The rise and fall of galaxy formation

August 30, 2016, Carnegie Institution for Science
A comparison of visualizing galaxies with and without ZFOURGE. Credit: Texas A&M University

An international team of astronomers, including Carnegie's Eric Persson, has charted the rise and fall of galaxies over 90 percent of cosmic history. Their work, which includes some of the most sensitive astronomical measurements made to date, is published by The Astrophysical Journal.

The FourStar Galaxy Evolution Survey (ZFOURGE) has built a multicolored photo album of as they grow from their faint beginnings into mature and majestic giants. They did so by measuring distances and brightnesses for more than 70,000 galaxies spanning more than 12 billion years of cosmic time, revealing the breadth of galactic diversity.

The team assembled the colorful photo album by using a new set of filters that are sensitive to infrared light and taking images with them with the FourStar camera at Carnegie's 6.5-meter Baade Telescope at our Las Campanas Observatory in Chile. They took the images over a period of 45 nights. The team made a 3-D map by collecting light from over 70,000 galaxies, peering all the way into the distant universe, and by using this light to measure how far these galaxies are from our own Milky Way.

The deep 3-D map also revealed young galaxies that existed as early as 12.5 billion years ago (at less than 10 percent of the current universe age), only a handful of which had previously been found. This should help astronomers better understand the universe's earliest days.

"Perhaps the most surprising result is that galaxies in the young universe appear as diverse as they are today," when the universe is older and much more evolved, said lead author Caroline Straatman, a recent graduate of Leiden University. "The fact that we see young galaxies in the that have already shut down star formation is remarkable."

A comparison of galaxy visualization with and without ZFOURGE. Credit: Texas A&M University

But it's not just about distant galaxies; the information gathered by ZFOURGE is also giving the scientists the best-yet view of what our own galaxy was like in its youth.

"Ten billion years ago, galaxies like our Milky Way were much smaller, but they were forming stars 30 times faster than they are today," said Casey Papovich of Texas A&M University.

"ZFOURGE is providing us with a highly complete and reliable census of the evolving galaxy population, and is already helping us to address questions like: How did galaxies grow with time? When did they form their stars and develop into the spectacular structures that we see in the present-day universe?" added Ryan Quadri, also of Texas A&M.

In the study's first images, the team found one of the earliest examples of a galaxy cluster, a so-called "galaxy city" made up of a dense concentration of galaxies, which formed when the was only three billion years old, as compared to the nearly 14 billion years it is today.

"The combination of FourStar, the special filters, Magellan, and the conditions at Las Campanas led to the detection of the cluster," said Persson, who built the FourStar instrument at the Carnegie Observatories in Pasadena. "It was in a very well-studied region of the sky—'hiding in plain sight.'"

The paper marks the completion of the ZFOURGE survey and the public release of the dataset, which can be found here: http://zfourge.tamu.edu/DR2016/data.html.

Explore further: Galaxy cluster hidden in plain view

More information: The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5. arxiv.org/abs/1608.07579

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Tuxford
1.3 / 5 (14) Aug 30, 2016
"Perhaps the most surprising result is that galaxies in the young universe appear as diverse as they are today,"

Said the committed merger maniac, still wishing fancifully for his Huge Bang Fantasy to be actually true.

Follow the logic maniacs, if it looks, walks, and quacks... Or keep up the wishful thinking, leading further down the path of daily confusion.

It looks the same back then because the fantasy is a myth. The universe is far older. Get over it.

http://phys.org/n...tml#nRlv

"The very fact that they exist is puzzling to astronomers,"
tinitus
Aug 30, 2016
This comment has been removed by a moderator.
RNP
3.2 / 5 (13) Aug 31, 2016
@tinitus
......why we should live in just oldest part of the Universe?

We don't, and nobody is saying we do. Where did you get that idea?

......even the modern cosmology is still based on religious geocentric model. It's time to finally grow up.


No it isn't. Where did you get THAT idea?
antialias_physorg
3.9 / 5 (11) Aug 31, 2016
......why we should live in just oldest part of the Universe?


We don't, and nobody is saying we do. Where did you get that idea?

......even the modern cosmology is still based on religious geocentric model. It's time to finally grow up.


No it isn't. Where did you get THAT idea?


