Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2410.23167

BPASS stellar evolution models incorporating $α$-enhanced composition -- I. Single star models from 0.1 to 316 M$_\odot$

Conor M Byrne·Jan J Eldridge·Elizabeth R Stanway
View original source ↗Read source document ↗Export metadata ↓

Abstract

Stellar evolution modelling is fundamental to many areas of astrophysics including stellar populations in both nearby and distant galaxies. It is heavily influenced by chemical composition. Observations of distant galaxies and nucleosynthesis calculations show that $α$-process elements are enriched faster than iron group elements. We present a dense grid of single-star models calculated using the BPASS stellar evolution code and covering masses ($0.1\le\mathrm{M/M}_\odot\le316$), metallicity mass fractions ($10^{-5} \le Z \le 0.04$) and $α$-to-iron abundance ratios ($-0.2\le[α/\mathrm{Fe}]\le+0.6$). By comparing Solar-scaled models to ones enriched in $α$-process elements, we find that stellar radii, surface temperatures, Main Sequence lifetimes, supernova progenitor properties and supernova rates are all sensitive to changes in [$α$/Fe]. Lifetimes of low-mass stars differ by up to 0.4 dex, while surface temperatures of massive stars at the end of the Main Sequence also differ by around 0.4 dex. Inferred supernova rates when [Fe/H] is unknown can be highly uncertain. Models with different [$α$/Fe] but comparable iron abundances show smaller variations, indicating that while iron primarily defines the course of evolution; $α$-enhancement nonetheless has an impact of up to 0.1 dex on stellar properties. Such changes are small for individual stars, but have a large cumulative effect when considering an entire stellar population as demonstrated by isochrone fitting to nearby clusters. Changes in radii and lifetimes have further consequences for a stellar population including binary stars, as they influence the timing, nature and occurrence rate of mass transfer events.

Explore related subjects

astro-ph.GAastro-ph.SR

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Conor M Byrne, Jan J Eldridge, Elizabeth R Stanway. 2025-01-28. BPASS stellar evolution models incorporating $α$-enhanced composition -- I. Single star models from 0.1 to 316 M$_\odot$. https://arxiv.org/abs/2410.23167

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

The Entangling of Supernova Feedback Impacts with Coarsening Simulation Resolution

It is often understood that supernova (SN) feedback in galaxies is responsible for regulating star formation (SF) and generating gaseous outflows. However, a detailed look at the small-scale effects of SNe on the interstellar medium (ISM) in simulations shows that the macroscopic processes of SF suppression and outflow generation proceed in distinct channels. We demonstrate this finding in two independent simulations of isolated dwarf galaxies with very high (m_gas ~ Msun) numerical resolution, LYRA and RIGEL. Our findings suggest that the macroscopic effect of a given SN on the galaxy is best predicted by its local density. Outflows are driven by SNe in diffuse regions expanding to their cooling radii on large (~kpc) scales, while dense SF regions are disrupted in a localized (~pc) manner. However, these separate feedback channels are only distinguishable at very high resolutions capable of following mass scales \lesssim 10^2 \msun. When averaging on coarser scales, ISM densities are greatly mis-estimated, and variations between different SF and SNe-affected regions are severely washed out. It therefore cannot be __self-consistently__ determined, from coarse-resolution information __alone__, (1) whether a SN tends to contribute to outflows or direct SF suppression, and (2) the rate of SF in a given region. In particular, commonly used parameters in coarse-resolution (subgrid) models, such as the SN cooling radius and SF density threshold, may require more detailed treatments informed by high-resolution studies.

astro-ph.GA↗
arXiv2026

Computational advances and challenges in simulations of turbulence and star formation

We review recent advances in the numerical modeling of turbulent flows and star formation. An overview of the most widely used simulation codes and their core capabilities is provided. We then examine methods for achieving the highest-resolution magnetohydrodynamical turbulence simulations to date, highlighting challenges related to numerical viscosity and resistivity. State-of-the-art approaches to modeling gravity and star formation are discussed in detail, including implementations of star particles and feedback from jets, winds, heating, ionization, and supernovae. We review the latest techniques for radiation hydrodynamics, including ray tracing, Monte Carlo, and moment methods, with comparisons between the flux-limited diffusion, moment-1, and variable Eddington tensor methods. The final chapter summarizes advances in cosmic-ray transport schemes, emphasizing their growing importance for connecting small-scale star formation physics with galaxy-scale evolution.

astro-ph.GA↗
arXiv2026

How significant is the lensing interpretation of GW231123?

GW231123 is one of the most unusual gravitational-wave (GW) events, with exceptionally large inferred masses and near-extremal spins, offering an opportunity to test whether propagation effects contribute to these properties. We therefore examine whether the data support wave-optics microlensing embedded in a strong-lensing galaxy, whose detection becomes increasingly likely as observations accumulate, whether this interpretation can explain these properties, and how significant the preference remains under detector noise and waveform systematics. We compare six hypotheses: unlensed, isolated point mass, and embedded point-mass (EPM) and binary-lens (EB) effective models in Type-I (minimum) and Type-II (saddle) macro images. The EB Type-I model is most favored. For the most accurate waveform model NRSur7dq4, it gives $\log_{10}B^{\rm EB-I}_{\rm U}=2.60$, versus $0.89$ for Type II, indicating sensitivity to macro-image geometry. Within Type I, however, the binary improves over the point mass by only $\log_{10}B^{\rm EB-I}_{\rm EPM-I}=0.16$ and $Δ\ln\mathcal{L}_{\max}=0.56$, providing no clear evidence for structure beyond a single effective perturber. Moreover, under embedded lensing, waveform-template discrepancies and inferred masses and spins are reduced. However, real O4a backgrounds from numerical-relativity injections show that the apparent lensing evidence is sensitive to waveform systematics and realistic detector noise: although the commonly used waveform IMRPhenomXPHM gives the largest Bayes factor, $\log_{10}B^{\rm EB-I}_{\rm U}=4.52$, it is less exceptional relative to its own background, with a false-alarm probability of $6.5$--$8\%$, whereas NRSur7dq4 gives only $2$--$3\%$. Thus, waveform systematics can amplify apparent lensing evidence, but GW231123 remains an intriguing lensing candidate.

astro-ph.GA↗