The family pictures of our neighbours: investigating the mass function and dynamical parameters of nearby open clusters

Abstract

We determine the mass functions (MFs) and the dynamical parameters of 15 nearby open clusters (OCs) using the unprecedented data set of the Gaia Early Data Release 3. We select the members of each cluster by combining the photometric (colour and magnitude) and astrometric (parallax and proper motions) parameters of stars, minimizing the contamination from Galactic field interlopers. By comparing the observed distribution of stars along the cluster main sequence with the best-fitting synthetic population, we find the present-day MF and the binary fraction of the OCs, along with their dynamical parameters like mass, half-mass radius, and half-mass relaxation time. We found that the global present-day MF of OCs are consistent with a single power-law function, $F(m)\propto m^{\alpha }$, with slopes $-3<\alpha <-0.6$ including both subsolar, $0.2<m/{\text{M}}_{\odot }<1$, and supersolar mass regimes. A significant correlation between the MF-slope and the ratio of age to half-mass relaxation time is evidenced, similarly to the same conclusion already observed among Galactic globular clusters. However, OCs evolve along different tracks in comparison with the globular clusters, possibly indicating primordial differences in their initial mass function (IMF). The comparison with Monte Carlo simulations suggests that all the analysed OCs could have been born with an IMF with slope ${\alpha }_{\text{IMF}}<-2.3$. We also show that the less evolved OCs have a MF consistent with that of the solar neighbourhood, indicating a possible connection between the dissolution of OCs and the formation of the Galactic disc.

arXiv comment20 pages, 14 figures, accepted for publication by MNRAS

References in corpus (82)

