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We investigate the morphology and kinematics of the Galactic spiral structurebased on a new sample of O- and early B-type stars. We select 6,858 highlyconfident OB star candidates from the combined data of the VST PhotometricH$\alpha$ Survey Data Release 2 (VPHAS+ DR2) and the Gaia Data Release 2 (GaiaDR2). Together with the O-B2 stars from the literature, we build a sampleconsisting of 14,880 O- and early B-type stars, all with Gaia parallaxuncertainties smaller than 20 per cent. The new sample, hitherto the largestone of O- and early B-type stars with robust distance and proper motionestimates, covers the Galactic plane of distances up to $\sim$ 6 kpc from theSun. 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 Wayas traced by O- and early B-type stars shows flocculent patterns. Accuratestructure parameters, as well as the means and dispersions of the verticalvelocity distributions of the individual Spiral Arms are presented.

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