Surface Nitrogen enrichment from the LMC to the Early Universe: the roles of rotation, overshooting and mass loss
Abstract
The strong nitrogen (N) features observed in high-redshift galaxies, such as GN-z11, with JWST point to an efficient source of N production in the early Universe. Very massive stars (VMSs) are promising candidates owing to their strong winds and large convective cores of CNO-processed material. Whether massive-star surfaces in general become N-enriched depends on the interplay of convective-boundary mixing (overshooting), rotation, and mass loss, which remains poorly constrained. Using a grid of MESA evolutionary models, we isolate the overshooting and rotation channels at $40$, $100$, and 200 M⊙ and investigate how these channels bring N-rich material to the surface of massive and very massive stars as a function of initial mass and metallicity. We also construct a synthetic Large Magellanic Cloud (LMC) population based on a larger initial mass grid ranging from 20−300 M⊙ for comparison with the observed N-enriched fraction. VMS surface enrichment is remarkably robust across cosmic metallicity. At lower metallicities, wind stripping is weaker and the overshooting channel shuts off entirely, yet a modest amount of rotation of ∼90 km s−1 alone still enriches the surface. At higher metallicity, stronger winds dominate and uncover the core almost independently of the adopted mixing. The two channels operate through physically distinct mechanisms: overshooting enriches the surface only once winds strip the envelope down into the N-rich layers left by the receding core, giving an abrupt jump. Rotation, by contrast, mixes N outward continuously through the layers above the core, producing a gradual rise. Applied to the LMC, a population with modest rotation drawn from the observed velocity distribution and modest overshooting reproduces the observed N-enriched fraction without large core boundary mixing efficiencies otherwise required by non-rotating models.
Related
- Nitrogen-Loud Quasars from the Dark Energy Spectroscopic Instrument. II. Broad-Line Region Metallicity and Relative Nitrogen Enrichment
- N/O-enhanced chemical enrichment by massive stars: the interplay of optically-thick winds and rotation
- The Single Breath Euler Universe: The dark sector as a glassy substance, and the rotation as its ring
- Shape of the direct-method mass-metallicity relation with JWST: Fast-Track Nitrogen and Helium Enrichment
- The Nature of Time, Entropy, and the Cyclic Structure of the Universe: A Unified Framework Based on Relational Time, the Second Law of Thermodynamics, and Complex Time Rotation at Black Hole Singularities
BibTeX
@misc{sabhahit2026surface,
title = {{Surface Nitrogen enrichment from the LMC to the Early Universe: the roles of rotation, overshooting and mass loss}},
author = {Gautham N. Sabhahit and Jorick. S Vink},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03798},
eprint = {2611.03798},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03798},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Surface Nitrogen enrichment from the LMC to the Early Universe: the roles of rotation, overshooting and mass loss
AU - Gautham N. Sabhahit
AU - Jorick. S Vink
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03798
UR - https://arxiv.org/abs/2611.03798
AB - The strong nitrogen (N) features observed in high-redshift galaxies, such as GN-z11, with JWST point to an efficient source of N production in the early Universe. Very massive stars (VMSs) are promising candidates owing to their strong winds and large convective cores of CNO-processed material. Whether massive-star surfaces in general become N-enriched depends on the interplay of convective-boundary mixing (overshooting), rotation, and mass loss, which remains poorly constrained. Using a grid of MESA evolutionary models, we isolate the overshooting and rotation channels at $40$, $100$, and 200 M_⊙ and investigate how these channels bring N-rich material to the surface of massive and very massive stars as a function of initial mass and metallicity. We also construct a synthetic Large Magellanic Cloud (LMC) population based on a larger initial mass grid ranging from 20−300 M_⊙ for comparison with the observed N-enriched fraction. VMS surface enrichment is remarkably robust across cosmic metallicity. At lower metallicities, wind stripping is weaker and the overshooting channel shuts off entirely, yet a modest amount of rotation of ∼90 km s^−1 alone still enriches the surface. At higher metallicity, stronger winds dominate and uncover the core almost independently of the adopted mixing. The two channels operate through physically distinct mechanisms: overshooting enriches the surface only once winds strip the envelope down into the N-rich layers left by the receding core, giving an abrupt jump. Rotation, by contrast, mixes N outward continuously through the layers above the core, producing a gradual rise. Applied to the LMC, a population with modest rotation drawn from the observed velocity distribution and modest overshooting reproduces the observed N-enriched fraction without large core boundary mixing efficiencies otherwise required by non-rotating models.
ER -