Old star, new trick

Apr 30, 2012

The Big Bang produced lots of hydrogen and helium and a smidgen of lithium. All heavier elements found on the periodic table have been produced by stars over the last 13.7 billion years. Astronomers analyze starlight to determine the chemical makeup of stars, the origin of the elements, the ages of stars, and the evolution of galaxies and the universe.

Now for the first time, astronomers have detected the presence of arsenic and selenium, neighboring elements near the middle of the periodic table, in an ancient star in the faint stellar halo that surrounds the . Arsenic and selenium are elements at the transition from light to heavy element production, and have not been found in old stars until now.

Lead author of the paper, Fellow Ian Roederer of the Carnegie Observatories explained: "Stars like our Sun can make elements up to oxygen on the periodic table. Other more can synthesize heavier elements, those with more protons in their nuclei, up to iron by nuclear fusion—the process in which atomic nuclei fuse and release lots of energy. Most of the elements heavier than iron are made by a process called neutron-capture nucleosynthesis.

"Although neutrons have no charge, they can decay into after they're in the nucleus, producing elements with larger atomic numbers. One of the ways that this method can work is by exposure to a burst of neutrons during the violent supernova death of a star. We call this process the rapid process (r-process). It can produce elements at the middle and bottom of the periodic table—from zinc to uranium—in the blink of an eye."

Roederer, with co-author James Lawler, looked at an ultraviolet spectrum from the Hubble Space Telescope public archives to find arsenic and selenium in a 12 billion year-old halo star dubbed HD 160617. These elements were forged in an even older star, which has long since disappeared, and then—like genes passed on from parent to infant—they were born into the star we see today, HD 160617."

The team also examined data for this star from the public archives of several ground-based telescopes and were able to detect 45 elements. In addition to arsenic and selenium, they found rarely seen cadmium, tellurium, and platinum, all of which were produced by the r-process. This is the first time these elements have been detected together outside the Solar System. Astronomers cannot replicate the r-process in any laboratory since the conditions are so extreme. The key to modeling the r-process relies on astronomical observations.

"What I find exciting is that arsenic and selenium can be found in other stars, even ones like HD 160617 that we've been studying for decades," remarked Roederer. "Now that we know where to look, we can go back and study these elements in other stars. Understanding the r-process helps us know why we find certain elements like barium on Earth, or understand why uranium is so rare."

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Lurker2358
1 / 5 (14) Apr 30, 2012
All heavier elements found on the periodic table have been produced by stars over the last 13.7 billion years.


Poor, poor physicists still don't get it.

If it takes light 13.7 billion years to travel 13.7 billion light years, then how long did it take the galaxies to reach their apparent positions BEFORE the light left them, eh?

You have never addressed that.

the "observable universe" is 27 billion light years radius, and the sun would require exactly 27 billion years to reach it's present day composition through the proton-proton chain if it started out as 100% hydrogen and burned at roughly the same rate as today.

Why are these numbers in such perfect agreement with one another, but so contradictory to the standard model?

When you can answer that question without making a complete self-contradiction, let me know.
Origin
1.6 / 5 (7) Apr 30, 2012
Standard model of cosmology suffers with abundance of heavy elements and with relative lack of lightweight elements, like the lithium. Recently we discussed a similar problem of star with abundance of even heavier element, i.e. the tellurium.
Shinichi D_
4.4 / 5 (14) Apr 30, 2012

If it takes light 13.7 billion years to travel 13.7 billion light years, then how long did it take the galaxies to reach their apparent positions BEFORE the light left them, eh?

Poor poor Lurker doesn't even understand what he doesn't understand. The light from distant objects started to travel towards us when they were much closer. As the universe expanded it took light 13 billion years to cover a distance that was originally about 40 million ly., but expanded constantly as the light traveled. The distance of these objects is over 40 billion ly. by now, and not 13.
The sun probably didn't started out as 100% Hydrogen. The radius of the observable universe is 46 billion ly. and not 27 billion.
javjav
2.3 / 5 (3) Apr 30, 2012
If it takes light 13.7 billion years to travel 13.7 billion light years,


Wrong.

It takes significant much less time than 13.7 billion years for light to travel 13.7 billion years distance.

