J/A+A/643/A60ivo://CDS.VizieR/J/A+A/643/A60doi:10.26093/cds/vizier.36430060CDSSpezzano S.Caselli P.Pineda J.E.Bizzocchi L.Prudenzano D.Nagy Z.2021-01-25T08:47:19Z2020-11-03T07:09:30ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmolecular-cloudsradio-astronomyThe spatial distribution of molecules around starless cores is a powerful tool for studying the physics and chemistry governing the earliest stages of star formation. Our aim is to study the chemical differentiation in starless cores to determine the influence of large-scale effects on the spatial distribution of molecules within the cores. Furthermore, we want to put observational constraints on the mechanisms responsible in starless cores for the desorption of methanol from the surface of dust grains where it is efficiently produced. We mapped methanol, CH_3_OH, and cyclopropenylidene, c-C_3_H_2_, with the IRAM 30m telescope in the 3mm band towards six starless cores embedded in different environments, and in different evolutionary stages. Furthermore, we searched for correlations among physical properties of the cores and the methanol distribution. From our maps we can infer that the chemical segregation between CH_3_OH and c-C_3_H_2_ is driven by uneven illumination from the interstellar radiation field (ISRF). The side of the core that is more illuminated has more C atoms in the gas-phase and the formation of carbon-chain molecules like c-C3H2 is enhanced. Instead, on the side that is less exposed to the ISRF the C atoms are mostly locked in carbon monoxide, CO, the precursor of methanol. We conclude that large-scale effects have a direct impact on the chemical segregation that we can observe at core scale. However, the non-thermal mechanisms responsible for the desorption of methanol in starless cores do not show any dependency on the H_2_ column density at the methanol peak.2020A&A...643A..60Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/643/A60CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/643/A60https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/643/A60http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/643/A60https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/643/A60https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/643/A60http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/643/A60GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/643/A60/table1 (Sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/643/A60/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/643/A60/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/643/A60/table1?GETtext/xml+votable180.050000true67.31541726.2347220.005555555555555556Cone search capability for table J/A+A/643/A60/list (List of fits maps)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/643/A60/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/643/A60/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/643/A60/list?GETtext/xml+votable180.050000true260.65832-23.826010.0055555555555555566/1051 1053 1075 29211 29560 30575 42969 42981 42993https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/643/A60?format=asciiRadiodefaultJ/A+A/643/A60/table1SourcesSimbadNameSimbad column added by the CDSmeta.idcharNameNamemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_NameNote on Name (1)meta.notecharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainVLSRLSR velocitykm/sphys.veloc;pos.lsrfloatDistDistance (2)pcpos.distanceintNH2H_2_ column density (3)1e+22cm**-2phys.columnDensityfloatVel1Velocity range, lower value (4)km/sphys.veloc;instr.bandwidth;stat.minfloatVel2Velocity range, upper value (4)km/sphys.veloc;instr.bandwidth;stat.maxfloatSize1Map size 30marcsecphys.angSize;obs.fieldintSize2Map size 30marcsecphys.angSize;obs.fieldintJ/A+A/643/A60/listList of fits mapsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fits