Starship Asterisk*

neufer wrote:

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MemyselfandI wrote:
Where did the matter come from in the first place?

https://en.wikipedia.org/wiki/A_Universe_from_Nothing wrote:
<<A Universe from Nothing: Why There Is Something Rather than Nothing is a non-fiction book by the physicist Lawrence M. Krauss, initially published on January 10, 2012 by Free Press. It discusses modern cosmogony and its implications for the debate about the existence of God. The main theme of the book is how "we have discovered that all signs suggest a universe that could and plausibly did arise from a deeper nothing—involving the absence of space itself and— which may one day return to nothing via processes that may not only be comprehensible but also processes that do not require any external control or direction.">>

Ann wrote:

ems57fcva wrote:Are you all sure that the colors are labeled properly? It shows low-mass stars contributing to everything between Strontium and Lead, while the exploding massive stars are only credited for elements as heavy as Zirconium. That does not look right. I thought that it took a stellar explosion to create elements heavier than iron. And even just a switch of the yellow and green still raises questions in that regard, as the yellow also extends past iron, but the exploding white dwarfs (white) do not.

I remember seeing a Hubble (or Chandra?) picture of a supernova remnant, and the caption said that we can be sure that this is the remnant of a massive star and its core collapse. And the reason why we can be sure of that is that the remnant contains so much oxygen, and oxygen is produced in core-collapse supernovas. And indeed, today's chart says that oxygen is produced almost exclusively by such supernovas.

I also remember reading about red giants and all the chemical processes that go on in them before they shed their outer layers altogether and turn into planetary nebulas and white dwarfs. The text where I read about that said that many elements are created here because neutrons are incorporated into the nuclei of other elements.

If you check out the chart, the "green" elements (green because they were created by low-mass stars) seem kind of weird. There are few well-known elements among them, apart from lithium, carbon and nitrogen, and the highly poisonous elements mercury and lead.

Fascinatingly, though, some silver and even some gold is apparently made by dying red giants!

Ann

ems57fcva wrote:

Ann wrote:

ems57fcva wrote:Are you all sure that the colors are labeled properly? It shows low-mass stars contributing to everything between Strontium and Lead, while the exploding massive stars are only credited for elements as heavy as Zirconium. That does not look right. I thought that it took a stellar explosion to create elements heavier than iron. And even just a switch of the yellow and green still raises questions in that regard, as the yellow also extends past iron, but the exploding white dwarfs (white) do not.

I remember seeing a Hubble (or Chandra?) picture of a supernova remnant, and the caption said that we can be sure that this is the remnant of a massive star and its core collapse. And the reason why we can be sure of that is that the remnant contains so much oxygen, and oxygen is produced in core-collapse supernovas. And indeed, today's chart says that oxygen is produced almost exclusively by such supernovas.

I also remember reading about red giants and all the chemical processes that go on in them before they shed their outer layers altogether and turn into planetary nebulas and white dwarfs. The text where I read about that said that many elements are created here because neutrons are incorporated into the nuclei of other elements.

If you check out the chart, the "green" elements (green because they were created by low-mass stars) seem kind of weird. There are few well-known elements among them, apart from lithium, carbon and nitrogen, and the highly poisonous elements mercury and lead.

Fascinatingly, though, some silver and even some gold is apparently made by dying red giants!

Ann

As I understand it, dying small stars lack the needed temperatures and pressures to create anything even as heavy as iron; and their planetary nebulas will be full of oxygen (which is not to say that supernovae do not produce a lot of oxygen themselves). In fact, in that other APOD that I referenced, Sulfur was as heavy an element as small stars could create. However, this arrangement seems to come from the LIGO-VIRGO collaboration or someone close to it. See http://growth.caltech.edu/images/gw1708 ... -table.jpg, which is associated with http://growth.caltech.edu/news-gw170817.html. If this is a mistake, it was made by someone who should have known better.

Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star or the sudden gravitational collapse of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through accretion or via a merger, to raise its core temperature enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical collapse mechanics have been established and accepted by most astronomers for some time.

BDanielMayfield wrote:And here’s the explanation, I believe, from the Wikipedia article on Supernova:

Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star or the sudden gravitational collapse of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through accretion or via a merger, to raise its core temperature enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical collapse mechanics have been established and accepted by most astronomers for some time.

This must be what is meant by “dying low mass star”, the detonation of a white dwarf.

Bruce

neufer wrote:

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MemyselfandI wrote:
Where did the matter come from in the first place?

https://en.wikipedia.org/wiki/A_Universe_from_Nothing wrote:
<<A Universe from Nothing: Why There Is Something Rather than Nothing is a non-fiction book by the physicist Lawrence M. Krauss, initially published on January 10, 2012 by Free Press. It discusses modern cosmogony and its implications for the debate about the existence of God. The main theme of the book is how "we have discovered that all signs suggest a universe that could and plausibly did arise from a deeper nothing—involving the absence of space itself and— which may one day return to nothing via processes that may not only be comprehensible but also processes that do not require any external control or direction.">>

MemyselfandI wrote:Where did the matter come from in the first place?

• Where did the energy come from?
  Where did the laws come from that govern that energy?

MemyselfandI wrote:My question was, where did the matter come from in the first place? An ex nihilo postulation only makes rational sense if one can argue for something (or someone) to create from nothing.

Chris Peterson wrote:

MemyselfandI wrote:My question was, where did the matter come from in the first place? An ex nihilo postulation only makes rational sense if one can argue for something (or someone) to create from nothing.

There is no good reason to assume that something can't come from nothing, nor to assume that effects require causes. The best answer we currently have to the origin of the Universe is that it came from nothing and had no cause. That is the answer most consistent with our understanding of physics.

BDanielMayfield wrote:

Chris Peterson wrote:

MemyselfandI wrote:My question was, where did the matter come from in the first place? An ex nihilo postulation only makes rational sense if one can argue for something (or someone) to create from nothing.

There is no good reason to assume that something can't come from nothing, nor to assume that effects require causes. The best answer we currently have to the origin of the Universe is that it came from nothing and had no cause. That is the answer most consistent with our understanding of physics.

Stepped in what? “There is no good reason to assume that something can’t come from nothing,” How about human experience in which we never see a cause that didn’t also have an effect?

BDanielMayfield wrote:

Chris Peterson wrote:

MemyselfandI wrote:
My question was, where did the matter come from in the first place? An ex nihilo postulation only makes rational sense if one can argue for something (or someone) to create from nothing.

There is no good reason to assume that something can't come from nothing, nor to assume that effects require causes. The best answer we currently have to the origin of the Universe is that it came from nothing and had no cause. That is the answer most consistent with our understanding of physics.

Stepped in what? “There is no good reason to assume that something can’t come from nothing,” How about human experience in which we never see an effect that didn’t also have a cause?

• Human experience isn't normally very aware of either quantum fluctuations or cosmological inflation.
  • (However, unlike "God", both can be studied scientifically.)

https://en.wikipedia.org/wiki/Unmoved_mover#First_cause wrote:
<<In book VIII of his Physics, Aristotle examines the notions of change or motion, and attempts to show by a challenging argument, that the mere supposition of a 'before' and an 'after', requires a first principle. He argues that in the beginning, if the cosmos had come to be, its first motion would lack an antecedent state, and as Parmenides said, "nothing comes from nothing". The Cosmological argument, later attributed to Aristotle, thereby draws the conclusion that God exists. However, if the cosmos had a beginning, Aristotle argued, it would require an efficient first cause, a notion that Aristotle took to demonstrate a critical flaw. The purpose of Aristotle's cosmological argument, that at least one eternal unmoved mover must exist, is to support everyday change.>>

Chris Peterson wrote:

BDanielMayfield wrote:“There is no good reason to assume that something can’t come from nothing,” How about human experience in which we never see a cause an effect that didn’t also have an effect a cause?