• On the variation of the Initial Mass Function
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Embedded Clusters in Molecular Clouds
• Dynamical evolution of star clusters in tidal fields
• A Gaia DR2 view of the Open Cluster population in the Milky Way
• Evolutionary models for low-mass stars and brown dwarfs: uncertainties and limits at very young ages
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• A catalogue of masses, structural parameters and velocity dispersion profiles of 112 Milky Way globular clusters
• A Substantial Population of Low Mass Stars in Luminous Elliptical Galaxies
• Gaia broad band photometry
• The Formation of a Bound Star Cluster: From the Orion Nebula Cluster to the Pleiades
• Origin of the system of globular clusters in the Milky Way
• On the fraction of star formation occurring in bound stellar clusters
• Inverse Dynamical Population Synthesis and Star Formation
• The Stellar Populations of Praesepe and Coma Berenices
• A Theory of the IMF for Star Formation in Molecular Clouds
• Clusters and mirages: cataloguing stellar aggregates in the Milky Way
• Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity
• Age determination for 269 $Gaia$ DR2 Open Clusters
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in IC2391: Lithium depletion and Halpha emission
• Hunting for open clusters in \textit{Gaia} DR2: $582$ new OCs in the Galactic disc
• The Stellar Initial Mass Function of Ultra-Faint Dwarf Galaxies: Evidence for IMF Variations with Galactic Environment
• The fraction of binary systems in the core of thirteen low-density Galactic globular clusters
• Direct determination of the spiral pattern rotation speed of the Galaxy
• Evidence for a non-universal stellar initial mass function from the integrated properties of SDSS galaxies
• Brown dwarfs in the Pleiades cluster : clues to the substellar mass function
• Star Cluster Evolution, Dynamical Age Estimation and the Kinematical Signature of Star Formation
• A deep all-sky census of the Hyades
• The Masses of Population II White Dwarfs
• Statistics of N-Body Simulations. III. Unequal Masses
• The Gaia-ESO Survey: radial distribution of abundances in the Galactic disc from open clusters and young field stars
• Photometry and membership for low mass stars in the young open cluster NGC 2516
• Detailed analysis of open clusters: a mass function break and evidence of a fundamental plane
• CCD BV survey of 42 open clusters
• Extended main sequence turnoff as a common feature of Milky Way open clusters
• Brown dwarfs and very low mass stars in the Hyades cluster : a dynamically evolved mass function
• Discovery of Tidal Tails in Disrupting Open Clusters: Coma Berenices and a Neighbor Stellar Group
• Evidence for two populations of Galactic globular clusters from the ratio of their half-mass to Jacobi radii
• The Seven Sisters DANCe. I. Empirical isochrones, Luminosity and Mass Functions of the Pleiades cluster
• 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3: its Relation to Cluster Dynamics
• The fraction of binary systems in the core of five Galactic open clusters
• The global mass functions of 35 Galactic globular clusters: I. Observational data and correlations with cluster parameters
• Optimal photometry for colour-magnitude diagrams and its application to NGC 2547
• The bound fraction of young star clusters
• The evolution of the stellar mass function in star clusters
• Direct N-body simulations of globular clusters: (I) Palomar 14
• Can a "standard" Initial Mass Function explain the metal enrichment in clusters of galaxies?
• Completeness of the Gaia-verse II: what are the odds that a star is missing from Gaia DR2?
• The lower mass function of the young open cluster Blanco 1: from 30 Mjup to 3 Mo
• Proper motion surveys of the young open clusters Alpha Persei and the Pleiades
• Testing the universality of the IMF with Bayesian statistics: young clusters
• Exploring open cluster properties with Gaia and LAMOST
• A comparison between the stellar and dynamical masses of six globular clusters
• Low mass stars, brown dwarf candidates and the mass function of the young open cluster NGC 2547
• Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster
• The Global Mass Functions of 35 Galactic globular clusters: II. Clues on the Initial Mass Function and Black Hole Retention Fraction
• Mass functions and photometric binaries in nine open clusters
• The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data
• Towards a complete stellar mass function of the Hyades. I. Pan-STARRS1 optical observations of the low-mass stellar content
• The stellar Initial Mass Function of the solar neighbourhood revealed by Gaia
• Direct $N$-body simulations of globular clusters - II. Palomar 4
• Population analysis of open clusters: radii and mass segregation
• The effects of Population III stars and variable IMF on the chemical evolution of the Galaxy
• A bottom-heavy initial mass function for the likely-accreted blue-halo stars of the Milky Way
• Formation of proto-clusters and star formation within clusters: apparent universality of the initial mass function ?
• Characterization of Stellar and Substellar Members in the Coma Berenices Star Cluster
• Proper motion measurements as indicators of binarity in open clusters
• The IMF of open star clusters with Tycho-2
• Brown dwarfs and very low mass stars in the Praesepe open cluster: a dynamically unevolved mass function?
• Global survey of star clusters in the Milky Way VI. Age distribution and cluster formation history
• Possible smoking-gun evidence for initial mass segregation in re-virialized post-gas expulsion globular clusters
• Radial Variation in the Stellar Mass Functions of Star Clusters
• The seven sisters DANCe IV. Bayesian hierarchical model
• The Binary Fraction and Mass Segregation in Alpha Persei Open Cluster
• Substellar Mass Function of Young Open Clusters as Determined through a Statistical Approach Using 2MASS and GSC Data
• Characterizing low contrast Galactic open clusters with GAIA DR2
• New Insight into the stellar mass function of Galactic globular clusters
• Treatment of realistic tidal field in Monte Carlo simulations of star clusters
• Low Mass Stars and Brown Dwarfs in Praesepe
• Nearly coeval intermediate-age Milky Way star clusters at very different dynamics evolutionary stages
• Characterizing dynamical stages of open clusters located in the Sagittarius spiral arm
• A photometric and astrometric investigation of the brown dwarfs in Blanco 1

Cited by in corpus (9)

• Revisiting the mass of open clusters with \emph{Gaia} data
• Evidence for a bottom-light initial mass function in massive star clusters
• Photometric binaries, mass functions, and structural parameters of 78 Galactic open clusters
• The multiplicity fraction in 202 open clusters from Gaia
• The membership of stars, density profile and mass segregation in open clusters using a new machine learning-based method
• Mass-Dependent Radial Distribution of Single and Binary Stars in the Pleiades and their Dynamical Implications
• A new tool to derive simultaneously exponent and extremes of power-law distributions
• The Small Magellanic Cloud through the lens of the James Webb Space Telescope : binaries and mass function within the galaxy outskirts
• Stellar masses and mass ratios for Gaia open cluster members