Rapid CO gas dispersal from NO Lup's class III circumstellar disc

Abstract

We observed the K7 class III star NO Lup in an ALMA survey of the 1-3 Myr Lupus association and detected circumstellar dust and CO gas. Here we show that the J = 3-2 CO emission is both spectrally and spatially resolved, with a broad velocity width $\sim 19$kms${}^{-1}$ for its resolved size $\sim 1^{\prime \prime }$ ($\sim 130$ au). We model the gas emission as a Keplerian disc, finding consistency, but only with a central mass of $\sim 11M_{\odot }$, which is implausible given its spectral type and X-Shooter spectrum. A good fit to the data can also be found by modelling the CO emission as outflowing gas with a radial velocity $\sim 22$kms${}^{-1}$. We interpret NO Lup's CO emission as the first imaged class III circumstellar disc with outflowing gas. We conclude that the CO is continually replenished, but cannot say if this is from the break-up of icy planetesimals or from the last remnants of the protoplanetary disc. We suggest further work to explore the origin of this CO, and its higher than expected velocity in comparison to photoevaporative models.

6 pages, 4 figures. Accepted for publication in MNRAS following peer review (this is a pre-copyedited, author-produced PDF version)

References in corpus (14)

• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• X-Shooter spectroscopy of young stellar objects in Lupus: Accretion properties of class II and transitional objects
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• Debris from giant impacts between planetary embryos at large orbital radii
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Molecular gas in debris disks around young A-type stars
• Five steps in the evolution from protoplanetary to debris disk
• A circumbinary protoplanetary disc in a polar configuration
• CO mass upper limits in the Fomalhaut ring - the importance of NLTE excitation in debris discs and future prospects with ALMA
• Population synthesis of exocometary gas around A stars
• On the Ubiquity and Stellar Luminosity Dependence of Exocometary CO Gas: Detection around M Dwarf TWA 7
• Radiation pressure clear-out of dusty photoevaporating discs
• The Observational Anatomy of Externally Photoevaporating Planet-Forming Discs I: Atomic Carbon
• Magnetohydrodynamics of protoplanetary discs

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