That is the worst possible reason. A logical fallacy of the highest order. I call it the Billiard Ball Fallacy: the belief that the Universe must work across all its scales in the same way that we evolved to sense and understand the tiny little bit we can see.

In fact, when we look beyond our primary senses, we do see things without cause (e.g. particle decay) and things that come from nothing (e.g. virtual particles). The Universe is apparently quite comfortable with these concepts.

BDanielMayfield wrote:

Chris Peterson wrote:

BDanielMayfield wrote:“There is no good reason to assume that something can’t come from nothing,” How about human experience in which we never see a cause an effect that didn’t also have an effect a cause?

That is the worst possible reason. A logical fallacy of the highest order. I call it the Billiard Ball Fallacy: the belief that the Universe must work across all its scales in the same way that we evolved to sense and understand the tiny little bit we can see.

In fact, when we look beyond our primary senses, we do see things without cause (e.g. particle decay) and things that come from nothing (e.g. virtual particles). The Universe is apparently quite comfortable with these concepts.

One can call black white or vice versa but it doesn’t make it so, just as one can call common sense “a logical fallacy of the highest order.”

Partical decay is without cause? The timing of one particle’s decay is unpredictable, but reason for (or in other words, cause of) its decay are laws governing the behavior of subatomic particles.

I would also argue that virtual particles are coming from something that caused them to come into existence.

ems57fcva wrote:

Ann wrote:

ems57fcva wrote:Are you all sure that the colors are labeled properly? It shows low-mass stars contributing to everything between Strontium and Lead, while the exploding massive stars are only credited for elements as heavy as Zirconium. That does not look right. I thought that it took a stellar explosion to create elements heavier than iron. And even just a switch of the yellow and green still raises questions in that regard, as the yellow also extends past iron, but the exploding white dwarfs (white) do not.

I remember seeing a Hubble (or Chandra?) picture of a supernova remnant, and the caption said that we can be sure that this is the remnant of a massive star and its core collapse. And the reason why we can be sure of that is that the remnant contains so much oxygen, and oxygen is produced in core-collapse supernovas. And indeed, today's chart says that oxygen is produced almost exclusively by such supernovas.

I also remember reading about red giants and all the chemical processes that go on in them before they shed their outer layers altogether and turn into planetary nebulas and white dwarfs. The text where I read about that said that many elements are created here because neutrons are incorporated into the nuclei of other elements.

If you check out the chart, the "green" elements (green because they were created by low-mass stars) seem kind of weird. There are few well-known elements among them, apart from lithium, carbon and nitrogen, and the highly poisonous elements mercury and lead.

Fascinatingly, though, some silver and even some gold is apparently made by dying red giants!

Ann

As I understand it, dying small stars lack the needed temperatures and pressures to create anything even as heavy as iron; and their planetary nebulas will be full of oxygen (which is not to say that supernovae do not produce a lot of oxygen themselves). In fact, in that other APOD that I referenced, Sulfur was as heavy an element as small stars could create. However, this arrangement seems to come from the LIGO-VIRGO collaboration or someone close to it. See http://growth.caltech.edu/images/gw1708 ... -table.jpg, which is associated with http://growth.caltech.edu/news-gw170817.html. If this is a mistake, it was made by someone who should have known better.

jajohnson51 wrote: One of the people who put the graphic together here ...

BDanielMayfield wrote:

BDanielMayfield wrote:And here’s the explanation, I believe, from the Wikipedia article on Supernova:

Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star or the sudden gravitational collapse of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through accretion or via a merger, to raise its core temperature enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical collapse mechanics have been established and accepted by most astronomers for some time.

This must be what is meant by “dying low mass star”, the detonation of a white dwarf.

Bruce

Scratch that. Looking at the table again, I see that there is already a white or grey code for the contribution from Exploding White Dwarf Stars, so the mystery remains unsolved.

terpsucka wrote: ...
I came here looking for the answer to this question as well. In fact, I've found references to this and similar periodic table efforts, with some level of explanation for every grouping except for this one!

