Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-31T19:54:14.878Z Has data issue: false hasContentIssue false
  • English
  • Français

Origin of Structural and Kinematic Properties of the Small Magellanic Cloud

Published online by Cambridge University Press:  05 March 2013

Kenji Bekki  and
Masashi Chiba
Kenji Bekki*
Affiliation:
School of Physics, University of New South Wales, Sydney 2052, Australia
Masashi Chiba
Affiliation:
Astronomical Institute, Tohoku University, Sendai, 980-8578, Japan
*
CCorresponding author. Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We investigate structural, kinematic and chemical properties of stars and gas in the Small Magellanic Cloud (SMC) interacting with the Large Magellanic Cloud (LMC) and the Galaxy based on a series of self-consistent chemodynamical simulations. We adopt a new ‘dwarf spheroidal model’ in which the SMC initially has both old stars with a spherical spatial distribution and an extended Hi gas disk. We mainly investigate the evolution of the SMC for the last ∼3 Gyr, during which the Magellanic Stream (MS) and the Magellanic Bridge (MB) could have formed as a result of the LMC–SMC–Galaxy interaction. Our principal results, which can be tested against observations, are as follows: The final spatial distribution of the old stars projected onto the sky is spherical, even after strong LMC–SMC–Galaxy interaction, whereas that of the new ones is significantly flattened and appears to form a bar structure. Old stars have a line-of-sight velocity dispersion σ ≃ 30 km s−1 and slow rotation, with a maximum rotational velocity, V < 20 km s−1 and show asymmetry in the radial profiles. New stars have a smaller Σ than old ones and a significant amount of rotation (V/σ > 1). Hi gas shows velocity dispersions of σ = 10–40 km s−1, a high maximum rotational velocity (V ∼ 50 km s−1) and a spatial distribution similar to that of new stars. New stars with ages younger than 3 Gyr show a negative metallicity gradient in the sense that more metal-rich stars are located in the inner regions of the SMC. The MB inevitably contains old stars with surface mass densities of 6−300 × 104 M⊙ deg−2 depending on initial stellar distributions of the modeled SMC. We find that the dwarf spheroidal model can explain more self-consistently the observed kinematic properties of stars and gas, compared with another type of the model (‘the disk model’) in which the SMC initially consists of stellar and gas disks. We suggest that, to better understand its evolution, the SMC needs to be modeled as having a spheroidal component, rather than being a pure disk.

Keywords

galaxies: Magellanic Cloudsgalaxies: star clustersgalaxies: stellar contentgalaxies: interactions
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 26 , Issue 1 , 2009 , pp. 37 - 57
Copyright
Copyright © Astronomical Society of Australia 2009

