scholarly journals An Upper Limit to the Mass Loss from the Centre of the Galaxy

1974 ◽  
Vol 64 ◽  
pp. 36-36
Author(s):  
Arcadio Poveda ◽  
Christine Allen
Keyword(s):  
Mass Loss ◽  
Gravitational Waves ◽  
Mass Distribution ◽  
Globular Clusters ◽  
Loss Rate ◽  
Galactic Centre ◽  
Isotropic Source ◽  
The Past ◽  
Upper Limit ◽  
The Galaxy

A mass loss of 200 M⊙ per year, as conservatively suggested if Weber is detecting gravitational waves from an isotropic source at the galactic centre, is shown to be incompatible with the existence of (a) globular clusters, (b) old wide binaries, if this loss rate has been constant over the past 1010 yr.From the orbit of ω Centauri in the galactic field and its observed mass distribution and tidal radius an upper limit to the mass loss from the galactic centre is found to be 1 M⊙ yr-1 over the past 1010 yr.

scholarly journals The properties of early-type stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 325-336
Author(s):  
Christopher J. Evans
Keyword(s):  
Physical Properties ◽  
Mass Loss ◽  
Temperature Scale ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Early Type ◽  
The Past ◽  
The Galaxy ◽  
Stellar Temperature ◽  
Early Type Stars

AbstractThe past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.

scholarly journals Tidal Heating of Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 283-296
Author(s):  
David F. Chernoff ◽  
Stuart L. Shapiro
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Galactic Center ◽  
Core Collapse ◽  
Giant Molecular Clouds ◽  
Tidal Disruption ◽  
The Galaxy ◽  
Tidal Perturbations ◽  
Tidal Heating ◽  
Hubble Time

The influence of tidal heating on the evolution of globular clusters (GC's) in circular orbits about the Galactic center is studied. Giant Molecular Clouds (GMC's) stretch a globular cluster in a direction transverse to its orbit through the disk. The variation in acceleration with height in the disk compresses the cluster in a longititudinal direction. Numerical and analytic calculations of heating and mass loss for GC's, represented by King models, show that disk heating dominates. We apply the results to calculate GC evolution prior to core collapse or tidal disruption using a three parameter (energy, mass, and tidal radius) sequence of King models. The changes in the parameters are calculated for tidal perturbations, relaxation and evaporation. Clusters close to the Galactic center (less than 3 kpc) undergo core collapse in a Hubble time. The effect of tidal perturbations on energy and mass loss of the cluster is strongest between 3 and 5 kpc where it can substantially effect the evolution of the cluster. Here, depending upon their initial concentration, clusters are either tidally heated and dissolved, or forced towards a gravothermal catastrophe in times that are a fraction of a Hubble time. These inner regions of the Galaxy should be fertile territory for the search for post-collapsed clusters.

scholarly journals Systematic study of AGB stars in the intermediate-age globular clusters in the Magellanic Clouds

1999 ◽  
Vol 191 ◽  
pp. 573-578
Author(s):  
T. Tanabé ◽  
S. Nishida ◽  
Y. Nakada ◽  
T. Onaka ◽  
I. S. Glass ◽  
...  
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Near Infrared ◽  
Magellanic Clouds ◽  
Agb Stars ◽  
Carbon Stars ◽  
Infrared Observations ◽  
The Past ◽  
Intense Mass ◽  
Infrared Stars

We performed systematic infrared observations of the intermediate-age Magellanic Clouds clusters NGC 419, NGC 1783 and NGC 1978. Mid-infrared stars discovered in NGC 419 and NGC 1978 are very red and must be undergoing intense mass loss (comparable to superwinds). They are probably carbon stars but do not seem to show any FIR excesses. Three optically visible carbon stars as well as (at least) 2 near-infrared carbon stars observed with ISOPHOT show 60 μm excesses which may indicate mass loss in the past. It seems that the MIR stars are fainter than the AGB tip luminosity and that their Mbols are close to those of the transition luminosity from M type to C stars. Therefore, these MIR stars may not be in the final stage of the AGB phase. This may suggest that AGB stars lose mass heavily at some other time, possibly during the transition from M type to C stars.

scholarly journals Structural and Kinematic Properties of Populations of the Andromeda Galaxy

1972 ◽  
Vol 44 ◽  
pp. 37-45 ◽  
Author(s):  
J. Einasto
Keyword(s):  
Mass Distribution ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Strong Dependence ◽  
Stellar Content ◽  
Distribution Models ◽  
Model Calculations ◽  
The Galaxy ◽  
Spectrophotometric Data ◽  
Virial Mass