MarkBour wrote:

terpsucka wrote: ...
I came here looking for the answer to this question as well. In fact, I've found references to this and similar periodic table efforts, with some level of explanation for every grouping except for this one!

So, did the post just above, from jajohnson51, help?

jajohnson51 wrote:

ems57fcva wrote:

Ann wrote:
I remember seeing a Hubble (or Chandra?) picture of a supernova remnant, and the caption said that we can be sure that this is the remnant of a massive star and its core collapse. And the reason why we can be sure of that is that the remnant contains so much oxygen, and oxygen is produced in core-collapse supernovas. And indeed, today's chart says that oxygen is produced almost exclusively by such supernovas.

I also remember reading about red giants and all the chemical processes that go on in them before they shed their outer layers altogether and turn into planetary nebulas and white dwarfs. The text where I read about that said that many elements are created here because neutrons are incorporated into the nuclei of other elements.

If you check out the chart, the "green" elements (green because they were created by low-mass stars) seem kind of weird. There are few well-known elements among them, apart from lithium, carbon and nitrogen, and the highly poisonous elements mercury and lead.

Fascinatingly, though, some silver and even some gold is apparently made by dying red giants!

Ann

As I understand it, dying small stars lack the needed temperatures and pressures to create anything even as heavy as iron; and their planetary nebulas will be full of oxygen (which is not to say that supernovae do not produce a lot of oxygen themselves). In fact, in that other APOD that I referenced, Sulfur was as heavy an element as small stars could create. However, this arrangement seems to come from the LIGO-VIRGO collaboration or someone close to it. See http://growth.caltech.edu/images/gw1708 ... -table.jpg, which is associated with http://growth.caltech.edu/news-gw170817.html. If this is a mistake, it was made by someone who should have known better.

One of the people who put the graphic together here. The heavy elements (=beyond the iron peak) are made by capturing neutrons onto "seed" nuclei, such as iron. Neutron capture is needed because the electric repulsion between a nucleus like iron (26 protons) and an additional proton is very strong, but between a neutron and an iron nucleus there is none. Dying low-mass stars can make heavier elements not because they reach very high temperatures, like those needed to fuse silicon towards iron, but because nuclear reactions happen in these stars that create free neutrons. These neutrons can then be captured by iron (for example) nuclei that are in the star not because they were formed in the star but because those seed nuclei were in the gas out of which the star was born. The Sun has iron nuclei in it for this reason.

These neutron-capture reactions are not important for creating energy in the star, so when we discuss nuclear fusion in stars, this process is rarely mentioned. For the origin of the elements it matters! And it has been spectacularly demonstrated to be correct, as we have seen newly-minted technetium in these dying low-mass stars. Because the longest-lived technetium isotope has a half-life of 4.2 million years, much, much shorter than the lives of these stars, any technetium in these stars must be made there, rather than being in the natal gas.

jajohnson51 wrote:One of the people who put the graphic together here. The heavy elements (=beyond the iron peak) are made by capturing neutrons onto "seed" nuclei, such as iron. Neutron capture is needed because the electric repulsion between a nucleus like iron (26 protons) and an additional proton is very strong, but between a neutron and an iron nucleus there is none. Dying low-mass stars can make heavier elements not because they reach very high temperatures, like those needed to fuse silicon towards iron, but because nuclear reactions happen in these stars that create free neutrons. These neutrons can then be captured by iron (for example) nuclei that are in the star not because they were formed in the star but because those seed nuclei were in the gas out of which the star was born. The Sun has iron nuclei in it for this reason.

These neutron-capture reactions are not important for creating energy in the star, so when we discuss nuclear fusion in stars, this process is rarely mentioned. For the origin of the elements it matters! And it has been spectacularly demonstrated to be correct, as we have seen newly-minted technetium in these dying low-mass stars. Because the longest-lived technetium isotope has a half-life of 4.2 million years, much, much shorter than the lives of these stars, any technetium in these stars must be made there, rather than being in the natal gas.

