Stellar Populations in the Dwarf Elliptical Galaxy NGC 147

Han, Mingsheng; Hoessel, John G.; Gallagher, J. S.; Holtzman, Jon; Stetson, P. B.; Trauger, John T.; Ballester, G. E.; Burrows, C. J.; Clarke, J. T.; Crisp, David; Griffiths, R. E.; Grillmair, Carl J.; Hester, J. J.; Krist, John; Mould, Jeremy; Scowen, Paul A.; Stapelfeldt, K.; Watson, A. M.; Westphal, James A.

doi:10.1086/118316

Cited by 91 publications

(129 citation statements)

References 24 publications

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“…These include the Local Group dwarf spheroidals Draco (M T V ¼ À8:8; Mateo 1998) and Leo I (M T V ¼ À11:9), with spectroscopic and photometric metallicity data from Faria et al (2007) and Koch et al (2007); the Local Group dwarf NGC 147 (M T V ¼ À15:6), with photometric (V ; I ) RGB data from Han et al (1997); the intermediate-luminosity Leo member NGC 3377 ; our data for NGC 3379; and the outermost NGC 5128 halo fields at R gc ¼ 40 kpc ( Rejkuba et al 2005). We use Draco and Leo I only as representative cases of dwarf spheroidals that allow us to exhibit as large as possible a range of host galaxy sizes.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of a substantial blue RGB population in the color range 1 P (V À I ) P1:6 is immediately evident, along with many redder RGB stars that continue redward until the F606W completeness cutoff line (dashed line at right). The first impression is therefore that the halo has primarily a blue, metal-poor giant branch like those in dwarf ellipticals (e.g., Han et al 1997;Butler & MartinezDelgado 2005). However, this initial reaction about the relative numbers of stars at various metallicities is deceptive because of the strongly nonlinear dependence of color on metallicity, as will be discussed in x 5 below.…”

Section: The Color-magnitude Diagrammentioning

confidence: 99%

“…Here, we plot CMDs separately for the upper half ( y > 2000 pixels, eastern side) and the lower half ( y < 2000 pixels, western side). The west side, which is the one further from the center of NGC 3379, has far fewer metal-rich giants, and its CMD begins to resemble rather closely that of a typical metal-poor dwarf elliptical ( Han et al 1997;Butler & MartinezDelgado 2005).…”

Section: The Metallicity Gradientmentioning

confidence: 99%

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The Leo Elliptical NGC 3379: A Metal‐Poor Halo Emerges

Harris¹,

Harris²,

Layden³

et al. 2007

ApJ

120

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We have used the ACS camera on HST to obtain (V, I ) photometry for 5300 red giant stars in the halo of the dominant Leo group member NGC 3379, a galaxy usually regarded as a classic normal giant elliptical. We use this data to derive the metallicity distribution function ( MDF ) for its outer-halo field stars at a location centered 33 kpc from the galaxy center. In at least two ways the MDF is distinctly unlike all the other E galaxies for which similar data exist. First, the NGC 3379 MDF is extremely broad and flat, with many stars at every interval in [m / H ]. Second, we see a metallicity gradient such that in ithe outermost parts of the field the low-metallicity stars (½m/H < À0:7) begin to dominate and the higher metallicity stars are rapidly diminishing. We find that a distinct two-stage chemical evolution model is necessary to explain the MDF shape. Our target field is centered at a projected distance of 12R e , twice as far out in units of effective radius as in any of the other galaxies yet surveyed. If NGC 3379 is indeed representative of large E/S0 galaxies, we predict that other such galaxies will reveal diffuse low-metallicity subpopulations, but that photometry at radii r ' (10Y15)R e will be necessary to get beyond the edge of the dominant metal-rich component.

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Section: Discussionmentioning

confidence: 99%

Section: The Color-magnitude Diagrammentioning

confidence: 99%

Section: The Metallicity Gradientmentioning

confidence: 99%

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The Leo Elliptical NGC 3379: A Metal‐Poor Halo Emerges

Harris¹,

Harris²,

Layden³

et al. 2007

ApJ

120

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“…The most recent star-forming event in NGC 147 happened ∼3 Gyr ago, according to broad-band near-infrared color−magnitude diagrams (Davidge 2005). On the other hand, the absence of mainsequence turn-off stars with M V < −1 indicates that the most recent large-scale star-forming activity occurred at least 1 Gyr ago (Han et al 1997). It may have coincided with the formation of the brightest M giants (Sohn et al 2006).…”

