YSOs Outflows, Disks and Accretion (YODA)
Towards a global framework for the evolution of planet forming systems
YODA is a project financed by INAF under the scheme LARGE-GRANTS 2022. The project aims at bringing together the observational and theoretical skills of the JEDI (JEts and Disks@INAF) collaboration to test the recently proposed models for proto-planetary disks evolution.
The new surveys of young stars and their disks have questioned the paradigm of disk viscous accretion evolution, motivating the development of alternative scenarios that consider wind-driven accretion. Establishing which mechanism drives the disk evolution, and consequently how gas and dust distribution is affected, has profound implications for the understanding of how planets form and migrate during the early phases of the disk life.
With this project we will build a coherent and comprehensive picture of this key topic thanks to the diverse expertise available within the JEDI team.
SCIENTIFIC THEMES
ACCRETION AT DIFFERENT SCALES
Distribution of mass accretion rates vs the disk mass for young star populations at different ages. Contrary to expectations from viscous theories, the sources of the old region UpSco (5-10Myr) show the same range of Macc and level of scatter as the younger (2-3 Myr) Lupus and Cha sources (Manara+2020).
Comparison between the mass accretion vs disk mass distribution observed in Lupus (red dots) and results of a population synthesis model (black dots) developed by members of the YODA team (Tabone, Rosotti+2021). The model assumes a mass ejection-to-accretion ratio fM = 0.6.
Integrated intensity (upper) and velocity map (bottom) of the SO line emission observed within the ALMA-DOT project on HL Tau (from Garufi+ 2022). The images show a clear case of inflowing streamer of material impacting the disk on the redshifted side. We will study these streamers by means of both ALMA and SPHERE observations, and in comparison with other properties of the disk. This will allow us to infer their impact for the disk mass content, composition and global stability.
THE ROLE OF JETS AND WINDS
Sketch of the different outflow manifestations occurring on the disk surface at different radial scales. Thanks to our multi-wavelength approach we will be able to observe the various type of jets and winds in the same source and relate them with the source properties, simultaneously derived from the UV/optical/NIR/MIR/submm data taken at different facilities (HST/VLT/JWST/ALMA).
Intensity map of the emission in the CO J(2-1) line centered on HL Tau, taken with ALMA (Bacciotti et al., in prep.). The magenta ellipse marks the position of the HL Tau disk from the continuum emission of the dust. The superimposed contours are from a seeing-limited map of the atomic jet. Within YODA, the link between the molecular wide angle flow and the atomic jet will be studied through new JWST diffraction limited images and theoretical models of MHD winds.
Comparison of atomic and molecular wind tracers taken at different facilities and wavelengths of one of the targets of our sample (Gangi+2020, Nisini+2023). The different lines probe different radial regions of the disk and will be used to infer the mass loss in the various regions. Thermo-chemical models predicting both the atomic and molecular lines will be also developed within the YODA team.
Theoretical line profiles of mid-IR lines of different ions predicted by the group of Barbara Ercolano in a photo-evaporative wind model (Picogna +2009; Weber+ 2020). These lines, which trace disk regions > 30 au, will be observed by JWST in a number of targets of our sample.
THE DISK GAS KINEMATICS AND RADIAL DISTRIBUTION
Gas disk sizes of a wind-driven model for two initial disk radii Rc,0 (left panel, from Trapman, Tabone, Rosotti + 2021) and a viscous disk model (right panel, from Trapman, Rosotti+ 2020) compared with observations of a sample of disks in Lupus (age 2 Myr) and Upper Sco (age 5-10 Myr). Observations acquired within the ALMA Large Programs ExoALMA and AgePRO (where the members of our team Lodato and Rosotti are involved), will inform us on the disk radii and the viscosity parameter alpha for a larger samples of disks at different ages. All the other parameters needed to tightly constrain the models (i.e. mass accretion, mass loss, disk mass and stellar parameters) will be delivered within the YODA project, thus it will be possible for the first time to obtain a coherent discrimination between the different theoretical expectations.