The complex environment and peculiar chemistry of the DR Tau protoplanetary disk

Jane Huang, Edwin Bergin, Jaehan Bae, Myriam Benisty, Sean M. Andrews, Romane Le Gal

The T Tauri star DR Tau has long been noted for its peculiar activity. To better understand the properties of this system, we obtained NOEMA observations of DR Tau across a suite of molecular lines. CO emission reveals an envelope, a faint asymmetric outflow, and a spiral arm. The 1200 au extent of the CO arm far exceeds that of the spiral arms previously detected in scattered light, which underlines the necessity of sensitive molecular imaging for contextualizing the disk environment. The complex environment of DR Tau is reminiscent of those of outbursting FUor sources and some EXor sources, suggesting that DR Tau’s extreme stellar activity could likewise be linked to disk instabilities promoted by large-scale infall. In striking contrast to most other disks observed so far, DR Tau exhibits strong SO emission and comparatively weak C2H and HCN emission, which may point to an atypical elemental C/O ratio.