Stellar evolution with rotation - VIII. Models at Z = 10$^\mathsf{-5}$ and CNO yields for early galactic evolution

By G. Meynet, Andre Maeder. 2002

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We calculate a grid of star models with and without the eects of axial rotation for stars in the mass range between 2 and 60 M for the metallicity Z= 10 5 . Star models with initial masses superior or equal to 9 M were computed up to the end of the carbon-burning phase. Star models with masses between 2 and 7 M were evolved beyond the end of the He-burning phase through a few thermal pulses during the AGB phase. Compared to models at Z = 0:02, the low Z models show faster rotating cores and stronger internal-gradients, which favour an important mixing of the chemical elements. The enhancement of N/C at the surface may reach 2 to 3 orders of magnitude for fast rotating stars. Surface enrichments may make the evolved stars less metal poor than they were initially. In very low Z models, primary nitrogen is produced during the He-burning phase by rotational diusion of 12 C into the H-burning shell. A large fraction of the primary 14 N escapes further destruction and enters the envelope of AGB stars, being ejected during the TP-AGB phase and the formation of a planetary nebula. The intermediate mass stars of very lowZ are the main producers of primary 14 N, but massive stars also contribute to this production; no significant primary nitrogen is made in models at metallicity Z= 0:004 or above. We calculate the chemical yields in He, C, N, O and heavy elements and discuss the chemical evolution of the CNO elements at very low Z. Remarkably, the C/ Ov s. O/H diagram is mainly sensitive to the interval of stellar masses, while the N/ Ov s. O/H diagram is mainly sensitive to the average rotation of the stars contributing to the element synthesis. The presently available observations in these diagrams seem to favour contributions either from stars down to about 2 M with normal rotation velocities or from stars above 8 M but with very fast rotation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9937db460845c81b9aa62035ad8a6f0dca20a7f5

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In Astronomy and Astrophysics

1. M. Pettini
2. C. Steidel
3. Naveen A. Reddy
4. A. Shapley
5. Stan Woosley
6. R. Hirschi
7. D. Erb
8. G. Meynet

Citations in the corpus

• Evolution of rapidly rotating metal-poor massive stars towards gamma-ray bursts (2005, methodology): “1989; Kudritzki 2002), with the consequence that the WolfRayet stage may actually never be reached (Heger et al. 2003; Marigo et al. 2003; Meynet & Maeder 2002).”
• STELLAR ABUNDANCES IN THE SOLAR NEIGHBORHOOD: THE HYPATIA CATALOG (2014, background): “…ejecta from stars, this history can be reconstructed using theoretical models (Burbidge et al. 1957; Cameron 1957; Woosley & Weaver 1995; Thielemann et al. 1996; Meynet & Maeder 2002a; Siess et al. 2002; Ventura et al. 2002; Limongi & Chieffi 2003; Karakas & Lattanzio 2007; José & Iliadis 2011).”
• Stellar evolution with rotation - XIII. Predicted GRB rates at various Z (2005, background): “The models reproduce many observational features at various metallicities very well, like surface enrichment (Meynet & Maeder 2002b) and ratios between red and blue supergiants (Maeder & Meynet 2001, hereinafter Paper VII).”
• Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti (2010, background): “…et al. (2008) have argued that their observed steadily declining [O/Mg] vs. [Mg/H] trends for both the bulge and the solar vicinity are the result of metallicity-dependt O yields due to mass-loss in massive stars, possibly augmented by stellar rotation (e.g. Maeder 1992; Meynet & Maeder 2002).”
• Evolution of Asymptotic Giant Branch Stars (2005, background): “Note that stars experiencing the rotationally induced mixing during the pre-AGB phase described in Section 6.1 (Meynet & Maeder 2002) would in no case evolve through a HIF event, because the envelope would be sufficiently enriched with CNO (in particular N) material that serves as a catalyst for H…”
• Europium production: neutron star mergers versus core-collapse supernovae (2013, background): “The production of (primary) nitrogen and s-process elements is boosted at low-metallicity in fast stellar rotators (Meynet & Maeder 2002a; Frischknecht, Hirschi & Thielemann 2012).”
• Thermohaline instability and rotation-induced mixing I. Low- and intermediate-mass solar metallicity stars up to the end of the AGB (2010, background): “…star and in the present case it already leads to variations of the surface abundances on the main sequence that are stronger for higher initial rotation velocities (this can be seen by looking at the abundance values at Mr/ ∗=1 in the various panels of Fig.11; (see also e.g. Meynet & Maeder 2002)).”
• The Evolution of the C/O Ratio in Metal-poor Halo Stars (2003, methodology): “Figure 6 shows, as a function of [O/H] and time, the [C/O] ratio computed with our ‘standard’ model which, to recap, uses the yields of Meynet & Maeder (2002) for massive stars, and those of van den Hoek & Groenewegen (1997) for low and intermediate mass stars.”
• Effects of rotation on the evolution of primordial stars (2008, methodology): “They show that the N/O ratio is much higher than what was predicted by a CEM using the yields of the slow-rotating Z = 10−5 models from Meynet & Maeder (2002) down to Z = 0.”
• Very low-metallicity massive stars: - Pre-SN evolution models and primary nitrogen production (2006, background): “In Meynet & Maeder (2002), they show that low metallicity (Z = 10−5) models have strong internal Ω-gradients, which favours a considerable mixing.”
• NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE METAL-FREE STARS (2008, methodology): “Calculations by Kudritzki (2002) and Meynet & Maeder (2002), for example, suggest that the mass loss for non-rotating stars lighter than 100 M and metallicity 10−5 Z can be neglected, though see Meynet et al. (2006).”
• The transition from Population III to normal galaxies: Lyα and He II emission and the ionising properties of high redshift starburst galaxies (2002, methodology): “At present the available limits are MWR > 60 M⊙ at Z = 10 −5 and (tWR/t⋆) <∼ 10 % from the rotating stellar models of Meynet & Maeder (2002), and MWR >∼ 750 M⊙ at Z = 0 from the simplified models of Marigo et al. (2002).”
• 7Li evolution in the thin and thick discs of the Milky Way (2018, background): “The initial mass function (IMF) is from Kroupa (2001), whereas the stellar lifetime are from Meynet & Maeder (2002).”
• Abundances of Baade’s Window Giants from Keck HIRES Spectra. II. The Alpha and Light Odd Elements (2006, background): “The Maeder (1992) and Meynet & Maeder (2002) predictions also indicate enhanced carbon yields from Wolf-Reyet stars, so bulge carbon abundances will provide a test of our proposed explanation for the steep decline in [O/Fe].”
• Mass loss from late-type WN stars and its Z-dependence: very massive stars approaching the Eddington limit (2008, background): “Moreover, evolutionary calculations indicate that rotating massive stars tend to approach critical rotation more easily at lowZ (Meynet & Maeder 2002).”