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arXiv · 2608.07048

Euclid Early Release Observations of the Barnard 30 dark cloud I. Brown dwarfs and planetary mass candidate members at the core of the association

D. Barrado·H. Bouy·E. L. Martin·J. -C. Cuillandre·N. Huélamo·M. Žerjal·C. Dominguez-Tagle·S. Muñoz Torres·J. -Y. Zhang·E. Bertin·J. Olivares
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Abstract

This study aims to identify very low-mass members within the Barnard 30 dark cloud, with a particular focus on detecting objects in the substellar domain, including those within the planetary-mass regime. We employed deep photometric observations using data from the Euclid mission, incorporating advanced data processing techniques, in particular the DeNeb tool for optimized source detection. We also analyze multi-wavelength ancillary observations and perform a Spectral Energy Distribution analysis for each candidate member. In addition, low-resolution near-infrared spectroscopy was obtained for one candidate to further assess its nature and properties. Our initial photometric analysis yielded a initial sample of nearly one hundred candidate members in the substellar mass range. A subsample of 23 probable members, located close to the 3 Myr isochrone, has been identified. Thus, we have substantially expanded the known population of faint, cool sources associated with the region. Low resolution near-IR spectroscopic analysis of one candidate reveals an L2 spectral type with low gravity, consistent with a young ultra-cool dwarf. If its membership is confirmed, its estimated mass lies in the range 15-20 Mjup. These findings validate the reliability of our multi-wavelength photometric selection methodology. These results offer valuable insights into the low-mass end of the initial mass function (IMF) and demonstrate the effectiveness of Euclid in identifying brown dwarf and planetary-mass candidates in nearby, densely packed star-forming regions.

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D. Barrado, H. Bouy, E. L. Martin, J. -C. Cuillandre, N. Huélamo, M. Žerjal, C. Dominguez-Tagle, S. Muñoz Torres, J. -Y. Zhang, E. Bertin, J. Olivares. 2026-08-07. Euclid Early Release Observations of the Barnard 30 dark cloud I. Brown dwarfs and planetary mass candidate members at the core of the association. https://arxiv.org/abs/2608.07048

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