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Astron. Astrophys. 330, 953-962 (1998)

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Towards a consistent model of the Galaxy

II. Derivation of the model

D. Méra 1 , 3, G. Chabrier 1, and R. Schaeffer 2

1 C.R.A.L. (UMR CNRS 5574), Ecole Normale Supérieure, F-69364 Lyon Cedex 07, France,
2 Service de Physique Théorique, CEA Saclay, F-91191 Gif-sur-Yvette, France
3 Physics Department, Whichita State University, 1845 Fairmount, Wichita KS 67260, USA

Received 30 April 1997 / Accepted 24 September 1997


We use the calculations derived in a previous paper (Méra, Chabrier and Schaeffer, 1997), based on observational constraints arising from star counts, microlensing experiments and kinematic properties, to determine the amount of dark matter under the form of stellar and sub-stellar objects in the different parts of the Galaxy. This yields the derivation of different mass-models for the Galaxy. In the light of all the afore-mentioned constraints, we discuss two models that correspond to different conclusions about the nature and the location of the Galactic dark matter. In the first model there is a small amount of dark matter in the disk, and a large fraction of the dark matter in the halo is still undetected and likely to be non-baryonic. The second, less conventional model is consistent with entirely, or at least predominantly baryonic dark matter, under the form of brown dwarfs in the disk and white dwarfs in the dark halo. We derive observational predictions for these two models which should be verifiable by near future infrared and microlensing observations.

Key words: stars: low-mass, brown dwarfs – Galaxy: stellar content – Galaxy: halo – cosmology: dark matter

© European Southern Observatory (ESO) 1998

Online publication: January 27, 1998