Year: 2025
Type: article
Abstract: Context . Edge-on disks offer a unique opportunity to directly examine their vertical structure, which provides valuable insights into planet formation processes. We investigated the dust properties as well as the CO and HCO + gas properties in the edge-on disk surrounding the T Tauri star 2MASS J04202144+281349 (SSTTau042021). Aims . We estimated the radial and vertical temperature and density profile for the gas and the dust. Methods . We used ALMA archival data of CO isotopologs and continuum emission at 2, 1.3, and 0.9 mm together with new NOEMA HCO + 3-2 observations. We retrieved the gas and dust disk properties using the tomographic method and the D ISK F IT model. Results . The vertical CO emission appears to be very extended and partly traces the H 2 wind observed by JWST. The C 18 O, 13 CO, and HCO + emission characterize the bulk of the molecular layer. The dust and gas have midplane temperatures of ∼7-11 K. The temperature of the molecular layer (derived from 13 CO and HCO + ) is on the order of 16 K. Because HCO + 3-2 is thermalized, we derived a lower limit for the H 2 volume density of ∼3 × 10 6 cm −3 at a radius of 100-200 au between one and two scale heights. The atmosphere temperature of the CO gas is ∼31 K at a radius of 100 au. We directly observed CO and HCO + gas in the midplane beyond the dust outer radius (≥300 au). The gas plus dust disk mass estimated up to a radius of 300 au is on the order of 4.6 × 10 −2 M ⊙ . Conclusions . The favorable disk inclination allows us to present the first quantitative evidence for vertical molecular stratification with a direct observation of CO and HCO + gas in the midplane. We estimate a temperature profile with a temperature of 7-11 K near the midplane and of 15-20 K in the dense part of the molecular layer up to ∼35 K above the midplane.
Source: Astronomy and Astrophysics
Institutions: Centre National de la Recherche Scientifique, Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, Instituto de Radioastronomía Milimétrica, Ausonius Institut de Recherche sur l'Antiquité et le Moyen age, University of Chile, Institut des Sciences Moléculaires d'Orsay, University of Bologna, Search for Extraterrestrial Intelligence, Max Planck Institute for Astronomy, Eötvös Loránd University, Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, Université Paris Sciences et Lettres, Observatoire de Paris, Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes, National Institute of Science Education and Research, Homi Bhabha National Institute, Queen Mary University of London, Trung tâm Vũ trụ Việt Nam, Vietnam Academy of Science and Technology, Heidelberg University, Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica, Christian-Albrechts-Universität zu Kiel
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Science Foundation, Vietnam Academy of Science and Technology, National Radio Astronomy Observatory, Centre National d’Etudes Spatiales, Korea Astronomy and Space Science Institute, Max-Planck-Gesellschaft, Ministry of Science and Technology, Taiwan, Centre National de la Recherche Scientifique, National Astronomical Observatory of Japan, Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, National Science and Technology Council, National Institutes of Natural Sciences
OpenAlex ID: W4416712895