We present the first detection of the 13C17O J=3-2 transition toward the HL Tau protoplanetary disc. We find significantly more gas mass (at least a factor of ten higher) than has been previously reported using C18O emission. This brings the observed total disc mass to 0.2 M, which we consider to be a conservative lower limit. Our analysis of the Toomre Q profile suggests that this brings the disc into the regime of gravitational instability. The radial region of instability (50-110 au) coincides with the location of a proposed planet-carved gap in the dust disc and a spiral in the gas. We, therefore, propose that if the origin of the gap is confirmed to be due to a forming giant planet, then it is likely to have formed via the gravitational fragmentation of the protoplanetary disc.
@article{arxiv.2001.07550,
title = {13C17O suggests gravitational instability in the HL Tau disc},
author = {Alice S. Booth and John D. Ilee},
journal= {arXiv preprint arXiv:2001.07550},
year = {2020}
}
Comments
Accepted 2020 January 21. Received 2020 January 21; in original form 2019 November 27