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Abstract. We measured the proper motions of 1250 pre-main sequence (PMS) stars and of 104 PMS candidates spread over all-sky major star-forming regions. This work is the continuation of a previous effort where we obtained proper motions for 213 PMS stars located in the major southern star-forming regions. These stars are now included in this present work with refined astrometry. The major upgrade presented here is the extension of proper motion measurements to other northern and southern star-forming regions including the well-studied Orion and Taurus-Auriga regions for objects as faint as V ≤ 16.5. We improve the precision of the proper motions which benefited from the inclusion of new observational material. In the PMS proper motion catalogue presented here, we provide for each star the mean position and proper motion as well as important photometric information when available. We provide also the most common identifier. The rms of proper motions vary from 2 to 5 mas/yr depending on the available sources of ancient positions and depending also on the embedding and binarity of the source. With this work, we present the first all-sky catalogue of proper motions of PMS stars.

The EROS and MACHO collaborations have each published upper limits on the amount of planetary mass dark matter in the Galactic Halo obtained from gravitational microlensing searches. In this paper the two limits are combined to give a much stronger constraint on the abundance of low mass MACHOs. Specifically, objects with masses 10 −7 M ⊙ < ∼ m < ∼ 10 −3 M ⊙ make up less than 25% of the halo dark matter for most models considered, and less than 10% of a standard spherical halo is made of MACHOs in the 3.5 × 10 −7 M ⊙ < m < 4.5 × 10 −5 M ⊙ mass range.

Abstract.We have investigated the 2-D stellar distribution in the outer parts of three nearby open clusters: NGC 2287 (≡M 41), NGC 2516, and NGC 2548 (≡M 48). Wide-field star counts have been performed in two colours on pairs of digitized ESO and SRC Schmidt plates, allowing us to select likely cluster members in the colour-magnitude diagrams. Cluster tidal extensions were emphasized using a wavelet transform. Taking into account observational biases, namely the galaxy clustering and differential extinction in the Galaxy, we have associated these stellar overdensities with real open cluster structures stretched by the galactic gravitational field. As predicted by theory and simulations, and despite observational limitations, we detected a general elongated (prolate) shape in a direction parallel to the galactic Plane, combined with tidal tails extended perpendicularly to it. This geometry is due both to the static galactic tidal field and the heating up of the stellar system when crossing the Disk. The time varying tidal field will deeply affect the cluster dynamical evolution, and we emphasize the importance of adiabatic heating during the Disk-shocking. In the case of NGC 2548, our dating of the last shocking with the Plane (based on a tidal clump) is consistent with its velocity. During the 10-20 Z-oscillations experienced by a cluster before its dissolution in the Galaxy, crossings through the galactic Disk contribute to at least 15% of the total mass loss. Using recent age estimations published for open clusters, we find a destruction time-scale of about 600 Myr for clusters in the solar neighbourhood.