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Mass segregation
About: Mass segregation is a research topic. Over the lifetime, 1024 publications have been published within this topic receiving 57729 citations.
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TL;DR: In this article, the authors used the recent observational data of Roser et al. to determine initial conditions of the Hyades cluster at the time of its formation in order to reproduce the present-day cumulative mass profile, stellar mass and luminosity function (LF).
Abstract: Context: Using the recent observational data of R\"oser et al. we present $N$-body simulations of the Hyades open cluster. Aims: We make an attempt to determine initial conditions of the Hyades cluster at the time of its formation in order to reproduce the present-day cumulative mass profile, stellar mass and luminosity function (LF). Methods: We performed direct $N$-body simulations of the Hyades in an analytic Milky Way potential that account for stellar evolution and include primordial binaries in a few models. Furthermore, we applied a Kroupa (2001) IMF and used extensive ensemble-averaging. Results: We find that evolved single-star King initial models with King parameters $W_0 = 6-9$ and initial particle numbers $N_0 = 3000$ provide good fits to the observational present-day cumulative mass profile within the Jacobi radius. The best-fit King model has an initial mass of $1721\ M_\odot$ and an average mass loss rate of $-2.2 \ M_\odot/\mathrm{Myr}$. The K-band LFs of models and observations show a reasonable agreement. Mass segregation is detected in both observations and models. If 33% primordial binaries are included the initial particle number is reduced by 5% as compared to the model without primordial binaries. Conclusions: The present-day properties of the Hyades can be well reproduced by a standard King or Plummer initial model when choosing appropriate initial conditions. The degeneracy of good-fitting models can be quite high due to the large dimension of the parameter space. More simulations with different Roche-lobe filling factors and primordial binary fractions are required to explore this degeneracy in more detail.
3 citations
TL;DR: In this paper, a revised X-ray source list of the Trumpler 16 region contains 1232 sources, including 1187 likely Carina members, which is matched to 1047 near-infrared counterparts detected by the HAWK-I instrument at the VLT.
Abstract: Trumpler 16 is a well--known rich star cluster containing the eruptive supergiant $\eta$ Carinae and located in the Carina star-forming complex. In the context of the Chandra Carina Complex Project, we study Trumpler 16 using new and archival X-ray data. A revised X-ray source list of the Trumpler 16 region contains 1232 X-ray sources including 1187 likely Carina members. These are matched to 1047 near-infrared counterparts detected by the HAWK-I instrument at the VLT allowing for better selection of cluster members. The cluster is irregular in shape. Although it is roughly circular, there is a high degree of sub-clustering, no noticeable central concentration and an extension to the southeast. The high--mass stars show neither evidence of mass segregation nor evidence of strong differential extinction. The derived power-law slope of the X-ray luminosity function for Trumpler 16 reveals a much steeper function than the Orion Nebula Cluster implying different ratio of solar- to higher-mass stars. We estimate the total Trumpler 16 pre-main sequence population to be > 6500 Class II and Class III X-ray sources. An overall K-excess disk frequency of ~ 8.9% is derived using the X-ray selected sample, although there is some variation among the sub-clusters, especially in the Southeastern extension. X-ray emission is detected from 29 high--mass stars with spectral types between B2 and O3.
3 citations
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TL;DR: In this paper, the evolution with angular velocity proportional to the square root of the density is predicted for self-similar core collapse in the Dynamical Main Sequence of globular clusters.
Abstract: Evolution with mass segregation and the evolution of the rotation of cores are both discussed for self-similar core collapse. Evolution with angular velocity proportional to the square root of the density is predicted. On the Dynamical Main Sequence of globular clusters the energy emission from binaries balances the energy expended in expanding the halo.
Newton's exactly solved N-body problem is then given, along with recent generalisations, all of which have no violent relaxation, but a new type of statistical equilibrium is discussed.
Finally, we set the creation of streams in the Galaxy's halo in the historical context of their discovery.
3 citations
TL;DR: In this article, the mass segregation of X-ray sources is quenched in globular clusters and the binary hardness ratio is lower than the correlation line of the dynamically normal GCs.
Abstract: Using X-ray sources as sensitive probes of stellar dynamical interactions in globular clusters (GCs), we study the mass segregation and binary burning processes in $\\omega$ Cen. We show that the mass segregation of X-ray sources is quenched in $\\omega$ Cen, while the X-ray source abundance of $\\omega$ Cen is much smaller than other GCs, and the binary hardness ratio (defined as $L_{\\rm X}/(L_{\\rm K}f_{b})$, with $f_{b}$ the binary fraction, $L_{\\rm X}$ and $L_{\\rm K}$ the cumulative X-ray and K band luminosity of GCs, respectively) of $\\omega$ Cen is located far below the $L_{\\rm X}/(L_{\\rm K}f_{b})-\\sigma_{c}$ correlation line of the dynamically normal GCs. These evidences suggest that the binary burning processes are highly suppressed in $\\omega$ Cen, and other \"heating mechanisms\", very likely a black hole subsystem (BHS), are essential in the dynamical evolution of $\\omega$ Cen. Through the \"black hole burning\" processes (i.e., dynamical hardening of the BH binaries), the BHS is dominating the energy production of $\\omega$ Cen, which also makes $\\omega$ Cen a promising factory of gravitational-wave sources in the Galaxy.
3 citations
TL;DR: In this article , the authors examined the origin of the relation by fitting Schechter mass functions as a function of galaxy mass, with and without accounting for mass loss by two-body relaxation, tidal shocks and/or dynamical friction.
Abstract: ABSTRACT The mass function of globular cluster (GC) populations is a fundamental observable that encodes the physical conditions under which these massive stellar clusters formed and evolved. The high-mass end of star cluster mass functions are commonly described using a Schechter function, with an exponential truncation mass Mc, *. For the GC mass functions in the Virgo galaxy cluster, this truncation mass increases with galaxy mass (M*). In this paper, we fit Schechter mass functions to the GCs in the most massive galaxy group ($M_{\mathrm{200}} = 5.14 \times 10^{13} \, {\rm M}_{\odot }$) in the E-MOSAICS simulations. The fiducial cluster formation model in E-MOSAICS reproduces the observed trend of Mc, * with M* for the Virgo cluster. We therefore examine the origin of the relation by fitting Mc, * as a function of galaxy mass, with and without accounting for mass loss by two-body relaxation, tidal shocks and/or dynamical friction. In the absence of these mass-loss mechanisms, the Mc, *-M* relation is flat above $M_* \gt 10^{10}\, {\rm M}_{\odot }$. It is therefore the disruption of high-mass GCs in galaxies with $M_{*}\sim 10^{10} \, {\rm M}_{\odot }$ that lowers the Mc, * in these galaxies. High-mass GCs are able to survive in more massive galaxies, since there are more mergers to facilitate their redistribution to less-dense environments. The Mc, * − M* relation is therefore a consequence of both the formation conditions of massive star clusters and their environmentally dependent disruption mechanisms.
3 citations