J/A+A/664/A146ivo://CDS.VizieR/J/A+A/664/A146doi:10.26093/cds/vizier.36640146CDSNegueruela I.Alfaro E.J.Dorda R.Marco A.Maiz Apellaniz J.,Gonzalez-Fernandez C.2024-06-05T16:35:01Z2022-08-19T12:29:33ZCDS support team

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

cds-question@unistra.fropen-star-clustersvisible-astronomytrigonometric-parallaxproper-motionsradial-velocityThe young massive cluster Westerlund 1 offers the promise of a grand laboratory for the study of high-mass star evolution, but its basic parameters are still poorly known. In this paper, we aim at a better characterisation of the cluster by determining some basic kinematic properties and analysing the area surrounding the cluster and the population in its foreground. We have used Gaia early data release 3 (EDR3) data, together with spectra of a large sample of luminous stars in the field surrounding Westerlund 1, to explore the extent of the cluster. We carried out a non-parametric analysis of proper motions and membership determination. We investigated the reddening and proper motions of several dozen OB stars and red supergiants less than one degree away from Westerlund 1. We identify a population of kinematic members of Westerlund 1 that largely includes the known spectroscopic members. From their EDR3 parallaxes, we derive a distance to the cluster of 4.23^+0.23^_-0.21_kpc. We analyse the extinction in this direction, finding that it increases by a large amount around 2.8kpc, which in all likelihood is due to dark clouds associated with the Scutum-Crux arm. As a consequence, we hardly see any stars at distances comparable (or higher) than that of the cluster. The proper motions of Westerlund 1, however, are very similar to those of stars in the field surrounding it which are - almost without exception - less distant, but distinct. We find a second, astrometrically well-defined population in the foreground (d~2kpc), centred ~8arcmin away, which is likely connected to the possible open cluster BH 197. Westerlund 1 is very elongated, an effect that seems real and not driven by the very heavy extinction to the east and south. We find a low-density halo extending to distances up to 10 arcmin from the cluster centre, mainly in the north-west quadrant. A few OB stars at larger distances from the cluster, most notably the luminous blue variable (LBV) MN48, share its proper motions, suggesting that Westerlund 1 has little or no peculiar motion with respect to the field population of the Norma arm. Despite this, we are unable to find any red supergiant that could belong to an extended population related to the cluster, although we observe several dozen such objects in the foreground, demonstrating the richness of the field population along this sightline. We find a substantial population of luminous OB members obscured by several more magnitudes of extinction than most known members. These objects, mostly located in the central region of the cluster, increase the population of OB supergiants by about 25%.2022A&A...664A.146Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/664/A146CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/350 : Gaia EDR3 (Gaia Collaboration, 2020)I/352 : Distances to 1.47 billion stars in Gaia EDR3J/A+A/635/A187 : Massive binaries in Westerlund 1. VII. (Clark+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/664/A146https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/664/A146http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/664/A146https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/664/A146https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/664/A146http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/664/A146GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/664/A146/tableb1 (Gaia DR3 parameters for stars discussed in the text)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/664/A146/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/664/A146/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/664/A146/tableb1?GETtext/xml+votable180.050000true251.7475-45.8463330.005555555555555556Cone search capability for table J/A+A/664/A146/tablec1 ("Blue" targets observed with