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Morphological transformation of NGC 205?

Published online by Cambridge University Press:  13 April 2010

Ivo Saviane ,
Lorenzo Monaco  and
Tony Hallas
Ivo Saviane
Affiliation:
European Southern Observatory, Chile email: [email protected]
Lorenzo Monaco
Affiliation:
Dept. of Astronomy, University of Concepcion, Chile
Tony Hallas
Affiliation:
Astrophoto, USA
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NGC 205 is a small galaxy (M/M⊙ = 0.7 × 109; MV = −16.6) currently located 36′ NW of M31. It is classified as dE because in ground-based images it appears as an elliptical body. However past investigations have revealed characteristics that are more typical of a disk galaxy: the specific frequency of globular clusters is 1.8; the large scale dynamics shows partial rotational support; there is a significant amount (106M⊙) of rotating gas (molecular and atomic) and dust; the central regions harbor a fairly complex stellar population, including a 100–500 Myr old nucleus surrounded by 50- and 100-Myr old stellar associations (see references in Monaco et al. 2009; M09). Very recently, thanks to hst/acs imaging we have been able to reveal a young central ‘field’ population (M09), extending out to ~40″ in radius (~160 pc). The luminosity function of the main sequence can be fitted with Saviane et al. (2004) model of continuous star formation (SF) from at least ~600 Myr ago to ~60 Myr ago. We found that 1.5 × 105M⊙ in stars were produced from ~300 Myr to ~60 Myr ago, with a SF rate of 7 × 10−4M⊙ yr−1. A continuous SF seems to support the latest simulations of NGC 205 orbit: Howley et al. (2008) found that the galaxy must be moving with a velocity 300–500 km s−1 (comparable to the escape velocity) along an almost radial orbit, and it should be approaching M31 for the first time. An episodic SF triggered by passages through M31 disk every ~300 Myr in a bound orbit (Cepa & Beckman 1988) is excluded by our data.

Type
Poster Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S262: Stellar Populations – Planning for the Next Decade , August 2009 , pp. 426 - 427
Copyright
Copyright © International Astronomical Union 2010

References

Bekki, K., Couch, W. J., Drinkwater, M. J., & Gregg, M. D. 2001, ApJ, 557, L39CrossRefGoogle Scholar
Cepa, J. & Beckman, J. E. 1988 A&A, 200, 21Google Scholar
Howley, K. M. et al. 2008, ApJ, 683, 722CrossRefGoogle Scholar
Koleva, M. 2009, Ph.D. Thesis, Université Lyon IGoogle Scholar
Koleva, M. et al. 2009, MNRAS, 396, 2133CrossRefGoogle Scholar
Kormendy, J., Fisher, D. B., Cornell, M. E., & Bender, R. 2009, ApJS, 182, 216CrossRefGoogle Scholar
Lisker, T., Glatt, K., Westera, P., & Grebel, E. K. 2006, AJ, 132, 2432CrossRefGoogle Scholar
Mayer, L. et al. 2001, ApJ, 559, 754CrossRefGoogle Scholar
Monaco, L. et al. 2009, A&A, 502, L9 (M09)Google Scholar
Moore, B., Katz, N., Lake, G., Dressler, A., & Oemler, A. 1996, Nature, 379, 613CrossRefGoogle Scholar
Moore, B., Lake, G., & Katz, N. 1998, ApJ, 495, 139CrossRefGoogle Scholar
Saviane, I., Hibbard, J. E., & Rich, R. M. 2004, AJ, 127, 660CrossRefGoogle Scholar