GD-1: The Relic of an Old Metal-poor Globular Cluster

Combining data from Gaia DR2, SDSS DR14, and LAMOST DR6, we update the fit to model of the properties of the stellar stream GD-1 and find that it has an age of similar to 13 Gyr, [Fe/H] of -2.2 +/- 0.12, and a distance from the Sun of similar to 8 kpc. We tabulate six-dimensional (6D) phase-space fiducial points along the GD-1 stream orbit over a 90 degrees arc. The fitted orbit shows that the stream has an eccentricity e similar to 0.3, perigalacticon of 14.2 kpc, apogalacticon of 27.0 kpc, and inclination i similar to 40 degrees. There is evidence along the arc for four candidate stellar overdensities, one candidate gap, two candidate stellar underdensities, and that the stream is cut off at phi(1) similar to 2 degrees (in the stream-aligned (phi(1), phi(2)) coordinate system of Koposov et al.). The spur originating at phi(1) similar to 40 degrees implies stars were pulled away from the stream trace by an encounter (potentially a dark matter subhalo). The narrowest place (FWHM similar to 44.6 pc) of the GD-1 trace is at (phi(1) , phi(c)(2)) similar to (14 degrees , 0 degrees. 15) which is (178 degrees.18, 52 degrees 19) in (R.A., decl.), where the progenitor is possibly located. We also find six blue horizontal branch and 10 blue stragglers spectroscopic stars in the GD-1 stream.