Exploring Halo Substructure with Giant Stars. XV. Discovery of a Connection between the Monoceros Ring and the Triangulum–Andromeda Overdensity?
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510 (United States)
- City University of New York, LaGuardia Community College, Department of Natural Sciences, 31-10 Thomson Ave., Long Island City, NY 11101 (United States)
- Department of Astronomy, Columbia University, Mail Code 5246, New York, NY 10027 (United States)
- Department of Physics and Astronomy, Texas A and M University, College Station, TX 77840 (United States)
- Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States)
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
- The Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101 (United States)
- Université Côte d’Azur, OCA, CNRS, Lagrange (France)
- Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)
- Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
Thanks to modern sky surveys, over 20 stellar streams and overdensity structures have been discovered in the halo of the Milky Way. In this paper, we present an analysis of spectroscopic observations of individual stars from one such structure, “A13,” first identified as an overdensity using the M giant catalog from the Two Micron All Sky Survey. Our spectroscopic observations show that stars identified with A13 have a velocity dispersion of ≲40 km s{sup −1}, implying that it is a genuine coherent structure rather than a chance superposition of random halo stars. From its position on the sky, distance (∼15 kpc heliocentric), and kinematical properties, A13 is likely to be an extension of another substructure at low Galactic latitude—the Galactic Anticenter Stellar Structure (also known as the Monoceros Ring)—toward smaller Galactic longitude and greater distance. Furthermore, the kinematics of A13 also connect it with another structure in the southern Galactic hemisphere—the Triangulum–Andromeda overdensity. We discuss these three connected structures within the context of a previously proposed scenario in which one or all of these features originate from the disk of the Milky Way.
- OSTI ID:
- 22875992
- Journal Information:
- Astrophysical Journal, Vol. 844, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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