BDs/VLM objects in the Coma Berenices open cluster
Final Report Abstract
Statistics of very low mass (VLM) stars and brown dwarfs (BD) in the Coma cluster (age ∼ 500 Myr) show that unlike younger open clusters (with ages < 250 Myr) there seems to be a prominent deficit of BDs/VLM members in this cluster. We have carried out a photometric survey in the Coma cluster with the Tautenburg Schmidt telescope, selected 82 member candidates and obtained low-resolution optical spectroscopy for 54 candidate members. Our ongoing analysis of the spectroscopic data shows that many of the objects are probably very low mass Coma members. Our goal was to obtain spectroscopy with MOSCA at the Calar Alto 3.5- m-telescope for the 26 fainter potential VLM cluster members. With these spectra we will derive spectral types, verify membership and thus derive a better initial mass function of this cluster. We were awarded three observing nights (1.-3. April 2013) in visitor mode. Due to bad weather we lost 80 percent of the allocated time and could observe only six objects. With such a small number of objects the planned investigation of the low-mass end of the cluster is obviously not possible. We will apply again for more observing time in service mode next year.
