Open cluster survival within the solar circle: Teutsch145 and Teutsch146

TL;DR

This study uses photometry to analyze two faint open clusters inside the solar circle, determining their fundamental parameters, masses, and structural features, highlighting their survival despite disruptive galactic processes.

Contribution

It provides detailed characterization of Teutsch145 and 146, including age, distance, mass, and structural parameters, demonstrating their resilience in a disruptive galactic environment.

Findings

Both clusters are relatively massive with ~1400 solar masses.

They are located deep inside the Galaxy near the Crux-Scutum arm.

Their MFs are similar to Salpeter's IMF, indicating typical stellar distributions.

Abstract

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 10^8yrs. 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 (CMDs) and stellar radial density profiles (RDPs). Cluster mass estimates are made based on the intrinsic mass functions (MFs). We derive the ages 200+100-50Myr and 400+/-100Myr, and the distances from the Sun 2.7+/-0.3kpc and 3.8+/-0.2kpc, respectively for Teutsch145 and 146. Their integrated apparent and absolute magnitudes are m_V ~ 12.4, m_V ~ 13.3, M_V ~- 5.6 and M_V ~- 5.3. The MFs (detected for stars with m>1Msun) have slopes similar to Salpeter's IMF. Extrapolated to the H-burning limit, the MFs would produce total stellar masses of ~1400Msun, 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 10^8yrs of external tidal stress.