This is due to the effect of the expansion of the universe. The exact time it takes will depend on when it starts to travel, as the universe expansion is accelerating.

You have to understand that even if the speed of light on the vacuum is always c, this only applies to the derivative of the position with respect to time (by definition of "speed"), but the actual distance that it travels in a period of time is different than the distance expressed in c.
dtyarbrough
1 / 5 (10) Apr 30, 2012
Heavy elements aren't created in stars or supernovae. This occurs only in the center of galaxies where stars collide at speeds exceeding 300 km/sec. Fission occurs within stars. The universe did not start with a big bang and is not expanding. This counterbalancing act of creation and then destruction of heavy elements will allow the universe to exist for trillions of years if it hasn't already. Read The Mystery of the Spiral Galaxies Explained
http://www.scribd...xplained
Lurker2358
1 / 5 (9) Apr 30, 2012
You two don't know anything.

lol? Shinichi_D:

The hubble constant is about 72 km/s/mparsec.

A mparsec is 3.6 million light years.

So you're looking at an expansion rate of 790km/s, which is nowhere near the speed of light, and would only add about 1 part per 500 to the apparent age...

40 million light years is not far enough away for the expansion of space-time to significantly effect the actual travel time of light.

You have to be 7.5 billion light years distance before space-time expansion roughly doubles the travel time of the light between the objects.

You cannot apply special relativity time dilation to a general relativity problem, because special relativity does not even address expanding space-time at all, in fact, special relativity assumes space-time doesn't expand.

The observable universe CANNOT have a radius greater than that which would produce hubble expansion equal to the speed of light, because at that point, photons could never reach us ahead of expansion...
Anorion
4.9 / 5 (8) Apr 30, 2012
The age of the universe is about 13.75 billion years, but due to the expansion of space humans are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distance at the present time) than a static 13.75 billion light-years distance.The diameter of the observable universe is estimated to be about 28 billion parsecs (93 billion light-years), putting the edge of the observable universe at about 4647 billion light-years away
Terriva
4.7 / 5 (12) Apr 30, 2012
Heavy elements aren't created in stars or supernovae. This occurs only in the center of galaxies
Metal rich star occur mostly along galactic arms at the galactic plane. The bulge of most of galaxies is of lower metallicity, than their boundary - which disproves your hypothesis sufficiently.
Lurker2358
1 / 5 (9) Apr 30, 2012
You can calculate the maximum limit of the radius of the observable universe, assuming the speed of light postulate is true, and assuming the hubble constant is true, by simply dividing the speed of light by the hubble constant, and then multiplying back by 3.6 million light years.

This comes to 14.98 billion light years.

this is the maximum distance from which any photon could reach earth.

Any farther in initial distance and the photon could never get ahead of the expansion between itself and the Earth.

What you look at in a telescope is where it used to be when the photon left it 13.7 billion years ago (assuming anything is right at all about our concept of time). The object itself is now several times farther away, and has long, long ago exited the observable universe.

The "Big Crunch" was never even remotely possible, based on any observational evidence.
Anorion
5 / 5 (9) Apr 30, 2012
calculation of comoving distance:
http://en.wikiped...distance

observable universe:
http://en.wikiped...universe
Terriva
1 / 5 (8) Apr 30, 2012
putting the edge of the observable universe at about 4647 billion light-years away
The question is actually quite simple: how distant the oldest material object in mainstream cosmology can be? Due the reionization period it cannot be farther, than some 12,7 billions of years. The Universe is 13.7 billions of years and the reionization epoch took 1 billion of years (at a redshift 6 < z < 20). Everything, what has red-shift higher than z > 6 actually violates the Big Bang model with no mercy, because before the reionization epoch no massive object should be formed. Currently we know about many objects with z > 6, for example the galaxy UDFy-38135539 with z = 8.6. Such a galaxy was former only 600 millions years after Big Bang, thus by-passing the reionization epoch nearly completely.
Terriva
1 / 5 (6) Apr 30, 2012
But we observed some protogalaxies with z=10.3, which do violate even baryonic dark era, which lasted lasted between 150 million to 800 million years after the Big Bang. These protogalaxies were formed, when the Universe was just 480 million years old - whereas the mainstream cosmology considers, all matter was still in form of photons only.
Shinichi D_
4.6 / 5 (10) Apr 30, 2012
Terriva:

"..violates the Big Bang model with no mercy, because before the reionization epoch no massive object should be formed."

