arXiv subjects

Andrés Moya

Publications and source records attributed to Andrés Moya.

4 recordsLinked to original sources

arXiv2025

Mapping the Ages of Stars with Chemistry

Chemical clocks, based on age-sensitive stellar abundance ratios, offer a powerful and scalable approach to reconstruct the formation history of the Milky Way. This white paper outlines how wide-field, high-resolution spectroscopy can transform chemical clocks into precise and broadly applicable stellar age estimators when combined with astrometry and asteroseismology. We summarize the current limitations, including calibration across Galactic environments and the impact of internal stellar evolution, and define the observational requirements needed to overcome them. The Wide-field Spectroscopic Telescope (WST), with its large field of view, high multiplex, and broad wavelength coverage at high spectral resolution, is uniquely suited to deliver the homogeneous datasets required to map the age structure of the Galaxy at unprecedented scale. Such a capability will enable decisive progress in Galactic archaeology and stellar evolution studies.

astro-ph.GA↗

arXiv2025

Unveiling the Power of Uncertainty: A Journey into Bayesian Neural Networks for Stellar dating

Context: Astronomy and astrophysics demand rigorous handling of uncertainties to ensure the credibility of outcomes. The growing integration of artificial intelligence offers a novel avenue to address this necessity. This convergence presents an opportunity to create advanced models capable of quantifying diverse sources of uncertainty and automating complex data relationship exploration. What: We introduce a hierarchical Bayesian architecture whose probabilistic relationships are modeled by neural networks, designed to forecast stellar attributes such as mass, radius, and age (our main target). This architecture handles both observational uncertainties stemming from measurements and epistemic uncertainties inherent in the predictive model itself. As a result, our system generates distributions that encapsulate the potential range of values for our predictions, providing a comprehensive understanding of their variability and robustness. Methods: Our focus is on dating main sequence stars using a technique known as Chemical Clocks, which serves as both our primary astronomical challenge and a model prototype. In this work, we use hierarchical architectures to account for correlations between stellar parameters and optimize information extraction from our dataset. We also employ Bayesian neural networks for their versatility and flexibility in capturing complex data relationships. Results: By integrating our machine learning algorithm into a Bayesian framework, we have successfully propagated errors consistently and managed uncertainty treatment effectively, resulting in predictions characterized by broader uncertainty margins. This approach facilitates more conservative estimates in stellar dating. Our architecture achieves age predictions with a mean absolute error of less than 1 Ga for the stars in the test dataset.

astro-ph.IM↗

arXiv2021

A fuzzy Multi-Criteria Decision Making approach for Exo-Planetary Habitability

Nowadays, we know thousands of exoplanets, some of them potentially habitable. Next technological facilities (JWST, for example) have exoplanet atmosphere analysis capabilities, but they also have limits in terms of how many targets can be studied. Therefore, there is a need to rank and prioritize these exoplanets with the aim of searching for biomarkers. Some criteria involved, such as the habitability potential of a dry-rock planet versus a water-rich planet, or a potentially-locked planet versus a tidally-locked planet, are often vague and the use of the fuzzy set theory is advisable. We have applied a combination of Multi-Criteria Decision-Making methodologies with fuzzy logic, the Fuzzy Reference Ideal Method (FRIM), to this problem. We have analyzed the habitability potential of 1798 exoplanets from TEPCat database based on a set of criteria (composition, atmosphere, energy, tidal locking, type of planet and liquid water), in terms of their similarity to the only ideal alternative, The Earth. Our results, when compared with the probability index SEPHI, indicate that Kepler-442b, Kepler-062e/f, and LHS_1140b are the best exoplanets for searching for biomarkers, regardless its technical difficulty. If we take into account current technical feasibility, the best candidate is TRAPPIST-1e.

astro-ph.EP↗

arXiv2018

On the thermodynamic origin of metabolic scaling

The origin and shape of metabolic scaling has been controversial since Kleiber found that basal metabolic rate of animals seemed to vary as a power law of their body mass with exponent 3/4, instead of 2/3, as a surface-to-volume argument predicts. The universality of exponent 3/4 -claimed in terms of the fractal properties of the nutrient network- has recently been challenged according to empirical evidence that observed a wealth of robust exponents deviating from 3/4. Here we present a conceptually simple thermodynamic framework, where the dependence of metabolic rate with body mass emerges from a trade-off between the energy dissipated as heat and the energy efficiently used by the organism to maintain its metabolism. This balance tunes the shape of an additive model from which different effective scalings can be recovered as particular cases, thereby reconciling previously inconsistent empirical evidence in mammals, birds, insects and even plants under a unified framework. This model is biologically motivated, fits remarkably well the data, and also explains additional features such as the relation between energy lost as heat and mass, the role and influence of different climatic environments or the difference found between endotherms and ectotherms.

physics.bio-ph↗