Study: The very first stars may have turned on when the universe was 750 million years old

Dec 05, 2012 by Jennifer Chu
Stars

As far back in time as astronomers have been able to see, the universe has had some trace of heavy elements, such as carbon and oxygen. These elements, originally churned from the explosion of massive stars, formed the building blocks for planetary bodies, and eventually for life on Earth.

Now researchers at MIT, the California Institute of Technology, and the University of California at San Diego have peered far back in time, to the era of the first , and found matter with no discernible trace of heavy elements. To make this measurement, the team analyzed light from the most distant known quasar, a more than 13 billion light-years from Earth.

These quasar observations provide a snapshot of our during its infancy, a mere 750 million years after the initial explosion that created the universe. Analysis of the quasar's provided no evidence of heavy elements in the surrounding gaseous cloud—a finding that suggests the quasar dates to an era nearing that of the universe's first stars.

"The first stars will form in different spots in the universe … it's not like they flashed on at the same time," says Robert Simcoe, an associate professor of physics at MIT. "But this is the time that it starts getting interesting."

Simcoe and his colleagues have published the results from their study this week in the journal Nature.

Hitting the universal wall

Based on numerous , most scientists agree on a general sequence of events during the universe's early development: Nearly 14 billion years ago, an immense explosion, now known as the Big Bang, threw off massive amounts of matter and energy, creating a rapidly expanding universe. In the minutes following the explosion, protons and neutrons collided in nuclear fusion reactions to form hydrogen and helium.

Eventually, the universe cooled to a point where fusion stopped generating these , leaving hydrogen as the dominant constituent of the universe. Heavier elements, such as carbon and oxygen, would not form until the first stars appeared.

Astronomers have attempted to identify the point at which the first stars were born by analyzing light from more distant bodies. (The farther away an object is in space, the older it is.) Until now, scientists have only been able to observe objects that are less than about 11 billion years old. These objects all exhibit heavy elements, suggesting stars were already plentiful, or at least well established, at that point in the universe's history.

"[The astrophysics community] sort of hit this wall," says Simcoe, an astrophysicist at MIT's Kavli Institute for Astrophysics and Space Research. "When this [quasar] was discovered, we could sort of leapfrog further back in time and make a measurement that was substantially earlier."

Looking for nothing

The quasar in question, discovered in August 2011, is the most distant of its kind. To study such distant objects, Simcoe and his colleagues built an infrared spectrometer, which they fitted onto the Magellan Telescope, a massive ground-based telescope in Chile. This past January, the team trained the telescope on the newly discovered quasar, and collected data from its light.

The spectrometer split the incoming light into different wavelengths, which the team plotted on a graph. Simcoe then looked for telltale dips in the data, correlating various wavelengths with the light given off by different chemicals.

"Each chemical has its own fingerprint," Simcoe says. "Based on the pattern of what light is absorbed, it tells you the chemical composition."

Simcoe and his colleagues determined the quasar's "intrinsic spectrum"—the amount of light naturally given off by such a body—and compared this with the observed data to search for the presence of heavy elements. The group found evidence of hydrogen, but no oxygen, silicon, iron or magnesium in the light data. But confirming the absence of evidence for heavy elements was a challenging task.

"It's always hard to establish the absence of something," Simcoe says.

To do so, the researchers considered every other scenario that might explain the light patterns they observed, including newborn galaxies and other matter situated in front of the quasar. Their efforts ultimately confirmed that the quasar's light spectrum indicated an absence of heavy elements 750 million years after the .

"[The birth of the first stars] is one of these important moments in the history of the universe," Simcoe says. "It went from looking like the early universe, which was just gas and dark matter, to looking like it does today, where there are stars and galaxies … it's the point when the universe started to resemble what it looks like today. And it's sort of amazing how early that happens. It didn't take long."

Going forward, Simcoe hopes to analyze other quasars from this early era to further confirm the absence of .

"If we can find things in this epoch, we can start to characterize them," Simcoe says. "There's always something interesting at the edge."

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Meyer
4 / 5 (21) Dec 05, 2012
The big bang is not "an immense explosion". Explosions occur over time. The big bang is the source/limit of time. Visualizing it as an explosion is counterproductive and leads to nonsensical questions like what was "before" it.
cantdrive85
1.6 / 5 (31) Dec 05, 2012
"The extraordinary thing is that scientists accept the Big Bang and in the same breath deride the Creationists." Wallace Thornhill
rubberman
3.7 / 5 (18) Dec 05, 2012
The big bang is not "an immense explosion". Explosions occur over time. The big bang is the source/limit of time. Visualizing it as an explosion is counterproductive and leads to nonsensical questions like what was "before" it.


