Context. Ruprecht 147 is the oldest (2.5 Gyr) open cluster in the solar vicinity (< 300 pc), making it an important target for stellar evolution studies and exoplanet searches.
Aims: We aim to derive a census of members and the luminosity, mass, and spatial distributions of the cluster.
Methods: We used an astro-photometric data set including all available information from the literature together with our own observations. We processed the data with an updated version of an existent membership selection methodology.
Results: We identify 259 high-probability candidate members, including 58 previously unreported. All these candidates cover the luminosity interval between G ≳ 6 mag and i ≲ 21 mag. The cluster luminosity and mass distributions are derived with an unprecedented level of details allowing us to recognize, among other features, the Wielen dip. The mass distribution in the low-mass regime drops sharply at 0.4 M⊙ even though our data are sensitive to stellar masses down to 0.1 M⊙, suggesting that most very-low-mass members left the cluster as the result of its dynamical evolution. In addition, the cluster is highly elongated (ellipticity ∼0.5) towards the galactic plane, and mass segregated.
Conclusions: Our combined Gaia+DANCe data set allows us to obtain an extended list of cluster candidate members, and to derive luminosity, mass, and projected spatial distributions in the oldest open cluster of the solar vicinity.
Astronomy and Astrophysics
- Pub Date:
- May 2019
- proper motions;
- stars: luminosity function;
- mass function;
- open clusters and associations: individual: NGC 6774;
- open clusters and associations: individual: Ruprecht 147;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- 25 pages