Section: Agesmentioning

confidence: 99%

Globular cluster content and evolutionary history of NGC 147

Шарина

Davoust

2009

A&A

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Context. Globular clusters are representative of the oldest stellar populations. It is thus essential to have a complete census of these systems in dwarf galaxies, from which more massive galaxies are progressively formed in the hierarchical scenario. Aims. We present the results of spectroscopic observations of eight globular cluster candidates in NGC 147, a satellite dwarf elliptical galaxy of M 31. Our goal is to make a complete inventory of the globular cluster system of this galaxy, determine the properties of their stellar populations, and compare these properties with those of systems of globular clusters in other dwarf galaxies. Methods. The candidates were identified on Canada-France-Hawaii telescope photographic plates. Medium resolution spectra were obtained with the SCORPIO spectrograph at the prime focus of the 6 m telescope of the Russian Academy of Sciences. They were analyzed using predictions of stellar population synthesis models. Results. We were able to confirm the nature of all eight candidates, three of which (GC5, GC7, and GC10) are indeed globular clusters, and to estimate evolutionary parameters for the two brightest ones and for Hodge II. The bright clusters GC5 and GC7 appear to have metallicities ([Z/H] ∼ −1.5 ÷ −1.8) that are lower than the oldest stars in the galaxy. The fainter GC Hodge II has a metallicity [Z/H] = −1.1, similar to that of the oldest stars in the galaxy. The clusters GC5 and GC7 have low alpha-element abundance ratios. The mean age of the globular clusters in NGC 147 is 9 ± 1 Gyr. We also measured the radial velocities of Hodge II and IV, and derived a mass of NGC 147 in good agreement with the value from the literature. The frequency, S n = 6.4, and mass fraction, T = 14 of globular clusters in NGC 147 appear to be higher than those for NGC 185 and 205. Conclusions. Our results indicate that the bright clusters GC5, GC7, and Hodge III formed in the main star-forming period ∼8−10 Gyr ago, while the fainter clusters Hodge I and II formed together with the second generation of field stars.

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“…Figure 2 reveals that the two dEs in the LG, (M B = −14.79) and NGC 185 (M B = −14.76), are conspicuously more luminous than other early-type dwarfs. Their intrinsic brightness is likely linked to the relatively large amount of intermediate age SF (e.g., Han et al 1997;Mateo 1998;Butler & Martínez-Delgado 2005;Dolphin et al 2005). In contrast, the seven dEs in the ANGST volume (F8D1, BK5N, KDG 61, KDG 64, KK 77, FM 1, and KDG 63;Caldwell et al 1998;da Costa 2007), span a broad range of lower luminosities from FM 1 (M B = −10.16) to KDG 61 (M B = −12.54).…”

Section: Variations Among Morphological Types In the Combined Local Gmentioning

confidence: 99%

How Typical Are the Local Group Dwarf Galaxies?

Weisz¹,

Dolphin²,

Dalcanton³

et al. 2011

ApJ

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We compare the cumulative star formation histories (SFHs) of Local Group (LG) dwarf galaxies with those in the volume-limited ACS Nearby Galaxy Survey Treasury (ANGST) sample (D 4 Mpc), in order to understand how typical the LG dwarf galaxies are relative to those in the nearby universe. The SFHs were derived in a uniform manner from high-quality optical color-magnitude diagrams constructed from Hubble Space Telescope imaging. We find that the mean cumulative SFHs of the LG dwarfs are comparable to the mean cumulative SFHs of the ANGST sample for the three different morphological types (dwarf spheroidals/ellipticals: dSph/dE; dwarf irregulars: dI; transition dwarfs: dTrans). We also discuss effects such as population gradients and systematic uncertainties in the stellar models that may influence the derived SFHs. Both the ANGST and LG dwarf galaxies show a consistent and strong morphology-density relationship, emphasizing the importance of environment in the evolution of dwarf galaxies. Specifically, we confirm that dIs are found at lower densities and higher luminosities than dSphs, within this large sample. We also find that dTrans are located in similar environments to those occupied by dwarf irregular galaxies, but have systematically lower luminosities that are more comparable to those of dwarf spheroidals. The similarity of the SFHs and morphology-density relationships of the LG and ANGST dwarf galaxies suggests that the LG dwarfs are a good representation of dwarf galaxies in the local universe.

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Stellar Populations in the Dwarf Elliptical Galaxy NGC 147

Cited by 91 publications

References 24 publications

The Leo Elliptical NGC 3379: A Metal‐Poor Halo Emerges

The Leo Elliptical NGC 3379: A Metal‐Poor Halo Emerges

Globular cluster content and evolutionary history of NGC 147

How Typical Are the Local Group Dwarf Galaxies?

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