It is certainly an answer worth considering.  Is there a a simple way to estimate how quickly one omemver of a triple system will be ejected?

There are exceptions to it. For example in the star forming region M17 (Omega Nabula) stars are seen to be born not in pairs. They start their lives alone.

Do we have good statistics on the spin rates of stars? It seems likely that there should be a correlation between spin rate and the number of "siblings" a star has.

`` It seems likely that there should be a correlation between spin rate and the number of "siblings" a star has.''

I am not sure. After all, a star can get rid of angular momentum quite efficiently via a planetary system: if memory serves, in the Solar System, 99% of the angular momentum is in the planets.

I guess the next logical question, then, is how the angular momentum of a planetary system correlates to that of the star.  Surely we now have enough data to answer this question.

Why ``less important'' planetary systems? In mass, they are essentially negligible, but as far as angular momentum goes, they are fundamental. This is what makes me doubtful about any attempts to connect a present star's angular momentum with that of the cloud from which it formed.

I believe I understand what you say, and I understood the question in this way. Planetary systems trouble me precisely because, observationally, they are hard to characterise for stars other than the Sun, whereas in angular momentum, they are major players. So looking at angular momentum of stellar systems, I think, is tricky, because, for stars other than our Sun, most of it could well be in an unobservable form.

I have just checked in Wikipedia ``Solar System'': it claims that the mass of the Sun is 99.96% of total mass, whereas the angular momentum of the Sun is 2% of total.

``Do those planets move more-or-less in the galactic plane ? How about our own solar system ?''

Again, according to Wikipedia, the galactic plane is at a declination of 27 degrees, so the ecliptic and the galactic plane are rather distant.

As to exoplanets, I would assume any correlation between the different orbital planes would have been noticed and reported.

Gas clouds have angular momentum, too much for a stable star in most cases, giving rise to companions that spin in the same direction as they orbit.

From a religio-cultural perspective, the pairing of the stars is a reflection of the unity and oneness in creation which humans are to mimic.

Dickson Adom

In a densely populated galactic the collisions of stars are very frequent. Some of these collisions result in the stars merging, but some of colliding stars  become stopped at a rather small distance by a repulsive force quickly falling with distance.

This force origins from a growing temperature in the zone of their contact. This growing temperature provides enlarged pressure that stops merging of stars. So, two stars rotate around their common center of mass. Their mutual attraction is compensated by a centrifugal force.

So, for this repulsive force is left a small problem to compensate the centrifugal force diminishing due to retardant rotation in a gaseous cloud. The smaller is the centrifugal force, the smaller is the distance and the larger is the gas pressure in the zone of contact!

Dear Thierry De Mees, I do not think that electromagnetic forces between double stars are as important as gravitational forces. For this forces the stars should have enormous charges, but surrounding them plasma provides a leak for these charges.

Best regards,

Boris Sedunov