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Stefano Ciabattini

Publications and source records attributed to Stefano Ciabattini.

2 recordsLinked to original sources

CRIMSONS: An Online Tool for Modeling Chemical Enrichment with Stochastic IMF Sampling

Chemical enrichment is a universal process shaped by several interconnected factors, including stellar feedback, the nature of chemical polluters, and the underlying distribution of stellar masses. Three key ingredients are often difficult to treat simultaneously in chemical-evolution models: the stochastic sampling of the stellar IMF, uncertainties in stellar nucleosynthesis yields, and pre-enrichment from primordial PopIII stars. In low star-formation rate environments, incomplete IMF sampling makes enrichment sensitive to the random presence or absence of massive supernova progenitors. Here, we present CRIMSONS, the first online tool designed to model chemical enrichment while self-consistently incorporating these three ingredients. The framework allows users to explore different IMFs, stellar population masses and metallicities, and multiple stellar yield sets. It follows the evolution of individual stars and tracks 30 elements(H-Zn), including contributions from SN, AGB stars, and TypeIa SNe. The current implementation adopts a closed-box framework, neglecting gas flows and spatial mixing, thus providing a controlled setup to isolate the effects of IMF sampling, stellar yields, and PopIII pre-enrichment. With CRIMSONS, we show that incomplete IMF sampling produces large abundance scatter, particularly in low-mass stellar populations. Different yield prescriptions introduce element-dependent variations, while some abundance ratios remain comparatively robust across models. Finally, comparison between models including primordial enrichment and those adopting only a metallicity floor shows that PopIII pre-enrichment can significantly affect subsequent chemical evolution. CRIMSONS therefore provides a controlled framework for quantifying the relative impact of stochastic IMF sampling, nucleosynthetic uncertainties, and primordial pre-enrichment on predicted abundance patterns

astro-ph.GA↗

Are Local Group Dwarf Spheroidal Galaxies the First Safe Planet-hosting Environments?

We explore whether Local Group dwarf spheroidal (dSph) galaxies might have hosted Earth-like planets dwelling unexposed for several billions of years to major galactic threats to life, such as supernovae and gamma-ray bursts. To this aim, we developed a novel semiempirical model that exploits the observed chemical abundances and star formation histories of a selected sample of local dSphs, to explore whether their stars may have (i) reached the minimum metallicity to trigger planet formation and (ii) avoided exposure to destructive events long enough to provide time for possible biological development. From our work two scenarios emerge. If planet formation is possible for ${\rm[Fe/H]}\lesssim-1$, then in all dSphs with $5\times10^{3}L_{\odot}\leq L_V\leq2\times10^{7}L_{\odot}$ a fraction $\approx0.1\%-10\%$ of stars might have safely hosted terrestrial planets for more than $1$ Gyr. In this scenario, ancient ultra-faint dwarf galaxies (UFDs, $L_V\leq10^{5}L_{\odot}$) would have been the first to reach this condition in the history of the Local Group. Conversely, if planets form for ${\rm[Fe/H]}\geq-0.6$ then they should not exist in UFDs, while only $\approx0.001\%-0.1\%$ of stars in dSphs with $L_V\geq3\times10^{5}L_{\odot}$ would host planets dwelling in safe conditions for long times. Interestingly, we find a "luminosity sweet spot" at $L_V\sim10^{6}L_{\odot}$ where dSphs in our sample safely host terrestrial planets up to $4$ Gyr and in any planet formation scenario explored. In conclusion, planet formation at low metallicity is key to understanding which types of galaxies might have formed Earth-like planets that dwelt unexposed to galactic threats over several billions of years, first in the history of the Local Group.

astro-ph.GA↗