Mass segregation

About: Mass segregation is a research topic. Over the lifetime, 1024 publications have been published within this topic receiving 57729 citations.

Comparative Properties of Virgo Cluster Dwarf Irregulars and Spirals

Abstract: The optical and neutral hydrogen data for all spiral and late-type dwarf irregular galaxies in the Virgo Cluster catalog are analyzed. In particular, the continuity of optical properties, hydrogen masses, and dynamical properties are examined as functions of morphology and luminosity from the largest spirals through the faintest dwarfs (omitting blue compact dwarf galaxies); the effects of environment on H I content; mass segregation; and the Tully-Fisher relations. The spiral plus dwarf sample forms a continuous but nonhomologous sequence. Indicative dynamical mass-to-light ratios are relatively constant throughout; hydrogen mass-to-light ratios show only a slight increase with decreasing luminosity. The Tully-Fisher relations extend with continuous slope from spirals through dwarfs. The dwarfs show some evidence of ram-pressure stripping by the intracluster medium, but as a group do not seem to be stripped more heavily than spirals. There is no evidence of mass segregation even for the very low mass dwarfs versus giant spirals.

A search for mass segregation of stars and brown dwarfs in \rho\ Ophiuchi

Abstract: We apply two different algorithms to search for mass segregation to a recent observational census of the rho Ophiuchi star forming region. Firstly, we apply the Lambda_MSR method, which compares the minimum spanning tree (MST) of a chosen subset of stars to MSTs of random subsets of stars in the cluster, and determine the mass segregation ratio, Lambda_MSR. Secondly, we apply the m-Sigma method, which calculates the local stellar surface density around each star and determines the statistical significance of the average surface density for a chosen mass bin, compared to the average surface density in the whole cluster. Using both methods, we find no indication of mass segregation (normal or inverse) in the spatial distribution of stars and brown dwarfs in rho Ophiuchi. Although rho Ophiuchi suffers from high visual extinction, we show that a significant mass segregation signature would be detectable, albeit slightly diluted, despite dust obscuration of centrally located massive stars.

The binary fraction and mass segregation in Alpha Persei open cluster

Abstract: We have obtained membership probabilities of stars within a field of similar to 3 degrees from the centre of the open cluster Alpha Persei using proper motions and photometry from the PPMXL and Wide-field Infrared Survey Explorer catalogues. We have identified 810 possible stellar members of Alpha Persei. We derived the global and radial present-day mass function (MF) of the cluster and found that they are well matched by two-stage power-law relations with different slopes at different radii. The global MF of Alpha Persei shows a turnover at m = 0.62 M-circle dot with low-and high-mass slopes of alpha(low) = 0.50 +/- 0.09 (0.1 < m/M-circle dot < 0.62) and alpha(high) = 2.32 +/- 0.14 (0.62 <= m/M-circle dot < 4.68), respectively. The high-mass slope of the cluster increases from 2.01 inside 1 degrees.10 to 2.63 outside 2 degrees.2, whereas the mean stellar mass decreases from 0.95 to 0.57 M-circle dot in the same regions, signifying clear evidence of mass segregation in the cluster. From an examination of the high-quality colour-magnitude data of the cluster and performing a series of Monte Carlo simulations, we obtained a binary fraction of f(bin) = 34 +/- 12 per cent for stars with 0.70 < m/M-circle dot < 4.68. This is significantly larger than the observed binary fraction, indicating that this open cluster contains a large population of unresolved binaries. Finally, we corrected the MF slopes for the effect of unresolved binaries and found low-and high-mass slopes of alpha(low) = 0.89 +/- 0.11 and alpha(high) = 2.37 +/- 0.09 and a total cluster mass of 352 M-circle dot for Alpha Persei.

An optical and near IR study of the old open cluster NGC 2141

Abstract: We report CCD optical (B and V passbands) and near IR (J and K bands) observations in the region of the old open cluster NGC 2141. By combining the two sets of photometry (500 stars in common) we derive new estimates of the cluster's fundamental parameters. We conrm that the cluster is 2.5 Gyrs old, but, with respect to previous investigations, we obtain a slightly larger reddening (E(B V )=0 :40), and a slightly shorter distance (3.8 kpc) from the Sun. Finally, we present the Luminosity Function (LF) in the V band, which is another age indicator. We provide a good t for the age range inferred from isochrones by assuming the Kroupa et al. (1993) IMF up to MV = 5.0. We interpret the disagreement at fainter magnitudes as evidence of mass segregation.

Star counts in the globular cluster M71

Abstract: Star counts were carried out on V CCD frames of the globular cluster M71. A systematic radial variation in the main-sequence luminosity function of the cluster is observed, clearly demonstrating that mass segregation is operative in the cluster. The mass segregation predicted by an isotropic multimass King model is shown to be in good agreement with the present observations. The observations are consistent with those expected from a cluster undergoing dynamical relaxation. 27 refs.