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Published January 10, 2017 | Published + Submitted
Journal Article Open

The Gould's Belt Distances Survey (GOBELINS). I. Trigonometric Parallax Distances and Depth of the Ophiuchus Complex

Abstract

We present the first results of the Gould's Belt Distances Survey (GOBELINS), a project aimed at measuring the proper motion and trigonometric parallax of a large sample of young stars in nearby regions using multi-epoch Very Long Baseline Array (VLBA) radio observations. Enough VLBA detections have now been obtained for 16 stellar systems in Ophiuchus to derive their parallax and proper motion. This leads to distance determinations for individual stars with an accuracy of 0.3 to a few percent. In addition, the orbits of six multiple systems were modelled by combining absolute positions with VLBA (and, in some cases, near-infrared) angular separations. Twelve stellar systems are located in the dark cloud Lynds 1688; the individual distances for this sample are highly consistent with one another and yield a mean parallax for Lynds 1688 of ω = 7.28 ± 0.06 mas, corresponding to a distance d = 137.3 ± 1.2 pc. This represents an accuracy greater than 1%. Three systems for which astrometric elements could be measured are located in the eastern streamer (Lynds 1689) and yield an estimate of ω = 6.79 ± .016 mas, corresponding to a distance d = 147.3 ± 3.4 pc. This suggests that the eastern streamer is located about 10 pc farther than the core, but this conclusion needs to be confirmed by observations of additional sources in the eastern streamer (currently being collected). From the measured proper motions, we estimate the one-dimensional velocity dispersion in Lynds 1688 to be 2.8 ± 1.8 and 3.0 ± 2.0 km s^(−1), in R.A. and decl., respectively; these are larger than, but still consistent within 1σ of, those found in other studies.

Additional Information

© 2017 The American Astronomical Society. Received 2016 June 29; revised 2016 October 27; accepted 2016 November 19; published 2017 January 11. G.N.O.-L., L.L., L.F.R., R.A.G.-L., G.P., and J.L.R. acknowledge CONACyT, Mexico, for financial support through grants 339802, 104497, 153522, and I0017-151671. L.L. and R.A.G.-L. were supported by DGAPA, UNAM grant PAPIIT IG100913. L.L. and G.N.O.-L. also acknowledge support from the von Humboldt Stiftung. N.J.E. was supported by NSF grant AST-1109116 to the University of Texas at Austin. P.A.B.G. acknowledges financial support from FAPESP. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. This work made use of the Swinburne University of Technology software correlator, developed as part of the Australian Major National Research Facilities Programme and operated under licence.

Attached Files

Published - Ortiz-León_2017_ApJ_834_141.pdf

Submitted - 1611.06466v1.pdf

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Created:
August 19, 2023
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October 24, 2023