On the Distance and Reddening of the Starburst Galaxy IC 10

The Astrophysical Journal (Impact Factor: 6.28). 12/2008; 688(2):L69. DOI: 10.1086/595551
Source: arXiv

ABSTRACT We present deep and accurate optical photometry of the Local Group starburst galaxy IC 10. The photometry is based on two sets of images collected with the Advanced Camera for Surveys and with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We provide new estimates of the tip of the red giant branch (TRGB) magnitude, = 21.90 ± 0.03, and of the reddening, E(B − V) = 0.78 ± 0.06, using field stars in the Small Magellanic Cloud (SMC) as a reference. Adopting the SMC and two globulars, ω Cen and 47 Tuc, as references we estimate the distance modulus to IC 10: independent calibrations give weighted average distances of μ = 24.51 ± 0.08 (TRGB) and μ = 24.56 ± 0.08 (RR Lyrae). We also provide a new theoretical calibration for the TRGB luminosity, and using these predictions we find a very similar distance to IC 10 (μ ≈ 24.60 ± 0.15). These results suggest that IC 10 is a likely member of the M31 subgroup.

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    ABSTRACT: In this paper we investigate the nature of 27 star cluster candidates, most of them projected towards the Galactic anticentre. We derive fundamental parameters for 20 confirmed clusters, among these 7 are new identifications. Four of the remaining are uncertain cases that require deeper photometry to establish their nature, and 4 are probably field fluctuations. In addition, we provide a partial census of the open clusters towards the Galactic anticentre. We also include in this study some interesting objects outside the anticentre region, in the second and third Galactic quadrants, mainly in the Perseus and Outer arms. These clusters confirm the extension of the Outer arm along the third quadrant. We also point out that the embedded cluster FSR 486, at a distance of 7.2 +/- 1.3 kpc from de Sun, is projected on the line of sight of the Local Group irregular dwarf galaxy IC 10. Thus, part of the unusual properties of IC 10 may be explained by a Galactic contamination. We point out the importance of embedded clusters in tracing the spiral structure.
    Monthly Notices of the Royal Astronomical Society 04/2013; 432(4). · 5.23 Impact Factor
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    ABSTRACT: We present new deep and accurate space (Advanced Camera for Surveys-Wide Field Planetary Camera 2 on board the Hubble Space Telescope) and ground-based (Suprime-Cam at Subaru Telescope, Mega-Cam at Canada-France-Hawaii Telescope) photometric and astrometric data for the Local Group dwarf irregular IC10. We confirm the significant decrease of the young stellar population when moving from the center toward the outermost regions. We find that the tidal radius of IC10 is significantly larger than previous estimates of rt 10'. By using the I, V-I color-magnitude diagram based on the Suprime-Cam data, we detect sizable samples of red giant (RG) stars up to radial distances of 18'-23' from the galactic center. The ratio between observed star counts (Mega-Cam data) across the tip of the RG branch and star counts predicted by Galactic models indicates a star count excess at least at a 3σ level up to 34'-42' from the center. This finding supports the hypothesis that the huge H I cloud covering more than 1° across the galaxy is associated with IC10. We also provide new estimates of the total luminosity (LV ~ 9 × 107 L ☉, MV ~ –15.1 mag) that agree with similar estimates available in the literature. If we restrict our study to the regions where rotational velocity measurements are available (r 13'), we find a mass-to-light ratio (~10 M ☉/L ☉) that is at least one order of magnitude larger than previous estimates. The new estimate should be cautiously treated, since it is based on a minimal fraction of the body of the galaxy.
    The Astrophysical Journal Letters 10/2010; 722(2):L244. · 5.60 Impact Factor
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    ABSTRACT: Context. Dwarf irregular galaxies are relatively simple unevolved objects where it is easy to test models of galactic chemical evolution. Aims: We attempt to determine the star formation and gas accretion history of IC 10, a local dwarf irregular for which abundance, gas, and mass determinations are available. Methods: We apply detailed chemical evolution models to predict the evolution of several chemical elements (He, O, N, S) and compared our predictions with the observational data. We consider additional constraints such as the present-time gas fraction, the star formation rate (SFR), and the total estimated mass of IC 10. We assume a dark matter halo for this galaxy and study the development of a galactic wind. We consider different star formation regimes: bursting and continuous. We explore different wind situations: i) normal wind, where all the gas is lost at the same rate and ii) metal-enhanced wind, where metals produced by supernovae are preferentially lost. We study a case without wind. We vary the star formation efficiency (SFE), the wind efficiency, and the time scale of the gas infall, which are the most important parameters in our models. Results: We find that only models with metal-enhanced galactic winds can reproduce the properties of IC 10. The star formation must have proceeded in bursts rather than continuously and the bursts must have been less numerous than ~10 over the whole galactic lifetime. Finally, IC 10 must have formed by a slow process of gas accretion with a timescale of the order of 8 Gyr.
    Astronomy and Astrophysics 09/2010; 520. · 4.48 Impact Factor

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