The Galactic spiral structure as revealed by O- and early B-type stars

Abstract

We investigate the morphology and kinematics of the Galactic spiral structure based on a new sample of O- and early B-type stars. We select 6,858 highly confident OB star candidates from the combined data of the VST Photometric H$\alpha$ Survey Data Release 2 (VPHAS+ DR2) and the Gaia Data Release 2 (Gaia DR2). Together with the O-B2 stars from the literature, we build a sample consisting of 14,880 O- and early B-type stars, all with Gaia parallax uncertainties smaller than 20 per cent. The new sample, hitherto the largest one of O- and early B-type stars with robust distance and proper motion estimates, covers the Galactic plane of distances up to $\sim$ 6 kpc from the Sun. The sample allows us to examine the morphology of the Scutum, Sagittarius, Local and Perseus Arms in great detail. The spiral structure of the Milky Way as traced by O- and early B-type stars shows flocculent patterns. Accurate structure parameters, as well as the means and dispersions of the vertical velocity distributions of the individual Spiral Arms are presented.

10 pages, 6 figures, accepted for publication in MNRAS

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• The observed spiral structure of the Milky Way
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Cited by in corpus (11)

• A large catalogue of molecular clouds with accurate distances within 4 kpc of the Galactic disk
• The spiral structure in the Solar neighborhood
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• Using classical Cepheids to study the far side of the Milky Way disk. II. The spiral structure in the first and fourth Galactic quadrants
• The power of co-ordinate transformations in dynamical interpretations of Galactic structure
• Towards a fully consistent Milky Way disk model -- IV. The impact of Gaia DR2 and APOGEE
• Kinematics of OB Stars with Data from the LAMOST and Gaia Catalogues
• The distances to molecular clouds in the fourth Galactic quadrant
• Galaxy Rotation Parameters from OB2 Stars with Proper Motions and Parallaxes from the Gaia EDR3 Catalog
• New Massive Contact Twin Binary in a Radio-quiet HII Region Associated with the M17 Complex
• Molecular Clouds Associated with {H \small{II}} regions and Candidates within l = 106.65${}^{\circ }$ to 109.50${}^{\circ }$ and b = $-$1.85${}^{\circ }$ to 0.95${}^{\circ }$