He just makes this stuff up in his head and then declares it fact. He's quite the religious nut that way. Has been for many years.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
RNP
2.9 / 5 (15) Aug 31, 2016
@tinitus
You have misunderstood "mainstream cosmology". Distant galaxies look young because it has taken the light a long time to reach us. We are therefore currently seeing them a long time ago when they were younger. The same would be true wherever we were in the universe. The model is therefore NOT geocentric. This also renders your claim that mainstream cosmology requires that we are in the oldest part of the universe untrue.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
tinitus
Aug 31, 2016
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tinitus
Aug 31, 2016
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RNP
2.5 / 5 (13) Aug 31, 2016
Well, in just this way the mainstream cosmology can be falsified easily. Because in this cosmology the Universe is of finite age, the distant galaxies should always look younger, i.e. of lower metallically and higher hydrogen content. They should also look more closely packed, http://aetherwave...me.html, than these ones, which we observe by now.


Well done, distant galaxies are indeed observed to have lower metallicities (e.g. see https://arxiv.org...01.5013)

Their space density of galaxies is much more complicated than you suggest, as both the number and size of galaxies change over cosmological time. What we do know is that the total matter density was higher in the past.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
shavera
4.5 / 5 (8) Aug 31, 2016
I don't see any 'rise' in metallicity in the graph you provided. I see a misunderstanding of error bars, perhaps. If anything it looks like it levels off to some 'baseline' metallicity at some distant time, which would make some degree of sense, if I may speculate, that it would take time for early star systems to generate 'metals' which would feed into new stellar populations after some time.
shavera
4.4 / 5 (7) Aug 31, 2016
Also, you definitely misunderstand metric expansion. Since we can't solve GR for particularly complicated systems, we have some general solutions for simplified cases. If you consider a boundary-free volume filled uniformly with mass and massless-energies (momentum, light, eg.), you get a solution that predicts some expansion or contraction depending on the relative densities of those various masses/energies. If you consider a volume near a compact source of mass, you get a Schwarzschild metric. The two are different approximations that describe different systems.

What we might expect is that there are regions of space where neither approximation is a really good approximation. Given the masses of galaxies, this distance appears to be the size scale of galactic clusters. So there's some area where it's both a bit like Schwarzschild and a bit like FLRW, and then even further out, a lot more like FLRW.

These are totally valid ways of approaching physics problems.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
shavera
4 / 5 (4) Aug 31, 2016
Why wouldn't the speed of light increase with distance...


Look, in any discussion of GR's predictions, we have to take the whole of relativity into consideration. There's simply no way that a massless particle/object/whatever can travel at any speed other than c. (as measured by local observers).

You're right that metric expansion is not like the expansion of a particle gas. It's more like comparing the meter sticks of two observers in relative motion. They both disagree on what the distance is between two points, and they're both right. With metric expansion, instead of two observers in relative motion, the difference is one of changing over time. A past observer would have measured one distance between two galaxy clusters, and a future observer would measure another distance.
shavera
4.2 / 5 (5) Aug 31, 2016
bschott: expansion is not 'happening to us as well.' That's my point about not understanding what is meant by Metric expansion. The approximation that gives us metric expansion does not hold in regions of space where mass is the dominant type of energy. The solution looks more like gravitation.

We do see light blueshift as it gets closer to a massive object. (Pound-Rebka experiment) So I don't know what you're talking about there.

We observe every other part of GR that we can measure locally to confirm the theory very well. The observations of redshift match the theory's predictions too. So if a theory is supported by a lot of data, and other data matches theoretical predictions, then it's reasonable to assume that the theory is explaining the other data too (ie, we do measure metric expansion by measuring redshift of galaxies).
RNP
1 / 5 (5) Aug 31, 2016
I don't see any 'rise' in metallicity in the graph you provided. I see a misunderstanding of error bars, perhaps. If anything it looks like it levels off to some 'baseline' metallicity at some distant time, which would make some degree of sense, if I may speculate, that it would take time for early star systems to generate 'metals' which would feed into new stellar populations after some time.


