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Application of machine learning techniques for analysing molecular emission lines

Karolina, Plakitina

Abstract

Modern astronomy deals with enormous set of spectral data obtained from observations of molecular emissions in various sources—including infrared dark clouds, protostars, and HII regions. Traditional data analysis methods become less effective when processing such extensive datasets. In this work, we explore the application of machine learning techniques for analysing molecular emission lines to characterise astronomical objects and their astrochemical properties. Utilising data from the MALT90 survey, which observes the Galactic plane at 3 mm wavelengths, we discuss various clustering algorithms and dimensionality reduction methods that simplify the identification of objects. Our findings demonstrate that machine learning methods effectively identify two groups of star-forming regions among other types of astronomical sources. These groups are distinguished by line intensities of molecules which have different astrochemical origins. This approach holds promise for processing data collected with advanced facilities like JWST and ALMA, leading to more efficient analysis of astronomical data.

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TOWARDS NEW FRONTIERS: THE ASTROCHEMICAL JOURNEY FROM YOUNG STELLAR NURSERIES TO EXOPLANETS 10 - 14 MARCH 2025 Karolina Plakitina1, Maria Kirsanova1, Andrej Ostrovskii2, Alina Gimalieva2, Svetlana Salii2 1Institute of Astronomy of the Russian Academy of Sciences 2Institute of Natural Sciences and Mathematics, Ural Federal University Machine Learning for Molecular Emission Analysis Contact me: [email protected] Motivation and goals How do we classify thousands of molecular emission sources efficiently? https://www.eso.org/public/images/eso1606e/ By applying machine learning techniques, we aim to explore whether an algorithm can effectively identify different types of sources within the dataset based on features from the MALT90 catalog. Dataset MALT90 J. M. Rathborne et al. 2016 We retined only those with t lest 40% coverge Clusterisation was performed with integrated intensities of 5 molecular lines + FLUX at 870µm A — protostellar clumps (753 objects) H — extended HII regions (688), U — uncertain (673), Q — IR quiescent clumps (616), P — PDR regions (345), C — compact HII regions (171) Results Ech dot represents n object from MALT90 Silhouette score > 0.5 —> clusteristion ws successful Results (HDBSCAN + t-SNE) CCH N2H+ HCN HNC HCO+ ATLASGAL 870 𝜇m 00.1 0.4 0.2 0.3 Feature importance Number of objects Classification Classification A — protostellar clumps (753 obj) H — extended HII regions (688), U — uncertain (673), Q — IR quiescent clumps (616), P — PDR regions (345), C — compact HII regions (171) Results (HDBSCAN + t-SNE) Number of objects Classification Classification 1) There re two stble clusters: •Str-forming regions + extended H II regions: A (51–54%) nd H (47–50%) • Drk infrred clumps + str-forming regions: Q (26–27%) nd A (19–20%). 3) The presence of 870 µm dust emission dt does not significntly ffect the clustering results, nor does the exclusion of U-clssified (uncertin) objects. 2) The key fetures used for clustering were the integrted intensities of the C₂H nd N₂H⁺ lines. Contact me: [email protected]