Structure and kinematics of the Taurus star-forming region from Gaia-DR2 and VLBI astrometry^⋆

¹ Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, 33615 Pessac, France
e-mail: phillip.galli@u-bordeaux.fr
² Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apartado Postal 3-72, Morelia 58089, Mexico
³ Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 Ciudad de México, Mexico
⁴ Depto. de Inteligencia Artificial, UNED, Juan del Rosal, 16, 28040 Madrid, Spain
⁵ Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁶ Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
⁷ Instituto de Astronomía, Universidad Nacional Autónoma de México, Unidad Académica en Ensenada, Ensenada 22860, Mexico
⁸ Department of Physics and Astronomy, Western Washington University, 516 High St, Bellingham, WA 98225, USA

Received: 20 May 2019
Accepted: 26 August 2019

Abstract

Aims. We take advantage of the second data release of the Gaia space mission and the state-of-the-art astrometry delivered from very long baseline interferometry observations to revisit the structure and kinematics of the nearby Taurus star-forming region.

Methods. We apply a hierarchical clustering algorithm for partitioning the stars in our sample into groups (i.e., clusters) that are associated with the various molecular clouds of the complex, and derive the distance and spatial velocity of individual stars and their corresponding molecular clouds.

Results. We show that the molecular clouds are located at different distances and confirm the existence of important depth effects in this region reported in previous studies. For example, we find that the L 1495 molecular cloud is located at d = 129.9^+0.4_−0.3 pc, while the filamentary structure connected to it (in the plane of the sky) is at d = 160.0^+1.2_−1.2 pc. We report B 215 and L 1558 as the closest (d = 128.5^+1.6_−1.6 pc) and most remote (d = 198.1^+2.5_−2.5 pc) substructures of the complex, respectively. The median inter-cloud distance is 25 pc and the relative motion of the subgroups is on the order of a few km s⁻¹. We find no clear evidence for expansion (or contraction) of the Taurus complex, but signs of the potential effects of a global rotation. Finally, we compare the radial velocity of the stars with the velocity of the underlying ¹³CO molecular gas and report a mean difference of 0.04 ± 0.12 km s⁻¹ (with rms of 0.63 km s⁻¹) confirming that the stars and the gas are tightly coupled.