J/A+A/661/A34ivo://CDS.VizieR/J/A+A/661/A34doi:10.26093/cds/vizier.36610034CDSRobrade J.Czesla S.Freund S.Schmitt J.H.M.M.Schneider P.C.2022-09-30T22:18:09Z2022-05-18T13:51:23ZCDS support team

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

cds-question@unistra.frx-ray-sourcesopen-star-clustersThe nearby young open cluster {eta} Chamaeleontis has been observed by eROSITA/SRG during its CalPV phase for 150ks. The extended ROentgen Survey with an Imaging Telescope Array (eROSITA) data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, here covering a 5x5deg field with an exposure depth of about 5ks. The {eta} Cha cluster with an age of about 8Myr is a key target for investigating the evolution of young stars, and we aim to study the known members in X-rays. Additionally, we search for potential new members of the anticipated dispersed low-mass cluster population in a sensitive wide-field X-ray observation. Using eROSITA X-ray data, we studied the {eta} Cha region. Detected sources were identified by cross-matching X-ray sources with Gaia and 2MASS, and young stars were identified by their X-ray activity, the position in the color-magnitude diagram, and by their astrometric and kinematic properties. X-ray-luminosities, light curves, and spectra of cluster members were obtained and compared with previous X-ray data. Literature results of other member searches were used to verify our new member candidates in the observed field. We determine X-ray properties of virtually all known {eta} Cha members and identify five additional stellar systems that show basically identical characteristics, but they are more dispersed. Four of them were previously proposed as potential members; this status is supported by our X-ray study. Based on their spatial distribution, further members are expected beyond the sky region we surveyed. The identified stellar systems very likely belong to the ejected halo population, which brings the total number of {eta} Cha cluster members to at least 23. Sensitive X-ray surveys are best suited to identifying active stars, and the combination of the ongoing eROSITA all-sky survey with Gaia measurements provides an unprecedented opportunity to study the nearby, young stellar population.2022A&A...661A..34Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/661/A34CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/661/A1 : The eFEDS X-ray catalogs (V7.4) (Brunner+, 2022)J/A+A/661/A2 : Galaxy clusters and groups in eFEDS (Liu+, 2022)J/A+A/661/A3 : eFEDS counterparts to point-like sources (Salvato+, 2022)J/A+A/661/A4 : eFEDS optical cluster and group catalog (Klein+, 2022)J/A+A/661/A5 : The eFEDS AGN catalog (Liu+, 2022)J/A+A/661/A7 : X-ray properties of eFEDS clusters and groups (Bahar+, 2022)J/A+A/661/A8 : eFEDS catalogue of variable X-ray sources (Boller+, 2022)J/A+A/661/A10 : eFEDS galaxy clusters and groups in disguise (Bulbul+, 2022)J/A+A/661/A23 : Exoplanet X-ray irradiation & evaporation rates (Foster+, 2022)J/A+A/661/A24 : Corona-chromosphere connection (Fuhrmeister+, 2022)J/A+A/661/A29 : First eROSITA study of nearby M dwarfs (Magaudda+, 2022)J/A+A/661/A35 : eROSITA study of 47 Tuc globular cluster (Saeedi+, 2022)J/A+A/661/A38 : SRG/ART-XC 1st year all-sky X-ray survey (Pavlinsky+, 2022)J/A+A/661/A40 : eRASS1 X-ray sources Sco-Cen members (Schmitt+, 2022)J/A+A/661/A44 : A first eROSITA view of ultracool dwarfs (Stelzer+, 2022)https://erosita.mpe.mpg.de : eROSITA EDR page at MPEhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/661/A34https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/661/A34http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/661/A34https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/661/A34https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/661/A34http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/661/A34GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/661/A34/etacha_m (X-ray source catalog of the eROSITA {eta} Cha field scan in the main (0.2-2.3keV) energy band)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/661/A34/etacha_m?