A Comprehensive Analysis of NGC 2158 in the Gaia Era: Photometric Parameters, Apex, and Orbit

Autor: Ing-Guey Jiang, Devesh P. Sariya, E. S. Postnikova, Alexander V. Tutukov, M. D. Sizova, N. V. Chupina, S. V. Vereshchagin, D. Bisht, Geeta Rangwal, R. K. S. Yadav
Rok vydání: 2021
Předmět:
Zdroj: The Astronomical Journal. 161:101
ISSN: 1538-3881
0004-6256
DOI: 10.3847/1538-3881/abd31d
Popis: We present an investigation of NGC 2158 using Gaia-DR2 data. We identified 800 most likely cluster members with membership probability higher than 90%. The mean proper motions of this object are determined as (mu_{x}=-0.203 \pm 0.003, mu_{y}=-1.99 \pm 0.004) mas yr^{-1}. The limiting radius, log(age), and distance of the cluster are obtained as 23.5 arcmin, 9.38 \pm 0.04 Gyr and 4.69 \pm 0.22 kpc, respectively. The overall mass function slope (0.93 \pm 0.14) is flatter than the Salpeter value (1.35) within the mass range 1.17-1.44 M_\odot. This cluster also shows the mass-segregation effect and our study demonstrates that NGC 2158 is a dynamically relaxed open cluster. Using the AD-diagram, the apex coordinates of the cluster are obtained in different ways and examined using (\mu_{U},\mu_{T}) diagram. The best value of apex coordinates is determined as A=87.24^\circ \pm 1.60^\circ, D=-36.61^\circ \pm 5.30 ^\circ. We also determined the orbit of the cluster and found that NGC 2158 moves almost in the Solar antapex direction. The resulting spatial velocity of NGC 2158 is 51 km s^{-1}. A significant oscillations along the Z-coordinate up to 529~pc is detected. Various scenarios regarding the origin of this cluster are also discussed.
Comment: 36 pages, 15 figures. Original submission on 25th June 2020 and accepted for the publication by The Astronomical Journal (AJ) on 10th December 2020
Databáze: OpenAIRE
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