Astronomy and Astrophysics, volume 485, 931-949 (2008/7-3)
Young stars and brown dwarfs surrounding Alnilam (ε Orionis) and Mintaka (δ Orionis).
CABALLERO J.A. and SOLANO E.
Abstract (from CDS):
We look for new regions to search for substellar objects. Two circular areas, 45arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, were explored. The regions are very young (less than 10Ma), have low extinction, and are neighbours to σ Orionis (∼3Ma), a young open cluster very rich in brown dwarfs and planetary-mass objects. We used Virtual Observatory tools, the astro-photometric Tycho-2, DENIS and 2MASS catalogues, 10 control fields at similar galactic latitudes, as well as X-ray, mid-infrared, and spectroscopic data from the literature. We compiled exhaustive lists of known young stars and new candidate members in the Ori OB1b association and of fore- and background sources. A total of 136 stars display features of extreme youth, like early spectral types, lithium in absorption, or mid-infrared flux excess. Other two young brown dwarf and 289 star candidates have been identified from an optical/near-infrared colour-magnitude diagram. We list another 74 known objects that might belong to the association. This catalogue can serve as input for characterising the stellar and high-mass substellar populations in the Orion Belt. Finally, we investigated the surface densities and radial distributions of young objects surrounding Alnilam and Mintaka and compared them with those in the σ Orionis cluster. We report on a new open cluster centred on Mintaka. Both regions can be analogues to the σ Orionis cluster, but more massive, more extended, slightly older, and less radially concentrated.
astronomical data bases: miscellaneous - Galaxy: open clusters and associations: individual: Ori OB1b - Galaxy: open clusters and associations: individual: Collinder 70 - stars: low mass, brown dwarfs - stars: individual: Alnilam - stars: individual: Mintaka
VizieR on-line data:
<Available at CDS (J/A+A/485/931): tablea1.dat to tablea18.dat refs.dat >
Tables a9, a11: EOri N-NNNN N=9. Tables a9, a16: Annizam NNNNNN N=181. Tables a10, a17: Mantaqah NNNNNNN N=103.
Status at CDS
All or part of tables of objects could be ingested in SIMBAD with priority 2.
Notes to table A.6 p.943 TYC 4767-2257-1 is a probable misprint for TYC 4766-757-1
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