ASTER -- Agentic Science Toolkit for Exoplanet Research

Emilie Panek; Alexander Roman; Gaurav Shukla; Leonardo Pagliaro; Katia Matcheva; Konstantin Matchev

astro-ph.EPMar 27, 2026

ASTER -- Agentic Science Toolkit for Exoplanet Research

Authors: Emilie Panek, Alexander Roman, Gaurav Shukla, Leonardo Pagliaro, Katia Matcheva, Konstantin Matchev

Organizations: Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL, 35487, USA · Department of Physics and Astronomy ‘Galileo Galilei’, University of Padova, Vicolo dell’Osservatorio 3, I-35122 Padova, Italy

Abstract

The expansion of exoplanet observations has created a need for flexible, accessible, and user-friendly workflows. Transmission spectroscopy has become a key technique for probing atmospheric composition of transiting exoplanets. The analyses of these data require the combination of archival queries, literature search, the use of radiative transfer models, and Bayesian retrieval frameworks, each demanding specialized expertise. Modern large language models enable the coordinated execution of complex, multi-step tasks by AI agents with tool integration, structured prompts, and iterative reasoning. In this study we present ASTER, an Agentic Science Toolkit for Exoplanet Research. ASTER is an orchestration framework that brings LLM capability to the exoplanetary community by enabling LLM-driven interaction with integrated domain-specific tools, workflow planning and management, and support for common data analysis tasks. Currently ASTER incorporates tools for downloading planetary parameters and observational datasets from the NASA Exoplanet Archive, as well as the generation of transit spectra from the TauREx radiative transfer model, and the completion of Bayesian retrieval of planetary parameters with TauREx. Beyond tool integration, the agent assists users by proposing alternative modeling approaches, reporting potential issues and suggesting solutions, and interpretations. We demonstrate ASTER's workflow through a complete case study of WASP-39b, performing multiple retrievals using observational data available on the archive. The agent efficiently transitions between datasets, generates appropriate forward model spectra and performs retrievals. ASTER provides a unified platform for the characterization of exoplanet atmospheres. Ongoing development and community contributions will continue expanding ASTER's capabilities toward broader applications in exoplanet research.

Figures & tables

Figure 1: Schema of internal workings of the agent object. The agent comprises the LLM, the tools and the context. Figure adapted from Roman and Roman (2026) .

Figure 2: Example of the Orchestral interface. The LLM provider can be changed in the bottom left corner, below the space where users write their messages. The cost tracking can be seen in the top right corner.

Molecule	Reference
H 2 O	Polyansky et al. (2018) ; Chubb et al. (2021)
CO	Li et al. (2015) ; Chubb et al. (2021)
CO 2	Yurchenko et al. (2025)
CH 4	Yurchenko et al. (2024)
NH 3	Coles et al. (2019) ; Chubb et al. (2021)
HCN	Barber et al. (2013) ; Chubb et al. (2021)

Table 1: Sources of cross-section data used in this work, downloaded from the Exomol website.

Figure 5: A plot generated, formatted, and displayed by the agent during the example conversation. It represents the transmission spectrum for WASP-39b, calculated by the agent and shown using the DisplayImage tool.

Figure 6: A plot generated, formatted, and displayed by the agent during the example conversation. It represents the best-fit model (orange curve) retrieved by the agent on WASP-39b NIRSpec observation (blue points).

Parameter	Value
Stellar mass	0.913 M ⊙
Stellar radius	0.939 R ⊙
Stellar effective temperature	5485 K
Planet mass	0.281 M jup
Planet radius	1.279 R jup
Planet equilibrium temperature	1166 K

Table 2: Planetary and stellar parameters for WASP-39b used in this study. Values were obtained automatically by the agent and verified against the NASA Exoplanet Archive.

Figure 7: Transmission spectrum at native resolution in the background (gray points), overlaid with a binned spectrum (red curve) recalculated by the agent. Prompt: Can you bin down the spectrum and plot both resolutions on a same plot?

Figure 8: Transmission spectrum at native resolution in the background (gray points), overlaid with a binned spectrum recalculated by the agent. Prompt: Can you now bin the forward model down to JWST medium resolution?

Figure 9: Transmission spectrum at native resolution in the background (gray points), with a binned down spectrum recalculated by the agent on top. Prompt: Can you now bin the forward model down to Ariel resolution?

Figure 10: Comparison of all nine observations for WASP-39b with NIRSpec. These observations are public and are published in JWST Transiting Exoplanet Community Early Release Science Team et al. (2023) ; Alderson et al. (2023) ; Rustamkulov et al. (2023) ; Carter et al. (2024) . This figure was produced by the agent. Prompt: Can you plot all the observations in a same figure for comparison?

Fitted Parameter	Retrieval 1	Retrieval 2
$T$	1318.5	666.5
$R_{p}$	1.29	1.30
$\log\mathrm{H_{2}O}$	-8.5	-4.0
$\log\mathrm{CH_{4}}$	-8.8	-7.1
$\log\mathrm{CO}$	-8.0	-5.7
$\log\mathrm{CO_{2}}$	-8.7	-5.0

Table 3: Fitted parameters from the two retrieval runs. The results are discussed in Section 5 .

Figure 11: Comparison of the two retrieval results launched by the agent. The first observation used by the agent ( JWST Transiting Exoplanet Community Early Release Science Team et al., 2023 ) and the corresponding retrieved spectrum are shown in blue. The second observation used by the agent ( Rustamkulov et al., 2023 ) and the corresponding retrieved spectrum are shown in red. Prompt: Can you do a plot with the two observations and the two retrieved spectra so I can compare the results?

Figure 12: Corner plot of the posterior distributions of the fitted parameters from the retrievals launched by the agent. The blue distributions are corresponding to the first retrieval on JWST Transiting Exoplanet Community Early Release Science Team et al. (2023) data. The red distributions are corresponding to the second retrieval on Rustamkulov et al. (2023) data. Prompt: Can you now do a corner plot with the probability distribution results of the two retrievals on the same corner plot figure?

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