A strong case for fast stellar rotation at very low metallicities

By C. Chiappini, R. Hirschi, G. Meynet, S. Ekström, Andre Maeder, F. Matteucci. 2006

150 citations recorded by the source corpus.

We investigate the effect of new stellar models taking rotation into account and computing for a metallicity Z = 10 -8 on the chemical evolution of the earliest phases of the Milky Way. These models were computed under the assumption that the ratio of the initial rotation velocity to the critical velocity of stars is roughly constant with metallicity. This naturally leads to faster rotation at lower metallicity, as metal-poor stars are more compact than metal-rich ones. We find that the new Z = 10 -8 stellar yields have a tremendous impact on the nitrogen enrichment of the interstellar medium for log(O/H) + 12 < 7 (or [Fe/H] < -3). We show that including Z = 10 -8 stellar yields in chemical evolution models, both high N/O and C/O ratios are obtained in the very-metal poor metallicity range, in agreement with observations. Our results give further support to the idea that stars at very low metallicities could have rotational velocities of the order of 600-800 km s -1 .

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ccdd33fc810b71c564917e0af88c9202033410ef

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Stan Woosley
2. R. Hirschi
3. A. Karakas
4. N. Langer
5. G. Meynet
6. C. Kobayashi
7. A. Chieffi
8. M. Limongi

In Instrumentation

1. R. Hirschi
2. N. Langer
3. A. Chieffi
4. M. Limongi
5. A. Karakas
6. Stan Woosley
7. G. Meynet
8. S. Ekström

Citations in the corpus

• Very low-metallicity massive stars: - Pre-SN evolution models and primary nitrogen production (2006, methodology): “The stellar yields of the fast-rotating models calculated here were used in a galactic chemical evolution model and successfully reproduced the early evolution of CNO elements (Chiappini et al. 2006).”
• Chemical evolution with rotating massive star yields - I. The solar neighbourhood and the s-process elements (2018, methodology): “Using GCE models Chiappini et al. (2006) showed then that such stars may explain the appearance of primary N in the early Galaxy.”
• NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE METAL-FREE STARS (2008, background): “Here only the heaviest stars became red supergiants because of nitrogen production, but the inclusion of rotation may extend the critical mass for primary nitrogen production downward (Heger et al. 2000; Chiappini et al. 2006; Meynet et al. 2006; Hirschi et al. 2006).”
• Non-standard s process in low metallicity massive rotating stars (2011, methodology): “When yields from these rotating models are used as input in chemical evolution models, a nice fit of the N/O in very metal poor halo stars (see e.g. Spite et al., 2005) can be obtained (Chiappini et al., 2006).”
• Nucleosynthesis in Stars and the Chemical Enrichment of Galaxies (2013, background): “Chiappini et al. (2006) have shown that a contribution from rotating massive stars is required to solve the primary N problem.”
• Effects of rotation on the evolution of primordial stars (2008, methodology): “Such a CEM is computed by Chiappini et al. (2006b) for example6.”
• C, N, O abundances in the most metal-poor damped Lyman alpha systems★ (2007, background): “More recently, Chiappini et al. (2006) have proposed that the observed behaviour can also be explained if stars of lower metallicity rotate faster: the higher rotation speeds greatly 7 Note that in the earlier compilation by Grevesse & Sauval (1998) the solar ratio of C and O had a similar value…”
• Carbon-enhanced Metal-poor Stars. I. Chemical Compositions of 26 Stars (2006, background): “Also of interest is the recent paper by Chiappini et al. (2006), where their new chemical evolution models require the large yields of carbon and nitrogen from the models discussed byHirschi et al. (2007) in order to account for the upturn of the observed [N/O] and [C/O] ratios in the ‘‘unmixed’’…”
• The evolution of isotope ratios in the Milky Way Galaxy (2011, background): “However, there are only a small number of theoretical predictions of the evolution of the isotopes including the studies by Timmes, Woosley, & Weaver (1995), Romano & Matteucci (2003), Fenner et al. (2003), Chiappini et al. (2006), and Hughes et al. (2008).”
• Single star progenitors of long gamma-ray bursts - I. Model grids and redshift dependent GRB rate (2006, background): “Recently, Chiappini et al. (2006) found strong primary nitrogen production in rotating very low metallicity massive star models.”
• The s-Process in Massive Stars at Low Metallicity: The Effect of Primary 14N from Fast Rotating Stars (2008, background): “Chiappini et al. (2006) show that the primary nature of nitrogen can be explained at low metallicity by using the yields of fast rotating massive stars.”
• s-process production in rotating massive stars at solar and low metallicities (2015, methodology): “When yields from these rotating models are used as input in chemical evolution models, a nice fit of the N/O in very metal poor halo stars (see e.g. Spite et al. 2005) can be obtained (Chiappini et al. 2006).”
• Classical Be stars (2013, background): “At very low metallicity Be stars may evolve very differently, since the maximally possible rotational velocities increase and can reach more than 800 km s−1 at very low metallicity (Chiappini et al. 2006, see also above for the interplay of metallicity, opacity, and stellar radius).”
• Quantifying the uncertainties of chemical evolution studies II. Stellar yields (2010, background): “The most significant result was the substantial quantity of primary N produced by including rotation in very-low metallicity massive star models (Hirschi 2005, 2007; Chiappini et al. 2006).”
• The most metal-poor damped Lyα systems: insights into chemical evolution in the very metal-poor regime★ (2011, background): “The increase in [C/O] with decreasing metallicity has thus been interpreted as evidence for an increased carbon yield from either Population III stars (Chieffi & Limongi 2002; Umeda & Nomoto 2003; Heger & Woosley 2010) or rapidly-rotating low-metallicity Population II stars (Chiappini et al. 2006).”