The slow neutron capture process or s-process is a series of reactions in nuclear astrophysics which occur in stars, particularly AGB stars. The s-process is responsible for the creation (nucleosynthesis) of approximately half the atomic nuclei heavier than iron.

In the s-process, a seed nucleus undergoes neutron capture to form an isotope with one higher atomic mass. If the new isotope is stable a series of increases in mass can occur, but if it is unstable then beta decay will occur, producing an element of the next highest atomic number. The process is slow (hence the name) in the sense that there is sufficient time for this radioactive decay to occur before another neutron is captured. A series of these reactions produces stable isotopes by moving along the valley of beta-decay stable isobars in the chart of isotopes.

A range of elements and isotopes can be produced by the s-process, because of the intervention of alpha decay steps along the reaction chain. The relative abundances of elements and isotopes produced depends on the source of the neutrons and how their flux changes over time. Each branch of the s-process reaction chain eventually terminates at a cycle involving lead, bismuth, and polonium.

The s-process contrasts with the r-process, in which successive neutron captures are rapid: they happen more quickly than the beta decay can occur. The r-process dominates in environments which have a higher flux of free neutrons; it produces heavier elements and more neutron-rich isotopes than the s-process. Together the two processes account for the majority of abundance evolution of elements heavier than iron.

...

The s-process is believed to occur mostly in asymptotic giant branch stars, seeded by iron nuclei left by a supernova during a previous generation of stars. In contrast to the r-process which is believed to occur over time scales of seconds in explosive environments, the s-process is believed to occur over time scales of thousands of years, passing decades between neutron captures. The extent to which the s-process moves up the elements in the chart of isotopes to higher mass numbers is essentially determined by the degree to which the star in question is able to produce neutrons. The quantitative yield is also proportional to the amount of iron in the star's initial abundance distribution. Iron is the "starting material" (or seed) for this neutron capture – beta-minus decay sequence of synthesizing new elements.

BDanielMayfield wrote:
Also, Mark, have you taken in any Magnesium today?

All life as we know it needs it, and it helps stars crank out heavy elements to boot.

Bruce

https://en.wikipedia.org/wiki/Brucite wrote:

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<<Brucite is the mineral form of magnesium hydroxide: Mg(OH)₂. Magnesium hydroxide is a common component of antacids, such as milk of magnesia, as well as laxatives. Brucite was first described in 1824 and named for the discoverer, American mineralogist, Archibald Bruce (1777–1818). It is a common alteration product of periclase in marble; a low-temperature hydrothermal vein mineral in metamorphosed limestones and chlorite schists; and formed during serpentinization of dunites. Brucite is often found in association with serpentine, calcite, aragonite, dolomite, magnesite, hydromagnesite, artinite, talc and chrysotile.>>

neufer wrote:

BDanielMayfield wrote:
Also, Mark, have you taken in any Magnesium today?

All life as we know it needs it, and it helps stars crank out heavy elements to boot.

Bruce

https://en.wikipedia.org/wiki/Brucite wrote:

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<<Brucite is the mineral form of magnesium hydroxide: Mg(OH)₂. Magnesium hydroxide is a common component of antacids, such as milk of magnesia, as well as laxatives. Brucite was first described in 1824 and named for the discoverer, American mineralogist, Archibald Bruce (1777–1818). It is a common alteration product of periclase in marble; a low-temperature hydrothermal vein mineral in metamorphosed limestones and chlorite schists; and formed during serpentinization of dunites. Brucite is often found in association with serpentine, calcite, aragonite, dolomite, magnesite, hydromagnesite, artinite, talc and chrysotile.>>

BDanielMayfield wrote: Also, Mark, have you taken in any Magnesium today? All life as we know it needs it, and it helps stars crank out heavy elements to boot.
Bruce