Abstract
In this paper, using 2MASS photometry, we study the structural and dynamical properties of four young star clusters viz. King 16, NGC 1931, NGC 637 and NGC 189. For the clusters King 16, NGC 1931, NGC 637 and NGC 189, we obtain the limiting radii of 7′, 12′, 6′ and 5′ which correspond to linear radii of 3.6 pc, 8.85 pc, 3.96 pc and 2.8 pc respectively. The reddening values E(B−V) obtained for the clusters are 0.85, 0.65–0.85, 0.6 and 0.53 and their true distances are 1786 pc, 3062 pc, 2270 pc and 912 pc respectively. Ages of the clusters are 6 Myr, 4 Myr, 4 Myr and 10 Myr respectively. We compare their structures, luminosity functions and mass functions (φ(M)=dN/dM ∝ M −(1+χ)) to the parameter τ=t age /t relax to study the star formation process and the dynamical evolution of these clusters. We find that, for our sample, mass seggregation is observed in clusters or their cores only when the ages of the clusters are comparable to their relaxation times (τ≥1). These results suggest mass seggregation due to dynamical effects. The values of χ, which characterize the overall mass functions for the clusters are 0.96±0.11, 1.16±0.18, 0.55±0.14 and 0.66±0.31 respectively. The change in χ as a function of radius is a good indicator of the dynamical state of clusters.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Balazs, B.A.: Astron. Abh. Hamb. Sternwarte 5, 317 (1961)
Bhatt, B.C., Pandey, A.K., Mahra, H.S., Paliwal, D.C.: Bull. Astron. Soc. India 22, 291 (1994)
Bica, E., Dutra, C.M., Barbuy, B.: Astron. Astrophys. 397, 177 (2003)
Bica, E., Bonatto, C., Blumberg, R.: Astron. Astrophys. 460, 83 (2006)
Binney, J., Merrifield, M.: Galactic Astronomy. Princeton Series in Astrophysics. Princeton University Press, Princeton (1998).
Binney, J., Tremaine, S.: Galactic Dynamics, 2nd edn. Princeton University Press, Princeton (2008). ISBN 978-0-691-13026-2 (HB)
Bonatto, C., Bica, E.: Astron. Astrophys. 437, 483 (2005)
Bonatto, C., Santos, J.F.C. Jr., Bica, E.: Astron. Astrophys. 445, 567 (2006)
Dias, W.S., Alessi, B.S., Moitinho, A., Lepine, J.R.D.: VizieR Online Data Catalog 1, 2022 (2007)
Dutra, C.M., Bica, E.: Astron. Astrophys. 376, 434 (2001)
Dutra, C.M., Santiago, B.X., Bica, E.: Astron. Astrophys. 381, 219 (2002)
Friel, E.D.: Annu. Rev. Astron. Astrophys. 33, 381 (1995)
Girardi, L., Bertelli, G., Bressan, A., Chiosi, C., Groenewegen, M.A.T., Marigo, P., Salasnich, B., Weiss, A.: Astron. Astrophys. 391, 195 (2002)
Grubissich, C.: Astron. Astrophys. Suppl. Ser. 21, 99 (1975)
Huestamendia, G., del Rio, G., Mermilliod, J.C.: Astron. Astrophys. Suppl. Ser. 87, 153 (1991)
Janes, K.A.: Astron. J. 86, 1210 (1981)
Kim, S.C.: J. Korean Astron. Soc. 39, 115 (2006)
King, I.: Astron. J. 67, 471 (1962)
Kjeldsen, H., Frandsen, S.: Astron. Astrophys. Suppl. Ser. 87, 119 (1991)
Kroupa, P.: The IMF of simple and composite populations. In: Knapen, J.H., Mahoney, T.J., Vazdekis, A. (eds.) Pathways through an Electric Universe. Astronomical Society of the Pacific Conference Series, vol. 390, p. 3 (2008). http://adsabs.harvard.edu/abs/2008ASPC..390....3K
Lada, C.J., Adams, F.C.: Astrophys. J. 393, 278 (1992)
Loktin, A.V., Gerasimenko, T.P., Malysheva, L.K.: Astron. Astrophys. Trans. 20, 607 (2001)
Lynga, G.: Astron. Astrophys. 109, 213 (1982)
Maciejewski, G., Niedzielski, A.: Astron. Astrophys. 467, 1065 (2007)
Mermilliod, J.C.: Astron. Astrophys. 53, 289 (1976)
Pandey, A.K., Mahra, H.S.: Astrophys. Space Sci. 120, 107 (1986)
Phelps, R.L., Janes, K.A.: Astrophys. J. Suppl. Ser. 90, 31 (1994)
Pietrukowicz, P., Olech, A., Wisniewski, M., Kedzierski, P., Mularczyk, K., Zloczewski, K., Starczewski, S., Szaruga, K.: Acta Astron. 56, 267 (2006)
Piskunov, A.E., Kharchenko, N.V., Röser, S., Schilbach, E., Scholz, R.D.: Astron. Astrophys. 445, 545 (2006)
Sagar, R., Griffiths, W.K.: Mon. Not. R. Astron. Soc. 299, 777 (1998)
Skrutskie, M.F., Cutri, R.M., Stiening, R., Weinberg, M.D., Schneider, S., Carpenter, J.M., Beichman, C., Capps, R., Chester, T., Elias, J., Huchra, J., Liebert, J., Lonsdale, C., Monet, D.G., Price, S., Seitzer, P., Jarrett, T., Kirkpatrick, J.D., Gizis, J.E., Howard, E., Evans, T., Fowler, J., Fullmer, L., Hurt, R., Light, R., Kopan, E.L., Marsh, K.A., McCallon, H.L., Tam, R., Van Dyk, S., Wheelock, S.: Astron. J. 131, 1163 (2006)
Tadross, A.L.: Chin. J. Astron. Astrophys. 8(3), 362 (2008)
Walker, G.A.H.: Astrophys. J. 141, 660 (1965)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hasan, P., Hasan, S.N. & Shah, U. The structure and dynamics of young star clusters: King 16, NGC 1931, NGC 637 and NGC 189. Astrophys Space Sci 318, 25–33 (2008). https://doi.org/10.1007/s10509-008-9888-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10509-008-9888-2