On the Cosmic Origins of Carbon and Nitrogen

By R. Henry, M. Edmunds, J. Köppen. 2000

315 citations recorded by the source corpus.

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 on analytical chemical evolution models fitted to the abundance data. We then use these yields to compute numerical chemical evolution models that 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 that flatten the age-metallicity relation and allow N/O to rise 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 caused by 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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a18c2871ce80750a471e0fe57d55b0e58a81b4cf

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Citations in the corpus

Stellar evolution with rotation. VII. - Low metallicity models and the blue to red supergiant ratio in the SMC (2001, background): “This is not a difficulty, because the evidence for the existence of some primary nitrogen concern metallicities still lower than that of the SMC (cf. Henry et al. 2000).”
The chemical composition of metal-poor emission-line galaxies in the Data Release 3 of the Sloan Digital Sky Survey (2005, unknown): “11) (e.g., Garnett , 1990; Pilyugin , 1993; Henry et al. , 2000).”
THE MASS–METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES (2012, background): “The M stacks form a tight sequence with a dispersion of only σ = 0.08 dex, compared with a more typical dispersion of σ ∼ 0.3 dex for individual objects (e.g., Henry et al. 2000).”
Oxygen, carbon and nitrogen evolution in galaxies (2002, methodology): “If the trend shown in Figure 6 is confirmed and [C/Fe]≃0 for all metallicities, this indicates that C, as Fe, is ejected into the ISM on long timescales (at variance with the results of, for example, Carigi 2000, Henry et al. 2000, Liang et al. 2001).”
Metallicity gradients in local field star-forming galaxies: insights on inflows, outflows, and the coevolution of gas, stars and metals (2015, background): “We note that the variation in the N/O ratio with O/H could be the largest uncertainty affecting these strong line diagnostics (Henry et al. 2000).”
C, N, O abundances in the most metal-poor damped Lyman alpha systems★ (2007, background): “Henry et al. (2000) calculated the delay to be 11 Henry, Edmunds, & Köppen (2000) pointed out that the rise in N/O with O/H is steeper than would be normally expected for a purely secondary element and proposed that it is augmented by a decreasing O yield with increasing metallicity.”
The Evolution of the C/O Ratio in Metal-poor Halo Stars (2003, methodology): “As explained above, the rise in the [C/O] ratio with metallicity from the halo to the disk has been known for several years and has been successfully modelled by a number of previous studies (e.g. Henry et al. 2000; Carigi 2003; Chiappini et al. 2003a,b; Prantzos 2003b).”
Deriving model-based Te-consistent chemical abundances in ionized gaseous nebulae (2014, background): “…of log(N/O) at a constant value of - 1.75-1.50 are obtained at 12+log(O/H) < 8.0, consistently with the predictions of a production of primary N in this regime, while for high-Z there is a dependence of N/O with O/H, as the main production of N has a secondary origin (e.g. Henry et al. 2000).”
PHYSICAL PROPERTIES OF EMISSION-LINE GALAXIES AT z ∼ 2 FROM NEAR-INFRARED SPECTROSCOPY WITH MAGELLAN FIRE (2014, background): “The connection between nitrogen-enriched galaxies and the influence of W-R stars has been known for some time (Pagel et al. 1986; Henry et al. 2000), and recent evidence has been found that low-redshift galaxies with W-R features in their optical spectra often display enhanced nitrogen abundances…”
Stellar evolution with rotation - VIII. Models at Z = 10$^\mathsf{-5}$ and CNO yields for early galactic evolution (2002, background): “Also, Henry et al. (2000) have calculated chemical evolution models which support the view that intermediate mass stars between 4 and 8 M⊙, with an age of about 250 Myr, are likely to dominate the nitrogen production.”
NEW STRONG-LINE ABUNDANCE DIAGNOSTICS FOR H ii REGIONS: EFFECTS OF κ-DISTRIBUTED ELECTRON ENERGIES AND NEW ATOMIC DATA (2013, background): “This relationship clearly has scatter, especially at the low abundance end, and the reasons for this scatter have been discussed by many authors (Matteucci & Tosi 1985; Henry et al. 2000; Contini et al. 2002; LópezSánchez & Esteban 2010)—see the recent summary by Pilyugin & Thuan (2011).”
Modelling the nebular emission from primeval to present-day star-forming galaxies (2016, background): “…indicate that the C/O ratio correlates with the O/H ratio in Galactic and extragalactic H ii regions as well as Milky-Way stars, presumably because of the dependence of the carbon yields of massive stars on metallicity (e.g., Garnett et al. 1995, 1999; Gustafsson et al. 1999; Henry et al. 2000b).”
THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z ≲ 1 (2013, background): “Instead, in galaxies, [C/O] ∼ −0.4 to −0.2 when [O/H] < −0.5 (with a large scatter, e.g., Garnett et al. 1999; Henry et al. 2000, and references therein).”
Dust formation in early galaxies (2003, methodology): “Using the notation given in Pagel (1997) and Henry et al (2000), we can follow the buildup of heavy elements over time in a closed galactic system.”
Evidence for Solar Metallicities in Massive Star-forming Galaxies at z ≳ 2 (2004, background): “Furthermore, at (O/H) metallicities above 0:2 ; (O=H) , the ratio of N/O increases because of the secondary nature of nitrogen in this regime (Henry et al. 2000).”