2010MNRAS.402.1685B

Teutsch145 and Teutsch146 are shown to be open clusters (OCs) orbiting well inside the solar circle, a region where several dynamical processes combine to disrupt most OCs on a time-scale of a few 10⁸yr. BVI photometry from the GALILEO telescope is used to investigate the nature and derive the fundamental and structural parameters of the optically faint and poorly known OCs Teutsch145 and 146. These parameters are computed by means of field-star-decontaminated colour-magnitude diagrams and stellar radial density profiles (RDPs). Cluster mass estimates are made based on the intrinsic mass functions (MFs). We derive the ages 200⁺¹⁰⁰_–50 and 400±100Myr, and the distances from the Sun d_☉= 2.7±0.3 and 3.8±0.2kpc, respectively, for Teutsch145 and 146. Their integrated apparent and absolute magnitudes are m_V ~ 12.4 and 13.3 and M_V ~ -5.6 and -5.3. The MFs (detected for stars with m ≳ 1M_☉) have slopes similar to Salpeter's initial mass function. Extrapolated to the H-burning limit, the MFs would produce total stellar masses of ∼1400M_☉, typical of relatively massive OCs. Both OCs are located deep into the inner Galaxy and close to the Crux-Scutum arm. Since cluster-disruption processes are important, their primordial masses must have been higher than the present-day values. The conspicuous stellar density excess observed in the innermost bin of both RDPs might reflect the dynamical effects induced by a few 10⁸yr of external tidal stress.