Letter to the Editor
The young, wide and very low mass visual binary Lambda Orionis 167*
1
Laboratorio de Astrofisica Espacial y Fisica Fundamental, LAEFF-INTA, Madrid, Spain e-mail: barrado@laeff.inta.es
2
IPAC, Caltech, Pasadena, USA e-mail: stauffer@ipac.caltech.edu
3
Astronomy Department, University of California, Berkeley, USA e-mail: hbouy@astro.berkeley.edu
Received:
8
February
2007
Accepted:
11
April
2007
Aims.We look for wide, faint companions around members of the 5 Myr Lambda Orionis open cluster.
Methods.We used optical, near-infrared, and Spitzer/IRAC photometry.
Results.We report the discovery of a very wide very low mass visual binary, LOri167, formed by a brown dwarf and a planetary-mass candidate located at 5 arcsec,
which seems to belong to the cluster. We derive Teff of 2125 and 1750 K. If they are members, comparisons with theoretical models indicate masses
of 17
and 8
Mjup, with a projected separation of 2000 AU.
Conclusions.Such a binary system would be difficult to explain in most models, particularly those where substellar objects form in the disks surrounding higher mass stars.
Key words: open clusters and associations: individual: Collinder 69 / stars: low-mass, brown dwarfs / stars: binaries: visual / stars: pre-main sequence
© ESO, 2007