While you may be right about flattening at high z, I do not know which graph you mean.
If you are looking at the paper I linked, then I think you are looking at the plot for DLAs (Fig.2). The galaxies plot is Fig. 4. Whether or not the galaxy relation flattens at high redshift is not clear from these plots.
RNP
1 / 5 (5) Aug 31, 2016
distant galaxies are indeed observed to have lower metallicities


Well, not really - the metallicity decreases only https://i.imgur.com/vc5v5DX.gif, after then it raises instead. In general the curve above can be also the result of sampling bias - the smaller galaxies are more difficult to observe, so that they're excluded from data, despite they have higher metallicity.


The plot you linked is for galaxies (lines) and DLAs (points). You are looking at the plot for DLAs. If you look at the galaxy plots there is no increase at high redshift. You are looking at the plot for DLAs.

Smaller galaxies have LOWER metallicities, not higher.
RNP
1 / 5 (4) Aug 31, 2016
@shavera
Sorry, just found the link you were referring to and now understand your post. Sorry about the mistake.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
shavera
4.3 / 5 (6) Aug 31, 2016
If all photons travelling towards earth are blueshifted in earths gravity well, how was it determined that the light is redshifted due to metric expansion prior to the launch of space based telescopes?


The effect of blue-shifting down Earth's gravitational well is negligible compared to the redshifting from metric expansion. It's there if you design a precision experiment to look for it, but otherwise, just think of it as distant light shifts red some wavelength, and then back blue another smidge, throwing off the absolute red shift we measure. But of course we can correct for the blue-shift of falling to Earth pretty easily as well.

Seriously, this isn't hard if you know even a little bit of the actual science instead of making things up that science doesn't say and then whinging on about how the things you made up aren't true.
shavera
4.3 / 5 (6) Aug 31, 2016
Perhaps I wasn't clear on other parts: Relative distances *are* changing, but it's not a kind of motion. It's a distance change because what used to be a meter is now a meter plus a little bit.

Yes, space expands in the areas where there's no mass in it. That's the results we see from GR. You can also compare the two metrics with the Schwarzschild-deSitter metric, which combines both expansion and gravitation.

No i'm not saying the distance changed is a function of the mass content of the galaxy. Only that the expansion happens in the vast empty spaces between galactic colors.

The science of standard candles is pretty straightforward. Light gets dimmer as it goes further. Certain astrophysical phenomena have predictable brightnesses (at some nominal distance). Therefore, you know how far a light is by how dim it is. Nothing at all is controversial about it. Maybe the calibrations need updated, but the basic rules are pretty clear.
shavera
4.4 / 5 (7) Aug 31, 2016
tinitus: again, no one cares what the 'inventor' of some idea thought about it later in their lives, or what scientists in the 60s thought about things, or whatever. They're interesting historical notes, but to say that X is wrong because famous scientist Y didn't like the idea is just as bad as saying A is right because famous scientist B says so.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
tinitus
Aug 31, 2016
This comment has been removed by a moderator.
RealityCheck
1 / 5 (7) Sep 03, 2016
Hi Phys1, bschott, everyone.

Saw this amusing exchange between you two:
The statement that our galaxy "weighs" 80% more than we thought should have triggered a massive recalculation regarding distances based on the additional gravity alone right? 80% more mass means the light entering the galaxy from others was blueshifted 80% more than originally thought, so the observed redshift has a blueshift component not accounted for.... how old is the universe now?

Why don't you do the calculation yourself?
And the thought sprung to mind that the professionals employed in this field are paid to do that as part of their work, are they not, Phys1?

If so, then it's a bit 'precious' and evasive of you to come back with that to bschott, isn't it?

Surely if the paid professionals in the field are competent in their work, they would already have done those re-calculations, wouldn't they? Why not just point bschott to the professionals' work where they have done so? :)
Uncle Ira
5 / 5 (8) Sep 03, 2016
Surely if the paid professionals in the field are competent in their work, they would already have done those re-calculations, wouldn't they? Why not just point bschott to the professionals' work where they have done so? :)


Because the bschoot-Skppy was the one who said the professionals were wrong? But I am not a scientist like you are not either, so that is just a guess.
RealityCheck
1 / 5 (6) Sep 03, 2016
Hi Ira. :)
Surely if the paid professionals in the field are competent in their work, they would already have done those re-calculations, wouldn't they? Why not just point bschott to the professionals' work where they have done so? :)


Because the bschoot-Skppy was the one who said the professionals were wrong? But I am not a scientist like you are not either, so that is just a guess.
That wasn't the point I made to Phys1, was it, Ira?

