Query : 2011A&A...527A...6H

2011A&A...527A...6H - Astronomy and Astrophysics, volume 527A, 6-6 (2011/3-1)

Modelling star counts in the Monoceros stream and the Galactic anti-centre.


Abstract (from CDS):

There is a continuing debate as to the form of the outer disc of the Milky Way galaxy, which has important implications for understanding the Galaxy's formation. Stars are known to exist at a galacto-centric distance of at least 20kpc. However, there is much debate as to whether these stars can be explained as part of the disc or whether another extragalactic structure, the so-called Monoceros ring/stream, is required We examine the outer disc of the Galaxy toward the anti-centre to determine whether the star counts can be explained by the thin and thick discs alone. By using Sloan star counts and extracting the late F and early G dwarfs, it is possible to directly determine the density of stars out to a galacto-centric distance of about 25kpc. These are then compared with a simple flared-disc model. A flared-disc model is shown to reproduce the counts along the lines of sight examined, if the thick disc does not have a sharp cut off. The flare starts at a Galacto-centric radius of 16kpc and has a scale length of 4.5±1.5kpc Whilst the interpretation of the counts in terms of a ring/stream cannot be definitely discounted, it does not appear to be necessary, at least along the lines of sight examined towards the anti centre.

Abstract Copyright:

Journal keyword(s): Galaxy: structure - Galaxy: disk - Galaxy: stellar content

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 NAME Sagittarius Stream St* 02 22 +00.0           ~ 769 0
2 NAME Gal Anticenter reg 05 46 +28.9           ~ 822 0
3 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13083 0
4 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1969 2
5 NAME Monoceros Stream St* ~ ~           ~ 337 0

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