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Stellar Populations in the Dwarf Elliptical Galaxy NGC 147

Han, M. and Hoessel, J. G. and Gallagher, J. S., III and Holtzman, J. and Stetson, P. B. and Trauger, J. and Ballester, G. E. and Burrows, C. and Clarke, J. and Crisp, D. and Griffiths, R. and Grillmair, C. and Hester, J. and Krist, J. and Mould, J. R. and Scowen, P. and Stapelfeldt, K. and Watson, A. and Westphal, J. (1997) Stellar Populations in the Dwarf Elliptical Galaxy NGC 147. Astronomical Journal, 113 (3). pp. 1001-1010. ISSN 0004-6256. doi:10.1086/118316.

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Deep V and I CCD images in a central and an outer field of the Local Group dwarf elliptical galaxy NGC 147 have been obtained with the Wide Field and Planetary Camera-2 (WFPC2) on board of the Hubble Space Telescope. The color-magnitude diagram shows a number of interesting features, including a well defined red giant branch (RGB), a red horizontal branch (HB), a strong red clump, and a small number of extended asymptotic giant branch (EAGB) stars. A mean distance modulus of (m- M)_0=24.39 is derived based on both the HB and the RGB tip brightness. The metallicity [Fe/H] as determined from the RGB color has a mean value of -0.91 in the central field, and -1.0 in the outer field; and the outer field shows a weak tendency of increasing metallicity with galactocentric radius. A metallicity dispersion is also present in the galaxy, and it shows a clear radial variation in the sense that a larger dispersion is seen at smaller radii. The small population of EAGB stars indicates the presence of intermediate-aged (several Gyr) stars in the galaxy, while the absence of the main sequence stars with M v< 1 shows that star formation ceased at least 1 Gyr ago. The distribution of the EAGB stars indicates that the younger stars are more centrally concentrated than the majority of older stars. A similar age gradient is also implied by the relative distribution of the HB stars, which appear to be more populous at larger radii. These results are considered within the context of theoretical models for the evolution of dwarf elliptical galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription
Gallagher, J. S., III0000-0001-8608-0408
Stetson, P. B.0000-0001-6074-6830
Crisp, D.0000-0002-4573-9998
Grillmair, C.0000-0003-4072-169X
Mould, J. R.0000-0003-3820-1740
Stapelfeldt, K.0000-0002-2805-7338
Additional Information:© 1997 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1996 August 7; revised 1996 December 10. We would like to thank Abi Saha for useful discussions and for his help with DoPHOT photometry, which allowed us to make an independent check on our photometry based on the DAO/ALLFRAME package. This work has been supported by NASA Contract NAS7-1260 to JPL.
Group:Infrared Processing and Analysis Center (IPAC)
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Official Citation:Stellar Populations in the Dwarf Elliptical Galaxy NGC 147 Han, M., Hoessel, J. G., Gallagher, J. S., III, Holtsman, J., Stetson, P. B., Trauger, J., , Astronomical Journal v.113, p.1001-1010
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53754
Deposited By: Ruth Sustaita
Deposited On:15 Jan 2015 17:09
Last Modified:10 Nov 2021 20:06

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