The evolution of C/O in dwarf galaxies from Hubble Space Telescope FOS observations

Garnett, D. R.; Skillman, Evan D.; Dufour, R. J.; Peimbert, M.; Torres-Peimbert, S.; Terlevich, R.; Terlevich, Elena; Shields, G. A.

doi:10.1086/175503

Cited by 187 publications

(304 citation statements)

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“…The peculiar position of NGC 2363 is indicated in Figure 6 because it will be discussed later. The figure shows the wellknown C/O vs. O/H correlation found in previous works by, for example, Garnett et al (1995Garnett et al ( , 1999) from observations of CELs or Esteban et al (2002Esteban et al ( , 2009) from observations of RLs. Figure 6 includes the time evolution of the abundances predicted by the chemical evolution models of the Milky Way disc presented by Esteban et al (2013).…”

Section: The C/o Vs O/h Relationsupporting

confidence: 60%

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

Esteban

García‐Rojas

Carigi³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present deep echelle spectrophotometry of the brightest emission-line knots of the star-forming galaxies He 2−10, Mkn 1271, NGC 3125, NGC 5408, POX 4, SDSS J1253−0312, Tol 1457−262, Tol 1924−416 and the H ii region Hubble V in the Local Group dwarf irregular galaxy NGC 6822. The data have been taken with the Very Large Telescope Ultraviolet-Visual Echelle Spectrograph in the 3100-10420Å range. We determine electron densities and temperatures of the ionized gas from several emission-line intensity ratios for all the objects. We derive the ionic abundances of C 2+ and/or O 2+ from faint pure recombination lines (RLs) in several of the objects, permitting to derive their C/H and C/O ratios. We have explored the chemical evolution at low metallicities analysing the C/O vs. O/H, C/O vs. N/O and C/N vs. O/H relations for Galactic and extragalactic H ii regions and comparing with results for halo stars and DLAs. We find that H ii regions in star-forming dwarf galaxies occupy a different locus in the C/O vs. O/H diagram than those belonging to the inner discs of spiral galaxies, indicating their different chemical evolution histories, and that the bulk of C in the most metal-poor extragalactic H ii regions should have the same origin than in halo stars. The comparison between the C/O ratios in H ii regions and in stars of the Galactic thick and thin discs seems to give arguments to support the merging scenario for the origin of the Galactic thick disc. Finally, we find an apparent coupling between C and N enrichment at the usual metallicities determined for H ii regions and that this coupling breaks in very low-metallicity objects.

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Section: The C/o Vs O/h Relationsupporting

confidence: 60%

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

Esteban

García‐Rojas

Carigi³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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111

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“…Right: C) The relation log(C/N) and d) log(C/O) vs. as 12 + log(O/H). Data are from Garnett et al (1995;1999, GAR), and from Clegg et al (1981, CLE). Thick lines mean N primary while thin lines are models with N as secondary.…”

Section: Resultsmentioning

confidence: 99%

Chemical Evolution of CNO Abundances

Gavilán

Mollá

2003

Highlights of Spanish Astrophysics III

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New low and intermediate mass star yields recalculated by Buell (1987) are evaluated by using them in a Galactic Chemical Evolution model. We analyze their effects on CNO elemental abundances IntroductionStellar yields for low and intermediate mass (LIM) stars have been recalculated by Buell (1997), who, taking into account the effects of the convective dredge up and the Hot Bottom Burning (HBB), incorporates the most recent improvements in the TP-AGB processes.The aim of this job is to evaluate these new yields for LIM stars by using them as input in a Galactic Chemical Evolution (GCE) model. In particular, we analyze if the contribution of these stars is enough to justify the observed behavior of nitrogen vs. oxygen. 2.Stellar structure for LIM stars during the TP-AGB phaseThe evolution of a LIM star during the TP-AGB phase is dominated mainly by two processes: The third dredge up events and the Hot Bottom Burning (HBB). The first ones affect stars with masses between 2 M ⊙ and 4 M ⊙ , by increasing the abundance of carbon. In stars more massive than 4 M ⊙ , the HBB produces an abrupt increase of nitrogen and a similar decrease of carbon. In Figure 1 we show the ejected masses of 12 C and 14 N as a function of the stellar mass M * , for Z = Z ⊙ , compared with those from RV, where we see that the described behaviour for both elements does not appear since those authors had not taken into account the transformation from carbon in nitrogen during the HBB phase. In fact, nitrogen shows a variation around 4 M ⊙ for RV but it does not increase for larger stellar masses.

