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Issue A&A
Volume 428, Number 2, December III 2004
Page(s) 451 - 458
Section Galactic structure, stellar clusters and populations
DOI 10.1051/0004-6361:20041080



A&A 428, 451-458 (2004)
DOI: 10.1051/0004-6361:20041080

Disk or halo white dwarfs?

Kinematic analysis of high proper motion surveys
A. Spagna, D. Carollo, M. G. Lattanzi and B. Bucciarelli

INAF - Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy
    e-mail: spagna@to.astro.it

(Received 13 April 2004 / Accepted 21 July 2004)

Abstract
We present an alternative method for the kinematic analysis of high proper motion surveys and discuss its application to the survey of Oppenheimer et al. (2001) for the selection of reliable halo white dwarfs (WDs). The local WD space density we estimate is $\rho_{\rm WD} \simeq 1
\div 2 \times 10^~ M_{\odot}$  pc -3, which is about an order of magnitude smaller than the value derived in Oppenheimer et al. (2001), and is consistent with the values obtained from recent reanalyses of the same data. Our result, which corresponds to a fraction of 0.1% $\div$ 0.2% of the local dark matter, does not support the scenario suggested by microlensing experiments that ancient cool WDs could contribute significantly to the dark halo of the Milky Way.


Key words: stars: kinematics -- white dwarfs -- dark matter -- Galaxy: stellar content -- surveys -- methods: statistical

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