J/A+A/685/A118ivo://CDS.VizieR/J/A+A/685/A118doi:10.26093/cds/vizier.36850118CDSAlmendros-Abad V.Manara C.F.Testi L.Natta A.Claes R.A.B.,Muzic K.Sanchis E.Alcala J.M.Bayo A.Scholz A.2025-04-16T20:01:20Z2024-05-15T09:09:21ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsspectroscopylate-type-starsThe time evolution of the dependence of the mass accretion rate with the stellar mass and the disk mass represents a fundamental way to understand the evolution of protoplanetary disks and the formation of planets. In this work we present observations with X-Shooter of 26 Class II very low-mass stars (<0.2M_{sun}_) and brown dwarfs in the Ophiuchus, Chamaeleon-I and Upper Scorpius star-forming regions. These new observations extend down to SpT of M9 (~0.02M_{sun}_) the measurement of the mass accretion rate in Ophiuchus and Chamaeleon-I and add 11 very low-mass stars to the sample of objects previously studied with broad-band spectroscopy in Upper Scorpius. We obtain the spectral type and extinction, as well as the physical parameters of the sources. We use the intensity of various emission lines in the spectra of these sources to derive the accretion luminosity and mass accretion rate for the entire sample. Combining these new observations with data from the literature, we compare relations between accretion and stellar/disk properties of four different star-forming regions with different ages: Ophiuchus (~1Myr), Lupus (~2Myr), Chamaeleon-I (~3Myr) and Upper Scorpius (5-12 Myr). We find the slopes of the accretion relationships (L*-L_acc_, M*-(dM_acc_/dt)) to steepen in the 1-3Myr age range (i.e. between Ophiuchus, Lupus and Chamaeleon-I), and that both relationships may be better described with a single power law. We find that previous claims for a double power law behavior of the M*-(dM_acc_/dt) relationship may have been triggered by the use of a different SpT-Teff scale. We also find the relationship between the protoplanetary disk mass and the mass accretion rate of the stellar population to steepen with time down to the age of Upper Scorpius. Overall, we observe hints of a faster evolution into low accretion rates of low-mass stars and brown dwarfs. At the same time, we also found that brown dwarfs present larger M_disk_/(dM_acc_/dt) ratios (i.e. longer accretion depletion timescales) than stars in Ophiuchus, Lupus and Cha-I. This apparently contradictory result may imply that the evolution of protoplanetary disks around brown dwarfs may be different than in the stellar regime.2024A&A...685A.118Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/685/A118CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/685/A118https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/685/A118http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/685/A118https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/685/A118https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/685/A118http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/685/A118GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/685/A118/spectra (List of X-Shooter spectra)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/685/A118/spectra?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/685/A118/spectra?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/685/A118/spectra?GETtext/xml+votable180.050000true167.12195833-77.655510.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/685/A1186/36956-36957 42976 42981 42985-42986 44358 44363 44367 44378 44389https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/685/A118?format=asciidefaultJ/A+A/685/A118/spectraList of X-Shooter spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainRegionStar-forming region to which each source belongsmeta.id.parentcharSpTypeSpectral typesrc.spTypecharAvVisual extinctionmagphys.absorptionfloatLumLuminositysolLumphys.luminosityfloatspUShow the spectrummeta.ref.urlcharUVBUVB spectrum filename in subdirectory spectrameta.id;meta.filecharspVShow the spectrummeta.ref.urlcharVISVIS spectrum filename in subdirectory spectrameta.id;meta.filecharspNShow the spectrummeta.ref.urlcharNIRNIR spectrum filename in subdirectory spectrameta.id;meta.filecharSLUWidth of the UVB slitspect.line.widthfloatSLVWidth of the VIS slitspect.line.widthfloatSLNWidth of the NIR slitspect.line.widthfloatSimbadSimbad column added by the CDSmeta.ref.urlchar