LOL agreed.

"The extraordinary thing is that scientists accept the Big Bang and in the same breath deride the Creationists." Wallace Thornhill


The "big bang" is simply the term used to describe the change of state of the universe into one that COULD produce the various phenomena we observe today, from one that couldn't. There is no vector co-ordinate or "date" for it's origin.
ValeriaT
2.1 / 5 (7) Dec 05, 2012
The "big bang" is simply the term used to describe the change of state of the universe into one that COULD produce the various phenomena we observe today, from one that couldn't
Does it imply, the universe is way larger and older? The "change of state" implies, the time existed during this change already. And maybe even more important question: from where you got such an idea? How could you prove it or at least support it with some observation?
GSwift7
3.5 / 5 (13) Dec 05, 2012
From Terry Pratchet's Discworld prologue:

"An alternative, favoured by those of a religious persuasion, was that A'Tuin was crawling from the Birthplace to the Time of Mating, as were all the stars in the sky which were, obviously, also carried by giant turtles. When they arrived they would briefly and passionately mate, for the first and only time, and from that fiery union new turtles would be born to carry a new pattern of worlds. This was known as the Big Bang hypothesis"

Now, that's a Big Bang.
Modernmystic
3 / 5 (8) Dec 05, 2012
Visualizing it as an explosion is counterproductive and leads to nonsensical questions like what was "before" it.


You weren't an explosion. What were you before you were here? Whatever you are was here in some form before you were.

It's not nonsensical, it's just difficult...
LariAnn
3.2 / 5 (11) Dec 05, 2012
Without at least two reference points, time and space cannot be measured. Imagine a "point" of consciousness in truly empty space, no objects present. What are the dimensions of that space? Answer: none - no reference points so no measurements can be taken. In that situation, infinite space and zero space are equally probable, along with everything in between. As for time, without change to observe, "time" cannot be measured. What we call "time" is really a measurement of the rate of change of an event when compared to a reference rate of change (a clock). Without such a reference (i.e. objectless space), where/what is time?
GSwift7
3 / 5 (11) Dec 05, 2012
Does it imply, the universe is way larger and older? The "change of state" implies, the time existed during this change already


That's kinda philosophical. If time and space actually began at this point, then anything that happened 'before' that point is technically 'outside' of the universe. Age and distance don't have any defined meaning outside the Universe. Before the BB, there could have been any number of dimensions, including none. The relationship between energy, mass and acceleration would be profoundly different if any parameter is changed or eliminted.
Modernmystic
2.6 / 5 (5) Dec 05, 2012
That's kinda philosophical. If time and space actually began at this point, then anything that happened 'before' that point is technically 'outside' of the universe.


"outside the universe" and/or "nonsensical/nonexistent" are not equivalent.

Age and distance don't have any defined meaning outside the Universe.


Tell that to the things that exist outside the universe...
DavidW
1.4 / 5 (9) Dec 05, 2012
The "big bang" is simply the term used to describe the change of state of the universe into one that COULD produce the various phenomena we observe today, from one that couldn't. There is no vector co-ordinate or "date" for it's origin.


It is an always now event that doesn't exist with life.
rubberman
3.3 / 5 (12) Dec 05, 2012
The "big bang" is simply the term used to describe the change of state of the universe into one that COULD produce the various phenomena we observe today, from one that couldn't
Does it imply, the universe is way larger and older? The "change of state" implies, the time existed during this change already. And maybe even more important question: from where you got such an idea? How could you prove it or at least support it with some observation?


Lariannes response would do Val, time is a human construct we use to identify events and place them in an order, or to apply a number to the duration of an event like a 30 day lunar cycle. If the universe had a conciousness, time would mean nothing to it. There are actually still tribal cultures on earth that don't view time as linear the way most cultures do (I have the NG at home but I can't remember the name of the tribe the particular article is about).
rubberman
3.4 / 5 (11) Dec 05, 2012
Does it imply, the universe is way larger and older? The "change of state" implies, the time existed during this change already. And maybe even more important question: from where you got such an idea? How could you prove it or at least support it with some observation?


As GS7, they are philosophical (but good questions). Is the universe filling space or making it as it expands? Can space be "filled"? What was the actual state of the universe before the BB? As GS7 pointed out, "it" could be anything or nothing....I am comfortable with either at this point.

