2005/02/22 by N. Lodieu, M. J. McCaughrean, D. Barrado +3 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20042048
13 pages, 10 figures, 3 tables and 1 electronic table, accepted for publication in A&A
arxiv created 2005/02/22 · openalex publication_date 2005/06/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present a near-infrared (-band) survey of 0.7 square degree area in the α Persei open cluster (age = 90 Myr, distance = 182 pc) carried out with the Omega-Prime camera on the Calar Alto 3.5-m telescope. Combining optical data ( R c and I c ) obtained with the KPNO/MOSA detector and presented in Stauffer et al. (1999) with the observations, a sample of new candidate members has been extracted from the optical-infrared colour–magnitude diagram. The location of these candidates in the colour–colour diagram suggests that two-thirds of them are actually reddened background giants. About 20 new candidate members with masses between 0.3 and 0.04 are added to the ~400 known α Per cluster members. If they are indeed α Per members, four of the new candidates would be brown dwarfs. We discuss the advantages and drawbacks of the near-infrared survey as compared to the optical selection method. We also describe the outcome of optical spectroscopy obtained with the Twin spectrograph on the Calar Alto 3.5-m telescope for about 30 candidates, including selected members from the optical sample presented in Barrado y Navascués et al. (2002) and from our joint optical/infrared catalogue. These results argue in favour of the optical selection method for this particular cluster.