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ABSTRACT Strong metallicity-dependent winds dominate the evolution of core He-burning, classical Wolf–Rayet (cWR) stars, which eject both H and He-fusion products such as $$^{14}$$N, $$^{12}$$C, $$^{16}$$O, $$^{19}$$F, $$^{22}$$Ne, and $$^{23}$$Na during their evolution. The chemical enrichment from cWRs can be significant. cWR stars are also key sources for neutron production relevant for the weak s-process. We calculate stellar models of cWRs at solar metallicity for a range of initial Helium star masses (12–50 $$\rm M_{\odot }$$), adopting recent hydrodynamical wind rates. Stellar wind yields are provided for the entire post-main sequence evolution until core O-exhaustion. While literature has previously considered cWRs as a viable source of the radioisotope $$^{26}$$Al, we confirm that negligible $$^{26}$$Al is ejected by cWRs since it has decayed to $$^{26}$$Mg or proton-captured to $$^{27}$$Al. However, in Paper I, we showed that very massive stars eject substantial quantities of $$^{26}$$Al, among other elements including N, Ne, and Na, already from the zero-age-main-sequence. Here, we examine the production of $$^{19}$$F and find that even with lower mass-loss rates than previous studies, our cWR models still eject substantial amounts of $$^{19}$$F. We provide central neutron densities (N$$_{n}$$) of a 30 $$\rm M_{\odot }$$ cWR compared with a 32 $$\rm M_{\odot }$$ post-VMS WR and confirm that during core He-burning, cWRs produce a significant number of neutrons for the weak s-process via the $$^{22}$$Ne($$\alpha$$,n)$$^{25}$$Mg reaction. Finally, we compare our cWR models with observed [Ne/He], [C/He], and [O/He] ratios of Galactic WC and WO stars.
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Stellar Neutrino Emission across the Mass–Metallicity Plane
Abstract We explore neutrino emission from nonrotating, single-star models across six initial metallicities and 70 initial masses from the zero-age main sequence to the final fate. Overall, across the mass spectrum, we find metal-poor stellar models tend to have denser, hotter, and more massive cores with lower envelope opacities, larger surface luminosities, and larger effective temperatures than their metal-rich counterparts. Across the mass–metallicity plane we identify the sequence (initial CNO →14N →22Ne →25Mg →26Al →26Mg →30P →30Si) as making primary contributions to the neutrino luminosity at different phases of evolution. For the low-mass models we find neutrino emission from the nitrogen flash and thermal pulse phases of evolution depend strongly on the initial metallicity. For the high-mass models, neutrino emission at He-core ignition and He-shell burning depends strongly on the initial metallicity. Antineutrino emission during C, Ne, and O burning shows a strong metallicity dependence with22Ne(α,n)25Mg providing much of the neutron excess available for inverse-βdecays. We integrate the stellar tracks over an initial mass function and time to investigate the neutrino emission from a simple stellar population. We find average neutrino emission from simple stellar populations to be 0.5–1.2 MeV electron neutrinos. Lower metallicity stellar populations produce slightly larger neutrino luminosities and averageβdecay energies. This study can provide targets for neutrino detectors from individual stars and stellar populations. We provide convenient fitting formulae and open access to the photon and neutrino tracks for more sophisticated population synthesis models.
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- PAR ID:
- 10480813
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal Supplement Series
- Volume:
- 270
- Issue:
- 1
- ISSN:
- 0067-0049
- Format(s):
- Medium: X Size: Article No. 5
- Size(s):
- Article No. 5
- Sponsoring Org:
- National Science Foundation
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