Supervisors: Heitor Ernandes and Rodolfo Smiljanic, email: hernandes@camk.edu.pl
Title: Aluminium abundances across multiple wavelength regimes instellar spectra
Time: 4 weeks on site. August - mid-September.
Project for CAMK Summer Program July/Sep 2026, on-site.
First week: Sample definition and literatureoverview.
Second week: Spectral handling and preparation.
Third week:Measurement of Aluminium abundances.
Fourth week: Consolidation andinterpretation of results.
Project description: Aluminium abundances derived from differentspectral lines and wavelength regimes often show significantdiscrepancies, and the origin of these inconsistencies is still notfully understood. This poses a limitation for high-precision stellarspectroscopy, where reliable abundance measurements are essential.Aluminium is a key tracer of nucleosynthesis, particularlyproton-capture processes in stellar interiors, and is widely used tostudy stellar evolution, multiple populations in globular clusters, andthe chemical history of the Milky Way and its satellites. In addition,the short-lived radionuclide 26Al can influence the thermal evolution ofplanetesimals, potentially affecting planetary water content and linkingstellar chemistry to planetary habitability.To address this issue, the project will measure Al abundances in starsusing spectra from three wavelength regimes: near-ultraviolet (~3900 Å),optical (5000–7000 Å), and the H-band (e.g. APOGEE). The student willwork with a carefully selected sample of 10 to 20 well-characteriseddwarf and giant stars spanning a range of metallicities, allowing acontrolled comparison across wavelengths. By fixing stellar parametersand focusing on spectral modelling, particularly the role of NLTEeffects, the student will generate and analyse synthetic spectra,compare them with observations, and evaluate the sources of systematicdifferences. This work will help improve the reliability and consistencyof abundance determinations in stellar astrophysics.
Workplan: After an introduction to stellar spectroscopy and abundanceanalysis techniques, the student will define a well-curated stellarsample that spans the Hertzsprung–Russell diagram as uniformly aspossible. They will then learn how to handle and process spectra fromdifferent wavelength domains, including normalisation and preparationfor analysis. In the third stage, the student will measure aluminiumabundances using spectral synthesis techniques, incorporating NLTEmodels where appropriate. Finally, they will compare results acrosswavelength regions, assess systematic differences, and interpret thefindings in the context of stellar physics and line formation processes.Audience: undergrads and early-stage PhDs with at least some knowledgeof coding, mainly Python.