Proper-motion, star counts and photometric catalog simulations are used to explain the detected stellar over-density in the region of Canis Major, claimed to be the core of a disrupted dwarf galaxy (CMa, Martin et al. \cite{martin04}, MNRAS, 348, 12; Bellazzini et al. \cite{luna04}, [arXiv:astro-ph/0311119]), as due to the Galactic warp and flare in the external disk. We compare the kinematics of CMa M-giant selected sample with surrounding Galactic disk stars in the UCAC2 catalog and find no peculiar proper motion signature: CMa stars mimic thick disk kinematics. Moreover, when taking into account the Galactic warp and flare of the disk, 2MASS star count profiles reproduce the CMa stellar over-density. This star count analysis is confirmed by direct comparison with synthetic color-magnitude diagrams simulated with the Besançon models (Robin et al. \cite{robin03}, A&A, 409, 523) that include the warp and flare of the disk. The presented evidence casts doubt on the identification of the CMa over-density as the core of a disrupted Milky Way satellite. This however does not make clear the origin of over-densities responsible for the ring structure in the anticenter direction of the Galactic halo (Newberg et al. \cite{newberg02}, ApJ, 569, 245; Yanny et al. 2003, ApJ, 588, 824).

Probing the Canis Major stellar over-density as due to the Galactic warp

AL MOMANY, YAZAN;PIOTTO, GIAMPAOLO;BEDIN, LUIGI;CARRARO, GIOVANNI
2004

Abstract

Proper-motion, star counts and photometric catalog simulations are used to explain the detected stellar over-density in the region of Canis Major, claimed to be the core of a disrupted dwarf galaxy (CMa, Martin et al. \cite{martin04}, MNRAS, 348, 12; Bellazzini et al. \cite{luna04}, [arXiv:astro-ph/0311119]), as due to the Galactic warp and flare in the external disk. We compare the kinematics of CMa M-giant selected sample with surrounding Galactic disk stars in the UCAC2 catalog and find no peculiar proper motion signature: CMa stars mimic thick disk kinematics. Moreover, when taking into account the Galactic warp and flare of the disk, 2MASS star count profiles reproduce the CMa stellar over-density. This star count analysis is confirmed by direct comparison with synthetic color-magnitude diagrams simulated with the Besançon models (Robin et al. \cite{robin03}, A&A, 409, 523) that include the warp and flare of the disk. The presented evidence casts doubt on the identification of the CMa over-density as the core of a disrupted Milky Way satellite. This however does not make clear the origin of over-densities responsible for the ring structure in the anticenter direction of the Galactic halo (Newberg et al. \cite{newberg02}, ApJ, 569, 245; Yanny et al. 2003, ApJ, 588, 824).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2467288
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