| Full text | |
| Author(s): |
Total Authors: 4
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| Affiliation: | [1] Ctr Fed Educ Tecnol Minas Gerais, Av Monsenhor Luiz de Gonzaga 103, BR-37250000 Nepomuceno, MG - Brazil
[2] Santos Jr, Jr., J. F. C., Univ Fed Minas Gerais, Dept Fis, ICEx, Av Antonio Carlos 6627, BR-31270901 Belo Horizonte, MG - Brazil
[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil
Total Affiliations: 3
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| Document type: | Journal article |
| Source: | Astronomy & Astrophysics; v. 624, APR 1 2019. |
| Web of Science Citations: | 3 |
| Abstract | |
Context. The stellar content of Galactic open clusters is gradually depleted during their evolution as a result of internal relaxation and external interactions. The final residues of the long-term evolution of open clusters are called open cluster remnants. These are sparsely populated structures that can barely be distinguished from the field. Aims. We aimed to characterise and compare the dynamical states of a set of 16 objects catalogued as remnants or remnant candidates. We employed parameters that are intimately associated with the dynamical evolution: age, limiting radius, stellar mass, and velocity dispersion. The sample also includes 7 objects that are catalogued as dynamically evolved open clusters for comparison purposes. Methods. We used photometric data from the 2MASS catalogue, proper motions and parallaxes from the Gaia DR2 catalogue, and a decontamination algorithm that was applied to the three-dimensional astrometric space of proper motions and parallaxes (mu(alpha), mu(delta),(omega) over bar) for stars in the objects' areas. The luminosity and mass functions and total masses for most open cluster remnants are derived here for the first time. Our analysis used predictions of N-body simulations to estimate the initial number of stars of the remnants from their dissolution timescales. Results. The investigated open cluster remnants present masses (M) and velocity dispersions (sigma(v)) within well-defined ranges: M between similar to 10-40 M-circle dot and sigma(v) between similar to 1-7 km s(-1). Some objects in the remnant sample have a limiting radius R-lim less than or similar to 2 pc, which means that they are more compact than the investigated open clusters; other remnants have R-lim between similar to 2-7 pc, which is comparable to the open clusters. We suggest that cluster NGC 2180 (previously classified as an open cluster) is entering a remnant evolutionary stage. In general, our clusters show signals of depletion of low-mass stars. This confirms their dynamically evolved states. Conclusions. We conclude that the open cluster remnants we studied are in fact remnants of initially very populous open clusters (N-0 similar to 10(3)-10(4) stars). The outcome of the long-term evolution is to bring the final residues of the open clusters to dynamical states that are similar to each other, thus masking out the memory of the initial formation conditions of star clusters. (AU) | |
| FAPESP's process: | 18/05535-3 - The study of the Magellanic Clouds and its link with the Milky Way is the objective of this project, including in particular the formation and dissolution of globular clusters. |
| Grantee: | Francisco Ferreira de Souza Maia |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |