Multi-scale radiative-transfer model of the protoplanetary disc DoAr 44

¹ Charles University, Faculty of Mathematics and Physics, Astronomical Institute, V Holešovičkách 2, 18000 Prague, Czech Republic
² Heidelberg University, Department of Physics and Astronomy, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany

^★ Corresponding author: marco.souza_de_joode@stud.uni-heidelberg.de

Received: 18 December 2024
Accepted: 18 July 2025

Abstract

Aims. Our aim was to construct a comprehensive global multi-scale kinematic equilibrium radiative-transfer model for the pretransitional disc of DoAr 44 (Haro 1-16, V2062 Oph) in the Ophiuchus star-forming region. This model integrates diverse observational datasets to describe the system, spanning from the accretion region to the outer disc.

Methods. Our analysis utilised a large set of observational data, including ALMA continuum complex visibilities, VLTI/GRAVITY continuum squared visibilities, closure phases, and triple products, as well as VLT/UVES and VLT/X-shooter Hα spectra. Additionally, we incorporated absolute flux measurements from ground-based optical observatories, Spitzer, IRAS, the Submillimeter Array, the IRAM, or the ATCA radio telescopes. These datasets were used to constrain the structure and kinematics of the object through radiative-transfer modelling.

Results. Our model reveals that the spectral line profiles are best explained by an optically thin spherical inflow or outflow within the co-rotation radius of the star, exhibiting velocities exceeding 380 km/s. The VLTI near-infrared interferometric observations are consistent with an inner disc extending from 0.1 to 0.2 au. The ALMA sub-millimetre observations indicate a dust ring located between 36 and 56 au, probably related to the CO₂ condensation line. The global density and temperature profiles derived from our model provide insight into an intermediate disc, located in the terrestrial planet-forming zone, which has not yet been spatially resolved.