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/661/A34/etacha_m?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/661/A34/etacha_m?GETtext/xml+votable180.050000true110.42162610243946-80.354382806909480.005555555555555556Cone search capability for table J/A+A/661/A34/etacha_h (X-ray source catalog of the eROSITA {eta} Cha field scan in the hard (2.3-5.0keV) energy band)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/661/A34/etacha_h?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/661/A34/etacha_h?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/661/A34/etacha_h?GETtext/xml+votable180.050000true113.04881005344646-79.402527363078190.0055555555555555564/2313 5/9229-9231 9242-9243 9264 6/36911 36913 36915 36962-36963 36997 36999 37004-37005 37007 37041 37044-37045 37060 37064 37066https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/661/A34?format=asciiX-raydefaultJ/A+A/661/A34/etacha_mX-ray source catalog of the eROSITA {eta} Cha field scan in the main (0.2-2.3keV) energy bandrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinthardindicates hard band datameta.ref.urlcharEROeROSITA/SRG source name, SRGE JHHMMSS.s+DDMMSS (ERO_NAME)meta.id;meta.maincharprimaryID-SRCSource ID within the table (ID_SRC)meta.idintRAJ2000Right ascension (J2000) (RA)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (DEC)degpos.eq.dec;meta.mainePosCombined error in RA/DEC (RADEC_ERR)arcsecstat.errordoubleExtSource extent (EXT)arcsecphys.angSizedoublee_ExtError of extent (EXT_ERR)arcsecstat.errordoubleExtLikeExtent likelihood (EXT_LIKE)stat.likelihooddoubleMLctsSource counts from PSF fitting (ML_CTS)ctphot.count;em.X-raydoublee_MLctsError on source counts (ML_CTS_ERR)ctstat.errordoubleMLRateSource rate (ML_RATE)ct/sphot.count;em.X-raydoublee_MLRateError on source rate (ML_RATE_ERR)ct/sstat.errordoubleMLFluxSource flux (ML_FLUX)mW.m**-2phot.flux;em.X-raydoublee_MLFluxError on source flux (ML_FLUX_ERR)mW.m**-2stat.errordoubleDetLikeDetection likelihood (DET_LIKE)stat.likelihooddoubleMLBkgBackground at source position (ML_BKG)ct/arcmininstr.backgrounddoubleJ/A+A/661/A34/etacha_hX-ray source catalog of the eROSITA {eta} Cha field scan in the hard (2.3-5.0keV) energy bandrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEROeROSITA/SRG source name, SRGE JHHMMSS.s+DDMMSS (ERO_NAME)meta.id;meta.maincharID-SRCSource ID within the table (ID_SRC)meta.idintID-MAIN? Corresponding ID (ID_SRC) in main catalog (etacha_m.dat) (ID_MAIN)meta.idintnullableRAJ2000Right ascension (J2000) (RA)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (DEC)degpos.eq.dec;meta.mainePosCombined error in RA/DEC (RADEC_ERR)arcsecstat.errordoubleExtSource extent (EXT)arcsecphys.angSizefloate_ExtError of extent (EXT_ERR)arcsecstat.errorfloatExtLikeExtent likelihood (EXT_LIKE)stat.likelihoodfloatMLctsSource counts from PSF fitting (ML_CTS)ctphot.count;em.X-raydoublee_MLctsError on source counts (ML_CTS_ERR)ctstat.errordoubleMLRateSource rate (ML_RATE)ct/sphot.count;em.X-raydoublee_MLRateError on source rate (ML_RATE_ERR)ct/sstat.errordoubleMLFluxSource flux (ML_FLUX)mW.m**-2phot.flux;em.X-raydoublee_MLFluxError on source flux (ML_FLUX_ERR)mW.m**-2stat.errordoubleDetLikeDetection likelihood (DET_LIKE)stat.likelihooddoubleMLBkgBackground at source position (ML_BKG)count.arcmin**-2instr.backgrounddouble