The Gould's Belt Distances Survey (GOBELINS). IV. Distance, Depth, and Kinematics of the Taurus Star-forming Region

Abstract

We present new trigonometric parallaxes and proper motions of young stellar objects in the Taurus molecular cloud complex from observations collected with the Very Long Baseline Array as part of the Gould's Belt Distances Survey. We detected 26 young stellar objects and derived trigonometric parallaxes for 18 stars with an accuracy of 0.3% to a few percent. We modeled the orbits of six binaries and determined the dynamical masses of the individual components in four of these systems (V1023 Tau, T Tau S, V807 Tau, and V1000 Tau). Our results are consistent with the first trigonometric parallaxes delivered by the Gaia satellite and reveal the existence of significant depth effects. We find that the central portion of the dark cloud Lynds1495 is located at d= 129.5±0.3 pc, while the B216 clump in the filamentary structure connected to it is at d=158.1±1.2 pc. The closest and remotest stars in our sample are located at d=126.6±1.7 pc and d=162.7±0.8 pc, yielding a distance difference of about 36pc. We also provide a new distance estimate for HLTau that was recently imaged. Finally, we compute the spatial velocity of the stars with published radial velocity and investigate the kinematic properties of the various clouds and gas structures in this region.

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

“…The discrepancy remains for Hubble 4 when considering the dynamical masses: It is difficult to reconcile the spectral type from the optical spectra with the dynamical system mass of 1.843±0.024 M and the NIR secondary-to-primary flux ratio of ∼0.65. Galli et al (2018) measured the component masses of the Hubble 4 system using Very Long Baseline Interferometry (VLBI), in combination with the orbit presented in this paper, and found the components to be 1.234±0.023 M and 0.730±0.020 M respectively. A 1.23 M star at <5 Myr is expected to be significantly hotter that 3900 K according to multiple stellar evolution models (Baraffe et al 2015;Dotter et al 2008;Chen et al 2014).…”

“…The unresolved spectrum of Hubble 4 is significantly different to the SED fit component temperature combined spectrum. Given the NIR flux ratios observed in the orbit monitoring data and the component masses from (Galli et al 2018), we suggest that Hubble 4 may be a hierarchical triple system, with Hubble 4 A being an as yet unresolved binary system. produce the size and slope the Hubble 4 A-B optical and NIR flux ratios.…”

“…Given the extent and variety of the observations of the Hubble 4, there is only a small region of parameter space in which a third component to the system could exist. Inside the orbit of the known companion, observations using VLBI rule out additional stellar companions at angular separations >3 mas (Galli et al 2018), and radial velocity monitoring rules out spectroscopic companions (Crockett et al 2012). The only remaining possible configuration is a near face-on orbit (i 0) with separation <0.5 AU.…”

“…Multiple-star systems have been a key testing ground for pre-main sequence models (e.g Simon et al 2013; Note-Spectral types are taken from Herczeg & Hillenbrand (2014), r' and K band magnitudes are taken from APASS (Henden et al 2012) and 2MASS (Skrutskie et al 2006) with typical uncertainties of 0.1 and 0.02 mags respectively. System parallaxes are from the VLBI observations of Torres et al (2007Torres et al ( , 2009 for HP Tau/G3 and FF Tau, and from the latest observations of Galli et al (2018). The parallaxes for FF Tau and HP Tau/G3 are given in parentheses because we are adopting the parallaxes measurement from the associated and bound star HP Tau/G2.…”

Searching for kinematic evidence of Keplerian disks around Class 0 protostars with CALYPSO

“…A recent study gives a slightly closer distance (130 pc;Galli et al 2018). Here we adopt a distance of 140 pc for consistency with previous studies of L1527.Article number, page 3 of 24 A&A proofs: manuscript no.…”