J/A+A/707/A241ivo://CDS.VizieR/J/A+A/707/A241CDSCorrea-Rodrigues J.V.Gregorio-Hetem J.2026-07-31T12:13:46Z2026-07-31T13:10:44ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsstellar-spectral-typesline-intensitiesvisible-astronomyStar formation is governed by multiple physical processes, making it inherently complicated. One excellent example is the Canis Major OB1/R1 association, whose complex history of star formation is related to different episodes. Three supernova (SN) events potentially altered the environment and impacted star formation and stellar evolution. Prior investigations revealed two stellar groups of different ages associated with GU CMa and Z CMa. This work focusses on identifying the low-mass young stellar population near FZ CMa, located between these two groups and spatially related to the HII region Sh 2-295. Our main goal is to verify whether this group is age-mixed and characterise its physical properties. We analysed multi-object spectroscopic data acquired with Gemini/GMOS to search for typical features of T Tauri stars (TTs) and to determine their spectral types. Lithium absorption line ({lambda} 6708{AA}) was used as a youth indicator, while H{alpha} emission was investigated to probe accretion activity. We also derived ages based on optical photometry from Gaia DR3 and compared the projected spatial distribution to diffuse infrared emission. We identified 29 TTs, including six new members of the association and three classical TTs. The equivalent width of the LiI absorption line suggests an age of 8.1^+2.1^_-3.8_Myr, while optical photometric data indicate stellar ages ranging from ~1 to 14Myr. Younger stars are concentrated around Sh 2-295, whereas the older ones are more widely dispersed. We increased the number of known TTs related to the CMa association. Our results support a scenario of multiple star formation episodes, including a younger group that may have been triggered by the expansion of Sh 2-295. The influence of SN events appears limited in this context.2026A&A...707A.241Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A241CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/A+A/609/A127 : X-ray sources in CMa OB1 (Santos-Silva+, 2018)J/AJ/161/133 : Astrometry & photometry for CMa R1 membersJ/ApJS/262/7 : 886 nearby star clusters (He+, 2022)J/A+A/630/A90 : Halpha emission-line stars in Canis Major (Pettersson+, 2019)J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)J/ApJ/827/96 : WISE census of YSOs in Canis Major (Fischer+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A241https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A241http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A241https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A241https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A241http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A241GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/707/A241/table2 (List of T Tauri stars identified and parameters derived in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A241/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A241/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A241/table2?GETtext/xml+votable180.050000true105.6511667-11.41688890.005555555555555556Cone search capability for table J/A+A/707/A241/tableb1 (List of objects with Halpha emission but no LiI (6708{AA}) absorption detected)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A241/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A241/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A241/tableb1?GETtext/xml+votable180.050000true105.6957917-11.45336110.0055555555555555566/216431.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/707/A241?format=asciiOpticaldefaultJ/A+A/707/A241/table2List of T Tauri stars identified and parameters derived in this workrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS identifiermeta.id;meta.maincharGaiaDR3? Gaia DR3 identifiermeta.idnullablen_2MASSNotes on individual objects (1)meta.notecharSimbadNameSimbad column added by the CDSmeta.idcharnullableEWLiEquivalent width of the LiI (6708{AA}) line0.1nmspect.line.eqWidthfloatEWHaEquivalent width of the Halpha line. Negative values indicate emission0.1nmspect.line.eqWidthfloatSNRSignal-to-noise ratio of the spectra used.stat.snr;instr.setupintSpTypeEstimated spectral typesrc.spTypecharTeffEstimated effective temperatureKphys.temperature.effectiveinte_TeffEstimated uncertainty associated with effective temperatureKstat.error;phys.temperature.effectiveintAVEstimated extinctionmagphys.absorptionfloatClassClassificationmeta.code.classcharb_Age? Estimated lower end of the age rangeMyrtime.end;stat.minfloatnullableB_Age? Estimated upper end of the age rangeMyrtime.end;stat.maxfloatnullableCMaXX-ray source identification according to Santos-Silva et al. 2018, Cat. J/A+A/609/A127meta.idcharIRClassInfrared classificationmeta.code.classcharn_IRClassNotes on Infrared classification (2)meta.notecharP? Membership probability (3)%stat.fit.goodnessfloatnullable_RAPositions from 2MASS name (right ascension part)degpos.eq.ra;meta.main_DEPositions from 2MASS name (declination part)degpos.eq.dec;meta.mainJ/A+A/707/A241/tableb1List of objects with Halpha emission but no LiI (6708{AA}) absorption detected2MASS2MASS identifiermeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintf_2MASS[)] ) if not an 2MASS identifiermeta.codecharGaiaDR3Gaia DR3 identifiermeta.idn_2MASSNotes on individual objects (1)meta.notecharEWHaEquivalent width of the Halpha line. Negative values indicate emission0.1nmspect.line.eqWidthfloatGmagG Gaia magnitudemagphot.mag;em.optfloatBPmagBP Gaia magnitudemagphot.mag;em.opt.BfloatRPmagRP Gaia magnitudemagphot.mag;em.opt.Rfloat_RAPositions from 2MASS name (right ascension part)degpos.eq.ra;meta.main_DEPositions from 2MASS name (declination part)degpos.eq.dec;meta.mainJ/A+A/707/A241/tabled1List of spectral types derived for each source in table2.dat using different methodsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS identifiermeta.id;meta.maincharSpTypeSpectral type adoptedsrc.spTypecharL18Spectral type estimated by comparison with Luhman et al. (2018AJ....156...76L, Cat. J/AJ/156/78) spectrasrc.spTypecharC24Spectral type estimated by comparison with Claes et al. (2024A&A...690A.122C) spectrasrc.spType;meta.modelledcharTiO(J07)Spectral type estimated by using the TiO index from Jeffries et al. (2007MNRAS.376..580J, Cat. J/MNRAS/376/580)src.spTypecharTiO(6800)Spectral type estimated by using the TiO 6800 index from Herczeg et al. (2014ApJ...786...97H, Cat. J/ApJ/786/97)src.spTypecharTiO(7140)Spectral type estimated by using the TiO 7140 index from Herczeg et al. (2014ApJ...786...97H, Cat. J/ApJ/786/97)src.spTypechar