It was the comeback of 'do it yourself' that was 'precious' evasive rather than fair reply. The point is, if the paid professionals should have done these recalculations consequent to the new observations, then all Phys1 had to do was point bschott to where these appear in the professional work. If they do not appear, then they have not done the recalculations; which makes bschott's question pertinent not only as to 'why are they not', but also as to 'what would the actual revised calculations show now'.

OK? Cheers. :)
Uncle Ira
4.6 / 5 (9) Sep 03, 2016
It was the comeback of 'do it yourself' that was 'precious' evasive rather than fair reply.
Yeah, I suppose he learn doing that from hanging out around you so long.

If they do not appear, then they have not done the recalculations; which makes bschott's question pertinent not only as to 'why are they not', but also as to 'what would the actual revised calculations show now'.
bschoot-Skippy thinks the calculations is wrong. If he wants them redone, he should redo them his own self. If the professionals are happy with their cyphering, why should they redo them for somebody else? Especially for some couyon on the interweb? Let the couyons on the interweb do them the way that makes them happy to do them.
RealityCheck
2 / 5 (8) Sep 03, 2016
Hi Ira. :)

You're being more stupid than usual today, Ira. If Phys1 is his own man, he doesn't need pointers from anyone. What you suggested makes him out to be as stupid as you, which I don't think is anywhere near possible. He is a smart guy, and he can take responsibility for his own words and actions, Ira. So don't speak for him or make gratuitous and unwanted (by him) excuses which are not necessary.

Oh, and you still don't get that if parameters change as they have been discussing, then the paid professionals should as a matter of course be doing the re-calculations already. All one need do is point bschott to where these appear in the paid professionals' work. If they do not appear and so cannot be cited by Phys1 for bschott's info, then why have they not bern done already by those paid professionals?

Never mind; it's much too complicated for you to 'get', what with your two brain cells being co-opted by your bot-voting program so often. Go back to sleep, Ira. :)
RealityCheck
1.6 / 5 (7) Sep 03, 2016
Hi Phys1. :)

@RC
I don't agree.
bschott not only has questions, he also claims to have the answers to them and claims that the scientists make a mistake.
A professional does not have to spend his time on explaining everything over and over again to an ignorant, narcissist troll.
Due to bullshit asymmetry your demand is unfair.
But why make such a meal out of it unnecessarily? All you had to do to shut him up (if that's what your aim is), was to just point out where the relevant present calculations, and any re-calculations necessitated by changed parameters etc, appear in the paid professionals' work to date. If indicated re-calculations are not being done by the paid professionals, then just tell him that instead of being 'precious' and telling him he should do it. Either way, it would be what a genuine interlocutor would say/do in reply to him.

Anyway, can't stay. Had my break for now. Cheers! :)
Uncle Ira
4.5 / 5 (8) Sep 03, 2016
Oh, and you still don't get that if parameters change as they have been discussing, then the paid professionals should as a matter of course be doing the re-calculations already.
Maybe you guys should let the peoples who pay the paid professionals decide when their work needs redoing.

All one need do is point bschott to where these appear in the paid professionals' work.
You sound like Zephir-Skippy harping on why nobody reproduces the cold fusioning experiments from 60 years ago.

If they do not appear and so cannot be cited by Phys1 for bschott's info, then why have they not bern done already by those paid professionals?
How the heck is Phys-Skippy, bachoot-Skippy, you-Skippy or any-Skippy supposed to know why not? The only person who knows why not is the paid professionals who did not redo the stuffs. Ask them why they think it is good enough and don't need to redo them every time some couyon on the interweb tells them they got it wrong.
Uncle Ira
4.6 / 5 (10) Sep 03, 2016
If Phys1 is his own man, he doesn't need pointers from anyone.
Anybody but you that is, eh?

Anyway, can't stay. Had my break for now. Cheers! :)


See you later Skippy. Do everything the docs say to do and everything will be alright.
RealityCheck
1.5 / 5 (8) Sep 03, 2016
Hi Ira. :)
If Phys1 is his own man, he doesn't need pointers from anyone.
Anybody but you that is, eh?