No. The limit for massive objects is the recombination event, that - in a sense - can be perceived as the beginning of the reionization epoch. It occured about 400.000 years after the big bang. The reionization happened because massive objects - stars - re-ionized most of the gas available. The reinization epoch STARTED and not ENDED with the first massive objects.
Terriva
1 / 5 (2) Apr 30, 2012
OK - so 400 millions of years is the last limit for observable object? I don't expect, you'll move this limit again whenever such object will be found...;-)
EverythingsJustATheory
2 / 5 (4) Apr 30, 2012
Of course it will be moved, science is based on observation. Right now the best guess is around 400M, until an observation contradicts this.
Shinichi D_
4.6 / 5 (9) Apr 30, 2012
OK - so 400 millions of years is the last limit for observable object? I don't expect, you'll move this limit again whenever such object will be found...;-)

Not 400 million, 400 thousand. For the recombination.
For the first stars i would say a 100-150 million years after BB. The first supernovae 150 million years, the first metal rich dwarf stars 250 million years. Dusty, metal-rich, "mature-looking" early galaxies at about 350-800 million years.
With the JWST, TMT, E-ELT, GMT under construction, we'll see in about 15 years. It's the most exiting era of astronomy.
kevinrtrs
1.3 / 5 (16) Apr 30, 2012
After all this discussion of ages and distances, please remind us all again - just how long is it supposed to take for a star to form from just gas - with no outside help from any exploding star or other disturbances??? Anyone?
When you've finally provided a rational answer to that one conundrum, please explain further how it happened that some of the furthest galaxies were already ripe and mature containing billions of stars in the same time?
TheGhostofOtto1923
4.6 / 5 (11) Apr 30, 2012
After all this discussion of ages and distances, please remind us all again - just how long is it supposed to take for a star to form from just gas - with no outside help from any exploding star or other disturbances??? Anyone?
When you've finally provided a rational answer to that one conundrum, please explain further how it happened that some of the furthest galaxies were already ripe and mature containing billions of stars in the same time?
You would say magic and be done with it. I would say that scientists are working hard to find the answers, and will tell us soon enough. And I am reasonably confident that these answers will make your magic look silly. They always have havent they?
Terriva
1 / 5 (6) Apr 30, 2012
Not 400 million, 400 thousand...
400 millions, until you prove your stance with reference.
Shinichi D_
4.5 / 5 (8) Apr 30, 2012
Not 400 million, 400 thousand...
http://upload.wikimedia.org/wikipedia/commons/2/29/Reion_diagram.jpg, until you prove your stance with reference.


http://en.wikiped...smology)
Plus your diagram. Look at the upper most line reading: "~380 thousand - the universe becomes neutral and transparent." That is the recombination event. From that moment the universe is filled with atomic hydrogen. You have hydrogen, gravity, so star formation is already going on.
antialias_physorg
5 / 5 (8) Apr 30, 2012
just how long is it supposed to take for a star to form from just gas

That really depends how much gas is there to begin with. After reionization the density of matter was pretty high n(because the universe wan't ver big back then), so it wouldn't take long at all for the first stars to form and no other stars were needed to seed them.

Disturbances are already innate in the universe. We can actually see them as temperature fluctuations in the cosmic microwave background (which is the redshifted glow of the reionization epoch)
Tuxford
1 / 5 (7) Apr 30, 2012
Metal rich star occur mostly along galactic arms at the galactic plane. The bulge of most of galaxies is of lower metallicity, than their boundary - which disproves your hypothesis sufficiently.


This would further support LaViolette's model, where older stars migrate to the edges of the galaxy, having had time to form metals in the life cycle of stars. The younger stars form from new matter formed mostly in the galactic core star, where perhaps 99% of galactic new matter is nucleated and then ejected. Remember that all stars seem to be migrating outward, contrary to conventional wisdom.

http://phys.org/n...ays.html

dtyarbrough
1 / 5 (3) May 01, 2012
Heavy elements aren't created in stars or supernovae. This occurs only in the center of galaxies
Metal rich star occur mostly along galactic arms at the galactic plane. The bulge of most of galaxies is of http://en.wikiped...llicity, than their boundary - which disproves your hypothesis sufficiently.

