SLICING THE MONOCEROS OVERDENSITY WITH SUPRIME-CAM

Journal Article · Wed Aug 01 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/754/2/101· OSTI ID:22039240

Conn, Blair C; Noeel, Noelia E. D.; Rix, Hans-Walter; Martin, Nicolas F ^[1]; Lane, Richard R ^[2]; Lewis, Geraint F ^[3]; Irwin, Mike J; Chapman, Scott ^[4]; Ibata, Rodrigo A ^[5]; Dolphin, Andrew ^[6]

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1. Max Planck Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)
2. Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)
3. Sydney Institute for Astronomy, School of Physics, The University of Sydney, A28, Sydney 2006 (Australia)
4. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. Observatoire de Strasbourg, 11 Rue de l'Universite, F-67000 Strasbourg (France)
6. Raytheon Company, P.O. Box 11337, Tucson, AZ 85734-1337 (United States)

We derive distance, density, and metallicity distribution of the stellar Monoceros Overdensity (MO) in the outer Milky Way, based on deep imaging with the Subaru Telescope. We applied color-magnitude diagram fitting techniques in three stripes at galactic longitudes, l {approx} 130 Degree-Sign , 150 Degree-Sign , 170 Degree-Sign , and galactic latitudes, +15 Degree-Sign {<=} b {<=} +25 Degree-Sign . The MO appears as a wall of stars at a heliocentric distance of {approx}10.1 {+-} 0.5 kpc across the observed longitude range with no distance change. The MO stars are more metal-rich ([Fe/H] {approx} -1.0) than the nearby stars at the same latitude. These data are used to test three different models for the origin of the MO: a perturbed disk model, which predicts a significant drop in density adjacent to the MO that is not seen; a basic flared disk model, which can give a good match to the density profile but the MO metallicity implies the disk is too metal-rich to source the MO stars; and a tidal stream model, which, from the literature, brackets the distances and densities we derive for the MO, suggesting that a model can be found that would fully fit the MO data. Further data and modeling will be required to confirm or rule out the MO feature as a stream or as a flaring of the disk.

• OSTI ID: 22039240
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 754; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
COLOR
DENSITY
DIAGRAMS
DISTANCE
HYDROGEN
IRON
MILKY WAY
STARS
STELLAR FLARES
TELESCOPES