Anyway, can't stay. Had my break for now. Cheers! :)


See you later Skippy. Do everything the docs say to do and everything will be alright.


Apparently you've been ignoring doctors' advice for years now, Ira. :)

The result being what you have become: an internet bot-voting idiot too dumb to keep anything straight but nevertheless trying to sound as if he is his own man; but isn't since his two brain cells were 'captured' by the bot -voting program which is now directing his stupidity to new levels here at PO. Sad case, Ira. You should have listened to your doctors advice and laid off that 'puff n stuff' all those years. Too bad, Ira. Take care of what you got left, Ira. You can't afford to lose even one of those two brain cells now. :)
RealityCheck
1.5 / 5 (8) Sep 03, 2016
Hi Phys1. :)
Why don't YOU explain why his idea is irrelevant ?

Been there; done that, mate. In many cases involving many posters. No time to spare for all that now that my off-line work has reached a 'critical mass' stage which consumes most of what time I can spare except for the occasional 'break' I take to read here and smile at the antics (and frown at the silliness by some, on all 'sides'---not to mention have rare 'fun' dishing back what a particularly stupid and malicious idiot here keeps dishing out because he is too stupid to learn a simple lesson not to dish it out; you know who I mean).

Anyway, I now depend on you and other sensible folk to take that burden on your shoulders and discharge that duty to inform and discuss fairly with whomever it is that you feel needs correcting etc. But make sure to do so politely; and even more sure that you are correct and not evading because you cannot answer the questions/challenges put to you by whomever.

Good luck! :)
Gigel
5 / 5 (2) Sep 05, 2016

The universe is far older.

If so, then can you name some red dwarf stars in their late lives? They should contain large amounts of helium and little hydrogen.
Gigel
not rated yet Sep 05, 2016
A common steady state universe or just https://en.wikipe...rinciple - why we should live in just oldest part of the Universe? The people never gave up the idea of their exclusiveness in fact: even the modern cosmology is still based on religious geocentric model. It's time to finally grow up.

Well, I'm wondering too why do I live in a place from where I always have to go, but never come to? Why do I always have to take the bus away from where I am, but never do I take it to where I am?
RealityCheck
1 / 5 (7) Sep 05, 2016
Hi Gigel. :)

I noted your fair, polite, intelligent question in reply to Tuxford.

I would remind you both, and anyone else interested in the subject and the (naive/misleading) assumptions currently used for 'determining' the 'age' of the observable universe (and beyond to infinity), of some recent astronomical discoveries:

- recycling nature of galactic black hole systems (via matter-deconstructing polar jets);

- great amount of 'pristine' looking 'reconstructed' hydrogen/helium constantly ejected to, and now being increasingly detected in, the deeps of inter-stellar and inter-galactic and inter-cluster space.

So, over Billions (probably infinite number) of years, such recycling must be continually sending 'newly deconstructed' material to space; to reform/replenish the 'pristine looking' Hydrogen/Helium 'abundance ratios' we observe. Local observable volume exhibits 'latest phase' in local volume recycling.

So BB 'beginning/aging' assumptions not needed. Cheers. :)
RealityCheck
1 / 5 (6) Sep 05, 2016
Hi Phys1. :)
@RC
You talk about fairness to lunatics, yet you spit on scientists who make important discoveries.
Read more at: http://phys.org/n...rk.html"


See, mate? You just proved me spot on re that problem I pointed out in that post! You use pejorative language/classification of questioners. It is such prejudiced attitudes and kneejerks that make your own assessments suspect; because it compromises your objectivity; leading you to 'confirmation biased reading/reaction' to questions/points; and to likely miss some important 'gems' amongst the 'dross'.

I treat each idea/question/challenge on its merits irrespective of author/source. That is the objective dispassionate way to approach proper scientific discourse/understanding.

No amount of irate/offended reaction properly substitutes for that. :)
Gigel
5 / 5 (1) Sep 06, 2016
So, over Billions (probably infinite number) of years, such recycling must be continually sending 'newly deconstructed' material to space; to reform/replenish the 'pristine looking' Hydrogen/Helium 'abundance ratios' we observe.