That actually add more credence to my theory. Heavy metals are formed at the center of the galaxy, not near the center, and are blasted out into the galactic halo. It reenters the plane of the galaxy arms to form stars with more heavy metal. By the time these star reach the center of the galaxy, fission has destroyed the heavy metals.
sethxdeath
5 / 5 (5) May 01, 2012
Just FYI: if you hope to help KevinRTRS understand the information available, you are wasting your time replying to him. If, however, you do it hoping that someone else with a similar question might read the exchange and learn something from you, then by all means continue.
dtyarbrough
1 / 5 (1) May 01, 2012
Heavy elements aren't created in stars or supernovae. This occurs only in the center of galaxies
Metal rich star occur mostly along galactic arms at the galactic plane. The bulge of most of galaxies is of lower metallicity http://en.wikiped...llicity, than their boundary - which disproves your hypothesis sufficiently.


As it turns out, the article says just the opposite. Perhaps the heavier metals fall back to the galactic plane before reaching the edge while the lighter gases spread farther out.
Terriva
1 / 5 (1) May 01, 2012
As it turns out, the article says just the opposite.
My English is far from perfect, but what I can read in it is:
Population II, or metal-poor stars, are those with relatively little metal....Population II stars are common in the bulge near the centre of our galaxy...
Whole the idea, the different density of elements should enable their segregation across the galaxy at the cosmic distances is incredibly naive. Such a segregation doesn't happen even inside of stars, which are way way smaller. It's because the density of plasma is given by its kinetic energy, i.e. the temperature, the mass of ionized particles plays no role here at all. At the 30.000 K or above the behavior of iron plasma will become indistinguishable from helium or hydrogen plasma. After all, the highest intensity of fusion in the Sun occurs at its nuclei. If this nuclei would contain the highest concentration of iron, the fusion would stop here.
Fleetfoot
5 / 5 (4) May 02, 2012
Not 400 million, 400 thousand...
http://upload.wikimedia.org/wikipedia/commons/2/29/Reion_diagram.jpg, until you prove your stance with reference.


It's rather obvious, reionisation was caused by the UV from stars so the stars had to exist before reionisation. We can see reionisation was COMPLETE around z=6 from the end of the Gunn Peterson Trough (950 million years) but WMAP suggests it started around z=25 (130 million years). The usual figure of z~11 (400 million years) is for partial reionisation, an average figure if you like.

Current simulations suggest the first stars would have formed around z=25. Early clumping of dark matter halos might push that as far back as z=65 (30 million) but the computers aren't powerful enough to be sure of that yet, the co-moving volmes get much larger going that far back.
Fleetfoot
5 / 5 (4) May 02, 2012
You can calculate the maximum limit of the radius of the observable universe, assuming the speed of light postulate is true, and assuming the hubble constant is true, by simply dividing the speed of light by the hubble constant, and then multiplying back by 3.6 million light years.


You are forgetting that the Hubble Constant is "constant" in space but not time. Neglecting dark energy (i.e. in the matter- and radiation-dominated eras), the value is inversely proportional to the age of the universe.

You should also note that galaxies beyond z~1 are spearating from us at more than the speed of light, you have to use GR, not SR.
Fleetfoot
5 / 5 (4) May 02, 2012
.. the cosmic microwave background (which is the redshifted glow of the reionization epoch)


Recombination, not reionisaton. The former was at circa 400 thousand years, the latter at about 400 million. I think there has been some confusion between these epochs in this thread.
A2G
1 / 5 (1) May 06, 2012
After reading the article and all of the above comments we still have this core problem to solve. WTF holds everything together?

We are looking for this with the LHC at CERN. Still no Higgs yet. Even on the CERN site they state that we made need an entirely new theory to explain it all.

If we do not know how the smallest of things are even held together when we can hold them in our hands and even explore them with a $6 billion collider, then all the talk about big bang or not etc. is just so much speculation.

We can not even explain how a single galaxy is held together for certain right now. Even the top guys in the field of astrophysics are saying this.

So the very top guys in the world from the smallest objects to the experts in the largest objects admit that they made need an entirely new theory.

But here in these postings we have "experts" from all points of view that think they know better than the very best people in the field of science.