The Abundance Scatter in M33 From H Ii Regions: Is There Any Evidence for Azimuthal Metallicity Variations?

Bresolin, Fabio

doi:10.1088/0004-637x/730/2/129

Cited by 93 publications

(100 citation statements)

References 55 publications

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“…These values are much fewer than the old ones, as also occurs with the estimates from Bresolin (2011) and Bresolin et al (2012) for M 33, M 31, NGC 4258, and M 51, which are now -0.042, -0.023, -0.011, and -0.020 dex/kpc, so smaller than the old numbers reported by Zaritsky et al (1994). In fact, the value of -0.017 dex/kpc for NGC 628 is very similar to the one found by Rosales-Ortega et al (2011), as indicated before (compatible with the value reported by Berg et al 2013).…”

Section: Discussionsupporting

confidence: 60%

A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

Sánchez

Rosales-Ortega

Iglésias-Páramo

et al. 2014

A&A

412

289

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We present the largest and most homogeneous catalog of H ii regions and associations compiled so far. The catalog comprises more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey. We describe the procedures used to detect, select, and analyze the spectroscopic properties of these ionized regions. In the current study we focus on characterizing of the radial gradient of the oxygen abundance in the ionized gas, based on the study of the deprojected distribution of H ii regions. We found that all galaxies without clear evidence of an interaction present a common gradient in the oxygen abundance, with a characteristic slope of α O/H = −0.1 dex/r e between 0.3 and 2 disk effective radii (r e ), and a scatter compatible with random fluctuations around this value, when the gradient is normalized to the disk effective radius. The slope is independent of morphology, the incidence of bars, absolute magnitude, or mass. Only those galaxies with evidence of interactions and/or clear merging systems present a significantly shallower gradient, consistent with previous results. The majority of the 94 galaxies with H ii regions detected beyond two disk effective radii present a flattening in the oxygen abundance. The flattening is statistically significant. We cannot provide a conclusive answer regarding the origin of this flattening. However, our results indicate that its origin is most probably related to the secular evolution of galaxies. Finally, we find a drop/truncation of the oxygen abundance in the inner regions for 26 of the galaxies. All of them are non-interacting, mostly unbarred Sb/Sbc galaxies. This feature is associated with a central star-forming ring, which suggests that both features are produced by radial gas flows induced by resonance processes. Our result suggests that galaxy disks grow inside-out, with metal enrichment driven by the local star formation history and with a small variation galaxy-by-galaxy. At a certain galactocentric distance, the oxygen abundance seems to be correlated well with the stellar mass density and total stellar mass of the galaxies, independently of other properties of the galaxies. Other processes, such as radial mixing and inflows/outflows seem to have a limited effect on shaping of the radial distribution of oxygen abundances, although they are not ruled out.

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Section: Discussionsupporting

confidence: 60%

A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

Sánchez

Rosales-Ortega

Iglésias-Páramo

et al. 2014

A&A

412

289

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“…The ONS and C methods should be preferred for this reason, although we note that any strong-line method could easily fail for H ii regions whose properties are not represented in the calibration sample (Stasińska 2010 den lines will still be based on the measurement of electron temperatures, but we stress that they require data of high quality. This is illustrated by the work of Bresolin (2011), who found that the scatter in the oxygen abundances derived with the direct method in the central part of the galaxy M33 is around 0.06 dex when using his observations, whereas the data of Rosolowsky & Simon (2008) lead to much larger variations, with a dispersion of 0.21 dex. The spectra of Bresolin (2011) were deeper than the ones observed by Rosolowsky & Simon (2008), which might explain this result, although there could be other effects involved in the explanation.…”

Section: Discussionmentioning

confidence: 91%

The oxygen abundance gradient in M81 and the robustness of abundance determinations in H ii regions

Arellano-Córdova

Rodríguez

Mayya

et al. 2015

Mon. Not. R. Astron. Soc.

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We study the sensitivity of the methods available for abundance determinations in H ii regions to potential observational problems. We compare the dispersions they introduce around the oxygen and nitrogen abundance gradients when applied to five different sets of spectra of H ii regions in the galaxy M81. Our sample contains 116 H ii regions with galactocentric distances of 3 to 33 kpc, including 48 regions observed by us with the OSIRIS long-slit spectrograph at the 10.4-m Gran Telescopio Canarias telescope. The direct method can be applied to 31 regions, where we can get estimates of the electron temperature. The different methods imply oxygen abundance gradients with slopes of −0.010 to −0.002 dex kpc −1 , and dispersions in the range 0.06-0.25 dex. The direct method produces the shallowest slope and the largest dispersion, illustrating the difficulty of obtaining good estimates of the electron temperature. Three of the strong-line methods, C, ONS, and N2, are remarkably robust, with dispersions of ∼ 0.06 dex, and slopes in the range −0.008 to −0.006 dex kpc −1 . The robustness of each method can be directly related to its sensitivity to the line intensity ratios that are more difficult to measure properly. Since the results of the N2 method depend strongly on the N/O abundance ratio and on the ionization parameter, we recommend the use of the C and ONS methods when no temperature estimates are available or when they have poor quality, although the behaviour of these methods when confronted with regions that have different properties and different values of N/O should be explored.

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“…The Mira subtype was tentatively inferred by using another Random Forest classifier trained on the same features, which yielded the probability of each candidate being O-rich (P O ). Using the features of Mira candidates in the LMC bar to classify variables in the inner disk of M33 should be a robust approach, given the similar chemical abundances of both regions (Romaniello et al 2008;Bresolin 2011). Fig.…”

Section: Random Forest Classification Of Mirasmentioning

confidence: 99%

The M33 Synoptic Stellar Survey. II. Mira Variables

Yuan¹,

He²,

Macri³

et al. 2017

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We present the discovery of 1847 Mira candidates in the Local Group galaxy M33 using a novel semiparametric periodogram technique coupled with a Random Forest classifier. The algorithms were applied to ∼ 2.4 × 10 5 I-band light curves previously obtained by the M33 Synoptic Stellar Survey. We derive preliminary Period-Luminosity relations at optical, near-& mid-infrared wavelengths and compare them to the corresponding relations in the Large Magellanic Cloud.

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The Abundance Scatter in M33 From H Ii Regions: Is There Any Evidence for Azimuthal Metallicity Variations?

Cited by 93 publications

References 55 publications

A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

The oxygen abundance gradient in M81 and the robustness of abundance determinations in H ii regions

The M33 Synoptic Stellar Survey. II. Mira Variables

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