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The 1st Generation of Stars
Andy_Howell writes "Astronomers may have found members of the first generation of stars in the universe. Using the Hubble Space Telescope and the Keck I telescope, they observed a faint red blob that had been magnified into a double image by a gravitational lens. The blob was found to be a cluster of stars 13.6 billion light years away, seen when the age of the universe was less than a billion years old. The clump appears to contain only about a million stars, and is less than a few million years old. It is thought that swarms of these clumps came together over the age of the universe to create the galaxies we see today."
Because it's not relative *constant* motion. Reputedly, due to the expansion of the universe, things father away appear to be moving away from use faster than things closer to us. This also means the light itself is being expaned -- shifted towards the red.
Go not to the Elves for counsel, for they will say both no and yes
Each dot on that image is a galaxy/star/something. The color of the dot is what's interesting -- the redder it is, typically the further away it is. If you look at the big image, there are a lot of dots, but they're only slightly reddish. The two "interesting" ones are extremely red, indicating that they're very far away. Astronomers have shown that, since the universe is expanding, things further away from us are moving away from us faster and faster. The end result is that the doppler shift caused towards the red end of the spectrum gives us a quick indication of how old things are, and hence, how interesting they might be.
Sensational is more like it. I tried to get into it in the bookstore one time, but every time the author got up to the really juicy part where he was going to explain everything, he dropped his thread and referred me to a later chapter. Also, he was attacking mostly the exterior consequences of Big Bang theory, and as I recall he failed to really get to the main premises. I opted to put the book down. It looked like a crank to me.
The author is intellectually dishonest: at one point he is discussing some electromagnetics simulations that have a spiral galaxy-like appearance, and saying how those support his cosmological electromagnetism theory. What he doesn't tell you is that the images are *cross sections* of tubular structures, and that the field strengths needed to create those structures are *enormous*.
If that BOOK were posted to USENET it would be UTTERLY INDISTINGUISHABLE from the other PHYSICS CRANKS.
-- ;-)
Kuro5hin.org: where the good times never end.
They're not just looking at it with red, green and blue CCD sensors -- Imaging Spectrometers give you a readout of the full spectrum, including characteristic bright (emission) and dark (absorption) lines. The position of these lines in the spectrum changes with distance (red shift due to expansion of the universe) which looks a lot different from just a naturally red star. In fact their estimate of the age of the galaxy is based mainly on how far the lines have shifted!
It is by observing the doplar shift, or "red shift", in the wavelength of a stars light that the length to almost every distant object is measured.
Think of yourself as being on the surface of an expanding baloon: relative to other objects that are close to you on the surface, you are moving very slowly. Relative to objects at the center of the baloon or halfway around the surface, you are moving a little faster (remember this is as the crow flies). Relative to objects clear on the other side of the baloon, you are moving the fastest of all.
On the scale of the universe, objects on the other side of the galaxy are moving extremely fast (relative to you). I'm not sure exactly how fast, but I remember reading somewhere that it is getting close to the speed of light (after all, they have had to cover a huge amount of space to get so far away). This is easily fast enough to have an affect on the wavelength of the light - even a small relative speed will have a small (but probably unmeasurable affect).
IANAAstroPhysicist, so whether this explains the visibly red shift (since scientific spectrographs are much more sensitive than our eyes ), I cannot say. Another explaination might be that the stars are young and therefore cool, but I couldn't say that for sure either.
It presumes the Big Bang, or something like it. Obviously you can't have young hydrogen-only stars unless the universe was different than it is today.
Either the universe exists into the arbitrarily distant past or it has some kind of a start. I've never heard a good hypothesis for a beggining to the universe that doesn't involve some sort of a big bang. Which premise is that book trying to sell? That we always existed?, or that we started from something other than a big bang?
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
The current best estimate of the universe, mainly from measurements of the Cosmic Microwave Background and Type Ia Supernovae, consistently give results around 14-15 billion years, leaning towards the lower half of that range.
In any case, the number "13.6 billion light years" is relative to the actual age of the universe. What was measured was a redshift of 5.58. You can map that into a lookback time, but it depends on the cosmological parameters you assume. The beginning of the universe is at redshift infinity, which will give you another lookback time (ie. age of the universe) that depends on the cosmological parameters.
I don't know what particular cosmology was used to map z=5.58 to 13.6 billion years lookback time, but the STScI press release mentions that the cosmology they used gives an age of the universe of 14 billion years. It's probably a "concordance model" flat universe with 0.3 of the closure density coming from matter and the rest from the cosmological constant, with a Hubble constant around 65-70 km/s/Mpc.
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Well, although the writer makes an indirect implication that isn't quite accurate, yes, there's news you've missed -- namely this article.
An interesting thing about this discovery, if I'm reading it correctly, is it could be a good indicator of the universe's age. It correlates two different facts:
the spectra of the stars suggest that they are _uniformly_ extremely young. This makes it likely that they were all formed when the universe was very young.
the red shift of the cluster indicates it's 13.6 billion light-years away.
So, it's a sighting of an "event" that could only have happened in the early universe, and since the light from the event took 13.6 billion years to get here, it means the universe is just over 13.6 billion years old.
Now, mind you, this is not enough evidence to be certain about that leap, the "red shift" fact has a wide margin of error (since the constancy of Hubble's constant is now in question) and there may be situations where a cluster like this could occur in the universe much later than its early epoch, but it could reduce the wide gap in universe age measurements.
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
A trivia point, for those interested. Helium was named for the sun, helios, first discovered when spectroscopy was very young. This element was not yet discovered on the earth and was thought only to be a "heavenly" element. That is until some researcher was told that if a piece of pitchblende was placed underwater, bubbles would form. He collected these gas bubbles in an inverted flask and analyzed them with the new spectroscope and found it to be helium.
