Abstract
In this paper, we investigate the spatial structure and dynamical state of the poorly studied old (\(\sim 4\) Gyr) open cluster Trumpler 19 based on reliable cluster members from \(Gaia\)-DR3. The DBSCAN clustering algorithm is used to estimate membership probabilities and select likely cluster members in a normalized 5D parametric space. We identify 859 likely cluster members down to \(G\sim 20\) mag in the field of the cluster. We estimate a cluster radius of \(R_{cl}\sim 18\) arcmin (13.1 pc) based on the radial distribution of the cluster members. We find that the cluster is deficient in faint and low-mass stars (\(G>18.5\) mag) and strong mass segregation has taken place within the cluster. We estimate a core radius of \(R_{c}=3.0\pm 0.2\) arcmin (\(2.2\pm 0.1\) pc) and a tidal radius of \(R_{t}=30.7\pm 9.0\) arcmin (\(22.3\pm 6.5\) pc) for the cluster. We estimate a concentration parameter of \(\log(R_{t}/R_{c})\sim 1.0\), indicating that Trumpler 19 has formed a clear core-halo structure due to dynamical evolution. We investigate the dynamical state of the cluster using 26 blue stragglers (BSs) identified in the cluster. We find that the BSs extend to a radius of \(\sim 10.5\) arcmin (\(3.5R_{c}\)), and 16 of them (\(\sim 62\%\)) are located in the core radius of the cluster. We also find that the BSs are significantly more concentrated than the red giant branch (RGB) and main-sequence (MS) stars, indicating that Trumpler 19 is a dynamically old cluster.
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Acknowledgements
This work was supported by the Foundation of Changzhou University (Grant Nos. GJY21020056, KYP2102197C and KYP2202231C). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France. This research has made use of the WEBDA database, operated at the Department of Theoretical Physics and Astrophysics of the Masaryk University.
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This work was supported by the Foundation of Changzhou University (Grant Nos. GJY21020056, KYP2102197C, KYP2202231C).
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This work was supported by the Foundation of Changzhou University (Grant Nos. GJY21020056, KYP2102197C and KYP2202231C). The authors declare that they have no conflicts of interest. Material preparation, data collection and analysis were performed by Xinhua Gao and Dan Fang. The first draft of the manuscript was written by Xinhua Gao. All authors read and approved the manuscript.
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Gao, X., Fang, D. A clustering study of the old open cluster Trumpler 19. Astrophys Space Sci 368, 73 (2023). https://doi.org/10.1007/s10509-023-04228-9
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DOI: https://doi.org/10.1007/s10509-023-04228-9