A Larger Extent for the Ophiuchus Stream

Abstract

We present new kinematic data for the Ophiuchus stellar stream. Spectra have been taken of member candidates at the MMT telescope using Hectospec, Hectochelle and Binospec, which provide more than 1800 new velocities. Combined with proper motion measurements of stars in the field by the Gaia - DR2 catalog, we have derived stream membership probabilities, resulting in the detection of more than 200 likely members. These data show the stream extends to more than three times the length shown in the discovery data. A spur to the main stream is also detected. The high resolution spectra allow us to resolve the stellar velocity dispersion, found to be $1.6\pm 0.3$ km/sec.

17 pages, 10 figures, to appear in AJ

References in corpus (10)

• The NumPy array: a structure for efficient numerical computation
• Distances and parallax bias in Gaia DR2
• Star Clusters in M31: I. A Catalog and a Study of the Young Clusters
• Clean Kinematic Samples in Dwarf Spheroidals: An Algorithm for Evaluating Membership and Estimating Distribution Parameters When Contamination is Present
• Binospec: A Wide-field Imaging Spectrograph for the MMT
• A Map of Dust Reddening to 4.5 kpc from Pan-STARRS1
• The effect of a disc on the population of cuspy and cored dark matter substructures in Milky Way-like galaxies
• Serendipitous Discovery of a Thin Stellar Stream near the Galactic Bulge in the Pan-STARRS1 3Pi Survey
• Palomar 5 and its Tidal Tails: A Search for New Members in the Tidal Stream
• Kinematics of the Palomar 5 stellar stream from RR Lyrae stars