AAOmega)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/664/A146/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/664/A146/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/664/A146/tablec1?GETtext/xml+votable180.050000true251.181667-46.28950.005555555555555556Cone search capability for table J/A+A/664/A146/tablec2 ("Red" targets observed with AAOmega)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/664/A146/tablec2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/664/A146/tablec2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/664/A146/tablec2?GETtext/xml+votable180.050000true252.196625-45.66689720.0055555555555555566/42203 42205-42207 42225 42228-42229 423788.650015785639275e-20 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/664/A146?format=asciiOpticaldefaultJ/A+A/664/A146/tableb1Gaia DR3 parameters for stars discussed in the textrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDCatalogue ID, NNNN or WNNNa (1)meta.idcharSimbadNameSimbad column added by the CDSmeta.idcharnullableRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainGaiaEDR3ID Gaia EDR3meta.id;meta.mainplx? Parallaxmaspos.parallax.trigfloatnullablee_plx? Error of the parallaxmasstat.error;pos.parallaxfloatnullablepmRA? Proper motion in RAmas/yrpos.pm;pos.eq.rafloatnullablee_pmRA? Error of the proper motion in RAmas/yrstat.error;pos.pm;pos.eq.rafloatnullablepmDE? Proper motion in DEmas/yrpos.pm;pos.eq.decfloatnullablee_pmDE? Error of the proper motion in DEmas/yrstat.error;pos.pm;pos.eq.decfloatnullableGmag? G magnitude from Gaia EDR3magphot.mag;em.optfloatnullablee_Gmag? Error of G magnitude from Gaia EDR3magstat.error;phot.magfloatnullableBPmag? BP magnitude from Gaia EDR3magphot.mag;em.opt.Bfloatnullablee_BPmag? Error of BP magnitude from Gaia EDR3magstat.error;phot.magfloatnullableRPmag? RP magnitude from Gaia EDR3magphot.mag;em.opt.Rfloatnullablee_RPmag? Error of RP magnitude from Gaia EDR3magstat.error;phot.magfloatnullableBP-RP? Colour BP-RPmagphot.color;em.opt.B;em.opt.RfloatnullableInAAOmega[+-] If present in the AAOmega surveymeta.codecharKinMember[+-] If tagged as Kinematic Membermeta.codecharJ/A+A/664/A146/tablec1"Blue" targets observed with AAOmegaSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDInternal name, NNN or BNNmeta.idcharGaiaEDR3ID Gaia EDR3meta.id;meta.mainRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainplxParallaxmaspos.parallax.trigfloate_plxParallax errormasstat.error;pos.parallaxfloatpmRAProper motion in RAmas/yrpos.pm;pos.eq.rafloate_pmRAError of the proper motion in RAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DECmas/yrpos.pm;pos.eq.decfloate_pmDEError of the proper motion in DECmas/yrstat.error;pos.pm;pos.eq.decfloatGmagG magnitude from Gaia EDR3magphot.mag;em.optfloatdDistance from Bailer-Jones+2021pcpos.distanceinte_dEstimation of lower error in distancepcstat.errorintE_dEstimation of upper error in distancepcstat.error;stat.maxintSpTypeEstimated spectral typesrc.spTypecharKmagKs magnitude in 2MASSmagphot.mag;em.IR.KfloatJ-KJ-K colour in 2MASSmagphot.color;em.IR.J;em.IR.KfloatJ/A+A/664/A146/tablec2"Red" targets observed with AAOmegadDistance from Bailer-Jones et al. (2021AJ....161..147B, Cat. I/352)pcpos.distanceinte_dEstimation of lower error in distancepcstat.errorintE_dEstimation of upper error in distancepcstat.error;stat.maxintSpTypeEstimated spectral typesrc.spTypecharRV? Radial velocity from AAOmega datakm/sphys.veloc;pos.heliocentricfloatnullableSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDInternal namemeta.idintGaiaEDR3ID Gaia EDR3meta.id;meta.mainRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainplxParallaxmaspos.parallax.trigfloate_plxParallax errormasstat.error;pos.parallaxfloatpmRAProper motion in RAmas/yrpos.pm;pos.eq.rafloate_pmRAError of the proper motion in RAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DEmas/yrpos.pm;pos.eq.decfloate_pmDEError of the proper motion in DEmas/yrstat.error;pos.pm;pos.eq.decfloatGmag? G magnitude from Gaia EDR3magphot.mag;em.optfloatnullableKmagKs magnitude in 2MASSmagphot.mag;em.IR.KfloatRVGDR2? Radial velocity from Gaia DR2km/sphys.veloc;pos.heliocentricfloatnullablee_RVGDR2? Error in Gaia radial velocitykm/sstat.errorfloatnullableJ-K? J-K colour in 2MASSmagphot.color;em.IR.J;em.IR.Kfloatnullable