Helium today mostly comes from mines. They are called mines and not wells because they produce a mineral but are essentially just like natural gas wells. This gas comes from radioactive decay which produces alpha particles---helium ions---which then capture electrons from its surrounding and becomes helium gas.
The stars WERE hot and blue when the emitted
the light we are now seeing; if you had looked
at the spectrum of the starlight back then
(because you were floating in space close to
the stars), it would have peaked in the
ultraviolet.
However, the light has travelled a long way
to reach us, and the universe has been expanding
since then. The redshift of these objects is
around z=5.58, which means that we observe photons
to have a wavelength (z+1) = 6.58 times longer
than their rest wavelength. The peak of the
spectrum has moved from the near UV to the near
infrared. Hence, the stars would appear red
if viewed by a person.
The pictures were formed by combining images
taken through several different filters with
HST. Each filter was in the visible range.
The astronomers who made the picture set the
Red plane of the image to correspond to the
picture taken in the reddest filter,
the Green plane to the filter of intermediate
wavelength, and the Blue plane to the bluest
filter. It's false color, but reasonably
like a person would see.
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
The horizon expands.
When the universe was two billion years old, no one object could receive information about anything farther than two billion light years away. But a billion years later, there is time for information to have come from objects that were originally outside of its light cone, but the light cone (in this case called a horizon, because it can't be seen beyond) has expanded beyond them.
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Ok, now for the more complex bit, actually saying what these are.
A photon multiplier is a device which takes in a stream of very low energy photons and generates a stream of much higher energy photons, as a result. It's a basic amplifier, for photons.
A very large telescope gives you a huge collection area. The larger your collection area, the more light you gather. By squishing that light into a much smaller area, you essentially generate a much brighter image.
The same is true of a long baseline. The idea, here, is to increase the time over which you collect the light. Double the time, double the light.
The consequence of using all three techniques is that you can easily collect a few photons from a vast distance, and turn them into an actual, visible image. But don't expect it to be easy. I imagine that the Hubble Telescope had to be pointed at that same spot for 24-48 hours, to generate such a view.
(When you recall that the Earth is rotating on its axis, that it's also rotating round the sun, and that the sun is moving round the galaxy, and that the galaxy has its own motion relative to other galaxies, and that ALL of these are complex, N-body problems, the challange of being able to keep the telescope pointing at a tiny cluster, billions of light-years away for more than a few seconds is an achievement. To manage it for maybe 1-2 DAYS is staggering.)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Looking at the images, they look like they've got pretty good S/N. I haven't seen the spectra, so I can't comment on that, but if they have spectra for the two different images that both give the same redshift, that's not likely noise.
Then it's haze that happens to shift all of the photons redward by a factor of 6.58. In both images independently. And doesn't make them fainter.
That's an interesting topic. All dust that we see in the universe is inside of galaxies, and preferentially blocks red light. So the places that you'd expect dust to make a difference is in the galaxy itself, in the Milky Way, or maybe in the cluster that's lensing the images (if you can come up with a way of expelling the dust out of a galaxy into the intracluster medium without destroying the dust, which isn't easy to do - dust is pretty fragile)
The only possible evidence for gray dust in the voids between large scale structure is as a way out of having the Type Ia Supernova measurements argue for the existence of a positive cosmological constant - some have argued that the reason that the supernovae are fainter isn't that they're farther away, it's that there's some fairly uniform gray dust (it can't be normal dust because then it would preferentially block red light, and we don't see that happening) that is absorbing some of the light. But there is plenty of other evidence pointing towards a positive cosmological constant, so the dust explanation is unlikely.
Hope that helps.
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They are moving away from each other because the universe is expanding. The amount of space between the two points is increasing as the light travels between. Relativity imposes no limit on how fast space can expand. During the inflationary era, the Universe expanded faster than the speed of light.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
Anyhow, assuming you're serious:
- Try radio astronomy data. For example, pulsar searches (related to what I do, forgive my bias) use simple time series data I(t) which would seem to be ideal for your work. Try this:
http://www.atnf.csiro.au/research/pulsar/pmsurv/
- HST data is always available for download,
once the proprietary period has expired, from the HST archive.
You don't care what the data is from, right? Note, though, that this is a 2-dimensional image, so it might have some "fake" compressibility due to redundant information. Radio data does not have this weakness, so I recommend that instead.
- For most astronomy data, you'll need to learn to read FITS format: try this.
Hope this helps - if you're serious and need help, feel free to drop me a note. (shami at astro dot cornell dot edu)"I will take the Ring," he said, "though I do not know the way."
Let's look at this classically. The classical picture is not correct, but it can give some rough idea of how this is possible.
We have two objects moving apart in the early universe. Classically, the distance D between them will be the relatvive velocity, v, times the age of the universe at the time the light in question was emitted.
So lets say D = v*1 Gyr (10^9 years)
Now light from one get's emitted and starts travelling towards the other at the speed of light, c.
In order to see the light from the other source, it has to catch up to us. In other words c*t = v*t + D, where t is the time since the light was emitted.
Substituting for D and solving for v, we get v = c*t/(t+1 Gyr). Hence in a strictly classical approximation, the two objects must be travelling apart at a relative velocity of 0.93c, in reality relativity and cosmology would probably tell you they don't have to moving apart nearly that fast, but the idea is there.
If two objects are moving apart fast enough it will take the light from one a long time to catch up with the other.
Don't forget that the image is actually a visual representation of extremely complex data. Those "little red dots" are just the result of reducing the usefulness of the information to create something pretty to look at. The signifigant parts of the image are picked out by computer algorithms specifically designed to pick out the signifigant parts. Eyeballing it just doesn't cut it.