Your hypothesis can hardly be taken into consideration without a known mechanism for recycling matter into H/He atoms. It's not that it's impossible, it's just too far fetched to be taken into consideration as it is now. What exactly do you mean by recycling? What is recycled into H and how?

Galactic BHs have low mass compared to galaxies, so their influence on galactic matter would be small, if they are to be converted into H/He. Also, what would they have to do with red dwarfs and their composition?
Protoplasmix
5 / 5 (4) Sep 06, 2016
Post totals for this thread:

Tuxford: posts=1; 1.4 / 5 (11)
tinitus: posts=11; 3.4 / 5 (39)
RNP: posts=6; 2.2 / 5 (30)
antialias_physorg: posts=1; 3.3 / 5 (7)
shavera: posts=7; 3.9 / 5 (29)
bschott: posts=4; 2.7 / 5 (12)
Phys1: posts=6; 4.6 / 5 (23)
RealityCheck: posts=8; 1.7 / 5 (17)
Uncle Ira: posts=4; 4.3 / 5 (18)
Gigel: posts=3; 3.3 / 5 (3)
RealityCheck
1 / 5 (6) Sep 08, 2016
Hi Phys1. :)
@RC
You don't have to prove that you are a hypocritical narcissist.
It is clear enough.
Mate, not only are you in denial of your own narcissism, but you also project it onto me who points out where you may also be in error while you keep personally attacking and insulting others. Be better than they, and actually listen and consider objectively and not be in denial of things pointed out for your benefit as well as theirs. Good luck, mate. :)
RealityCheck
1 / 5 (6) Sep 08, 2016
Hi Gigel. :)
Your hypothesis can hardly be taken into consideration without a known mechanism for recycling matter into H/He atoms. It's not that it's impossible, it's just too far fetched to be taken into consideration as it is now. What exactly do you mean by recycling? What is recycled into H and how?

Galactic BHs have low mass compared to galaxies, so their influence on galactic matter would be small, if they are to be converted into H/He. Also, what would they have to do with red dwarfs and their composition?
I explained all that during my discussion with Da Schneib et al. And it is not my hypothesis, it is known science re observed accretion disc-jets systems at all scales. Especially galactic/blackhole jets are hugely energetic recycling systems which deconstruct matter into quark-gluon plasma as well as electrons/protons; all of which deconstructed matter reforms into 'pristine' looking hydrogen. This also happens in our (comparatively) puny LHC. Cheers. :)
Gigel
not rated yet Sep 09, 2016
I explained all that during my discussion with Da Schneib et al. And it is not my hypothesis, it is known science re observed accretion disc-jets systems at all scales. Especially galactic/blackhole jets are hugely energetic recycling systems which deconstruct matter into quark-gluon plasma as well as electrons/protons; all of which deconstructed matter reforms into 'pristine' looking hydrogen. This also happens in our (comparatively) puny LHC. Cheers. :)

I still don't see how that would prevent very old red dwarfs from being observed if the universe is really much older than we believe.
RealityCheck
1 / 5 (6) Sep 09, 2016
Hi Gigel. :)

I am assuming you are familiar with the unusual nature/lifetime possibilities etc of the Red Dwarf types. I remind you that they are very faint, have trillion year lifetime even before turning into Blue or White Dwarf types (assuming they even make it that far). At any point once the Red Dwarf becomes so 'cool' that little or no significant 'stellar wind' present to clear its neighborhood of gas and dust, they may, after Trillions of years become ACCUMULATORS of new material which may eventually change their mass, elemental contents and spectral type; and eventually even may become a new Nova or even a Supernova 'event'!

Anyhow, as you can see, despite what local observable volume presently shows, the matter within it may have been 'recycled' many times by most recent EPOCHS of galactic etc polar-jet processes; to produce elemental abundances in that space which look 'pristine'; thus complicating present observed stellar types/life estimates etc. Cheers. :)
Gigel
not rated yet Sep 11, 2016
Current models show red dwarfs actually increase their temperature in time, thus they should have even stronger stellar winds late in their life. I don't know what is the reason for this, but I suppose it's because they increase their density as they burn more H, so the fusion rate and temperature also increase. Still I don't know why we shouldn't be able to detect red dwarfs or subdwarfs with ages of 20-50-100 billion years.

