Starship Asterisk*

dougettinger wrote:Then, I presume the stars in galaxial globular star clusters are consistently very old stars with very little higher metals. I believe astronomers call them Population I stars. I would also presume that these stars are all mid-size or smaller stars that would have long lives that compare with the age of the universe less 1 or 2 billion years. Are these presumptions proven by observational data?

dougettinger wrote:Thanks for sharing that information that stars can form in various ways. I have not heard that explanation before but suspected that was the case.

Then, I presume the stars in galaxial globular star clusters are consistently very old stars with very little higher metals. I believe astronomers call them Population I stars. I would also presume that these stars are all mid-size or smaller stars that would have long lives that compare with the age of the universe less 1 or 2 billion years. Are these presumptions proven by observational data?

dougettinger wrote:Are the globular clusters and their stars that are a halo around the Milky Way possibly as old as the age of the universe?

Chris Peterson wrote:

dougettinger wrote:Then, I presume the stars in galaxial globular star clusters are consistently very old stars with very little higher metals. I believe astronomers call them Population I stars. I would also presume that these stars are all mid-size or smaller stars that would have long lives that compare with the age of the universe less 1 or 2 billion years. Are these presumptions proven by observational data?

Population I stars are high metal content, like the Sun. Globular clusters are made up of low metal, Population II stars, like those found in the galactic halo and bulge. The stars all appear to have formed at the same time, but they don't all have the same mass, so you find a range of luminosities. The stars in globulars are very old, as you suggest. Most seem to be about a billion years younger than the Universe- the same as galaxies. This is all well supported by observation. There are a small number of globulars that have different characteristics, such as split star populations. These aren't well understood, but might be the product of later evolution due to collisions or tidal effects.

dougettinger wrote:Chris, thanks for answering my question and correcting me about Population I and Population II stars. Is it correct to assume then that most subsequent generation stars, young massive short-lived blue stars, and Population I stars with high metal content are mostly made in spiral and barred galaxies and irregular galaxies like the LMC? Older, possibly original stars, are mostly found in elliptical galaxies and the bulges/globular clusters of spiral galaxies.

tesla wrote:... Are the stars moving towards the center or moving outwards? If they are moving outwards, it is not gravity. If they are in a static position, it is not gravity. If they are moving inwards I guess it is a mythical black hole!

rstevenson wrote:None of the above. They are orbiting their mutual center of mass.

The simulation
This visualization presents a globular cluster composed of 6,144 stars. The width of the frame represents more than a hundred trillion miles. As the movie unfolds, the evolution of the cluster is shown in this time-lapse movie, in which each second represents thousands of years passing by! As the stars orbit one other, several stars are ejected from the cluster through close gravitational encounters with more massive stars. The stars are shown in a scientific approximation of what the human eye would see: each star's brightness depends both on its intrinsic brightness and on its distance away from the “virtual camera,” while each star's color is only slightly exaggerated

The simulation
This visualization presents a globular cluster composed of 6,144 stars. The width of the frame represents more than a hundred trillion miles. As the movie unfolds, the evolution of the cluster is shown in this time-lapse movie, in which each second represents thousands of years passing by! As the stars orbit one other, several stars are ejected from the cluster through close gravitational encounters with more massive stars. The stars are shown in a scientific approximation of what the human eye would see: each star's brightness depends both on its intrinsic brightness and on its distance away from the virtual camera, while each star's color is only slightly exaggerated.

BMAONE23 wrote:I've never heard of one of these breaking up (though anything is poossible).

dougettinger wrote:To use your term - everything in the known universe "evaporates" over tens of billions of years.