Unresolved multiple stars and Galactic clusters' mass estimates

Abstract

If not properly accounted for, unresolved binary stars can induce a bias in the photometric determination of star cluster masses inferred from star counts and the luminosity function. A correction factor close to 1.15 (for a binary fraction of 0.35) was found in \citep{Boro19}, which needs to be applied to blind photometric mass estimates. This value for the correction factor was found to be smaller than literature values. In an attempt to lift this discrepancy, in this work the focus is on higher order multiple stars with the goal of investigating the effect of triple and quadruple systems adopting the same methodology and data-set as in the quoted work. Then the result is found that when triple and quadruple together with binary systems are properly accounted for, the actual cluster mass (computed as all stars were single) should be incremented by a factor of 1.18$-$1.27, depending on the cluster and when the binary fraction $\alpha$ is 0.35. Fitting formulae are provided to derive the increment factor for different binary star percentages.

9 pages, 1 figure, in press in the Astrophysical Journal

References in corpus (22)

• Gaia Data Release 2: The astrometric solution
• Tertiary companions to close spectroscopic binaries
• From binaries to multiples II: hierarchical multiplicity of F and G dwarfs
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. V. Constraints on Formation Scenarios
• Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties
• On the Origin of GW190521-like events from repeated black hole mergers in star clusters
• Do binaries in clusters form in the same way as in the field?
• Measuring the Recoverability of Close Binaries in Gaia DR2 with the Robo-AO Kepler Survey
• Exploring the consequences of pairing algorithms for binary stars
• The evolution of binary populations in cool, clumpy star clusters
• Wide binaries are rare in open clusters
• The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data
• Modelling unresolved binaries of open clusters in color-magnitude diagram. I. method and application of NGC3532
• The binary companion mass ratio distribution: an imprint of the star formation process?
• Ruprecht 147: a paradigm of dissolving star cluster
• Milky Way globular clusters in gamma-rays: analyzing the dynamical formation of millisecond pulsars
• On the Motion of Stars in the Pleiades according to Gaia DR2 Data
• Effect of binarity in star cluster dynamical mass determination
• Unresolved binaries and Galactic clusters' mass estimates
• On the mass of the Galactic star cluster NGC 4337
• X-ray sources in Galactic globular clusters and old open clusters
• An analysis of the blue straggler population in the Sgr dSph globular cluster Arp 2

Cited by in corpus (4)

• The multiplicity fraction in 202 open clusters from Gaia
• Unresolved Binaries in the Intermediate Mass Range in the Pleiades Star Cluster
• Star-by-star dynamical evolution of the physical pair of the Collinder 135 and UBC 7 open clusters
• The young Galactic cluster NGC 225: binary stars content and total mass estimate