{"paper":{"title":"The substellar mass function in sigma Orionis. II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objects","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"C. A. L. Bailer-Jones, D. Barrado y Navascu\\'es, E. L. Mart\\'in, G. Bihain, J. A. Caballero, J. Eisl\\\"offel, M. R. Zapatero Osorio, R. Mundt, R. Rebolo, T. Forveille, V. J. S. B\\'ejar","submitted_at":"2007-05-07T15:12:06Z","abstract_excerpt":"We investigate the mass function in the substellar domain down to a few Jupiter masses in the young sigma Orionis open cluster (3+/-2 Ma, d = 360^+70_-60 pc). We have performed a deep IJ-band search, covering an area of 790 arcmin^2 close to the cluster centre. This survey was complemented with an infrared follow-up in the HKs- and Spitzer 3.6-8.0 mum-bands. Using colour-magnitude diagrams, we have selected 49 candidate cluster members in the magnitude interval 16.1 mag < I < 23.0 mag. Accounting for flux excesses at 8.0 mum and previously known spectral features of youth, 30 objects are bona "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0705.0922","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}