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“…3 Metallicity mass fraction, where z =0.02 Garnett et al (1995Garnett et al ( , 1997Garnett et al ( , 1999, Izotov & Thuan (1999;I), and Kobulnicky & Skillman (1998, K). The symbols M and S show the positions of the Galactic H II region M8 and the sun, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…They note that theoretical chemical evolution models (Carigi 1994) in which carbon comes from intermediate stars apparently predict too shallow a C/O relation to fit their observed galaxy abundance gradients. Other recent discussions of C/O gradients across our own or other galaxies, or of C/O ratios in low metallicity galaxies, have been given by Götz and Köppen (1992), Prantzos, Vangioni-Flam & Chauveau (1994), Kunth et al (1995), Garnett et al (1995), Carigi et al (1995), Mollá, Ferrini, and Díaz (1997) and Chiappini, Matteucci & Gratton (1997).…”

Section: Introductionmentioning

confidence: 88%

“…1A is a plot of log(C/O) versus 12+log(O/H) for numerous Galactic and extragalactic objects. Results for extragalactic H II regions are taken from Garnett et al (1995;, Izotov & Thuan (1999), and Kobulnicky & Skillman (1998), and are shown with symbols 'G', 'I', and 'K', respectively. The filled circles correspond to stellar data from Gustafsson et al (1999) for a sample of F and G stars, the filled boxes correspond to B star data from , and the filled diamonds are halo star data points from Tomkin et al (1992).…”

Section: Datamentioning

confidence: 99%

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On the Cosmic Origins of Carbon and Nitrogen

Edmunds

Henry

Köppen

2001

The Evolution of Galaxies

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We analyze the behavior of N/O and C/O abundance ratios as a function of metallicity as gauged by O/H in large, extant Galactic and extragalactic H II region abundance samples. We compile and compare published yields of C, N, and O for intermediate mass and massive stars and choose appropriate yield sets based upon analytical chemical evolution models fitted to the abundance data. We then use these yields to compute numerical chemical evolution models which satisfactorily reproduce the observed abundance trends and thereby identify the most likely production sites for carbon and nitrogen. Our results suggest that carbon and nitrogen originate from separate production sites and are decoupled from one another. Massive stars (M>8 M ) dominate the production of carbon, while intermediate-mass stars between 4 and 8 M , with a characteristic lag time of roughly 250 Myr following their formation, dominate nitrogen production. Carbon production is positively sensitive to metallicity through mass loss processes in massive stars and has a pseudo-secondary character. Nitrogen production in intermediate mass stars is primary at low metallicity, but when 12+log(O/H)>8.3, secondary nitrogen becomes prominent, and nitrogen increases at a faster rate than oxygen -indeed the dependence is steeper than would be formally expected for a secondary element. The observed flat behavior of N/O versus O/H in metal-poor galaxies is explained by invoking low star formation rates which flatten the age-metallicity relation and allow N/O to rise koppen@astro.u-strasbg.fr -2 -to observed levels at low metallicities. The observed scatter and distribution of data points for N/O challenge the popular idea that observed intermittent polluting by oxygen is occurring from massive stars following star bursts. Rather, we find most points cluster at relatively low N/O values, indicating that scatter is caused by intermittent increases in nitrogen due to local contamination by Wolf-Rayet stars or luminous blue variables. In addition, the effect of inflow of gas into galactic systems on secondary production of nitrogen from carbon may introduce some scatter into N/O ratios at high metallicities.

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The evolution of C/O in dwarf galaxies from Hubble Space Telescope FOS observations

Cited by 187 publications

References 0 publications

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

Chemical Evolution of CNO Abundances

On the Cosmic Origins of Carbon and Nitrogen

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