LAMOST meets Gaia: The Galactic open clusters

Abstract

Open clusters (OCs) are born and evolve along the Milky Way (MW) plane. On them is imprinted the history of the Galactic disc, including its chemical and dynamical evolution. Chemical and dynamical properties of OCs can be derived from photometric, spectroscopic, and astrometric data of their member stars. Based on the photometric and astrometric data from the Gaia mission, the membership of stars in more than two thousand Galactic clusters has been identified in the literature. The chemical properties (e.g. metallicity) and kinematical properties (e.g. radial velocity, RV), however, are still poorly known for many of these clusters. In synergy with the large spectroscopic survey LAMOST (data release 8) and Gaia (data release 2), we report a new comprehensive catalogue of 386 OCs. This catalogue has homogeneous parameter determinations of RV, metallicity, and dynamical properties, such as orbit, eccentricity, angular momenta, total energy, and 3D Galactic velocity. These parameters enable the first RV determination for 44 cclusters, and the first spectroscopic [Fe/H] determination for 137 clusters. The metallicity distributions of the majority of clusters show falling trends in the parameter space of the Galactocentric radius, the total energy, and the Z component of angular momentum, except for two old groups that show flat tails in their own parameter planes. Cluster populations of ages younger and older than 500 Myrs distribute diversely on the disc. The latter have a spatial consistency with the Galactic disc flare. The 3D spatial comparison between very young clusters (< 100 Myr) and nearby molecular clouds revealed a wide range of metallicity distribution along the Radcliffe gas cloud wave, indicating a possible inhomogeneous mixing or fast star formation along the wave. This catalogue will serve the community as a useful tool to trace the chemical and dynamical evolution of the MW.

A study on the metallicity gradients in the galactic disk using open clusters

“…To create a comprehensive list of OCs with the best available metallicity estimate, we started by collecting all the metallicity estimates along with other related information like the method of estimation (photometric or spectroscopic), spectral resolution, signal-to-noise ratio (SNR), number of member stars used for average metallicity estimation, and the year of reporting from all the major studies published in the last three decades. This resulted in a total of 4,772 metallicity reports for known OCs, Baratella, 2020;Bragaglia, 2008;Caetano, 2015;Carraro, 2004;Carraro G. et al, 2007;Carraro Giovanni et al, 2007;Carraro, 2008;Carrera, 2012;Carrera et al, 2015;Carrera et al, 2019;Casamiquela et al, 2019;Casamiquela et al, 2021;Claria et al, 1989;Clariá, 2003;Clariá, 2008;Conrad, 2014;D'Orazi et al, 2009;De Silva et al, 2007;De Silva, 2015;Dias et al, 2021;Donati et al, 2015a;Donor, 2018;Donor, 2020;Ford et al, 2005;Fossati, 2011;Friel and Boesgaard, 1992;Friel et al, 2002;Frinchaboy, 2004;Frinchaboy, 2013b;Fu et al, 2022;Geisler et al, 2012;Gonzalez and George, 2000;Gratton et al, 1994;Hasegawa et al, 2008;Hill et al, 1999;Jacobson et al, 2008;Jacobson and Eileen, 2013;Krisciunas et al, 2015;…”

“…For all the six clusters, the adopted metallicities are based on spectroscopic data. For NGC 6204 and Trumpler 33, metallicity estimates are adopted from Conrad (2014), which provided the metallicity estimates based on a spectral resolution of 7,500, while for NGC 2129, Dolidze 5, NGC 6910, and FSR 932, metallicity estimates are adopted from Fu et al (2022), which provided metallicity estimates based on data from the LAMOST survey with a spectral resolution of 1,800. For NGC 2129 and NGC 6910, Zhong et al (2020) provided independent spectroscopic metallicity estimates of −1.426 ± 0.856 and −1.97, respectively, based on data from the LAMOST survey with a spectral resolution of 1,800.…”