The Villafranca catalog of Galactic OB groups: I. Systems with O2-O3.5 stars

Abstract

CONTEXT. The GOSSS spectral classifications and Gaia data have significantly improved our ability to measure distances and determine memberships of stellar groups with OB stars. AIMS. We have started a program to identify, measure distances, and determine the membership of Galactic stellar groups with OB stars. We start with the identification and distance determinations of groups with O stars. In this paper we concentrate on groups that contain stars with the earliest spectral subtypes. METHODS. We use GOSSS to select Galactic stellar groups with O2-O3.5 stars and a method that combines Gaia DR2 photometry, positions, proper motions, and parallaxes to assign robust memberships and measure distances. We also include the two clusters in that paper to generate our first list of 16 O-type Galactic stellar groups. RESULTS. We derive distances, determine the membership, and analyze the structure of sixteen Galactic stellar groups with O stars, Villafranca O-001 to O-016, including the 14 groups with the earliest-O-type optically-accessible stars known in the Milky Way. We compare our distance with previous results and establish that the best consistency is with VLBI parallaxes and the worst is with kinematic distances. Our results indicate that massive stars can form in relatively low-mass clusters or even in near-isolation, as is the case for the Bajamar star in the North America nebula. This lends support to the hierarchical scenario of star formation, where some stars are born in well-defined bound clusters but others are born in associations that are unbound from the beginning: groups of newborn stars come in many shapes and sizes. We propose that HD 64 568 and HD 64 315 AB could have been ejected simultaneously from Villafranca O-012 S. Our results are consistent with a difference of approx. 20 microas in the Gaia DR2 parallax zero point between bright and faint stars. (ABRIDGED)

Accepted for publication in A&A

References in corpus (43)

• The Gaia mission
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
• A Compendium of Distances to Molecular Clouds in the Star Formation Handbook
• Hunting for open clusters in \textit{Gaia} DR2: $582$ new OCs in the Galactic disc
• Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision
• The Electron Temperature Gradient in the Galactic Disk
• Hunting for open clusters in \textit{Gaia} DR2: the Galactic anticentre
• The VLT-FLAMES Tarantula Survey XVI. The optical+NIR extinction laws in 30 Doradus and the photometric determination of the effective temperatures of OB stars
• The very massive binary NGC3603-A1
• The Massive Star Content of NGC 3603
• Not all stars form in clusters -- $Gaia$-DR2 uncovers the origin of OB associations
• MONOS: Multiplicity Of Northern O-type Spectroscopic systems. I. Project description and spectral classifications and visual multiplicity of previously known objects
• Pismis 24-1: The Stellar Upper Mass Limit Preserved
• How do bound star clusters form?
• The Gaia DR2 parallax zero point: Hierarchical modeling of red clump stars
• The Formation of a Stellar Association in the NGC 7000/IC 5070 Complex: Results from Kinematic Analysis of Stars and Gas
• Chandra monitoring of the very massive binary WR20a and the young massive cluster Westerlund2
• Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2
• On the Distance and Molecular Environment of Westerlund 2 and HESS J1023-575
• The very massive X-ray bright binary system Wack 2134 (= WR 21a)
• The deep OB star population in Carina from the VST Photometric H$\alpha$ Survey (VPHAS+)
• Reddening, Distance, and Stellar Content of the Young Open Cluster Westerlund 2
• The Gaia-ESO Survey: Membership probabilities for stars in 32 open clusters from 3D kinematics
• Gaia DR2 distances to Collinder 419 and NGC 2264 and new astrometric orbits for HD 193 322 Aa,Ab and 15 Mon Aa,Ab
• A close encounter of the massive kind
• A Gaia view of the two OB associations Cygnus OB2 and Carina OB1: The signature of their formation process
• A Catalog of New Spectroscopically Confirmed Massive OB Stars in Carina
• The O star hinterland of the Galactic starburst, NGC 3603
• Spatially resolved spectroscopy of close massive visual binaries with HST/STIS: I. Seven O-type systems
• Distances to Galactic OB-stars: Photometry vs. Parallax
• A tale of two clusters: dynamical history determines disc survival in Tr14 and Tr16 in the Carina Nebula
• The little-studied cluster Berkeley 90. I. LS III +46 11: a very massive O3.5 If* + O3.5 If* binary
• Variability of young stellar objects in the star-forming region Pelican Nebula
• The massive multiple system HD 64315
• Probing embedded star clusters in the HII complex NGC 6357 with VVV
• Spectroscopic study of the extremely young O-type triple system Herschel 36 A in the Hourglass Nebula. I. Orbital properties
• On the origin of very massive stars around NGC 3603
• The GALANTE Photometric System
• The young stellar content of the giant HII regions M8, G333.6-0.2, and NGC6357 with VLT/KMOS
• Spectrophotometric calibration of low-resolution spectra
• The little-studied cluster Berkeley 90. III. Cluster parameters
• Deep optical survey of the stellar content of Sh2-311 region

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• Gaia-ESO Survey: massive stars in the Carina Nebula. II. The spectroscopic analysis of the O-star population
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• An in-depth analysis of the differentially expanding star cluster Stock 18 (Villafranca O-036) using Gaia DR3 and ground-based data
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