KINEMATICS IN KAPTEYN'S SELECTED AREA 76: ORBITAL MOTIONS WITHIN THE HIGHLY SUBSTRUCTURED ANTICENTER STREAM
- Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
- Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)
We have measured the mean three-dimensional kinematics of stars in Kapteyn's Selected Area (SA) 76 (l = 209.{sup 0}3, b = 26.{sup 0}4) that were selected to be Anticenter Stream (ACS) members on the basis of their radial velocities (RVs), proper motions (PMs), and location in the color-magnitude diagram. From a total of 31 stars ascertained to be ACS members primarily from its main-sequence turnoff, a mean ACS RV (derived from spectra obtained with the Hydra multi-object spectrograph on the WIYN 3.5 m telescope) of V{sub helio} = 97.0 {+-} 2.8 km s{sup -1} was determined, with an intrinsic velocity dispersion {sigma}{sub o} = 12.8 {+-} 2.1 km s{sup -1}. The mean absolute PMs of these 31 ACS members are {mu}{sub {alpha}} cos {delta} = -1.20 {+-} 0.34 mas yr{sup -1} and {mu}{sub {delta}} = -0.78 {+-} 0.36 mas yr{sup -1}. At a distance to the ACS of 10 {+-} 3 kpc, these measured kinematical quantities produce an orbit that deviates by {approx}30{sup 0} from the well-defined swath of stellar overdensity constituting the ACS in the western portion of the Sloan Digital Sky Survey footprint. We explore possible explanations for this and suggest that our data in SA 76 are measuring the motion of a kinematically cold sub-stream among the ACS debris that was likely a fragment of the same infalling structure that created the larger ACS system. The ACS is clearly separated spatially from the majority of claimed Monoceros ring detections in this region of the sky; however, with the data in hand, we are unable to either confirm or rule out an association between the ACS and the poorly understood Monoceros structure.
- OSTI ID:
- 21476648
- Journal Information:
- Astrophysical Journal, Vol. 725, Issue 2; Other Information: DOI: 10.1088/0004-637X/725/2/2290; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
KINEMATICS AND CHEMISTRY OF STARS ALONG THE SAGITTARIUS TRAILING TIDAL TAIL AND CONSTRAINTS ON THE MILKY WAY MASS DISTRIBUTION
The Milky Way Tomography with SDSS. 2. Stellar Metallicity