Quote:
Originally Posted by Suzy
Shelley is learning about stars as well and we often facebook each other trying to learn astro things. So you have two very eager students here  desperate for knowledge on all things (confusing  ) stars. We also have to be careful on facebook that we get our genetives correct when we talk about constellations because Les doesn't like that.  Sometimes he issues us a quizz (hard ones  ) which i fail at because Shell goes off googling and I use up the time looking through my books or pondering my brain, so one guess who wins by getting the answers first.
To Shelley:  |
I had a hard enough time getting to sleep on Friday night because I couldn't stop thinking about Wolf Rayet stars
and their temperatures and their violent conditions and...and...and...phewf!
But I am very, very intrigued to learn as much as possible about stars, how they are born, how they live and die, everything! It can be so confusing though...
And in my defence Suz, I went away and went through goodness knows how many constellations on wiki to figure it out without google's trusty assistance
But no, it was utterly baffling! I will forever remember now that Alpha Muscae is the lowest mag "alpha" star in any constellation
The genetive is right and everything (Hi Les
)
Quote:
Originally Posted by renormalised
PopIII and PopII are designations for stars of a certain type that depend on their metals content and orbital dynamics about the centre of the galaxy (any galaxy, actually). Once a star's metals content drops below a certain percentage relative to the Fe/H ratio of the Sun, it's given the designation PopII or PopIII. Most PopII stars have low to extremely low metals content (10%< relative to the Sun) and PopIII stars, the hypothetical stars that formed only a few hundred million years after the BB, have no metals at all, except for a tiny amount of Lithium (and possibly Beryllium) that formed during the BB.
Most PopII stars either reside in the galactic bulge of galaxies or in their halos. They were amongst the first stars to form within the galaxies.
All stars, whether they're SDSS J102915+172927, a PopIII object or the normal run of the mill ones we see today all form in the same way...the collapse of a cloud of hydrogen and helium. It's just that later generations of stars after the PopIII stars burnt out contain more heavy elements in their makeup than the original stars. All due to those stars and other spewing those elements out into the cosmos after they die. The previous generations of stars made the elements out of which the new generations were born from.
The mechanisms by which a gas/dust cloud collapses to form a star are a little more complicated than just gravity collapsing the cloud, but once it starts to collapse gravity becomes the dominant force.
The lifetime of a star is directly proportional to the inverse 2.5 power of the mass of the star....This value is multiplied by 10^10, or the average MS lifetime of a star like the Sun, to give the star's MS lifetime. The star in question is 0.8 solar masses, which is why it can last for 13 billion year or more, because its MS lifetime is (1/0.8^2.5) x 10^10 or 17.5 billion years. However, for very high mass and low mass stars, the relationship of mass to lifetime is a little more complicated and the exponent of the mass is slightly different. Though, the above example will generally give good approximate ages for stars between 0.1 to 40 solar masses.
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This makes a lot more sense! Even after I wrote my response, I had a feeling I hadn't really thought about it hard enough or read enough
But this clears it up for me perfectly, thanks Carl
And that is one doozy of an equation... (well, for me anyway
) but generally what it represents makes sense...although what does MS stand for? I just spent the past 15 minutes trying to figure out that equation on my calculator...
and I got 17469281074.217107003196669286963
LOL.
Not sure why I even bothered trying