Apresentação em tema: "Sua Conexão Cósmica com os Elementos"— Transcrição da apresentação:
1Sua Conexão Cósmica com os Elementos James Lochner (USRA) & Suzanne Pleau Kinnison (AESP), NASA/GSFCFirst public version. Notes are from presentation by Sara Mitchell in Aug The notes provide a script that may be used with the slides.Tell participants that we will be pondering the question asked on the poster, “What is your cosmic connection to the elements?”Traduzido por Paulo Marcelo Pontes,
2Conexões Elementares What is this? [Periodic Table] What does it show? How is it arranged?Can you tell me some of the elements you encounter every day, in the objects all around you? Tell me an object and the element(s) in it.[Have audience make the connection between everyday objects and the elements in the periodic table. For example:Gold in jewelryAluminum in soda cansTitanium in eye glass framesHydrogen and oxygen in waterCalcium in milk and bonesNitrogen in the air]Make sure they identify some elements heavier than Iron.End with question: Where do these elements come from? (Some may say, the earth. Let this lead to solar system (and its formation), and ultimately the stars.)
3O Big BangNow let’s start at the beginning, with the Big Bang. The Big Bang created Hydrogen, Helium, and a tiny amount of Lithium. [Click for WMAP.]The image is from the Wilkinson Microwave Anisotropy Probe, which is a long and fancy name that we usually shorten to “WMAP.” This is a baby picture of the universe, from when it was a mere 379,000 years old.The image shows differences in the temperature of the microwave background. The average background temperature is 2.73 degrees above absolute zero. The red areas are “warmer” than this, and the blue areas are “cooler.”WMAP is sensitive to measuring differences in temperature as small as millionths of a degree, so when we say “warmer” or “cooler,” we may be referring to fluctuations of thousandths or millionths of degrees.The WMAP results confirmed several ideas we had about the universe -- the age of the universe is 13.7 billion years, and stars started forming 200 million years after the Big Bang. It did this using the fluctuations measured this image.The Cosmic Microwave Background was one of the strongest pieces of evidence for the Big Bang theory.Source WMAP result of Feb 2003.
4A Cosmologia do Big Bang A expansão do universo começou iniciou há um tempo finito no passado, em um estado de enorme densidade, pressão e temperatura.“Big Bang” é uma família de teorias bem sucedidas que não possuem competidores óbvios.Explica o que nós observamos, e tem realizado diversas previsões com sucesso.The first important question is:What is the Big Bang?Most astronomers theorize that the Universe started with a massive explosion. This happened at a finite time, and everything was very hot, very dense, and under a lot of pressure.The Big Bang is a very successful family of theories that explains what we see and has made several predictions that have been confirmed. The Big Bang is consistent with observations we’ve made.[This explanation of what the Big Bang is and why it is used may be helpful to some teachers in areas where formation of the universe is a sensitive topic.]
5Big Bang Nucleossíntese Nos primeiros três minutos, Hidrogênio & Hélio foram formados.Quando t =1 s, T= K: sopa de partículas: fótons, elétrons, pósitrons, prótons, nêutrons. Particulas criadas & destruídas.Quando t =3 min, T= K: p + n DD + D => HeRight after the explosion, things are very, very hot, over 10^32 degrees! Matter and energia are expanding outward.At one second after the Big Bang, the temperature is ten billion degrees and we have a “particle soup.” It’s really too hot and energetic for any nuclei heavier than Hydrogen to form, so we mostly have lots of particles being created and destroyed -- protons, electrons, neutrons, positrons, and plenty of other “-ons.”But things are cooling down pretty quickly. After three minutes have passed, the temperature has dropped to one billion degrees, and we see the first particles coming together. A proton and a neutron join to form Deuteron, the nucleus of Deuterium (or “heavy water”).From the Deuterium, we can get Helium -- two Deuterons join to form one Helium. Very occasionally, enough Deuterium collide to form Lithium, but this was rare.As the Universe expands, the temperature falls and soon it is too cool for more nuclei to form. This is what the Big Bang forms in the first few minutes -- 95% Hydrogen and 5% Helium (and a trace amount of Lithium).Atoms form at T=3,000K when the electrons “recombine” with the nuclei to form atoms. At this “recombination”, the universe becomes transparent. This 3,000K black body radiation has been redshifting ever since, and is now 2.7K.
