Are All the DIGs the Same?

Hidalgo-Gámez, A. M.

doi:10.1007/1-4020-2620-x_12

Cited by 12 publications

(24 citation statements)

References 5 publications

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“…This set of data, fully reduced and calibrated, was divided into a number of spectra, covering five rows each. This value matches the seeing conditions during the observations and corresponds to 90 pc at a distance of 3.53 Mpc (Hidalgo-Gámez & Olofsson 1998). A total of 86 one-dimensional spectra were studied, covering eight slit positions throughout the galaxy.…”

Section: Observations and Data Reductionsupporting

confidence: 61%

“…First, it has a high gas content with a total gas mass of 2.45 × 10 8 M ⊙ (Hunter & Elmegreen 2004) and a star formation rate of 5 × 10 −3 M ⊙ yr −1 . Second, it is located at only 3.53 Mpc (Hidalgo-Gámez & Olofsson 1998); therefore, the DIG can be detected easily with medium-size telescopes and not very long integration times. Moreover, the spatial resolution is good enough to study the details of the DIG and differentiate it from the classical H ii regions.…”

Section: Introductionmentioning

confidence: 99%

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Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53

Hidalgo-Gámez

2007

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The spectral characteristics throughout the dwarf irregular galaxy DDO 53 are studied. The results are very similar to those for other irregular galaxies: high excitation and low values of the [SII]/Halpha ratio. The most likely ionization source is photon leakage from the classical HII regions, without any other source, although the interstellar medium of the galaxy is quite perturbed. Moreover, the physical conditions throughout the galaxy do not change very much because both the photon leakage percentage and the ionization temperature are very similar. In addition, the determined metal content for two HII regions indicates that DDO 53 is a low-metallicity galaxy.Comment: 32 pages, 9 figures, 7 tables. AJ, in pres

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Section: Observations and Data Reductionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53

Hidalgo-Gámez

2007

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“…Comparing these results with previously determined B-band L − Z relations is difficult because the slope and intercept are sensitive to sample selec-tion effects (e.g., the distribution of absolute magnitudes) and, obviously, the adopted abundance calibration. For example, Tremonti et al (2004) Other studies have obtained L − Z relation slopes ranging from −0.149 dex mag −1 to −0.280 dex mag −1 Hidalgo-Gamez & Olofsson 1998;Lamareille et al 2004;Salzer et al 2005; van Zee & Haynes 2006; J. Moustakas et al, in prep.).…”

Section: Synthesis: Central and Characteristic Oxygenmentioning

confidence: 98%

OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER /SINGS GALAXIES

Moustakas¹,

Kennicutt²,

Tremonti³

et al. 2010

ApJS

527

797

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We present intermediate-resolution optical spectrophotometry of 65 galaxies obtained in support of the Spitzer Infrared Nearby Galaxies Survey (SINGS). For each galaxy we obtain a nuclear, circumnuclear, and semi-integrated optical spectrum designed to coincide spatially with mid-and far-infrared spectroscopy from the Spitzer Space Telescope. We make the reduced, spectrophotometrically calibrated one-dimensional spectra, as well as measurements of the fluxes and equivalent widths of the strong nebular emission lines, publically available. We use optical emission-line ratios measured on all three spatial scales to classify the sample into star-forming, active galactic nuclei (AGN), and galaxies with a mixture of star formation and nuclear activity. We find that the relative fraction of the sample classified as star-forming versus AGN is a strong function of the integrated light enclosed by the spectroscopic aperture. We supplement our observations with a large database of nebular emission-line measurements of individual H ii regions in the SINGS galaxies culled from the literature. We use these ancillary data to conduct a detailed analysis of the radial abundance gradients and average H iiregion abundances of a large fraction of the sample. We combine these results with our new integrated spectra to estimate the central and characteristic (globally-averaged) gas-phase oxygen abundances of all 75 SINGS galaxies. We conclude with an in-depth discussion of the absolute uncertainty in the nebular oxygen abundance scale.

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“…Over the last three decades, numerous studies have measured the oxygen and nitrogen abundances of H II regions in dwarf irregular galaxies (e.g., Alloin et al 1979;Lequeux et al 1979;Kinman & Davidson 1981;Campbell, Terlevich, & Melnick 1986;Garnett 1990;Miller & Hodge 1996;van Zee et al 1997a;Izotov & Thuan 1998;Hidalgo-Gámez & Olofsson 2002;Skillman, Côté, & Miller 2003;Lee, Grebel, & Hodge 2003;Lee, Salzer, & Melbourne 2004). Lequeux et al (1979) were the first to note a strong correlation between metallicity and mass, in the sense that more massive galaxies also have higher measured oxygen abundances (see also Kinman & Davidson 1981); Skillman et al (1989) determined that a stronger correlation was found between metallicity and luminosity (see also Richer & McCall 1995;Hunter & Hoffman 1999;Pilyugin 2001;Tremonti et al 2004, for an alternative view, see Hidalgo-Gámez & Olofsson 1998). However, despite extensive observational effort, the origin of the luminosity-metallicity relation is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Oxygen and Nitrogen in Isolated Dwarf Irregular Galaxies

Zee

Haynes

2006

ApJ

208

163

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We present long slit optical spectroscopy of 67 HII regions in 21 dwarf irregular galaxies to investigate the enrichment of oxygen, nitrogen, neon, sulfur, and argon in low mass galaxies. Oxygen abundances are obtained via direct detection of the temperature sensitive emission lines for 25 HII regions; for the remainder of the sample, oxygen abundances are estimated from strong line calibrations. The direct abundance determinations are compared to the strong-line abundance calibrations of both McGaugh (1991) and Pilyugin (2000). Global oxygen and nitrogen abundances for this sample of dwarf irregular galaxies are examined in the context of open and closed box chemical evolution models. While several galaxies are consistent with closed box chemical evolution, the majority of this sample have an effective yield ~1/4 of the expected yield for a constant star formation rate and Salpeter IMF, indicating that either outflow of enriched gas or inflow of pristine gas has occurred. The effective yield strongly correlates with M_H/L_B in the sense that gas-rich galaxies are more likely to be closed systems. However, the effective yield does not appear to correlate with other global parameters such as dynamical mass, absolute magnitude, star formation rate or surface brightness. A correlation is found between the observed nitrogen-to-oxygen ratio and the color of the underlying stellar population; redder dwarf irregular galaxies have higher N/O ratios than blue dwarf irregular galaxies. The relative abundance ratios are interpreted in the context of delayed release of nitrogen and varied star formation histories.Comment: 47 pages, 11 figures. Accepted to Ap

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Are All the DIGs the Same?

Cited by 12 publications

References 5 publications

Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53

Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53

OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER /SINGS GALAXIES

Oxygen and Nitrogen in Isolated Dwarf Irregular Galaxies

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