Ha ha...turtles. :P
guillaume_pussetto
3.9 / 5 (15) Dec 05, 2012
@cantdrive85 : Creationism is not Science is faith (there is not scientific method) and as such must be put aside of science domain. Creationisms is more or less just a sophisticated lie. It took an incredible amount of scientists, a huge effort and hundred of years to know what we now know regarding the big bang. So if you want to talk about science then you shouldn't quote Wallace Thornhill.
Maggnus
3.7 / 5 (12) Dec 05, 2012
So if you want to talk about science then you shouldn't quote Wallace Thornhill.


Could not have put it better.
Parsec
4.4 / 5 (13) Dec 05, 2012
"The extraordinary thing is that scientists accept the Big Bang and in the same breath deride the Creationists." Wallace Thornhill

The comparison is quite inapt. On the one hand we are required to accept the spontaneous creation of a vast intelligence with magical and mystical properties, on the other hand we are asking for the acceptance of quite reasonable physical properties of the universe.

You have to admit that its quite a bit less of a stretch to imagine that the properties of ice include that it spontaneously freezes into ice when the temp falls than the entire universe, complete with life and all its properties spontaneously being created because a mystical creature waved its magic wand.
cantdrive85
1.6 / 5 (18) Dec 05, 2012
So if you want to talk about science then you shouldn't quote Wallace Thornhill.


Neither Thornhill or I was talking about science, the two subjects of the quote are religion (creationism) and metaphysics (BBT).
ValeriaT
2.6 / 5 (10) Dec 05, 2012
The absence of heavy elements is important with respect to falsification of Big Bang cosmology, because this cosmology considers the matter was formed in finely divided state composed of lightweight elements only. But we have evidence of many distant galaxies with surprisingly mature stars of high metallicity and vice-versa, the lightweight elements like the lithium are notoriously lacking in the early Universe.
yyz
3.9 / 5 (11) Dec 05, 2012
Who is Wallace Thornhill again?

One bio notes "Wallace Thornhill earned a degree in physics and electronics at the University of Melbourne, Australia, and began postgraduate studies."( http://www.biblio...ds_c.htm )

Uh, OK. Where can I find any peer-reviewed EU science papers published by Mr Thornhill? Not books, blogs, DVDs, or YT videos.

Where can I find a paper by Thornhill in a *science* journal?
Kron
2 / 5 (12) Dec 06, 2012
And on the 273,937,500,000th day God turned on the stars?

When will this naive Big Bang Model be thrown in the garbage where it belongs. I'm sick and tired of hearing this 13.75 billion year nonsense. Where was all this energy we see around us 13,750,000,001 years ago?

Quantum fluctuations (particle-antiparticle) occur in a medium. Even in the model where space has negative energy while matter is positive energy, the emergence requires a dividing force. A Universe out of nothing is just not logical at all. Why do we need to set a starting date? Why make this assumption?

What is wrong with an infinite Universe model where our local region is visually separated from the Universe as a whole by gravity? In this model any light leaving our Sun has a finite distance it can travel before gravity has it turned back. Our local Universal region is confined visually to itself.

This, in turn, means that Universal regions which aren't ours are also confined visually to themselves.
Kron
1.4 / 5 (11) Dec 06, 2012
How about this. It is the death-throws of the most massive of stars that produce, by fusion, heavy elements such as uranium. If the Big Bang was a such an energetic event, one being able to overcome the massive gravitational attraction of all the energy of the Universe confined to a space smaller than a marble, why were heavy elements not produced at the Big Bang?

Why does a huge star produce the heaviest of elements during a supernova? Why do massive stars not shred to produce atomic constituents (electrons, neutrons, protons, or, quarks and electrons, or some variation)? Why does a stellar explosion cause construction (fusion), rather than destruction (fission, decay), while the Big Bang (the greatest of explosions) caused no such thing?

The core of the exploding star presses into the outlying sphere, this pressure fuses heavy elements. Shouldn't the core of the 'marble' have pressed into its shell to produce elements at least as massive as those created in a supernova?
Kron
1.4 / 5 (11) Dec 06, 2012
Why do we have gamma photons as the first energy of the Universe? Is it because God said let there be light? After this radiation, we have pair production (electrons-positrons, up-antiup quarks, etc.. etc. etc.!). If this model is true, where is the antimatter? If annihilation of these produced pairs took place and took out the antimatter, why is there still matter remaining?
Kron
2.1 / 5 (14) Dec 06, 2012
There is absolutely no need for this creationist science! 13.75 billion years ago there was nothing - and then - Bang the whole of reality came into existence. I mean really??? Is this Universal CREATION model necessary?

Logically, it is easiest to accept that the energy of the Universe always was, in one form or another, present. No creation model. We dismiss the models where God CREATES the Universe, yet grasp the Big Bang model where nothingness CREATES the Universe. Nonsense.

