A Low-Latitude Halo Stream around the Milky Way

By Brian Yanny, Heidi Jo Newberg, E. Grebel, S. Kent, M. Odenkirchen, C. Rockosi, David Schlegel, Mark SubbaRao, J. Brinkmann, M. Fukugita and 4 more. 2003

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We present evidence for a ring of stars in the plane of the Milky Way, extending at least from l = 180° to 227° with turnoff magnitude g ~ 19.5; the ring could encircle the Galaxy. We infer that the low Galactic latitude structure is at a fairly constant distance of R = 18 ± 2 kpc from the Galactic center above the Galactic plane and has R = 20 ± 2 kpc in the region sampled below the Galactic plane. The evidence includes 500 Sloan Digital Sky Survey spectroscopic radial velocities of stars within 30° of the plane. The velocity dispersion of the stars associated with this structure is found to be 27 km s-1 at (l, b) = (198°, - 27°), 22 km s-1 at (l, b) = (225°, 28°), 30 km s-1 at (l, b) = (188°, 24°), and 30 km s-1 at (l, b) = (182°, 27°). The structure rotates in the same prograde direction as the Galactic disk stars but with a circular velocity of 110 ± 25 km s-1. The narrow measured velocity dispersion is inconsistent with power-law spheroid or thick-disk populations. We compare the velocity dispersion in this structure with the velocity dispersion of stars in the Sagittarius dwarf galaxy tidal stream, for which we measure a velocity dispersion of 20 km s-1 at (l, b) = (165°, - 55°). We estimate a preliminary metallicity from the Ca II (K) line and color of the turnoff stars of [Fe/H] = -1.6 with a dispersion of 0.3 dex and note that the turnoff color is consistent with that of the spheroid population. We interpret our measurements as evidence for a tidally disrupted satellite of 2 × 107 to 5 × 108 M☉ that rings the Galaxy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a577587ade69f0050c52e8242cc30f04745887bc

