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

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. 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 13 CO molecular gas and report a mean difference of 0.04 ± 0.12 km/s (with r.m.s. of 0.63 km/s) confirming that the stars and the gas are tightly coupled.

Rotation of Low-mass Stars in Taurus with K2

“…Despite the fact that Taurus is close (∼140 pc) and has been studied for decades, membership is still controversial. Recent literature combines years of prior data collection with the Gaia DR2 data in an attempt to create a complete list of members (e.g., Luhman et al 2017;Luhman 2018;Esplin & Luhman 2019;Galli et al 2019; and references therein). Numerous approaches have sought a dispersed population of young stars (e.g., Wichmann et al 1996;Slesnick et al 2006;Rebull et al 2010;Rebull et al 2011;Kraus et al 2017; and references therein).…”

Dynamical Masses of Young Stars. II. Young Taurus Binaries Hubble 4, FF Tau, and HP Tau/G3

“…The stellar membership of the Taurus-Auriga starforming region is certainly not a coeval population. There are clear regions of ongoing stars formation surrounded by ∼ 1 − 3 Myr old pre-main sequence stars (Luhman et al 2009), with spatial and kinematic subclustering (Galli et al 2019;Luhman 2018). Additionally, the presence of a distributed, older disk-free membership has been identified through spectral youth indicators with ages potentially as old as ∼20 Myr , and confirmed with variability measurements with time-series photometry (e.g., David et al 2019).…”

“…This is unlikely to be the case for HP Tau/G2, HP Tau/G3 and FF Tau, which are likely coeval, potentially bound, and not associated with a deep column of gas or dust. Additionally, Galli et al (2019) place these systems in a single Taurus sub-cluster. The discrepancies in age seen in this coeval test-case are largely mirrored for the wider Taurus population.…”

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT)

“…An ideal target to investigate the disk chemical structure is the edge-on disk (i = 90 ± 3 •1 , Wolf et al 2003) around the Class I source IRAS 04302+2247 (hereafter IRAS04302), also known as the butterfly star (Lucas & Roche 1997) and located in Taurus (d = 161 ± 3 pc, Galli et al 2019). This source was observed with the IRAM-30 m in CO, H 2 CO, CS, SO, HCO + , and HCN lines (Guilloteau et al 2013(Guilloteau et al , 2016, and with the PdBI in the continuum (Guilloteau et al 2011).…”