New observational data (Spinrad, 1970; Van den Bergh, 1970; Rubin and Ford, 1970) are used to determine structural and kinematic parameters of the nucleus, the subsystem of globular clusters, and interstellar hydrogen in M31.The mass derived for the nucleus from the new spectrophotometric data is in good agreement with the virial mass 6 × 108M⊙. Model calculations show that there is no appreciable exchange of stars between the nucleus and the bulge. The rotation energy of the nucleus is only 7.5% of the total kinetic energy; the central density is 2 × 106M⊙ pc−3.The mean radius of the subsystem of globular clusters is 4.5 kpc. This indicates that the subsystem of old stars is not identical with the spheroidal component of the galaxy, whose mean radius is only 1 kpc. Radial velocity dispersion of globular clusters is only half of that of the nucleus. This shows a strong dependence of the velocity dispersion on distance to the center of the galaxy and a bias in mass determination of a galaxy from velocity dispersion near the nucleus.On the basis of data on rotation two mass distribution models have been found, differing from each other in respect of the mass concentration to the center. Spectrophotometric data on the stellar content of the bulge are urgently needed to solve the mass distribution problem.

scholarly journals In hot pursuit of the hidden companion of η Carinae: an X-ray determination of the wind parameters

2003 ◽  
Vol 212 ◽  
pp. 218-219
Author(s):  
Julian M. Pittard ◽  
Michael F. Corcoran
Keyword(s):  
Binary System ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
X Ray ◽  
The Galaxy ◽  
Binary Hypothesis ◽  
Η Car

We perform X-ray spectral fits to a recently obtained Chandra grating spectrum of η Carinae, one of the most massive and powerful stars in the Galaxy and which is strongly suspected to be a colliding wind binary system. The good fit that we obtain gives us further confidence in the binary hypothesis, and we find M ≈ 2.5 × 10–4 M⊙ yr–1 for the mass loss rate of η Car.

scholarly journals The Evolution of Stars on the AGB: The Mass Loss Intensity and the Formation of Carbon Stars

1989 ◽  
Vol 106 ◽  
pp. 224-224
Author(s):  
Yu. L. Frantsman
Keyword(s):  
Mass Loss ◽  
Mass Distribution ◽  
White Dwarfs ◽  
Magellanic Clouds ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Element Abundance ◽  
Agb Stars ◽  
Carbon Stars ◽  
The Galaxy

Simulated populations of white dwarfs and N type carbon stars were generated for a Salpeter initial mass function and constant stellar birth rate history. The effect of very strong mass loss on the mass distribution of white dwarfs and the luminosity distribution of carbon stars is discussed and the results are compared with observations. A significant mass loss by stars on the TP-AGB occurs besides regular stellar wind and planetary nebulae ejection. Thus it is possible to explain the luminosity functions of carbon and M stars in the Magellanic Clouds (with very few stars brighter than Mbol = -6.0), the very narrow mass distribution of white dwarfs, and the very small number of white dwarfs with M > 1.0 MΘ. The luminosity of some AGB stars in the SMC is so high that they may be supernova of type 1 1/2 precursors. There are no such stars in the LMC. Comparison of the theoretical and observed luminosity distributions of high-luminosity AGB stars in the Magellanic Clouds shows that the mass-loss rate of these stars in the LMC is about an order of magnitude larger than in the SMC. In the Galaxy carbon stars may form only from stars with initial mass less than 1.5 MΘ due to the relatively small initial heavy element abundance in these stars; this is perhaps the main reason for the absence of carbon stars in open clusters in the Galaxy.

Extra-tidal features using Gaia DR2

2019 ◽  
Vol 14 (S351) ◽  
pp. 420-421
Author(s):  
Julio A. Carballo-Bello
Keyword(s):  
Mass Distribution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Space Mission ◽  
Cluster Center ◽  
Proper Motions ◽  
The Galaxy ◽  
Tidal Tails ◽  
Gaia Dr2

AbstractIn recent years, we have gathered enough evidence showing that most of the Galactic globular clusters extend well beyond their King tidal radii and fill their Jacobi radii in the form of “extended stellar haloes”. In some cases, because of the interaction with the Milky Way, stars are able to exceed the Jacobi radius, generating tidal tails which may be used to trace the mass distribution in the Galaxy. In this work, we use the precious information provided by the space mission Gaia (photometry, parallaxes and proper motions) to analyze NGC 362 in the search for member stars in its surroundings. Our preliminar results suggest that it is possible to identify member stars and tidal features up to distances of a few degrees from the globular cluster center.

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