If indeed matter is recycled, then I think we should see old stars inside molecular clouds where normally young stars are expected to form. Is there any such known case?
RealityCheck
1 / 5 (3) Sep 12, 2016
Hi Gigel. :)

Sorry; been busy with off-line work; still am; so must be brief again...

IIRC, the mostly convective dynamics within RD stars means their inner heat is transported to surface via hot plasma and very little if any inner radiation transport. That convection mixes the hydrogen and the helium 'ash' so that hydrogen fuel fusion is 'steady' with little increase in fusion rate over time; and contraction rate is also steady over time; as is the increase in density. The highly convection 'structure' of such RD stars means their magnetic fields are strong, and get stronger as the diameter decreases and density increases. As far as the heat energy/temperature goes, it mainly leaves the the RD surface as INFRARED wavelengths (fewer X-RAY and very little ULTRAVIOLET). The RADIATION gets past the stronger magnetic fields; but most of PLASMA ions/electrons etc for potential 'stellar wind' gets RE-TRAPPED, so RD 'stellar wind' not very strong.

Cheers till next time, Gigel. :)
Uncle Ira
5 / 5 (3) Sep 12, 2016
@ Really-Skippy. How you are Cher? I am good, thanks for asking. But I am really surprised you have changed up your tune as far the RD's and IIRC's. This means you now agree with what I was trying to say about two years go on the RD article. Did you do like I suggested way back then and buy a book about the stellar physics like the one I was reading then? Anyhoo, good job Cher, there is hope for you yet.
Gigel
not rated yet Sep 13, 2016
If RD core density increases, then so does the fusion rate and thus the RD temperature; this shows that a RD really becomes a blue dwarf as it ages. The RD surface magnetic field is probably highly variable. RDs show very strong sunspot activity. There are probably coronal mass ejections too during starspot maximum.
RealityCheck
1 / 5 (3) Sep 13, 2016
Hi Gigel. :)

Take care not to conflate higher massed Blue Dwarf range (that eventually eject most of their mass etc because their core not 'convective', and so build HELIUM up in their core etc), with HYPOTHESIZED 'Blue Dwarf stage' of LOWER MASS Red Dwarf (which slowly, STEADILY burn ALL their Hydrogen fuel as it gets convected down to the fusing core).

See? The lower mass Red Dwarf is convective throughout; hence CORE Hydrogen PROPORTION does not change much at all, even though core becomes denser (because HELIUM from fusion increases as a proportion but is re-mixed with more Hydrogen CONVECTED DOWN from upper Hydrogen layers while HELIUM is CONVECTED UP from core).

Hence why LOW MASS Red Dwarf has 'steady decline'; 'stellar wind' strength settles down even as surface temp/radiations slowly rises from gravitational contraction (as fusion Hydrogen fuel depleted); magnetic field gets stronger as convection in more concentrated plasma more 'settled pattern'.

Gotta go. :)
RealityCheck
1 / 5 (3) Sep 13, 2016
ERRATA PS to Gigel: :)

Apologies, but the first line of my previous post to you should have read ..."higher massed Red Dwarf range...".

And the caution against conflation was reffering to the possible conflation of Higher Massed RD and Lower Massed RD (which latter are Hypothesized to become a certain type of Blue Dwarf and then White Dwarf type after trillions of years).

Sorry about the typo and rushed post composition, mate. Really busy and rushed lately. Cheers. :)
Gigel
not rated yet Sep 14, 2016
Let's not lose the grand picture from sight. Is there any evidence of not-very-young red dwarfs that are eating matter and growing up to more massive stars? Any red dwarf that is eating a molecular cloud that is not the cloud it was formed from? Elsewise, where are very old RDs that should be there if the universe is far older than thought?
RealityCheck
1 / 5 (3) Sep 16, 2016
Hi Gigel. :)