6Estrelas Pequenas So where do we get the rest of these elements? Let’s move along, to small stars. What do we mean by “small”?Well, only in astronomy can you call something 2 x 10^30 kg “small”! Our Sun is a small star, and so are stars smaller than about five times the mass of our Sun. These stars run on similar processes, and share a similar fate.[click to show waterfall]These small stars form Helium, Carbon, Nitrogen, and Oxygen in their cores through FUSION
7Estrelas Pequenas: Fusão dos elementos leves (a 15 milhões de graus Celsius !)4 (1H) => 4He + 2 e+ + 2 neutrinos + energiaDe onde vem a energia ?Massa de quatro 1H > Massa de um 4He[Click to reveal “Fusion.”]Elements in small stars are formed through FUSION. At what temperature does fusion start? Does anyone remember?[let people “bid” on the temperature until ~15 million degrees][Click to reveal answer]Why does it after to be that hot?[To overcome the electrostatic repulsion of the positive protons.][Click for equation.]These small stars fuse Hydrogen into Helium in their cores.The energia comes from the slight excess of mass of the 4 input H as compared to the resulting He. The mass gets converted into energia via E=mc^2E = mc2
8De Estrelas Pequenas a Gigantes Vermelhas Depois que o Hidrogênio acaba no núcleo,energia liberada pela fusão nuclear não consegue neutralizar por mais tempo a força da gravidade.Núcleo colapsa,Energia cinética do colapso convertida em calor.Esse calor expande as camadas exteriores.Provisoriamente, quando o núcleo colapsa,Aumentando Temperatura e Pressão ...Eventually, the Hydrogen runs out. Remember, there is a balance between the energia created by fusion and the star’s gravity that keeps it from collapsing. Without fusion, the gravity isn’t balanced, and the star’s core collapses. This collapse causes an increase in temperature and pressure, and the star puffs up and becomes a red giant!
9Produção de Elementos Pesados A 100 milhões de graus Celsius, Hélio entra em fusão:3 (4He) 12C + energiaDepois que o Hélio acaba, pequenas estrelas não são grandes o bastante para atingir temperaturas necessárias para que o Carbono entre em fusão.The core continues to increase in temperature and pressure, reaching 100 million degrees. At this temperature, it is hot enough to fuse Helium into Carbon. The energia from this fusion keeps the star from collapsing. Nitrogen and Oxygen fuse in a similar way.But eventually, the core runs out of materials again, and we don’t make any heavier elements. In fact, this cycle ends with another core collapse, expelling the extended atmosphere as a planetary nebula.So where do we get the heavier elements? At this point, we only have Hydrogen, Helium, Carbon, Nitrogen, and Oxygen..
10Estrelas Gigantes Large stars continue where small stars leave off. These are stars larger than 5 times the mass of our Sun.[Click twice to reveal Calcium and Aluminum examples.]Large stars create many of the heavier elements beyond what the small stars produce, like the Calcium in milk and the Aluminum in cans.
11Elementos Pesados das Estrelas Gigantes Estrelas gigantes também têm fusão de Hidrogênio em Hélio, e Hélio em Carbono.Mas suas grandes massas lead to temperaturas muito altas, nas quais ocorre a fusão de Carbono em Magnésio, etc.Just like small stars, large stars fuse Hydrogen into Helium, and Helium into Carbon.But the larger mass leads to higher temperatures, and a series of core collapses create heavier elements through fusion.
12Formação de Elementos por Fusão Elementos Leves Elementos Pesados4 (1H) He + energia28Si + 7(4He) Ni + energia Fe3(4He) C + energia4He + 16O Ne + energia4He + 12C O + energia12C + 12C Mg + energia16O + 16O S + energiaThis periodic table demonstrates the fusion reactions in large stars. [click]Notice that we’re always moving from lighter to heavier, from left to right.We’ve seen (click #1) 1H -> 4He and (2) 4He -> 12C.These are further representative reactions that occur in massive stars:(3) Carbon to Magnesium (12C -> 24Mg)(4) Helium and Carbon to Oxygen (4He + 12C -> 16O)(5) Oxygen to Silicon (16O -> 32Si) or Oxygen to Sulfer and He(6) Helium and Oxygen to Neon (4He + 16O -> 20Ne)(7) Helium and Silicon to Nickel (which decays to Cobalt and then to Iron via successive positive beta decays) (28Si + 7(4He) -> 56Ni -> 56Co + e+ -> 56Fe + e+NEARLY ALL ELEMENTS THROUGH IRON ARE CREATED THROUGH FUSION IN LARGE STARS.energia is no longer released in the reactions to form elements heavier than Iron. These heavier elements require the INPUT of energia for creation. Again, we lose the balance between internal pressure and the force of gravity, and the star collapses again.Periodic table is from
13SupernovaThe collapse of a large star causes an explosive shock wave, blowing most of the star’s mass into space in a SUPERNOVA.A supernova is very hot and energetic, and able to create heavier elements than fusion created in the star’s core.[Click to reveal Gold and Titanium.]The input of energia needed the create elements beyond Iron is available in the supernova. From this we get the remaining naturally occurring elements, like the Gold in jewelry and Titanium in glasses frames.
14Então a fusão para no Ferro. SupernovaA fusão de Ferro absorve energia, mais que a energia liberada.Então a fusão para no Ferro.energia liberada pela fusão nuclear não neutraliza a força da gravidade por mais tempo.Mas agora there is nothing para neutralizar a gravidade.Estrelas Massivas acabam sua vida em uma explosão supernova.
