Spitzer: Accretion in Low-Mass Stars and Brown Dwarfs in the λ Orionis Cluster

  title={Spitzer: Accretion in Low-Mass Stars and Brown Dwarfs in the $\lambda$ Orionis Cluster},
  author={David Barrado y Navascu{\'e}s and John R. Stauffer and M. Morales-Calder{\'o}n and Amelia Bayo and Giovanni Fazzio and Tom Megeath and Lori Allen and Lee Hartmann and Nuria Calvet},
  journal={The Astrophysical Journal},
  pages={481 - 500}
We present multiwavelength optical and IR photometry of 170 previously known low-mass stars and brown dwarfs of the 5 Myr Collinder 69 cluster (λ Orionis). The new photometry supports cluster membership for most of them, with less than 15% of the previous candidates identified as probable nonmembers. The near-IR photometry allows us to identify stars with IR excesses, and we find that the Class II population is very large, around 25% for stars (in the spectral range M0-M6.5) and 40% for brown… 


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