References

Andredakis, Y. C. & Sanders, R. H., 1994, MNRAS, 267, 283 CrossRefGoogle Scholar
Bekki, K., 1998, ApJ, 502, L133 CrossRefGoogle Scholar
Bekki, K., 2007, MNRAS, 380, 1669 CrossRefGoogle Scholar
Bekki, K., Couch, W. J., Beasley, M. A., Forbes, D. A., Chiba, M. & Da Costa, G., 2004, ApJ, 610, L93 Google Scholar
Bekki, K. & Chiba, M., 2005, MNRAS, 356, 680 Google Scholar
Bekki, K. & Chiba, M., 2007, MNRAS, 381, L16 Google Scholar
Bekki, K. & Chiba, M., 2006, ApJ, 637, L97 Google Scholar
Bekki, K. & Chiba, M., 2008, ApJ, 679, L89 CrossRefGoogle Scholar
Bekki, K., Chiba, M. & McClure-Griffiths, N. M., 2008, ApJ, 672, L17 Google Scholar
Bekki, K. & Stanimirović, S., 2009, MNRAS, submitted (arXiv/0807.2102v1)Google Scholar
Besla, G., Kallivayalil, N., Hernquist, L., Robertson, B., Cox, T. J., van der Marel, R. P. & Alcock, C., 2007, ApJ, 668, 949 CrossRefGoogle Scholar
Binney, J. & Tremaine, S., 1987, Galactic Dynamics (Princeton: Princeton Univ. Press)Google Scholar
Broeils, A. H. & van Woerden, H., 1994, A&AS, 107, 129 Google Scholar
Brüns, C. et al., 2005, A&A, 432, 45 Google Scholar
Burkert, A., 1995, ApJ, 447, L25 CrossRefGoogle Scholar
Caldwell, J. A. R. & Coulson, I. M., 1986, MNRAS, 218, 223 CrossRefGoogle Scholar
Cioni, M.-R. L., Girardi, L., Marigo, P. & Habing, H. J., 2006, A&A, 448, 77 Google Scholar
Connors, T. W., Kawata, D. & Gibson, B. K., 2006, MNRAS, 371, 108 Google Scholar
de Blok, W. J. G. & Walter, F., 2003, MNRAS, 341, L39 Google Scholar
Dopita, M. A., Lawrence, C. J., Ford, H. C. & Webster, B. L., 1985, ApJ, 296, 390 Google Scholar
Duc, P.-A., Brinks, E., Springel, V., Pichardo, B., Weilbacher, P. & Mirabel, I. F., 2000, AJ, 120, 1238 CrossRefGoogle Scholar
Gardiner, L. T. & Noguchi, M., 1996, MNRAS, 278, 191 Google Scholar
Hardy, E., Suntzeff, N. B. & Azzopardi, M., 1989, ApJ, 344, 210 Google Scholar
Harris, J. & Zaritsky, D., 2004, AJ, 127, 1531 CrossRefGoogle Scholar
Harris, J. & Zaritsky, D., 2006, AJ, 131, 2514 CrossRefGoogle Scholar
Harris, J., 2007, ApJ, 658, 345 Google Scholar
Hatzidimitriou, D., Croke, B. F., Morgan, D. H. & Cannon, R. D., 1997, A&AS, 122, 507 Google Scholar
Hernquist, L. & Katz, N., 1989, ApJS, 70, 419 Google Scholar
Hunter, D. A., Elmegreen, B. G. & Baker, A. L., 1998, ApJ, 493, 595 Google Scholar
Ichikawa, S. I., Wakamatsu, K. I. & Okamura, S., 1986, ApJS, 60, 475 Google Scholar
Idiart, T. P., Maciel, W. J. & Costa, R. D. D., 2007, A&A, 472, 101 Google Scholar
Irwin, M. J., Demers, S. & Kunkel, W. E., 1990, AJ, 99, 191 CrossRefGoogle Scholar
Kallivayalil, N., van der Marel, R. P. & Alcock, C., 2006, ApJ, 652, 1213 Google Scholar
Kato, D. et al., 2007, PASJ, 59, 615 CrossRefGoogle Scholar
Kennicutt, R. C. Jr., 1998, ARA&A, 36, 189 Google Scholar
Mayer, L. et al., 2001, ApJ, 559, 754 Google Scholar
Monaghan, J. J. & Lattanzio, J. C., 1985, A&A, 149, 135 Google Scholar
Mastropietro, C., Moore, B., Mayer, L., Wadsley, J. & Stadel, J., 2005, MNRAS, 363, 509 Google Scholar
Mizuno, N. et al., 2006, ApJ, 643, L107 Google Scholar
Muller, E., Stanimirović, S., Rosolowsky, E. & Staveley-Smith, L., 2004, ApJ, 616, 845 CrossRefGoogle Scholar
Muller, E. & Bekki, K., 2007, 381, L11 Google Scholar
Muñoz, R. R. et al., 2006, ApJ, 649, 201 Google Scholar
Murai, T. & Fujimoto, M., 1980, PASJ, 32, 581 Google Scholar
Navarro, J. F., Frenk, C. S. & White, S. D. M., 1996, ApJ, 462, 563 Google Scholar
Nidever, D. L., Majewski, S. R. & Butler, B. W., 2007, ApJ, 679, 432 CrossRefGoogle Scholar
Nishiyama, S. et al., 2007, ApJ, 658, 358 Google Scholar
Noël, N. E. D. & Gallart, C., 2007, ApJ, 665, 23 Google Scholar
Noguchi, M., 1988, A&A, 203, 259 Google Scholar
Pagel, B. E. J. & Tautvaisiene, G., 1998, MNRAS, 299, 535 Google Scholar
Piatek, S., Pryor, C. & Olszewski, E. W., 2008, AJ, 135, 1024 Google Scholar
Piatti, A. E., Sarajedini, A., Geisler, D., Clark, D. & Seguel, J., 2007, MNRAS, 377, 300 CrossRefGoogle Scholar
Putman, M. E. et al., 1998, Natur, 394, 752 Google Scholar
Russell, S. C. & Dopita, M. A., 1992, ApJ, 384, 508 Google Scholar
Salucci, P. & Burkert, A., 2000, ApJ, 537, L9 Google Scholar
Shattow, G. & Loeb, A., 2009, MNRAS, 392, 21 Google Scholar
Stanimirović, S., Staveley-Smith, L. & Jones, P. A., 2004, ApJ, 604, 176 Google Scholar
Schmidt, M., 1959, ApJ, 129, 243 Google Scholar
Spite, M., Huille, S., Spite, F. & Francois, P., 1988, A&AS, 76, 405 Google Scholar
Sugimoto, D., Chikada, Y., Makino, J., Ito, T., Ebisuzaki, T. & Umemura, M., 1990, Natur, 345, 33 CrossRefGoogle Scholar
Suntzeff, N. B., Friel, E., Klemola, A., Kraft, R. P. & Graham, J. A., 1986, AJ, 91, 275 Google Scholar
Thornton, K., Gaudlitz, M., Janka, H.-Th. & Steinmetz, M., 1998, ApJ, 500, 95 Google Scholar
Torres, G. & Carranza, G. J., 1987, MNRAS, 226, 513 Google Scholar
Tsujimoto, T., Nomoto, K., Yoshii, Y., Hashimoto, M., Yanagida, S. & Thielemann, F.-K., 1995, MNRAS, 277, 945 Google Scholar
van den Bergh, S., 2000, The Galaxies of the Local Group (Cambridge: Cambridge Univ. Press)Google Scholar
Vazdekis, A., Casuso, E., Peletier, R. F. & Beckman, J. E., 1996, ApJS, 106, 307 CrossRefGoogle Scholar
Westerlund, B. E., 1997, The Magellanic Clouds (Cambridge: Cambridge Univ. Press)Google Scholar
Widrow, L. M. & Dubinski, J., 2005, ApJ, 631, 838 Google Scholar
Yoshizawa, A. & Noguchi, M., 2003, MNRAS, 339, 1135 Google Scholar