Do star clusters form in a completely mass-segregated way?

Abstract

ALMA observations of the Serpens South star-forming region suggest that stellar protoclusters may be completely mass segregated at birth. Independent observations also suggest that embedded clusters form segregated by mass. As the primordial mass segregation seems to be lost over time, we aim to study on which timescale an initially perfectly mass-segregated star cluster becomes indistinguishable from an initially not mass-segregated cluster. As an example, the Orion Nebula Cluster (ONC) is also discussed. We used $N$-body simulations of star clusters with various masses and two different degrees of primordial mass segregation. We analysed their energy redistribution through two-body relaxation to quantify the time when the models agree in terms of mass segregation, which sets in only dynamically in the models that are primordially not mass segregated. A comprehensive cross-matched catalogue combining optical, infrared, and X-ray surveys of ONC members was also compiled and made available. The models evolve to a similar radial distribution of high-mass stars after the core collapse (about half a median two-body relaxation time, $t_{\mathrm{rh}}$) and become observationally indistinguishable from the point of view of mass segregation at time ${\tau }_{\mathrm{v}}\approx 3.3t_{\mathrm{rh}}$. In the case of the ONC, using the distribution of high-mass stars, we may not rule out either evolutionary scenario (regardless of whether they are initially mass segregated). When we account for extinction and elongation of the ONC, as reported elsewhere, an initially perfectly mass-segregated state seems to be more consistent with the observed cluster.

A&A (in press), 17 pages, 15 figures, data available at CDS

References in corpus (55)

• On the variation of the Initial Mass Function
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• The Stellar IMF from Turbulent Fragmentation
• The distance to the Orion Nebula
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• The Formation of a Bound Star Cluster: From the Orion Nebula Cluster to the Pleiades
• The Luminosity & Mass Function of the Trapezium Cluster: From B stars to the Deuterium Burning Limit
• Chandra Orion Ultradeep Project: Observations and Source Lists
• Global Hierarchical Collapse In Molecular Clouds. Towards a Comprehensive Scenario
• Constraints on the Stellar/Sub-stellar Mass Function in the Inner Orion Nebula Cluster
• A Theory of the IMF for Star Formation in Molecular Clouds
• The Dynamical Properties of Stellar Systems in the Galactic Disc
• Analytical star formation rate from gravoturbulent fragmentation
• The stellar and sub-stellar IMF of simple and composite populations
• Using the minimum spanning tree to trace mass segregation
• An ALMA study of the Orion Integral Filament: I. Evidence for narrow fibers in a massive cloud
• The relation between the most-massive star and its parental star cluster mass
• Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations
• Mass segregation and fractal substructure in young massive clusters: (I) the McLuster code and method calibration
• The Initial Mass Function of the Orion Nebula Cluster across the H-burning limit
• Membership of the Orion Nebula Population from the Chandra Orion Ultradeep Project
• Dynamical ejections of massive stars from young star clusters under diverse initial conditions
• Chandra X-ray Observation of the Orion Nebula Cluster. II Relationship between X-ray activity indicators and stellar parameters
• 3D shape of Orion A from Gaia DR2
• The mmax-Mecl relation, the IMF and IGIMF: probabilistically sampled functions?
• Fibers in the NGC1333 proto-cluster
• Young Stellar Groups and Their Most Massive Stars
• Evidence for primordial mass segregation in globular clusters
• Dependency of dynamical ejections of O stars on the masses of very young star clusters
• Orion Revisited - I. The massive cluster in front of the Orion Nebula Cluster
• X-ray properties of protostars in the Orion Nebula
• A Tale of Three Cities: OmegaCAM discovers multiple sequences in the color-magnitude diagram of the Orion Nebula Cluster
• Star Formation in Space and Time: The Orion Nebula Cluster
• Age spreads in star forming regions: The lithium test in the Orion Nebula Cluster
• Direct N-body simulations of globular clusters: (I) Palomar 14
• Distribution of Serpens South protostars revealed with ALMA
• Chandra X-ray Observation of the Orion Nebula Cluster. I Detection, Identification and Determination of X-ray Luminosities
• A Multi-Color Optical Survey of the Orion Nebula Cluster. Part I: the Catalog
• On the initial binary population for star cluster simulations
• Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster
• Multiplicity and clustering in Taurus star forming region. II. From ultra-wide pairs to dense NESTs
• Stellar clusterings around "Isolated" Massive YSOs in the LMC
• A new method to create initially mass segregated star clusters in virial equilibrium
• Direct $N$-body simulations of globular clusters - II. Palomar 4
• The JCMT Gould Belt Survey: Dense Core Clusters in Orion A
• Structure and Fragmentation of a high line-mass filament: Nessie
• Neutron stars and millisecond pulsars in star clusters: implications for the diffuse $\gamma$-radiation from the Galactic Centre
• Captured older stars as the reason for apparently prolonged star formation in young star clusters
• The extinction map of the OMC-1 molecular cloud behind the Orion Nebula
• 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 effect of primordial mass segregation on the size scale of globular clusters
• Massive open star clusters using the VVV survey V. Young clusters with an OB stellar population
• Catch me if you can: is there a runaway-mass black hole in the Orion Nebula Cluster?

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• Unifying low and high mass star formation through density amplified hubs of filaments
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• 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3: its Relation to Cluster Dynamics
• Uncovering a 260 pc wide, 35 Myr old filamentary relic of star formation
• How fast do young star clusters expel their natal gas?: Estimating the upper limit of the gas expulsion time-scale
• Physics and evolution of the most massive stars in 30 Dor. Mass loss, envelope inflation, and a variable upper stellar mass limit
• Stellar mass segregation as separating classifier between globular clusters and ultra-faint dwarf galaxies
• Extended Tidal Tails of IC 4756 detected by {\it Gaia} EDR3
• Do ultra compact dwarf galaxies form monolithically or as merged star cluster complexes?
• The Lifetimes of Star Clusters Born with a Top-heavy IMF
• Not so different after all: Properties and Spatial Structure of Column Density Peaks in the Pipe and Orion A Clouds
• Photometric study of the young open clusters IC 1442, King 21, and Trumpler 7
• Central Dynamics of Multi-mass Rotating Star Clusters
• The initial mass function of stars and the star-formation rates of galaxies
• Primordial mass segregation of star clusters with primordial binaries
• On the thermal structure of the proto-Super Star Cluster 13 in NGC 253
• Are hierarchically formed embedded star clusters surviving gas expulsion depending on their initial conditions?
• Spatial mixing of stellar populations in globular clusters via binary-single star scattering
• Primordial mass segregation of star clusters: The role of binary stars
• Assessing membership projection errors in star forming regions
• Mass Segregation in the CMZoom Survey
• The mmax-Mecl relation in the LEGUS clusters