EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 445/1 Article
Free access article

Issue A&A
Volume 445, Number 1, January I 2006
Page(s) 69 - 77
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20053583



A&A 445, 69-77 (2006)
DOI: 10.1051/0004-6361:20053583

Near-IR photometry of asymptotic giant branch stars in the dwarf elliptical galaxy NGC 147

Y.-J. Sohn1, 2, A. Kang1, 2, J. Rhee1, 2, M. Shin1, M.-S. Chun1 and Ho-Il Kim3

1  Department of Astronomy, Yonsei University, Seoul 120-749, Korea
    e-mail: sohnyj@yonsei.ac.kr; breeze82@galaxy.yonsei.ac.kr
2  Center for Space Astrophysics, Yonsei University, Seoul 120-749, Korea
3  Korea Astronomy and Space Science Institute, Daejeon 305-348, Korea

(Received 7 June 2005 / Accepted 31 July 2005)

Abstract
Near-infrared J, H and K' images were used to investigate the stellar contents of the asymptotic giant branch (AGB) population in the nearby dwarf elliptical galaxy NGC 147. The obtained (K, J-K) and (K, H-K) color-magnitude diagrams contain stars of AGB and red giant branch populations, where the former consists of a group of bright blue stars, a dominant population of M giant and a red C star population. We identified 91 AGB C stars in NGC 147 with the mean absolute magnitude and colors of $\langle M_K\rangle = -7.56$, $\langle(J-K)_0\rangle = 1.81$ and $\langle(H-K)_0\rangle = 0.74$. The estimated number ratio of C stars to M giant stars (C/M) is $0.16\pm0.02$. The estimated local C/M ratios of $0.14\pm 0.02$ for the inner region (r<70'') and $0.19\pm 0.03$ for the outer region (r>70'') indicate a weak radial gradient. The mean bolometric magnitude of 91 C stars in NGC 147 is $\langle M_{\rm bol}\rangle = -4.32\pm 0.49$. The bolometric luminosity function of M giant stars in NGC 147 extends up to $M_{\rm bol} = -5.8$ mag, and that of only C stars spans $-5.6<M_{\rm bol}<-3.5$. The color histograms of AGB stars in (J-K) and (H-K) show a main peak containing M giant stars, a red tail containing C stars with a weak excess, and a blue excess possibly due to bright blue foreground stars and AGB stars younger than M giants. The comparison of the theoretical isochrone models with the color distribution and the brightness of AGB stars indicates that most of the bright M giants in NGC 147 were formed at log $(t_{\rm yr})\sim8.4$ with a range of $8.2\sim8.6$. Ages of the majority of M giant stars in NGC 147 are similar to those of younger M giant stars in its companion NGC 185, while their formation occurred more recently than the older M giant stars in NGC 185 by ~2 Gyr.


Key words: galaxies: individual: NGC 147 -- galaxies: stellar content -- stars: AGB and post-AGB

SIMBAD Objects
Tables at the CDS



© ESO 2005


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.