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Optical spectroscopy of isolated planetary mass objects in the σ Orionis cluster

Barrado y Navascués, D. and Zapatero Osorio, M. R. and Béjar, V. J. S. and Rebolo, R. and Martín, E. L. and Mundt, R. and Bailer-Jones, C. A. L. (2001) Optical spectroscopy of isolated planetary mass objects in the σ Orionis cluster. Astronomy & Astrophysics, 377 (2). L9-L13. ISSN 0004-6361.

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We have obtained low resolution optical spectra of 15 isolated planetary mass objects (IPMOs) in the σ 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 Hα 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 similar masses. These results confirm that the substellar mass function of the σ Orionis cluster, in the form dN/dM, keeps rising in the planetary domain.

Item Type:Article
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URLURL TypeDescription Paper
Rebolo, R.0000-0003-3767-7085
Alternate Title:Optical spectroscopy of isolated planetary mass objects in the sigma Orionis cluster
Additional Information:© 2001 ESO. Received: 29 May 2001. Accepted: 15 August 2001. We thanks the ESO staff at Paranal Observatory. The referee, G. Chabrier, has helped to improve the original version with his comments and suggestions. Partial financial support was provided by the Spanish DGES project PB98-0531-C02-02 and CICYT grant ESP98-1339-CO2.
Funding AgencyGrant Number
Direcção-Geral do Ensino Superior (DGES)PB98-0531-C02-02
Comisión Interministerial de Ciencia y Tecnología (CICYT)ESP98-1339-CO2
Subject Keywords:stars: planetary systems: formation - open clusters and associations: individual: σ Orionis - stars: low mass, brown dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20180307-084140419
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Official Citation:Optical spectroscopy of isolated planetary mass objects in the Formula Orionis cluster D. Barrado y Navascués, M. R. Zapatero Osorio, V. J. S. Béjar, R. Rebolo, E. L. Martín, R. Mundt and C. A. L. Bailer-Jones A&A, 377 2 (2001) L9-L13 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85167
Deposited By: Ruth Sustaita
Deposited On:07 Mar 2018 17:14
Last Modified:09 Mar 2020 13:19

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