I have some questions about galaxies.

Are all Milky Way-size galaxies (or bigger) approximately the same age?
If the oldest star in the Milky Way is about 13.8m years, how did those stars get to be so darn old?
Is “interstellar dust” just gas that isn’t illuminated by nearby stars?
Could dark matter be the matter inside black holes?
Are you likely to find more newer stars near the centre of a galaxy than the outer bits, or are new stars heavily outnumbered by very old stars?

Divine Angel said:

If the oldest star in the Milky Way is about 13.8m years, how did those stars get to be so darn old?

I’m sure you meant 13.8 Billion.

Good question though. I always assumed that all the stars we see today are later generations.

Yeah, that.

My guess is that continued star formation from the first early stars to birthing stars now is because of the massive variance is gas densities over the life time of the universe as the universe is expanding and cooling, there probably are many other factors, I’m not sure, maybe uneven temperatures that can blow around scatter gas clouds which can re-collapse forming new stars later

A lot can happen over 13.7 billion years

And… when stars die and create new stars which are increasingly richer in heavier metals, does this mean there’s a finite number of new stars which can be created?

no, it is too evenly distributed to be black holes.

interstellar dust

If the oldest star in the Milky Way is about 13.8m years, how did those stars get to be so darn old?

dunno if they’d be quite that old. small stars, similar to our sun, live a really long time. these old stars burn their fuel very ecomonically.

Are all Milky Way-size galaxies (or bigger) approximately the same age?

dunno. globular clusters are the oldest galaxy type.

yes, the main star forming era ended about 6 billion years ago, iirc.

I always assumed that all the stars we see today are later generations.

most are. astronomers tell by the metal content in the spectral lines of star what population they are.

metallicity of stars

Maybe, if most of the metals accrete into planets, that leaves other elements to form stars?

The periodic table according to astrologers:

H
He
Metals

Maybe, if most of the metals accrete into planets, that leaves other elements to form stars?

in a solar system the stars will have the same percentage of elements as the planets. not individual planets but the whole lot, plus all the other bits and pieces, oort cloud etc.

Hmm. OK. I’ll keep thinking. I’d love to see the DA Theory on Something in print one day ;)

bloody metals.

missed a question in a quizz night because of them.

what metal is added to iron to make steel?

carbon.

Boris said:

bloody metals.

missed a question in a quizz night because of them.

what metal is added to iron to make steel?

carbon.

WTF?

yeah, wtf indeed.

Geoff D said:

Boris said:

bloody metals.

missed a question in a quizz night because of them.

what metal is added to iron to make steel?

carbon.

.

+1

That’s just weird.

WTF?

And the award for Employee of the Month goes to… Inanimate Carbon Rod!

Divine Angel said:

And… when stars die and create new stars which are increasingly richer in heavier metals, does this mean there’s a finite number of new stars which can be created?

Yes and no. The thinking is that as galaxies evolve they tend to lose their star making regions. They lose the well defined spiral arms which help trigger star formation as the density wave (which is all a spiral arm is) passes through that region.

Also it seems like the earliest stars in the universe were very large short living stars which went supernova quickly.. Supernova also helps trigger star formation.
These days the majority of stars are small long living stars that will not go nova

Dropbear said:

These days the majority of stars are small long living stars that will not go nova

And the mass they shed without going nova is too tenuous to re-aggregate into another star formation system! So this is where the cold, black, starless end-of-universe theory comes from.

Carbon is a metal now?

Well I never

Divine Angel said:

Dropbear said:

These days the majority of stars are small long living stars that will not go nova

And the mass they shed without going nova is too tenuous to re-aggregate into another star formation system! So this is where the cold, black, starless end-of-universe theory comes from.

There generally needs to be something to trigger a nebulous cloud to collapse, yeh…

Well according to my understanding of the theory anyway

And the mass they shed without going nova is too tenuous to re-aggregate into another star formation system!

these gas clouds seem to need the shockwaves from supernova to push them around to form clumps that will become new star systems.

Well yes. A passing star or a runaway would do the trick nicely. I’ve also been reading up on Betelgeuse; I didn’t know there were 6 shells surrounding the star but I did know that it pulsates irregularly.

Divine Angel said:

Well yes. A passing star or a runaway would do the trick nicely. I’ve also been reading up on Betelgeuse; I didn’t know there were 6 shells surrounding the star but I did know that it pulsates irregularly.

Betelgeuse may well not be there anymore :)

Aye. We won’t know for a while. I hope we see it in my lifetime and I don’t think I’ll quite get to a million years old…