You may have an overly simplistic picture of the otherwise complex and wide range of behaviors and conditions which any stellar-like body comes across over time and deep space travel/evolutions. Astronomers recently discovered the rich variety of local conditions which affect what we 'see' here when we observe the various novae and supernovae burst. These local conditions may compromise the previous 'standard candle' assumptions which were naively applied to categorize and age and distance any particular novae/supernovae. The same type of rich variety of local conditions over time and space also affect the evolutions of sub-stellar mass RD type stars. It especially affects their ACCUMULATION rate/contents once their stellar winds died down (as I explained earlier) and their magnetic fields strengthen and become dominant in the accumulation dynamics.Most importnat difference is that their MAGNETIC POLES rather than Equatorial Accretion Discs...CONTINUED
RealityCheck
1 / 5 (3) Sep 16, 2016
@ Gigel...CONTINUED

...becomes a major system for accumulating randomly incoming charged (plasmic) gases/dust/chunks which get trapped in the magnetic fields nd directed onto the RD surface at the poles. Also, any 'formation leftovers' debris cloud previously associated with that RD formation (think OOrt Cloud) will no longer be repelled/vaporized away by RD's now-weakened stellar winds, and so will also approach the RD from all directions.

CONSIDER: Over billions/trillions years, this accumulating process can RE-build such a RD to much larger mass than when it started! Also consider the random motion through EONS of 'old' highly evolved MOLECULES of HEAVIER METALS which such a star can accumulate because of weakened stellar wind (think of a SUPER HEAVY JUPITER). Such UNUSUAL/REBORN stars are known; and may contain EXTREMELY high levels of MERCURY ETC, which goes against the HYPOTHESIS of BB CHRONOLOGY CONSTRAINED stellar evolution types/times....AGAIN CONTINUED
RealityCheck
1 / 5 (3) Sep 16, 2016
AGAIN @ Gigel...CONTINUED

Add to all that variety and complexity over time and recycling/rebirthing etc etc, the 'pristine like' Hydrogen/Helium stars which seem 'old' in BB CHRONOLOGY, but may be 'young' NEW stars formed from the recycled (deconstructed/reconstructed matter) ejecta into deep space between the galaxies/clusters etc, over eons of black hole etc polar-jets and galactic-disc-winds etc (as explained before).

There is much more detail and complexity which there is no time/space for me to go into now here. But you get the gist? The whole gammut of unusual (if BB hypothesis is used to 'interpret' the observations) stellar and galactic types and evolutions make the BB hypothesis CHRONOLOGY and EVOLUTIONARY types/stages untenable.

The variety NOW BEING SEEN and interpreted under INFINITE/ETENAL UNIVERSE of minimal OCCAMS RAZOR assumptions explains observations better than BB etc hypothesis/interpretations/assumptions do.

No more time for now, mate. Cheers! :)
Gigel
not rated yet Sep 17, 2016
OK... is there any known red/blue dwarf much older than the current accepted age of the universe, that still retains its stellar wind?

I still don't get why a RD should increase its magnetic field but reduce stellar wind. It doesn't make sense, at least as long as it still burns fuel. Magnetic field is produced by convection, and magnetic filed+differential rotation (since it is not solid) gives stellar cycles and starspots. Btw, the Sun has a very strong mag. field in sunspot areas compared to the polar one. So as long as there is convection (for trillions of years), there will be starspots and presumably mass ejection phenomena, which would have the effect of stellar wind.

And I still don't get where is all the matter that is supposed to inflate a RD to a larger star. Is there any evidence of sufficient matter that stars meet, eat and that get them more massive? Any computation in that sense?
Gigel
not rated yet Sep 17, 2016
Under current theories it is supposed that stars' mass remains practically unchanged during billions of years, except for mass ejections and nuclear fuel burning. I don't know of any theory that posits that stars' mass slowly increases in time due to interstellar gas. For billions of years that seems to be unimportant. So maybe it's still unimportant for say 50 billion years. Is there any 50 Gy old RD out there? Or maybe even a population of them? There should be I think if the universe is eternal.
Gigel
not rated yet Sep 17, 2016
Under current theories it is supposed that stars' mass remains practically unchanged during billions of years, except for mass ejections and nuclear fuel burning.

I forgot stellar winds and... !!!!STAR MERGERS!!!!
Gigel
not rated yet Sep 17, 2016
Under current theories it is supposed that stars' mass remains practically unchanged during billions of years, except for mass ejections and nuclear fuel burning.

I forgot stellar winds and... !!!!STAR MERGERS!!!! (or matter transfer between stars)

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