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  • - I'm here with Philipp Heck, who is the Robert A. Pritzker, Associate Curator of MeteachsadfaaMeteoraww shoot...

  • - The Robert A. Pritzker, Associate Curator for Meteoritics and Polar Studies.

  • - There. - I practiced this many times.

  • - Yeah. Today we're going to talk about the age of the solar system.

  • -These large, white, aluminum ridge inclusions that you can see here, these are the oldest minerals that formed in the solar system,

  • and they can be dated, and it' basically the start of the solar system. We call it T-0, time 0. It's 4.567 billion years.

  • It's an easy number to remember. 4.567 billion.

  • - We know how old the solar system is because of this specific specimen. - Exactly, exactly. This defines T-0.

  • When I give public talks, I usually give people a slice in plastic, and I say "You can hold the oldest piece of material in the solar system."

  • And, even, you don't see it, but the oldest material available to anyone on this planet is in there.

  • There's nothing older that you can touch. - Wow.

  • - Pre-solar grains. They're older than the sun, older than the meteorite itself.

  • Some of them might be as old as 5.5 billion years. - And how do you know that?

  • - So these pre-solar grains, they can be analyzed chemically.

  • Their isotopic composition is highly anomalous, very different than anything in the Solar System.

  • Their composition cannot be explained by any process that can occur in the Solar System.

  • The fact that they are embedded in that rock tells us they could not have been incorporated later;

  • They must have been part of that mixture from which the rock formed.

  • And since the rock formed 4.6 billion years ago, they must be older. - Older the 4.6 billion years.

  • - And some minerals even can be dated. So far we have only dated approximately 30 grains.

  • Most of them are about 200 million years older than the sun.

  • And a few of them are about a billion years older than the sun, which makes them about 5.6 billion years old.

  • We think the solar system formed, basically from a cloud of gas and dust, and this cloud of gas and dust formed from different sources, from different stars.

  • Some of these stars were indeed stellar explosions, supernovae. They exploded, and during these explosions, new elements formed.

  • After the matter cooled down, some of this matter condensed as gas.

  • There were other starsmany other starswhich were like the sun, but they were already at the end of their life.

  • They expanded, became red giants, and expelled the matter into space. And from all these mixtures of stellar ejecta, this pre-solar cloud formed.

  • Within this pre-solar molecular cloud, the protosolar disk formed. It's basically a rotating disk of gas and dust.

  • The protosun formed, and later, the sun. Planetary building blocks formed.

  • Most of the matter was alteredheatedthe pre-solar signature is not visible anymore, but some of this pre-solar matter survived without having been altered.

  • That's whats trapped in hereit's only a tiny fraction. The most abundant type of pre-solar materials are diamondsnano-diamonds.

  • These diamonds are tinythey're only 2 nanometers acrossmaybe consist of 1000 to 2000 carbon atoms. We can extract them from meteorites.

  • We basically dissolve everything else, just are left with the acid residue of diamondsand in this little vial I have billions of diamonds.

  • You normally wouldn't see them because they are so small they wouldn't scatter light, but they clump togetheras you can see, that white residue

  • - Yeah - These are all diamonds. It's literally stardust.

  • - It's awfully ethereal looking. Kind of like floats around in this nebulousness.

  • -These diamonds, they were discovered in Chicago, in 1987, at the University of Chicago, with a Field Museum meteorite.

  • -Really? That...it's overwhelming.

  • It's...It's— How did you... how did you get into this?

  • - Yeah, so when I heard about this first, I was extremely fascinated, and I heard about it when I was a student of earth science in Switzerland,

  • and did an undergraduate project in a cosmo-chemistry lab there. "This is so fascinating, would it be possible to do a PhD there?" -Yeah

  • - Just because I was completely hooked. I was always interested in astronomy, and volunteered at the local observatory there, and thought, "Oh, if I could do that for a living, that would be fantastic."

  • And, yeah, actually, the opportunity came up, and I was able to work on the stardust duringfor my PhD. -Really?

  • - And everything, yeah, so I'm very fortunate to work on such a very—I would sayon the oldest matter that is available anywhere on this planet.

  • It keeps us very motivated, and it's really great. -Yeah

  • - With every question that you answer, you open 10 more questions that can be studied, but then you have to make a wise decision, which questions are actually worth pursuing to answer?

  • -Yeah. - Worth the time and money. And one of these is the origin of those nano-diamonds.

  • Because nano-diamonds are basically pure carbon, and they survived the formation and evolution of our Solar Systemand almost nothing else did survivealmost everything has been altered.

  • So the carbon in our body and our skin, you don't see a pre-solar signature anymore. - Yeah

  • - Although it might have the same origin as these diamonds. -So, the carbon that makes up those diamonds is the same carbon that makes uplike the carbon within me and you.

  • - Exactly. - And all of life on Earth.

  • - Exactly. - So this is like our great times infinitygreat, greatancestor, essentially.

  • - Yeah, so I think we have a common origin. - Yeah.

  • - These diamonds, and life on Earth, and this is a proxy ofit's basically the tiny fraction that survived all these billions of years since the planets and the Earth formed.

  • And by studying those diamonds, they open upthey are like a time capsule. By studying them, we can learn about the pastabout the time before the Solar System.

  • (So if you were to take those diamonds down to a pawn shop, how much is one of them worth?)

  • - He would not even know.

  • - I don't know, but I always tellthey probably wouldn't make nice engagement rings, because they are so small, but there are millions!

- I'm here with Philipp Heck, who is the Robert A. Pritzker, Associate Curator of MeteachsadfaaMeteoraww shoot...

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スタースタフとナノダイヤ (Starstuff and Nanodiamonds)

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    Hhart Budha に公開 2021 年 01 月 14 日
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