Dynamical mass measurements of two protoplanetary discs

Abstract

ALMA observations of line emission from planet forming discs have demonstrated to be an excellent tool to probe the internal disc kinematics, often revealing subtle effects related to important dynamical processes occurring in them, such as turbulence, or the presence of planets, that can be inferred from pressure bumps perturbing the gas motion, or from detection of the planetary wake. In particular, we have recently shown for the case of the massive disc in Elias 2-27 how one can use such kind of observations to measure deviations from Keplerianity induced by the disc self-gravity, thus constraining the total disc mass with good accuracy and independently on mass conversion factors between the tracer used and the total mass. Here, we refine our methodology and extend it to two additional sources, GM Aur and IM Lup, for which archival line observations are available for both the 12CO and the 13CO line. For IM Lup, we are able to obtain a consistent disc mass of Mdisc = 0.1 M⊙, implying a disc-star mass ratio of 0.1 (consistent with the observed spiral structure in the continuum emission) and a gas/dust ratio of ∼65 (consistent with standard assumptions), with a systematic uncertainty by a factor ≃ 2 due to the different methods to extract the rotation curve. For GM Aur, the two lines we use provide slightly inconsistent rotation curves, that cannot be attributed only to a difference in the height of the emitting layer, nor to a vertical temperature stratification. Our best fit disc mass measurement is Mdisc = 0.26 M⊙, implying a disc-star mass ratio of ∼0.35 and a gas/dust ratio of ∼130. Given the complex kinematics in the outer disc of GM Aur and its interaction with the infalling cloud, the CO lines might not well trace the rotation curve and our results for this source should then be considered with some caution.

Early Planet Formation in Embedded Disks (eDisk). II. Limited Dust Settling and Prominent Snow Surfaces in the Edge-on Class I Disk IRAS 04302+2247

“…There is growing evidence of other Class 0/I sources that are marginally gravitationally unstable (e.g., Kwon et al 2011;Tobin et al 2020;Xu 2022). Furthermore, from an evolutionary standpoint, this is in line with evidence of Class II sources with Q that largely falls within 1−10 (e.g., Kwon et al 2015;Cleeves et al 2016;Booth et al 2019;Paneque-Carreño et al 2021;Schwarz et al 2021;Sierra et al 2021;Veronesi et al 2021;Lodato et al 2023;Ueda et al 2022;Yoshida et al 2022).…”

CI Traces the Disk Atmosphere in the IM Lup Protoplanetary Disk

“…Although IM Lup and HD 142527 are both disks around T Tauri stars, they show more than one order of magnitude difference in their C I column densities. The IM Lup disk is also one order of magnitude more massive (Zhang et al 2021;Lodato et al 2023) than that of HD 142527 (Temmink et al 2023), which implies that the inferred C I column density is not particularly sensitive to the total disk mass, as previously indicated in the models of Pascucci et al (2023). The large millimeter dust cavity (≈100 au) of the HD 142527 disk leads to increased UV transparency, and thus also likely contributes to its larger C I column density.…”

“…IM Lup is a young (∼1 Myr), approximately solar-mass, T Tauri star located in the Lupus star-forming region (Mawet et al 2012;Alcalá et al 2017;) at a distance of d = 158 pc (Gaia Collaboration et al 2018) that hosts a massive (Zhang et al 2021;Lodato et al 2023) and unusually large protoplanetary disk extending to several hundreds of astronomical units in its millimeter dust (Andrews et al 2018;Huang et al 2018), near-infrared (NIR)/scattered light (Avenhaus et al 2018), and molecular line emission (Panić et al 2009;Cleeves et al 2016;Law et al 2021a). The outer region of its 12 CO gas disk, which reaches a maximum radius of ∼1000 au, is diffuse and envelope-like, potentially indicating the presence of an external photoevaporative wind (Haworth et al 2017).…”

Gravitational Instability, Spiral Substructure, and Modest Grain Growth in a Typical Protostellar Disk: Modeling Multiwavelength Dust Continuum Observations of TMC1A

“…Later on, Xu (2022) further demonstrates that the majority of Class 0/I disks in a recent multi-wavelength survey are consistent with being gravitationally self-regulated, and the low apparent mass is mainly a result of high optical depth hiding most disk mass. High masses in young disks have also been independently demonstrated in observational studies using techniques that are less affected by high optical depth (e.g., McClure et al 2016;Terry et al 2022;Lodato et al 2023).…”