Herschel confirms the origin of cosmic dust

Jan 08, 2013
The Crab Nebula as seen in visible (left), showing the glow from hot, energised gas, and far-infrared (right), showing warm dust (green/blue) and cooler dust (yellow/orange) shining in the remnant. Credit: ESA/Herschel/SPIRE/PACS/MESS (Far-IR); NASA/ESA/STScI (Visible).

(Phys.org)—The Herschel space observatory has produced an intricate view of the remains of a star that died in a stellar explosion a millennium ago. It has provided further proof that the interstellar dust which lies throughout our Galaxy is created when massive stars reach the end of their lives.

The Crab Nebula lies about six and a half thousand light years away from Earth and is the remnant of a dramatic explosion, called a supernova, originally seen by Chinese Astronomers in 1054 AD. Starting out at 12-15 times more massive than the Sun, all that was left after the dramatic death of the star is a tiny, rapidly rotating neutron star and a complex network of ejected stellar material.

The Crab Nebula is well known for its intricate nature, with beautiful filamentary structures seen at . Now, for the first time, thanks to Herschel's exquisite resolution, we can see these filaments of dust in the far-infrared region of the . After ruling out other sources, astronomers using Herschel showed that these filaments are made of cosmic dust, lying in exactly the same place that we see the densest clumps of supernova ejecta. This provides definitive evidence that the Crab Nebula is an efficient dust factory, containing enough dust to make around 30,000-40,000 planet Earths. The dust is made of a combination of carbon and silicate materials, which are crucial for the formation of planetary systems like our own Solar System.

Far-infrared, showing warm dust (green/blue) and cooler dust (yellow/orange) shining in the remnant. Credit: ESA/Herschel/SPIRE/PACS/MESS

Previous of the Crab Nebula, using the , used much shorter wavelengths and so only showed the warmer dust. Spitzer found only a tiny amount of dust, simply because it missed the massive reservoir of colder dust now known to exist. Herschel, observing at longer wavelengths, is able to detect both warm dust (shown in green/blue in the image) and also cool dust (shown as yellow/orange), some as cold as -260 Celsius. This has allowed astronomers to measure the total mass of dust for the first time.

Large amounts of dust have been seen in supernova remnants before, but the Crab Nebula is particularly exciting as it provides the cleanest view of what is going on. Unlike many other remnants there is almost no dusty Galactic material in front of or behind the Crab Nebula, so the image is uncontaminated by material in between it and the Earth. This also allows astronomers to rule out the possibility that the dust was swept up as the shockwave expanded throughout the surrounding region.

In most supernova remnants, much of the dust is destroyed as it ploughs into the surrounding interstellar gas and dust, crushed by violent shockwaves. A final treat is that the is a much kinder environment for dust grains, so the dust does not seem to be destroyed. This may be the first observed case of dust being freshly-cooked in a supernova and surviving its outward journey carried along by the shock wave. We now have definitive evidence that supernovae created the raw materials for the first solid particles, the building blocks of rocky planets and life itself, in a blink of an eye.

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kevinrtrs
1 / 5 (13) Jan 08, 2013
Now of course the question is what is the mass number of the heaviest element detectable in the dust?
Will this explain where elements heavier than iron came from?
Is there any trace of Osmium, Barium, Nickel, Gold, Lead, Strontium, Uranium, Tellurium or even Tantalum to be found in there?

If not, then the claim that supernovas are the source for planetary materials is rather light on substance.
In fact I'd say it's pretty much bogus.
Q-Star
3 / 5 (4) Jan 08, 2013
Now of course the question is what is the mass number of the heaviest element detectable in the dust?


My guess is 1, it would be very surprising to me if there were zero hydrogen in the dust.
Torbjorn_Larsson_OM
5 / 5 (8) Jan 08, 2013
Creationists shouldn't comment on science, it is hilarious and makes deconverts from religion, see Dawkins's Convert's Corner.

