{"paper":{"title":"Optical spectroscopy of isolated planetary mass objects in the sigma Orionis cluster","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"2), 5), C.A.L. Bailer-Jones (2). ((1) Universidad Aut\\'onoma de Madrid, CSIC, D. Barrado-y-Navascu\\'es (1, E.L. Mart\\'in (6), Hawaii, Heidelberg. Germany (3) California Institute of Technology, Madrid, M.R. Zapatero-Osorio (3), Pasadena, R. Mundt (2), R. Rebolo (4, Spain. (2) Max-Planck-Institut f\\\"ur Astronomie, Spain (5) Consejo Superior de Investigaciones Cient\\'ificas, Spain (6) Institute of Astronomy. University of Hawaii, Tenerife, USA), USA (4) Instituto de Astrof\\'isica de Canarias, V.J.S. B\\'ejar (4)","submitted_at":"2001-08-15T01:37:09Z","abstract_excerpt":"We have obtained low resolution optical spectra of 15 isolated planetary mass objects (IPMOs) in the sigma Orionis cluster, and derived spectral types by comparison with nearby M and L dwarfs. The spectral types are in the range late M - mid L, in agreement with our expectations based on colors and magnitudes for bona fide members. Therefore, most of these objects have masses below the deuterium burning limit. About 2/3 show H(alpha) in emission at our spectral resolution. From our spectroscopic and photometric data, we infer that three IPMOs in this sample may be binaries with components of s"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0108249","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"}