The chemical composition gradient across M 33

Vı́lchez, J. M.; Pagel, B. E. J.; Díaz, Ángeles I.; Terlevich, Elena; Edmunds, M. G.

doi:10.1093/mnras/235.3.633

Cited by 191 publications

(212 citation statements)

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“…The metallicity gradient in M 33, from 1 to ∼7 kpc is rather shallow (Vilchez et al 1988;Magrini et al 2007b), with a central abundance of 12 + log(O/H) = 8.36 ± 0.04 and a slope of 0.027 ± 0.012 dex kpc −1 (Rosolowsky & Simon 2008). This can be explained by the global chemical evolution of the M 33 disc through an inside-out formation process (Magrini et al 2007a).…”

Section: Metallicitymentioning

confidence: 91%

Young stellar clusters and associations in M 33

Grossi

Corbelli

Giovanardi

et al. 2010

A&A

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Aims. We analyse multi-wavelength observations of 32 young star clusters and associations in M 33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7). The data set includes ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (Hi) observations. We derive the spectral energy distribution (SED) of these systems and the properties of their gaseous environment to investigate the process of star formation and the interplay with the interstellar medium (ISM). Methods. We determine age, bolometric luminosities, masses, and the extinction by comparing the multi-band integrated photometry to single-age stellar population models. The best-fit solutions have been obtained using the Large Magellanic Cloud (LMC) extinction curves.Results. The stellar system ages range between 2 and 15 Myr, masses are between 3 × 10 2 and 4 × 10 4 M , and the intrinsic extinction, A V , varies from 0.3 to 1 mag. We find a correlation between age and extinction (young clusters being more reddened than older ones), and between the cluster mass and size. From the MIR emission we infer the presence of a dust component around the clusters whose fractional luminosity at 24 μm, L 24 /L Bol , decreases with the galactocentric distance. However, the total infrared luminosity inferred from L 24 is smaller than what we derive from the extinction corrections. We also find that the Hα luminosity predicted by population synthesis models is higher than the observed one, especially for low-mass systems (M < 10 4 M ). This difference is reduced, but not erased, when the incomplete sampling of the initial mass function (IMF) at the high-mass end is taken into account. Conclusions. Our results suggest that a non-negligible fraction of UV ionising and non-ionising radiation is leaking into the ISM outside the Hii regions. This agrees with the large UV and Hα diffuse fractions observed in M 33, but it implies that stellar systems younger than 3 Myr retain, on average, only 30% of their Lyman-continuum photons. However, the uncertainties in cluster ages and the stochastic fluctuations of the IMF do not allow us to accurately quantify this issue. We also consider the possibility that this discrepancy is the consequence of a suppressed or delayed formation of the most massive stars, given that it mainly affects the young and less massive clusters. We do not find any clear correlation between the cluster mass and the gas surface density or metallicity.

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Section: Metallicitymentioning

confidence: 91%

Young stellar clusters and associations in M 33

Grossi

Corbelli

Giovanardi

et al. 2010

A&A

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“…The secular evolution of disk galaxies produces a regular pattern with the metallicity decreasing inside out, i.e., having a negative gradient with galactocentric distance (Vilchez et al 1988;Edmunds and Greenhow 1995;van Zee et al 1998;Magrini et al 2007;). The timescale for gas mixing in a disk inside an annulus is fairly short, on the order of a rotational period or a few hundred Myr (Sect.…”

Section: Metallicity Inhomogeneities and Inverted Gradientsmentioning

confidence: 99%

Star formation sustained by gas accretion

Alméida

Elmegreen

Muñoz–Tuñón

et al. 2014

Astron Astrophys Rev

171

130

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Numerical simulations predict that metal-poor gas accretion from the cosmic web fuels the formation of disk galaxies. This paper discusses how cosmic gas accretion controls star formation, and summarizes the physical properties expected for the cosmic gas accreted by galaxies. The paper also collects observational evidence for gas accretion sustaining star formation. It reviews evidence inferred from neutral and ionized hydrogen, as well as from stars. A number of properties characterizing large samples of star-forming galaxies can be explained by metal-poor gas accretion, in particular, the relationship among stellar mass, metallicity, and star-formation rate (the so-called fundamental metallicity relationship). They are put forward and analyzed. Theory predicts gas accretion to be particularly important at high redshift, so indications based on distant objects are reviewed, including the global star-formation history of the universe, and the gas around galaxies as inferred from absorption features in the spectra of background sources.

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“…Since the percentage of re-radiated light for normal galaxies is only around 30% (Popescu & Tuffs 2002b), the calibration factor used for starburst galaxies will probably underestimate the SFR in M 33. Hughes et al (1998) Applying the F Hα -S FR calibration given by Kennicutt (1998) to the total Hα line luminosity of M 33, and correcting it for a mean A V = 1.2, (Israel & Kennicutt 1980;Devereux et al 1997) and for a mean [N ] contribution (averaged over the galaxy) of 20% (McCall et al 1985;Vilchez et al 1988), the star-forming rate results to S FR(Hα) = 0.47 M yr −1 , which is in satisfactory agreement with the FIR values.…”

Section: Star Formationmentioning

confidence: 99%

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

Hippelein

Haas

Tuffs

et al. 2003

A&A

119

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Abstract. The Sc galaxy M 33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170 µm. The spatial resolution of these FIR maps allows the separation of spiral arms and interarm regions and the isolation of a large number of star-forming regions. The spectral energy distribution in the FIR indicates a superposition of two components, a warm one originating from dust at ∼45 K, and a cold one, at ∼16 K. The warm component is concentrated towards the spiral arms and the star-forming regions, and is likely heated by the UV radiation from OB stars. The cold component is more smoothly distributed over the disk, and heated by the diffuse interstellar radiation. For the about 60 star-forming regions detected the Hα/FIR flux ratio increases significantly with the distance from the galaxy center, probably due to decreasing extinction. An anti-correlation of F Ha /F 60 with F 170 suggests the intrinsic extinction to be related to the cold dust surface brightness according to A V /S 170 ∼ 0.03 mag MJy −1 sr. For the total galaxy the star formation rate (SFR) derived from the FIR is in agreement with that derived from the de-extincted Hα emission. For individual star-forming regions, a consistency between SFRs derived from the optical and from the FIR requires only a fraction of the UV radiation to be absorbed locally. The individual star-forming regions also show a local radio-FIR correlation. This local correlation is, however, due to quite different components than to those that lead to the well-known global radio-FIR correlation for entire galaxies.

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The chemical composition gradient across M 33

Cited by 191 publications

References 0 publications

Young stellar clusters and associations in M 33

Young stellar clusters and associations in M 33

Star formation sustained by gas accretion

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

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