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Citations in the corpus

RINGS AND RADIAL WAVES IN THE DISK OF THE MILKY WAY (2015, background): “…discovered at low Galactic latitude near the Galactic anticenter, at an estimated distance of 18 kpc from the Galactic center (Newberg et al. 2002; Yanny et al. 2003; Li et al. 2012); this structure has been called the Monoceros Ring, but some authors have called it the Monoceros Overdensity or…”
The Metal-poor Halo of the Andromeda Spiral Galaxy (M31) (2006, background): “In the Milky Way, the Sagittarius stream (Ibata et al. 1994; Majewski et al. 2003), the Magellanic stream (Mathewson, Cleary, & Murray 1974) and the Monoceros stream (Yanny et al. 2003) present clear evidence that merging processes are prominent in massive galaxies and are still occuring today.”
Outer structure of the Galactic warp and flare: explaining the Canis Major over-density (2006, background): “A kinematic and spectroscopic study of the Ring structure by Yanny et al. (2003) confirmed (i) a Galactocentric distance of 18 and 20 kpc (respectively above and below the Galactic plane); (ii) an inconsistency of its velocity dispersion with typical Galactic halo and thick disk structures; and…”
Tracing Galaxy Formation with Stellar Halos. I. Methods (2005, background): “In addition, both theoretical (Abadi et al. 2003; Brook et al. 2005a; Robertson et al. 2005) and observational (Gilmore, Wyse, & Norris 2002; Yanny et al. 2003; Ibata et al. 2003; Crane et al. 2003; Rocha-Pinto, Majewski, Skrutskie, & Crane 2003; Frinchaboy et al. 2004; Helmi et al. 2005) work is…”
The Origin of the Magellanic Stream and Its Leading Arm (2007, background): “…(Odenkirchen et al. 2001; Grillmair & Dionatos 2006), the Sagittarius stream (e.g., Ibata et al. 2001; Newberg et al. 2002; Majewski et al. 2003); the Monoceros stream (e.g., Yanny et al. 2003); the orphan stream (Belokurov et al. 2006; Grillmair 2006a); and the anticenter stream (Grillmair 2006b).”
A New Milky Way Dwarf Galaxy in Ursa Major (2005, background): “…(Willman et al. 2005a) and a faint M31 dwarf satellite (Zucker et al. 2004), as well as large-scale stellar structures and dwarf galaxy remnants around the Milky Way (Newberg et al. 2002; Yanny et al. 2003; Ibata et al. 2003; Rocha-Pinto et al. 2003, 2004; Majewski et al. 2003; Martin et al. 2004).”
Taking measure of the Andromeda halo: A Kinematic analysis of the giant stream surrounding M31 (2004, background): “The Milky Way satellite Sagittarius, which has a velocity dispersion of 11 km s−1 (Ibata et al. 1997), also has a gigantic stellar stream, but with a larger velocity dispersion of 20 kms−1 (Yanny et al. 2003).”
ERRATUM: “THE LUMINOSITY AND MASS FUNCTIONS OF LOW-MASS STARS IN THE GALACTIC DISK. II. THE FIELD” (2010, AJ, 139, 2679) (2010, background): “Other notable SDSS results include the discovery of new stellar streams in the halo (e.g., Yanny et al. 2003; Belokurov et al. 2006) and new Milky Way companions (e.g., Willman et al. 2005; Belokurov et al. 2007), as well as unprecedented in situ mapping of the stellar density (Jurić et al. 2008)…”
THE DUAL ORIGIN OF STELLAR HALOS (2009, background): “Numerous stellar streams believed to have originated from small accreted galaxies have been observed in the Milky Way’s outer halo (e.g., Newberg et al. 2002; Yanny et al. 2003; Belokurov et al. 2006; Grillmair 2009).”
Structural Parameters of Thin and Thick Disks in Edge-on Disk Galaxies (2005, background): “For example,Martin et al. (2004) find asymmetries in the distribution of M giant stars (e.g., the Galactic ‘‘Ring’’; Newberg et al. 2002; Yanny et al. 2003) that are well explained by a single dwarf galaxy accretion event.”
A Two Micron All Sky Survey View of the Sagittarius Dwarf Galaxy. II. Swope Telescope Spectroscopy of M Giant Stars in the Dynamically Cold Sagittarius Tidal Stream (2004, methodology): “This Monoceros feature (as referred to by Yanny et al. 2003) is also visible in the 2MASS data, as discussed in x 8.1 of Paper I (see Fig.”
A Comprehensive Model for the Monoceros Tidal Stream (2004, background): “Starting with the original stream detections (Newberg et al. 2002.,Yanny et al. 2003) and the comprehensive kinematic survey of Mstars (Crane et al. 2003) spanning 100◦ in the sky.”
Kinematics of SDSS subdwarfs: structure and substructure of the Milky Way halo (2009, background): “…Digital Sky Survey (SDSS; York et al. 2000) has made a significant contribution to this field, with a series of major discoveries, including the Monoceros Ring (Newberg et al. 2002; Yanny et al. 2003), the Virgo Overdensity (Jurić et al. 2008) and the Hercules-Aquila Cloud (Belokurov et al. 2007).”
LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan (2012, background): “The anticenter direction has proven to be particular rich insubstructure, including the Monoceros Ring (Newberg et al. 2002, Yanny et al. 2003, Penarrubia et al. 2005), the Anticenter Stream (Grillmair 2006b, Grillmair, Carlin, & Majewski 2008, Carlin et al. 2010), theEBS stream (Grillmair 2006b,…”
The discovery of Segue 2: a prototype of the population of satellites of satellites (2009, background): “Another possibility is the Monoceros ring (Yanny et al. 2003), visible in the SDSS data at the same Galactic longitude but positive latitude.”
The Wobbly Galaxy : kinematics north and south with RAVE red-clump giants (2013, background): “…stellar overdensities: outwards from the Sun at a Galactocentric distance of R = 18–20 kpc there is the Monoceros Stream (Newberg et al. 2002; Yanny et al. 2003), inwards from the Sun (d ∼ 2 kpc) there is the Hercules thick-disc cloud (HTDC; Larsen & Humphreys 1996; Parker, Humphreys &…”
The QUEST RR Lyrae Survey. II. The Halo Overdensities in the First Catalog (2006, background): “…a preliminary report of our results (Zinn et al. 2004), groups 1 and 3 lie approximately in the same direction and at the same distance as the Monoceros stream that was discovered by Newberg et al. (2002) in the SDSS photometry and confirmed by the spectroscopic observations of Yanny et al. (2003).”