Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions
We use a kernel density estimator method to evaluate the stellar velocity dispersion in the open cluster NGC 2571. We derive the 3D velocity dispersion using both proper motions as extracted from Gaia Data Release 3 and single-epoch radial velocities as obtained with the instrument FLAMES at ESO...
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| Format: | Article |
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IOP Publishing
2024-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/ad32cc |
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| author | Maxim V. Kulesh Aleksandra E. Samirkhanova Giovanni Carraro Joao V. Sales-Silva Roberto Capuzzo Dolcetta Anton F. Seleznev |
| author_facet | Maxim V. Kulesh Aleksandra E. Samirkhanova Giovanni Carraro Joao V. Sales-Silva Roberto Capuzzo Dolcetta Anton F. Seleznev |
| author_sort | Maxim V. Kulesh |
| collection | DOAJ |
| description | We use a kernel density estimator method to evaluate the stellar velocity dispersion in the open cluster NGC 2571. We derive the 3D velocity dispersion using both proper motions as extracted from Gaia Data Release 3 and single-epoch radial velocities as obtained with the instrument FLAMES at ESO's Very Large Telescope. The mean-square velocity along the line of sight is found to be larger than the one in the tangential direction by a factor of 6–8. We argue that the most likely explanation for such an occurrence is the presence of a significant quantity of unresolved binary and multiple stars in the radial velocity sample. Special attention should be paid to single-line spectroscopic binaries (SB1) since in this case we observe the spectral lines of the primary component only, and therefore the derived radial velocity is not the velocity of the binary system center of mass. To investigate this scenario, we performed numerical experiments varying the fractional abundance of SB1 in the observed sample. These experiments show that the increase of the mean-square radial velocity depends on the fractional abundance of SB1 to a power in the range [0.39, 0.45]. We used the 3D velocity dispersion obtained by the dispersions in the tangential directions and the assumption that the radial velocity dispersion is the same as a tangential one to estimate the virial cluster mass and the cluster mass, taking into account the gravitational field of the Galaxy and the nonstationarity of the cluster. These estimates are 650 ± 30 M _⊙ and 310 ± 80 M _⊙ , respectively, in substantial agreement with the photometric cluster mass. |
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| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2024-04-24T10:51:51Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj.art-2b2a6f7f9469493897e81dccc5865ea12024-04-12T09:41:30ZengIOP PublishingThe Astronomical Journal1538-38812024-01-01167521210.3847/1538-3881/ad32ccVelocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper MotionsMaxim V. Kulesh0https://orcid.org/0000-0003-2125-8740Aleksandra E. Samirkhanova1Giovanni Carraro2https://orcid.org/0000-0002-0155-9434Joao V. Sales-Silva3https://orcid.org/0000-0003-0636-7463Roberto Capuzzo Dolcetta4Anton F. Seleznev5https://orcid.org/0000-0001-8669-803XUral Federal University , 51 Lenin Street, Ekaterinburg, 620000, RussiaUral Federal University , 51 Lenin Street, Ekaterinburg, 620000, RussiaDipartimento di Fisica e Astronomia, Università di Padova , Vicolo Osservatorio 3, I-35122, Padova, ItalyObservatório Nacional/MCTIC , R. Gen. José Cristino, 77, 20921-400, Rio de Janeiro, BrazilDipartimento di Fisica, Sapienza Università di Roma , P.le A. Moro 5, I-00165 Roma, ItalyUral Federal University , 51 Lenin Street, Ekaterinburg, 620000, RussiaWe use a kernel density estimator method to evaluate the stellar velocity dispersion in the open cluster NGC 2571. We derive the 3D velocity dispersion using both proper motions as extracted from Gaia Data Release 3 and single-epoch radial velocities as obtained with the instrument FLAMES at ESO's Very Large Telescope. The mean-square velocity along the line of sight is found to be larger than the one in the tangential direction by a factor of 6–8. We argue that the most likely explanation for such an occurrence is the presence of a significant quantity of unresolved binary and multiple stars in the radial velocity sample. Special attention should be paid to single-line spectroscopic binaries (SB1) since in this case we observe the spectral lines of the primary component only, and therefore the derived radial velocity is not the velocity of the binary system center of mass. To investigate this scenario, we performed numerical experiments varying the fractional abundance of SB1 in the observed sample. These experiments show that the increase of the mean-square radial velocity depends on the fractional abundance of SB1 to a power in the range [0.39, 0.45]. We used the 3D velocity dispersion obtained by the dispersions in the tangential directions and the assumption that the radial velocity dispersion is the same as a tangential one to estimate the virial cluster mass and the cluster mass, taking into account the gravitational field of the Galaxy and the nonstationarity of the cluster. These estimates are 650 ± 30 M _⊙ and 310 ± 80 M _⊙ , respectively, in substantial agreement with the photometric cluster mass.https://doi.org/10.3847/1538-3881/ad32ccOpen star clustersBinary stars |
| spellingShingle | Maxim V. Kulesh Aleksandra E. Samirkhanova Giovanni Carraro Joao V. Sales-Silva Roberto Capuzzo Dolcetta Anton F. Seleznev Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions The Astronomical Journal Open star clusters Binary stars |
| title | Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions |
| title_full | Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions |
| title_fullStr | Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions |
| title_full_unstemmed | Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions |
| title_short | Velocity Dispersion of the Open Cluster NGC 2571 by Radial Velocities and Proper Motions |
| title_sort | velocity dispersion of the open cluster ngc 2571 by radial velocities and proper motions |
| topic | Open star clusters Binary stars |
| url | https://doi.org/10.3847/1538-3881/ad32cc |
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