Scientists glimpse little galactic clusters on their way to greatness

Nature ◽  
2021 ◽  
Keyword(s):  
Galactic Clusters

Galactic Clusters with Associated Cepheid Variables. VI. Anonymous van den Bergh (C0634+031) and CV Monocerotis

1998 ◽  
Vol 115 (5) ◽  
pp. 1958-1971 ◽  
Author(s):  
David G. Turner ◽  
Mario H. Pedreros ◽  
Alistair R. Walker
Keyword(s):  
Galactic Clusters ◽  
Cepheid Variables

scholarly journals The emergence of the galactic stellar mass function from a non-universal IMF in clusters

2018 ◽  
Vol 614 ◽  
pp. A43 ◽  
Author(s):  
Sami Dib ◽  
Shantanu Basu
Keyword(s):  
Mass Range ◽  
Mass Function ◽  
Stellar Mass ◽  
Stellar Clusters ◽  
Galactic Clusters ◽  
Power Law Function ◽  
Low Mass ◽  
Mass Functions ◽  
Characteristic Mass ◽  
The Imf

We investigate the dependence of a single-generation galactic mass function (SGMF) on variations in the initial stellar mass functions (IMF) of stellar clusters. We show that cluster-to-cluster variations of the IMF lead to a multi-component SGMF where each component in a given mass range can be described by a distinct power-law function. We also show that a dispersion of ≈0.3 M⊙ in the characteristic mass of the IMF, as observed for young Galactic clusters, leads to a low-mass slope of the SGMF that matches the observed Galactic stellar mass function even when the IMFs in the low-mass end of individual clusters are much steeper.

scholarly journals Orbits of Open Star Clusters NGC 6067, NGC 2506 ANG IC 465

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Geeta Rangwal ◽  
R. K. S. Yadav ◽  
Alok K. Durgapal
Keyword(s):  
Proper Motion ◽  
Star Clusters ◽  
Open Star Clusters ◽  
Motion Data ◽  
Open Star ◽  
Galactic Clusters

The studies of the orbits of star clusters are very important to understand the evolution of these objects. The survival or dissolution of star clusters in galactic tides within which they orbit depends on their orbit history. The orbits of three galactic clusters namely NGC 6067, NGC 2506 and IC 4651 are calculated using newly available proper motion data taken from GAIA data. These orbits are traced backwards in time which is equal to the age of the clusters. The main parameters of the orbits such as eccentricity, apogalactic distance and perigalactic distance are calculated.

scholarly journals Etoiles Multiples Et Amas Ouverts

1977 ◽  
Vol 33 ◽  
pp. 67-72
Author(s):  
J. Dommanget
Keyword(s):  
Frequency Distribution ◽  
Basic Difference ◽  
Multiple Systems ◽  
Number Of Components ◽  
Double Stars ◽  
Dense Part ◽  
Galactic Clusters

AbstractIt is generally suspected that multiple systems and galactic clusters are objects of different kinds. Their frequency distribution as a function of the number of components, n, as well as their sizes and their masses, show important differences between both categories and also the probable existence of a limit lying between n = 10 and n = 20 components. The basic difference between these objects seems to be that the multiple systems finally appear to be components of the stellar medium in th same way as single and double stars, whereas the galactic clusters are groups of components of a particularly dense part of this medium.

scholarly journals The Trapezium Radio Cluster of the Orion Nebula

1989 ◽  
Vol 120 ◽  
pp. 333-338
Author(s):  
Guido Garay
Keyword(s):  
Radio Sources ◽  
Orion Nebula ◽  
Galactic Clusters ◽  
Dense Group

Abstract.We review the characteristics and discuss the nature of a dense group of compact radio sources found projected toward the Trapezium cluster of the Orion nebula. There are twenty-six radio sources, with flux densities greater than 2 mJy, clustered within a region of 35” radius around θ1C Orionis, the most luminous star of the Trapezium. The density of radio objects, of 1.4×104 pc-3, is extraordinarily high, about a thousand times greater than the density of stars in typical galactic clusters.

scholarly journals X-Ray Observations of B-Emission Stars (Review Paper)

1987 ◽  
Vol 92 ◽  
pp. 291-308 ◽  
Author(s):  
E.P.J. van den Heuvel ◽  
S. Rappaport
Keyword(s):  
Review Paper ◽  
Circumstellar Disks ◽  
Close Binaries ◽  
Be Stars ◽  
X Ray ◽  
Blue Stragglers ◽  
Galactic Clusters ◽  
Be Star ◽  
Emission Stars ◽  
X Ray Binaries

Most evidence on X-ray emission from the vicinity of Be stars concerns the Be/X-ray binaries. Presently some 20 of these systems are known, making them the most numerous class of massive X-ray binaries. Evidence for the binary nature of these systems comes from (i) Doppler modulation of X-ray pulse periods, (ii) periodic X-ray flaring behavior, and (iii) correlated optical and X-ray variability. The correlation between X-ray pulse period and orbital period found by Corbet (1984) can potentially provide important information on the densities and velocities in the circumstellar disks of Be stars.Evolutionary models indicate that the Be/X-ray binaries represent a later stage in the evolution of normal close binaries with initial primary masses predominantly in the the range 8 to 15 M⊙ . These models indicate that also a class of slightly less massive Be star binaries should exist in which the compact companions are white dwarfs. Be-type blue stragglers in galactic clusters may be such systems.

scholarly journals A Study of Be Stars in Clusters

1976 ◽  
Vol 70 ◽  
pp. 31-32
Author(s):  
R. Schild ◽  
W. Romanishin
Keyword(s):  
Main Sequence ◽  
Sequence Evolution ◽  
Be Stars ◽  
Rotating Stars ◽  
Time Duration ◽  
Hydrogen Burning ◽  
Fourfold Increase ◽  
Cluster Membership ◽  
Galactic Clusters ◽  
Short Time

Calibrated spectrograms at Hα of 566 stars in 29 young galactic clusters led to the detection of 41 Be stars in clusters. Using cluster membership we have inferred ages and intrinsic (B – V) colors of Be stars to permit a discussion of their evolutionary states.Rotating stars can become Be stars in their early hydrogen burning evolution away from the main sequence. Both the fraction of stars showing hydrogen emission and the strength of emission appear to vary little during the first 80% of post main sequence evolution. However, at the onset of gravitational core contraction, both the fraction of stars showing emission and their mean emission strength undergo a fourfold increase. Many stars in the core contraction phase develop an intrinsic (B – V) excess of 0.15 mag. due to the H− free-bound continuum radiation. Because of the great strength of Hα emission and the short time duration of the effect, the extreme Be stars would be excellent probes for studies of spiral structure and would also serve as probes for studies of ages and distances of extragalactic systems.Analysis of the corrected colors of the Be stars in clusters suggests that the Lucy and Solomon (1970) mechanism for reduction of effective surface gravity by ultraviolet resonance line scattering is probably important for the hotter Be stars. However, a discrepancy exists for the cooler stars between the predicted and observed colors.

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