All this because we reach a visual limit. Why assume that the Universe ends at the point where we see nothing else? Why not assume that we are limited in scope (and the Universe is infinite), rather than assume that the Universe is finite (and our scope is unlimited)?
stellar-demolitionist
5 / 5 (6) Dec 06, 2012
Element production in BB nucleosynthesis (BBN) v. SN nucleosynthesis, why is it different?

By the BB theory, when the universe expanded and cooled to the point where it was neutrons (n), protons (p), electrons and photons, there were about 6p:1n, very proton rich. Nuclear reactions happened so frequently that they were in equilibrium. (an equilibrium set by the temperature, density and p:n ratio)

As the temperature and density dropped the reactions became less "violent" and frequent and heavier elements could survive in large numbers. He-4 (alpha particles) He3, Li, H-2, H-3 all formed. In the BB this is where it stops for a couple of reasons. The big one is that the density is dropping rapidly. Another is the fairly common He4 He4 --> Be8 --> He4 He4 as Be8 is so unstable it falls apart unless hit by another He4 to make C12. If Be8 were more stable or the expansion had been slower, BBN would have likely made some elements all the way to Fe, just like stars can w/o exploding.
stellar-demolitionist
5 / 5 (6) Dec 06, 2012
A simplified version of the r-process (maker of U, etc. in SN or other sites)

For the r-process (rapid neutron capture process) you start with a gas with more neutrons than protons. As it cools and expands equilibrium will result in a mixture of He4 leftover neutrons. (see a theme here). Further cooling and expansion allows He4 to stick together and make some heavier nuclei, C12 and beyond. With some build up of nuclei near Fe (and being out of equilibrium) neutrons are captured on the heavier elements in large numbers creating very unstable, very neutron rich nuclei. After expansion has shut down the nuclear reactions (including neutron capture) those unstable nuclei decay to become things like Uranium and Gold.

The big difference between BBN and the r-process is the neutron/proton ratio, starting temperature/density and the expansion rate.

There is no "blast" in the BB and both BBN and r-process happen because the matter is hot and relatively dense.
Kron
1 / 5 (7) Dec 06, 2012
At the densities and temperatures present at Big Bang, proton-proton chain reactions should have been quite frequent. Transmutations of protons to neutrons plus positrons plus neutrinos would have occured at rates far exceeding stellar fusion. H H --> He2, He2 --> D positron neutrino, D H --> He3, He3 He3 --> He4 plus 2protons.

The ratio of protons to neutrons would quickly have gone down. In the above example to get to He4 we are starting with 6 protons. Those 6 protons ended up being 4 protons and 2 neutrons.

Let us not assume that neutrons are required at all. Depending on density and temperature 56 protons could be pressed into a nuclear region (given enough energy to overcome coulomb repulsion), 30 of those protons transmutate, and from 56 protons you are suddenly left with Fe56.
Fleetfoot
5 / 5 (3) Dec 06, 2012
"The very first stars may have turned on when the universe was 750 million years old"

That is badly misleading. What they have found is that there is minimal contribution of metals at that age, the first stars probably formed much earlier. Current simulations suggest either about 130 millions years or around 32 million years if dark matter coalesces earlier as it didn't couple to the early radiation. Of course those are only the first stars and prior to the formation of any galaxies so the results are not in conflict, it is only the article heading that is misleading.
lengould100
1 / 5 (1) Dec 07, 2012
Considering that at z = 1100 (400,000 years after the Big Bang), sufficient re-ionization occurred to allow light to travel as we now expect, we may never know if stars turned on earlier than that.
ValeriaT
1.6 / 5 (7) Dec 07, 2012
The stars cannot be formed from ionized hydrogen, so we safely know, that the older stars cannot exist in Big Bang model. But so far we never observed any sign of re-ionization in the distant Universe. We already observed ancient galaxies which would fall deeply into era of re-ionization and which shouldn't be visible as such. In AWT the Universe is infinite, the red shift is the product of light scattering at the density fluctuations of vacuum and the observable Universe is limited in scope in similar way, like the scope of view inside of landscape under the haze. The remote galaxies aren't visible because the Universe was reionized or something similar, but because their light is too red-shifted and blurred.
Fleetfoot
4.2 / 5 (5) Dec 07, 2012
Considering that at z = 1100 (400,000 years after the Big Bang), sufficient re-ionization occurred to allow light to travel as we now expect, we may never know if stars turned on earlier than that.


