The young Galactic cluster NGC 225: binary stars content and total mass estimate

Abstract

Galactic star clusters are known to harbour a significant amount of binary stars, yet their role in the dynamical evolution of the cluster as a whole is not comprehensively understood. We investigated the influence of binary stars on the total mass estimate for the case of the moderately populated Galactic star cluster NGC 225. The analysis of multi-epoch radial velocities of the 29 brightest cluster members, obtained over two observational campaigns, in 1990-1991 and in 2019-2020, yields a value of binary fraction of $\alpha =0.52$ (15 stars out of 29). Using theoretical isochrones and Monte Carlo simulations we found that the cluster mass increases at least 1.23 times when binaries are properly taken into account. By combining Gaia EDR3 photometric data with our spectroscopic observations, we derived estimates of NGC 225 fundamental parameters as follows: mean radial velocity $<V_r>=-9.8\pm 0.7$ km s${}^{-1}$, $\log (\tau )$=8.0-8.2 dex, distance $D=676\pm 22$ pc, and colour excess $E(B-V)=0.29\pm 0.01$ mag.

References in corpus (6)

• Completeness of the Gaia-verse II: what are the odds that a star is missing from Gaia DR2?
• CCD UBV Photometry and Kinematics of the Open Cluster NGC 225
• On the mass of the Galactic star cluster NGC 4337
• A new look at Sco OB1 association with Gaia DR2
• Unresolved multiple stars and Galactic clusters' mass estimates
• Multiple Stellar Populations in NGC 2808: a Case Study for Cluster Analysis

Cited by in corpus (1)

• Revisiting the mass of open clusters with \emph{Gaia} data