Volume 484, Number 2, June III 2008
|Page(s)||609 - 620|
|Section||Catalogs and data|
|Published online||19 March 2008|
II. A star catalog for M 67: WFI@2.2 m MPG/ESO astrometry, FLAMES@VLT radial velocities
Dipartimento di Astronomia, Universita di Padova, Vicolo dell' Osservatorio 2, 35122 Padova, Italy e-mail: [giampaolo.piotto;sandro.villanova]@unipd.it
2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA e-mail: [bedin;jander]@stsci.edu
3 INAF – Osservatorio Astronomico di Collurania, via M. Maggini, 64100 Teramo, Italy e-mail: firstname.lastname@example.org
4 Grupo de Astronomía, Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile e-mail: email@example.com
5 Dept. of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA e-mail: firstname.lastname@example.org
6 European Southern Observatory, Garching, Karl-Schwarzschild-Str. 2, 85748 Germany e-mail: email@example.com
7 INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35132, Italy e-mail: firstname.lastname@example.org
8 Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 129, India e-mail: email@example.com
Corresponding author: firstname.lastname@example.org
Accepted: 25 February 2008
Context. The solar-age open cluster M 67 (C0847+120, NGC 2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, the census of cluster membership for M 67 at fainter magnitudes and their properties are not well-established.
Aims. Using proprietary and archival ESO data, we have obtained astrometric, photometric, and radial velocities of stars in a arcmin2 field centered on the old open cluster M 67.
Methods. The two-epoch archival observations separated by 4 years and acquired with the Wide-Field Imager at the 2.2 m MPG/ESO telescope were reduced with our new astrometric techniques, as described in the first paper in this series. The same observations served to derive calibrated BVI photometry in M 67. Radial velocities were measured using the archival and new spectroscopic data obtained at the VLT.
Results. We have determined relative proper motions and membership probabilities for ~2400 stars. The precision of proper motions for optimally exposed stars is 1.9 mas yr-1, gradually degrading down to ~5 mas yr-1 at . Our relatively precise proper motions at were first obtained in this magnitude range for M 67. Radial velocities were measured for 211 stars in the same field. We also present a detailed comparison with recent theoretical isochrones from several independent groups.
Conclusions. For the M 67 area, we provide positions, calibrated BVI photometry, relative proper motions, membership probabilities, and radial velocities. We demonstrate that ground-based CCD mosaic observations just a few years apart are producing proper motions, allowing reliable membership determination. We have produced a catalog that is electronically available to the astronomical community.
Key words: Galaxy: open clusters and associations: individual: M 67 / astrometry / catalogs
Based on observations with the MPG/ESO 2.2 m and ESO/VLT telescopes, located at La Silla and Paranal Observatory, Chile, under DDT program 278.D-5027, and the archive material.
© ESO, 2008
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