The influence of multiple stars on the high-mass stellar initial mass function and age-dating of young massive star clusters

Abstract

The study of young stellar populations has revealed that most stars are in binary or higher order multiple systems. In this study the influence on the stellar initial mass function (IMF) of large quantities of unresolved multiple massive stars is investigated by taking into account stellar evolution and photometrically determined system masses. The models where initial masses are derived from the luminosity and colour of unresolved multiple systems show that even under extreme circumstances (100% binaries or higher order multiples) the difference between the power-law index of the mass function of all stars and the observed mass function is small (~0.1). Thus, if the observed IMF has the Salpeter index alpha = 2.35 then the true stellar IMF has an index not flatter than alpha = 2.25. Additionally, unresolved multiple systems may hide between 15 and 60% of the underlying true mass of a star cluster. While already a known result, it is important to point out that the presence of a large number of unresolved binaries amongst pre-main-sequence (PMS) stars induces a significant spread in the measured ages of these stars even if there is none. Also, lower-mass stars in a single-age binary-rich cluster appear older than the massive stars by about 0.6 Myr.

accepted for publication in MNRAS, 27 pages, 12 figures, 4 tables

References in corpus (53)

• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• The Optical and Near-Infrared Properties of Galaxies: I. Luminosity and Stellar Mass Functions
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• Comprehensive analytic formulae for stellar evolution as a function of mass and metallicity
• A Non-Gray Theory of Extrasolar Giant Planets and Brown Dwarfs
• Stellar evolution with rotation VIII: Models at Z = 10^{-5} and CNO yields for early galactic evolution
• On the Formation of Massive Stars
• Stellar evolution with rotation X: Wolf-Rayet star populations at solar metallicity
• The hierarchical formation of a stellar cluster
• Massive star formation: Nurture, not nature
• How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars
• Inverse Dynamical Population Synthesis and Star Formation
• A UBVR CCD Survey of the Magellanic Clouds
• The maximum stellar mass, star-cluster formation and composite stellar populations
• An upper limit to the masses of stars
• The Dynamical Properties of Stellar Systems in the Galactic Disc
• Evidence for a fundamental stellar upper mass limit from clustered star formation
• Comparative statistics and origin of triple and quadruple stars
• Formation of massive stars by growing accretion rate
• From star clusters to dwarf galaxies: The properties of dynamically hot stellar systems
• Numerical biases on IMF determinations created by binning
• Statistical Confirmation of a Stellar Upper Mass Limit
• The primordial binary population II: Recovering the binary population for intermediate mass stars in Sco OB2
• Limits on the primordial stellar multiplicity
• The secrets of the nearest starburst cluster: II. The present-day mass function in NGC 3603
• A Radial Velocity Survey of the Cygnus OB2 Association
• The massive star binary fraction in young open clusters I. NGC 6231 revisited
• The initial stellar mass function from random sampling in hierarchical clouds II: statistical fluctuations and a mass dependence for starbirth positions and times
• A highly abnormal massive star mass function in the Orion Nebula cluster and the dynamical decay of trapezia systems
• A Spectroscopic Survey of WNL Stars in the LMC: General Properties and Binary Status
• The Low End of the Initial Mass Function in Young LMC Clusters: I. The Case of R136
• The very massive binary NGC3603-A1
• A discontinuity in the low-mass initial mass function
• The dynamical evolution of Taurus--Auriga-type aggregates
• Adaptive Optics Photometry and Astrometry of Binary Stars. III. A Faint Companion Search of O-Star Systems
• On the Mass of Dense Star Clusters in Starburst Galaxies from Spectro-Photometry
• On the universal outcome of star-formation: Is there a link between stars and brown-dwarfs?
• Faint Stars in the Ursa Minor Dwarf Spheroidal Galaxy: Implications for the Low-Mass Stellar Initial Mass Function at High Redshift
• The effect of binaries on the dynamical mass determination of star clusters
• Spectroscopic binaries with components of similar mass
• Brown dwarf formation by binary disruption
• Early-type stars in the young open cluster IC1805. II. The probably single stars HD15570 and HD15629, and the massive binary/triple system HD15558
• A discontinuity in the low-mass IMF - the case of high multiplicity
• UNIFICATION OF THE NEARBY AND PHOTOMETRIC STELLAR LUMINOSITY FUNCTIONS
• Biases on initial mass function determinations. II. Real multiple systems and chance superpositions
• On the determination of age and mass functions of stars in young open star clusters from the analysis of their luminosity functions
• Captured older stars as the reason for apparently prolonged star formation in young star clusters
• Massive binaries in high-mass star-forming regions: A multi-epoch radial velocity survey of embedded O-stars
• Ultraviolet and Optical Observations of OB Associations and Field Stars in the Southwest Region of the Large Magellanic Cloud
• Complex stellar populations in massive clusters: trapping stars of a dwarf-disc galaxy in a newborn stellar super-cluster
• ARE THE NEARBY AND PHOTOMETRIC STELLAR LUMINOSITY FUNCTIONS DIFFERENT?
• Quasi-binarity of massive stars in young dense clusters - the case of the ONC