Supernova's are known for their production of elements higher than some isotopes if iron and nickel. [ http://en.wikiped...ynthesis ]

"Gamma ray lines identifying 56Co nuclei and 57Co nuclei, whose radioactive halflives limit their age to about a year, proved that 56Fe and 57Fe were created by radioactive parents. ... Other proofs of explosive nucleosynthesis are found within the stardust grains that condensed within the interiors of supernovae as they expanded and cooled. Stardust grains are one component of cosmic dust. In particular, radioactive 44Ti was measured ... Other unusual isotopic ratios within these grains reveal many specific aspects of explosive nucleosynthesis."

Creationism is unwarranted science doubt, devoid of substance. In fact I'd say it's known to be not only myth but completely bogus as social stunt.
RealScience
5 / 5 (7) Jan 08, 2013
@kevin - You probably realize that ~99% of the earth (our best known example of planetary material) is elements iron or lighter, mostly and silicates and iron that have already been found in Crab Nebula dust.
And you probably realize that these elements are known to be synthesized in stars.
So EVEN YOU should know that 99% of planetary material could be from the dust without even looking for heavier elements.

And are you saying that there are no heavier elements in the Crab Nebula dust? Do you promise to stop posting if any are ever found? Nickel is BY FAR the most abundant heavier-than-iron element on earth, and it is VERY abundant in Crab Nebula dust (and was found over 30 years ago).

From your question it sounds like you are unfamiliar with the s-process and the r-process for neutron capture, which produce heavier elements. Both processes occur in large stars, especially the R process during a supernova.

At least start with Wikipedia and learn something before posting.

cantdrive85
1 / 5 (6) Jan 08, 2013
Now, for the first time, thanks to Herschel's exquisite resolution, we can see these filaments of dust in the far-infrared region of the electromagnetic spectrum. After ruling out other sources, astronomers using Herschel showed that these filaments are made of cosmic dust, lying in exactly the same place that we see the densest clumps of supernova ejecta. This provides definitive evidence that the Crab Nebula is an efficient dust factory


Why is that definitive evidence? It's not at all unexpected for the dust to be in the densest "clumps of supernova ejecta". The plasma filaments which are claimed to be clumps create powerful magnetic fields which will draw the dust and "gas" from vast regions about them.
Torbjorn_Larsson_OM
3.7 / 5 (3) Jan 09, 2013
@ cantdrive85: Because this is the main theoretical dust mechanism, the supernova material has to end up somewhere.

As for your speculations, there are no such "powerful magnetic fields", according to observations of field strength.
astrofairy
5 / 5 (3) Jan 17, 2013
@kevinrts: I wrote the paper which this blog is referring too and I'd like to respond to your statement that our claim is "pretty bogus". We certainly wouldn't publish anything we didn't have evidence for. In fact your question is rather a good one as it's actually pretty hard to figure out what the dust in the Crab is made of. This is because the signature (or fingerprint if you like) of cosmic dust is pretty smooth. Carbon-rich or silicate-rich dust explains the data pretty well (we know it can't all be iron dust because if it was, we would need more than 10Sun's worth to explain the data - this is not realistic).

We know that in the ejecta itself, there is a lot of carbon, oxygen and iron from the star which blew up and then a load of extra heavier stuff was created in the explosion. So the dust probably reflects some mixture of these elements. @RealScience is correct -carbon and silicate dust created by stellar explosions *is* a source of materials needed to make planets
astrofairy
5 / 5 (3) Jan 17, 2013
@cantdrive85:

"the definitive evidence that the Crab Nebula is an efficient dust factory" statement from Phil's blog and from the original paper (which I wrote) *is* related to the location of the dust. You are correct that it is not at all unexpected for dust to be seen in the same place as the densest bits of gas, but what is unexpected is that there is a large amount of dust in the Crab Nebula in the first place. And as a bonus we can now tell (using sharp images) that these dust clouds are in *exactly* the same place as the material ejected from the explosion i.e. the cosmic dust was created only after the star exploded.

If the dust wasn't in the same location as these dense filaments, then we may suspect it wasn't made in the supernova at all. But then we'd expect all the dust to simply sit around the outside of the Nebula - we see this in the more violent stellar explosions where the dust is definitely not created by the supernova.

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