AustralieFrV1, Main, Exploration, bibRecord, 00A851

Why the Canis Major overdensity is not due to the Warp: analysis of its radial profile and velocities

Identifieur interne : 00A851 ( Main/Exploration ); précédent : 00A850; suivant : 00A852

Why the Canis Major overdensity is not due to the Warp: analysis of its radial profile and velocities

Auteurs : N. F. Martin [France] ; R. A. Ibata [France] ; B. C. Conn [Australie] ; G. F. Lewis [Australie] ; M. Bellazzini [Italie] ; M. J. Irwin ; A. W. Mcconnachie

Source :

Monthly Notices of the Royal Astronomical Society [ 0035-8711 ] ; 2004-12.

RBID : ISTEX:6F7B029DAD3DE4077494471C145AA47638727611

Descripteurs français

Pascal (Inist)
- Disque galactique, Distribution radiale, Etoile M, Etoile géante, Formation galaxies, Galaxies naines, Hémisphère Nord, Modèle, Morphologie, Population stellaire, Structure galaxies, Vitesse radiale.

English descriptors

KwdEn :
- Accretion scenario, Algorithm, Asymptotic correction, Bottom panel, Canis, Centred, Circular velocity, Disc population, Disc stars, Dispersion, Double gaussian model, Dwarf, Dwarf galaxies, Dwarf galaxy, Extra population, Galactic, Galactic disc, Galactic disks, Galactic latitude, Galactic plane, Galactic warp, Galaxy, Galaxy formation, Galaxy structure, Gaseous warp, Giant branch, Giant stars, Ibata, Irwin, Large distances, Local stars, M stars, Majewski, Many stars, Mnras, Models, Morphology, Northern hemisphere, Overdensity, Peak centred, Radial, Radial distribution, Radial velocities, Radial velocity, Rotational velocity, Sagittarius dwarf galaxy, Same region, Scenario, Southern hemisphere, Spectrograph, Star counts, Stellar population, Tidal stream, Trgb, Trgb algorithm, Warp, Warp model.
Teeft :
- Accretion scenario, Algorithm, Asymptotic correction, Bottom panel, Canis, Centred, Circular velocity, Disc population, Disc stars, Dispersion, Double gaussian model, Dwarf, Dwarf galaxy, Extra population, Galactic, Galactic disc, Galactic latitude, Galactic plane, Galactic warp, Galaxy, Gaseous warp, Giant branch, Ibata, Irwin, Large distances, Local stars, Majewski, Many stars, Mnras, Overdensity, Peak centred, Radial, Radial distribution, Radial velocities, Radial velocity, Rotational velocity, Sagittarius dwarf galaxy, Same region, Scenario, Southern hemisphere, Spectrograph, Star counts, Tidal stream, Trgb, Trgb algorithm, Warp, Warp model.

Abstract

In response to recent criticism by Momany et al., that the recently identified Canis Major (CMa) overdensity could be simply explained by the Galactic warp, we present proof of the existence of a stellar population in the direction of CMa that cannot be explained by known Galactic components. By analysing the radial distribution of counts of M‐giant stars in this direction, we show that the Momany et al. warp model overestimates the number of stars in the Northern hemisphere, hence hiding the CMa feature in the South. The use of a better model of the warp has little influence on the morphology of the overdensity and clearly displays an excess of stars grouped at a distance of D= 7.2 ± 0.3 kpc. To lend further support to the existence of a population that does not belong to the Galactic disc, we present radial velocities of M‐giant stars in the centre of the CMa structure that were obtained with the 2dF spectrograph at the Anglo‐Australian Telescope. The extra population shows a radial velocity of vr= 109 ± 4 km s−1, which is significantly higher than the typical velocity of the disc at the distance of CMa. This population also has a low dispersion (13 ± 4 km s−1). The Canis Major overdensity is therefore highly unlikely to be due to the Galactic warp, adding weight to the hypothesis that we are observing a disrupting dwarf galaxy or its remnants. This leads to questions on what part of CMa was previously identified as the Warp and how possibly to disentangle the two structures.

Url:

https://api.istex.fr/document/6F7B029DAD3DE4077494471C145AA47638727611/fulltext/pdf

DOI: 10.1111/j.1365-2966.2004.08521.x

Affiliations:

Le document en format XML

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<front><div type="abstract" xml:lang="en">In response to recent criticism by Momany et al., that the recently identified Canis Major (CMa) overdensity could be simply explained by the Galactic warp, we present proof of the existence of a stellar population in the direction of CMa that cannot be explained by known Galactic components. By analysing the radial distribution of counts of M‐giant stars in this direction, we show that the Momany et al. warp model overestimates the number of stars in the Northern hemisphere, hence hiding the CMa feature in the South. The use of a better model of the warp has little influence on the morphology of the overdensity and clearly displays an excess of stars grouped at a distance of D= 7.2 ± 0.3 kpc. To lend further support to the existence of a population that does not belong to the Galactic disc, we present radial velocities of M‐giant stars in the centre of the CMa structure that were obtained with the 2dF spectrograph at the Anglo‐Australian Telescope. The extra population shows a radial velocity of vr= 109 ± 4 km s−1, which is significantly higher than the typical velocity of the disc at the distance of CMa. This population also has a low dispersion (13 ± 4  km s−1). The Canis Major overdensity is therefore highly unlikely to be due to the Galactic warp, adding weight to the hypothesis that we are observing a disrupting dwarf galaxy or its remnants. This leads to questions on what part of CMa was previously identified as the Warp and how possibly to disentangle the two structures.</div>
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Why the Canis Major overdensity is not due to the Warp: analysis of its radial profile and velocities

Why the Canis Major overdensity is not due to the Warp: analysis of its radial profile and velocities

Source :

Descripteurs français

English descriptors

Abstract

Links toward previous steps (curation, corpus...)

Le document en format XML

Pour manipuler ce document sous Unix (Dilib)

Pour mettre un lien sur cette page dans le réseau Wicri

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