CODELLA, CLAUDIOCLAUDIOCODELLAPODIO, LINDALINDAPODIOGARUFI, ANTONIOANTONIOGARUFIPerrero, J.J.PerreroUgliengo, P.P.UgliengoFEDELE , DAVIDEDAVIDEFEDELEFavre, C.C.FavreBianchi, E.E.BianchiCeccarelli, C.C.CeccarelliMercimek, S.S.MercimekBACCIOTTI, FrancescaFrancescaBACCIOTTIRYGL, Kazi Lucie JessicaKazi Lucie JessicaRYGLTESTI, LeonardoLeonardoTESTI2021-12-272021-12-2720200004-6361http://hdl.handle.net/20.500.12386/31259Context. Planet formation starts around Sun-like protostars with ages ≤1 Myr, but the chemical compositions of the surrounding discs remains unknown. <BR /> Aims: We aim to trace the radial and vertical spatial distribution of a key species of S-bearing chemistry, namely H<SUB>2</SUB>CS, in protoplanetary discs. We also aim to analyse the observed distributions in light of the H<SUB>2</SUB>CS binding energy in order to discuss the role of thermal desorption in enriching the gas disc component. <BR /> Methods: In the context of the ALMA chemical survey of disk-outflow sources in the Taurus star forming region (ALMA-DOT), we observed five Class I or early Class II sources with the o-H<SUB>2</SUB>CS(7<SUB>1,6</SUB>-6<SUB>1,5</SUB>) line. ALMA-Band 6 was used, reaching spatial resolutions ≃40 au, that is, Solar System spatial scales. We also estimated the binding energy of H<SUB>2</SUB>CS using quantum mechanical calculations, for the first time, for an extended, periodic, crystalline ice. <BR /> Results: We imaged H<SUB>2</SUB>CS emission in two rotating molecular rings in the HL Tau and IRAS 04302+2247 discs, the outer radii of which are ~140 au (HL Tau) and 115 au (IRAS 04302+2247). The edge-on geometry of IRAS 04302+2247 allows us to reveal that H<SUB>2</SUB>CS emission peaks at radii of 60-115 au, at z = ±50 au from the equatorial plane. Assuming LTE conditions, the column densities are ~10<SUP>14</SUP> cm<SUP>-2</SUP>. We estimate upper limits of a few 10<SUP>13</SUP> cm<SUP>-2</SUP> for the H<SUB>2</SUB>CS column densities in DG Tau, DG Tau B, and Haro 6-13 discs. For HL Tau, we derive, for the first time, the [H<SUB>2</SUB>CS]/[H] abundance in a protoplanetary disc (≃10<SUP>-14</SUP>). The binding energy of H<SUB>2</SUB>CS computed for extended crystalline ice and amorphous ices is 4258 and 3000-4600 K, respectively, implying thermal evaporation where dust temperatures are ≥50-80 K. <BR /> Conclusions: H<SUB>2</SUB>CS traces the so-called warm molecular layer, a region previously sampled using CS and H<SUB>2</SUB>CO. Thioformaldehyde peaks closer to the protostar than H<SUB>2</SUB>CO and CS, plausibly because of the relatively high excitation level of the observed 7<SUB>1,6</SUB>-6<SUB>1,5</SUB> line (60 K). The H<SUB>2</SUB>CS binding energy implies that thermal desorption dominates in thin, au-sized, inner and/or upper disc layers, indicating that the observed H<SUB>2</SUB>CS emitting up to radii larger than 100 au is likely injected in the gas phase due to non-thermal processes. <P />Reduced datacubes are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A120">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A120</A>STAMPAenArticle10.1051/0004-6361/2020393092-s2.0-85097896350WOS:000600214800002https://www.aanda.org/articles/aa/full_html/2020/12/aa39309-20/aa39309-20.htmlhttp://arxiv.org/abs/2011.02305v12020A&A...644A.120CFIS/05 - ASTRONOMIA E ASTROFISICA