WMAP has given a measured value for the redshift of reionisation. Click the "answer" button (bottom right) then try different values on the "reionisation redshift" slider:

http://phys.org/n...ars.html
Fleetfoot
4.3 / 5 (6) Dec 07, 2012
The stars cannot be formed from ionized hydrogen, so we safely know, that the older stars cannot exist in Big Bang model. But so far we never observed any sign of re-ionization in the distant Universe.


We also observe the Gunn-Peterson Trough which shows the end of reionisation.

We already observed ancient galaxies which would fall deeply into era of re-ionization and which shouldn't be visible as such.


Only the Lyman lines are significant, we see them at other wavelengths.

In AWT ...


There is no such thing as you well know.
antialias_physorg
4.2 / 5 (6) Dec 09, 2012
Does it imply, the universe is way larger and older?

No. It simply means that this change of state put the universe into a state where the notion of time has any meaning at all. There's no 'before' which would make the universe older than this state change.

Remember that the notion of time is also part of our model of the universe. You could look at the universe - with complete equal validity - as an unchanging 5D object with no temporal component at all. What i'm trying to illustrate here is that time (and space) aren't indepenedent of the universe but are properties of it. So talking about time (or space) outside the universe is nonsensical.
Fleetfoot
not rated yet Dec 09, 2012
.. as an unchanging 5D object with no temporal component at all.


5D without time? The "Block Universe" interpretation is 4D including time, what are the other two spatial dimensions. Are you extending Kalusa-Klein in some way?
antialias_physorg
5 / 5 (2) Dec 09, 2012
Are you extending Kalusa-Klein in some way?

Nah, I'm just qouting Douglas Adams.
(There the fifth dimension is the probability spread in his WSOGMM* interpretation of the universe. The spread is basically the many-worlds interpretation. So the 'block universe' would encompass all possible worldlines)

But all joking aside: I really do think that time is just a way of looking at the universe - and it only seems natural to us because what we call 'life' is a process that is only possible in a linear timelike fashion.

What I'm trying to say is: Never forget to figure in your own bias (in this case all life's) when trying to explain things.

* Whole Sort Of Geeneral Mish Mash
Fleetfoot
not rated yet Dec 09, 2012
Are you extending Kalusa-Klein in some way?

Nah, I'm just qouting Douglas Adams.
(There the fifth dimension is the probability spread in his WSOGMM* interpretation of the universe.


Cool, I didn't recognise that one :-)

But all joking aside: I really do think that time is just a way of looking at the universe


By that reasoning, so it distance, but we'd best not drift into a discussion of substantivalism or the cranks will have a field day.
joo5t
1 / 5 (1) Dec 10, 2012
Does this mean that it could be possible that there is early life out there that is like 13 billion years more evolved than us?
Meyer
1 / 5 (1) Dec 10, 2012
Does this mean that it could be possible that there is early life out there that is like 13 billion years more evolved than us?
Sure, it's possible that life started elsewhere about 10 billion years before it did on Earth, but you'll have to define "more evolved".

Perhaps the bacteria on that planet are more robust than anything on Earth (until their environment changes in a novel way), but multicellular organisms never evolved.

Or conversely, life could have emerged on a young planet 200 million years ago and rapidly evolved into an organism that we would consider more intelligent and creative and wonderful than humans today.

Or, it could be that the original life on Earth was the result of 10 billion years of evolution somewhere else in the galaxy before hitching a ride on an asteroid to the early Earth. In that case, we are "equally as evolved" as any other lineage that started at the time and survived 'til now.
Fleetfoot
1 / 5 (1) Dec 10, 2012
Does this mean that it could be possible that there is early life out there that is like 13 billion years more evolved than us?


Not quite, 13 billion years ago all matter was hydrogen or helium. It some generations of stars exploding as supernovae to produce the heavier elements to make planets and their occupants. Life could have started something like 10 billion years ago though which would be a head start of about 6 billion years on us.
ValeriaT
1.3 / 5 (4) Dec 10, 2012
Does this mean that it could be possible that there is early life out there that is like 13 billion years more evolved than us?

Such a life formation would be rather improbable, because the heavy elements need multiple stellar generations to concentrate itself during supernova explosions. Each stellar generation takes five billions of years in average. In some wild stellar systems full of interstellar gas the evolution of stars could proceed faster, but such a systems aren't very comfortable for life in general...
Fleetfoot
3.7 / 5 (3) Dec 11, 2012
Each stellar generation takes five billions of years in average.


Their low metallicity meant that Pop III stars were much more massive than later generations so the average lifetime would have been in the tens of millions of years.

The average metallicity seems to have been low around 750 million years according to a single recent study but rose rapidly after that.

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