Talk:General Astronomy/Mass

Mizar and Alcor--maybe mention briefly where they are, which galaxy they're in.

Maybe explain what you mean by "period of 10,000 years" in case don't understand. Also, maybe define binary system more clearly.

Maybe can clarify on what is a star's "proper motion". Pictures of wavy and straight paths?

Maybe explain why escape velocity gets smaller as a star gets bigger in addition to mathematical relationship given by equation, seems counterintuitive, at least to me...

Elements
The elements section here is grossly wrong as it stands. Nearly all stars are about 75% H, 25% He, and 2% or less other stuff ... yes, I know that sums to more than 100%, but those are good ball-park numbers. Main sequence stars fuse H to He. Red giants continue that, and also fuse He to C and O, and fuse to heavier elements still, depending on stellar mass, evolutionary stage, and so on. AGB stars make elements heavier than Fe via the s-process. Only white dwarfs and neutron stars don't have hydrogen as their primary constituent! (And yes, there are other oddball things like the hydrogen-deficient carbon stars that seem to be lacking H, but there is not yet a consensus about what those things are and how they are made, so omitting those is within the tradition of textbook writing for low levels, as is the complex variety of binary star evolution, maybe.) Getting into the nuclear processing is part of stellar structure and evolution, a later part of the book. Here, the point should be that most stars are H and He and a percent or so of other elements, and heavier elements produced in stars' interiors stay there until the end stages of stars' lifetimes. BSVulturis (discuss • contribs) 00:26, 8 August 2013 (UTC)