronomical Society, 2018, 864 (2), pp.id. 133. 〈10.3847/1538-4357/aad80e〉
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https://hal.archives-ouvertes.fr/hal-01868353
Contributeur : Marie-Paule Pomies <>
Soumis le : mercredi 5 septembre 2018 - 13:42:42
Dernière modification le : dimanche 30 septembre 2018 - 18:22:02

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Richard Teague, Thomas Henning, S. Guilloteau, Edwin Bergin, Dmitri Semenov, et al.. Temperature, Mass and Turbulence: A Spatially Resolved Multi-Band Non-LTE Analysis of CS in TW~Hya. Astrophysical Journal, American Astronomical Society, 2018, 864 (2), pp.id. 133. 〈10.3847/1538-4357/aad80e〉. 〈hal-01868353〉

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