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• Stellar Populations in the Central 0.5 pc of the Galaxy II: The Initial Mass Function
• An excess of massive stars in the local 30 Doradus starburst
• The stellar and sub-stellar IMF of simple and composite populations
• The relation between the most-massive star and its parental star cluster mass
• Dynamical ejections of massive stars from young star clusters under diverse initial conditions
• The Dawes Review 8: Measuring the Stellar Initial Mass Function
• The mmax-Mecl relation, the IMF and IGIMF: probabilistically sampled functions?
• A comparison between star formation rate diagnostics and rate of core collapse supernovae within 11 Mpc
• Evolution of Mass Functions of Coeval Stars through Wind Mass Loss and Binary Interactions
• The galaxy-wide IMF of dwarf late-type to massive early-type galaxies
• The masses, and the mass discrepancy of O-type stars
• Properties of hierarchically forming star clusters
• The Gaia-ESO Survey: Stellar content and elemental abundances in the massive cluster NGC 6705
• Direct N-body simulations of globular clusters: (I) Palomar 14
• Stellar population of the superbubble N206 in the LMC II. Parameters of the OB and WR stars, and the total massive star feedback
• A New Method for the Assessment of Age and Age-Spread of Pre-Main Sequence Stars in Young Stellar Associations of the Magellanic Clouds
• The Complete Initial Mass Function Down to the Sub-Solar Regime in the Large Magellanic Cloud with Hubble Space Telescope ACS Observations
• Top-heavy integrated galactic stellar initial mass functions (IGIMFs) in starbursts
• The Initial Mass Function and the Surface Density Profile of NGC 6231
• Properties of Stellar Clusters around High-Mass Young Stars
• Direct $N$-body simulations of globular clusters - II. Palomar 4
• Star formation in the outskirts of DDO 154: A top-light IMF in a nearly dormant disc
• On the true shape of the upper end of the stellar initial mass function: The case of R136
• Near-infrared adaptive optics imaging of infrared luminous galaxies: the brightest cluster magnitude - star formation rate relation
• Sampling methods for stellar masses and the mmax-Mecl relation in the starburst dwarf galaxy NGC 4214
• The influence of stellar-dynamical ejections and collisions on the relation between the maximum-star and star-cluster-mass
• Measurement of the core-collapse progenitor mass distribution of the Small Magellanic Cloud
• The role of the H${}_2$ adiabatic index in the formation of the first stars
• Physical parameters of pre-main sequence stars in open clusters
• Constraining the Thin Disc Initial Mass Function using Galactic Classical Cepheids
• Unveiling hidden properties of young star clusters: differential reddening, star-formation spread and binary fraction
• Mass accretion rates from multi-band photometry in the Carina Nebula: the case of Trumpler 14
• The initial mass function of stars and the star-formation rates of galaxies
• Escaping stars from young low-N clusters
• Effects of physical conditions on the stellar initial mass function: The low-metallicity star-forming region Sh 2-209
• Deriving reliable fundamental parameters of PMS-rich star clusters affected by differential reddening
• Is the young star cluster NGC 376 dissolving in the field of the SMC?
• Enhancing the detection of low-energy M dwarf flares: Wavelet-based denoising of CHEOPS data
• A search for High Mass Stars Forming in Isolation using CORNISH & ATLASGAL
• Variable binaries and variables in binaries in the Binary Star Database BDB
• The long-term evolution of Ultra Faint Dwarf Galaxies and observational implications
• First, Second and Third Massive Stars in Open Clusters