Gravitational field of globular clusters ?

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SUMMARY

The gravitational field at the center of a globular cluster is characterized by a lack of angular momentum and a smooth density distribution of stars. In spherical globular clusters, the center of mass serves as a convenient reference point for calculations, but it does not indicate the presence of a supermassive black hole or a distinct nucleus, as seen in elliptical or spiral galaxies. Observations show that the density of stars increases smoothly towards the center without any significant spikes in light intensity.

PREREQUISITES
  • Understanding of Newtonian physics and equations of motion
  • Familiarity with concepts of center of mass and gravitational fields
  • Knowledge of stellar dynamics and density distributions
  • Basic astronomy, particularly regarding globular clusters
NEXT STEPS
  • Research the properties of different types of globular clusters, such as Omega Centauri
  • Study the mathematical calculations for center of mass in astrophysical contexts
  • Explore the dynamics of star motions within globular clusters
  • Investigate the differences between globular clusters and other galaxy types, such as elliptical and spiral galaxies
USEFUL FOR

Astronomers, astrophysicists, and students interested in stellar dynamics and the structural properties of globular clusters will benefit from this discussion.

billy_boy_999
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what does the gravitational field at the center of a globular cluster look like? it doesn't look as though there is any angular momentum - is there a 'center' of gravity inside? a black hole?
 
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The 'centre of gravity' or 'centre of mass' of any collection of objects (with mass!) can - in principle - be calculated with some simple math; it's just a point. However, it's a very convenient 'point'! Re-writing your (Newtonan) equations of motion using this point as the origin of your coordinate system makes the math easier to crunch.

Let's assume that your favourite globular cluster is spherical and has no net angular momentum (some globulars aren't like this; e.g. Omega Cen - the brightest as seen from Earth - is clearly somewhat elliptical). Then its 'centre' will be the centre of mass (assuming we define 'centre' appropriately). What lies at the centre of a globular cluster? In most cases, nothing special. Unlike elliptical (or spiral) galaxies, there is no obvious nucleus in globulars ... a curve of light intensity (for example) vs radius is smooth with no 'spike'. This means that the density of stars - say, per cubic light-year - increases smoothly to a maximum. Further, the motions of stars in the inner part of a globular suggest that there isn't a supermassive black hole lurking at the centre.
 

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