The age of the oldest Open Clusters

By Maurizio Salaris, A. Weiss, S. C. A. R. Institute, L. F. C. F. Astrophysics, Garching. 2003

167 citations recorded by the source corpus.

We determine ages of 71 old Open Clusters by a two-step method: we use main-squence fitting to 10 selected clusters, in order to obtain their distances, and derive their ages from comparison with our own isochrones used before for Globular Clusters. We then calibrate the morphological age indicator δ(V), which can be obtained for all remaining clusters, in terms of age and metallicity. Particular care is taken to ensure consistency in the whole procedure. The resulting Open Cluster ages connect well to our previous Globular Cluster results. From the Open Cluster sample, as well as from the combined sample, questions regarding the formation process of Galactic components are addressed. The age of the oldest open clusters (NGC 6791 and Be 17) is of the order of 10 Gyr. We determine a delay by 2.0 ± 1.5 Gyr between the start of the halo and thin disk formation, whereas thin and thick disk started to form approximately at the same time. We do not find any significant age- metallicity relationship for the open cluster sample. The cumulative age distribution of the whole open cluster sample shows a moderately significant (∼2σ level) departure from the predictions for an exponentially declining dissolution rate with timescale of 2.5 Gyr. The cumulative age distribution does not show any trend with galactocentric distance, but the clusters with larger height to the Galactic plane have an excess of objects between 2-4 and 6 Gyr with respect to their counterpart closer to the plane of the Galaxy.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6a80b85e85a506ec6980b1e2b93b12c71d783a7e

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Citations in the corpus

Painting a portrait of the Galactic disc with its stellar clusters (2020, background): “…between its turn off and red clump (used by e.g. Lynga 1982; Janes & Adler 1982; Janes et al. 1988; Phelps et al. 1994; Carraro & Chiosi 1994; Janes & Phelps 1994; Friel 1995; Salaris et al. 2004), or the morphological age ratio (Anthony-Twarog & Twarog 1985; Twarog & Anthony-Twarog 1989).”
Y2 Isochrones with an Improved Core Overshoot Treatment (2004, result): “…and http://www.astro.yale.edu/ demarque/yyiso.html. the uncertainties, which are still very large (see, e.g., the recent compilation by Salaris et al. 2004), the ages listed in Table 2 are compatible with the ages derived in other investigations using independent isochrone…”
Chemical abundance analysis of the open clusters Cr 110, NGC 2099 (M 37), NGC 2420, NGC 7789, and M 67 (NGC 2682) (2009, methodology): “…relation (hereafter AMR) of the disk (e.g. Janes, 1979; Panagia & Tosi, 1980; Twarog et al., 1997; Friel et al., 2002; Chen et al., 2003; Salaris et al., 2004), but they were Send offprint requests to: E. Pancino ⋆ Based on data collected with the fiber spectrograph FOCES at the 2.2m…”
On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk (2014, methodology): “In particular, we selected determinations provided by Salaris et al. (2004) and Friel (1995) (30 OCs), by the Carraro’s group (13 OCs), by BOCCE7 (8 OCs), and by Friel & Janes (1993) (8 OCs).”
The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters (2008, methodology): “On the contrary Salaris et al. (2004) find a steeper slope for younger clusters.”