15Supernova O poder da explosão de uma supernova: X-raySilícioCálcioFerroO poder da explosão de uma supernova:Dispersa elementos criados nas estrelas gigantes.Cira novos elementos, especialmente aqueles mais pesados que o Ferro.Supernovae are able to do two very important things:(1) Create new, heavier elements.(2) Disperse the elements that were created in the star that exploded.These images are from Chandra, showing the Cassiopeia A supernova remnant in different x-ray energies. These images show the distribution of elements ejected in the explosion. They are part of a gas that’s about 50 million degrees.In these images, yellow regions show the most intense concentration, followed by red, purple, and green.The upper left image is from all X-ray energies, and the others are centered on the lines of particular elements (Silicon, Calcium, and Iron).Note the asymmetry, especially in silicon, possibly due to an asymmetry in the explosion. The iron image suggests that the layers of the star were overturned either before or during the explosion.[All images are 8.5 arc minutes on a side (28.2 light years for a distance to Cas A of 11,000 light years).]See
16Raios Cósmicos Did anyone notice that we missed a few elements? We get H and He from the Big Bang, and C through Iron in stars, and heavier elements from supernovae… what did we miss?LITHIUM, BERYLLIUM, AND BORON![Click to reveal Lithium batteries.]These elements are mostly formed through cosmic ray interactions.What are cosmic rays?Cosmic rays are high-energia particles moving through space at velocities close to the speed of light. They’re little bits of matter, often the nuclei of the elements, most likely sent zinging through space by supernova explosions (or perhaps stellar winds).
17Raios CósmicosLítio, Berílio, e Boro são dificilmente produzidos nas estrelas.(Li, Be, e B são formados nas cadeias de fusão, mas eles são instáveis a altas temperaturas, e tendem a quebrar-se em resíduos de He, os quais são muito estáveis).Então qual é a origem desses elementos raros?=> Colisões de Raios Cósmicos com Hidrogênio & Hélio no espaço interestelar.Lithium, Beryllium, and Boron are formed in stars, but they’re very unstable at the high temperatures in the core of stars. Therefore, they break down quickly into Helium.These elements are predominantly created through the collision of cosmic rays with the atoms of Hydrogen and Helium found in interstellar space. When cosmic rays hit atoms, they produce new elements.
18Colisões de Raios Cósmicos e ISM Núcleo leveMatéria interestelar(~1átomo de hidrogênio por cm3)Raio cósmicoLítio, berílio, e boro e crescimento sub-ferro atribuídos a fragmentação nuclear de carbono, nitrogênio, oxigênio, e ferro com matéria interestelar (primariamente hidrogênio e hélio).(CNO ou Fe) + (H & He)ISM (LiBeB ou sub-Fe)The cosmic rays are travelling so fast through space, it hits the Hydrogen or Helium with a lot of force, and parts of its nucleus can be “chipped off.”Here’s a diagram of such a collision!When the cosmic ray hits the Hydrogen or Helium, it fragments into two smaller, lighter nuclei.In the equation at the bottom of this slide, Carbon, Nitrogen, Oxygen, or Iron nuclei collide with Hydrogen or Helium in the interstellar medium to create lighter elements -- Lithium, Beryllium, Boron, or other elements lighter than Iron.So these interactions create elements that weren’t stable enough to be created at the high temperatures required for fusion in a star.
19Elementos Cósmicos Branco - Big Bang Rosa – Raios Cósmicos This is a summary of the major production mechanisms for each of the elements. Note that it is the background for the poster.Many elements are generated from more than one process, and where there are two nearly equal contributors, we gave the element two colors.White - Big BangYellow - Small StarsGreen - Large StarsBlue - SupernovaePink - Cosmic Ray InteractionsBranco - Big Bang Rosa – Raios CósmicosAmarelo – Estrelas Pequenas Verde – Estrelas GigantesAzul - Supernova
20Sua Conexão Cósmica com os Elementos? The poster draws together all of the ideas in this presentation.We’re in the center, surrounded by all sorts of everyday objects (glasses, balloon, plants, etc.).These objects demonstrate our connection to the elements of which they are composed.The background is the periodic table, which represents all of the elements.And the sphere around the center connects the elements (and the objects) to the cosmic processes which created them!So we are all made of stars (or at least of space)!Note that the back of the poster has some of the basic information from this presentation for a quick guide to the poster.
21Composição do Universo Atualmente, esta é a composição apenas do sistema solar.A composição varia de lugar para lugar no universo, e entre objetos diferentes.This is a graph of elemental composition.The vertical scale is logarithmic, with H arbitrarily set to 10^12 so that the elements with the lowest abundance still have a value of 10^0, or 1.So this scale reflects powers of ten -- Hydrogen is at 10^12, Helium is around 10^11, and so on.You can see the big peaks for Hydrogen and Helium, both produced in the Big Bang. There’s a dip for Lithium, Beryllium, and Boron because they’re not really produced through fusion, but by cosmic ray interactions. From there, there’s a relatively steady decrease in abundance, moving through the elements made in small stars to the ones only made in large stars, then supernovae…[Lead is striped to show creation by radioactive decay.][Click for the text!]This is really just the solar system! It’s hard to get a picture like this for the whole universe -- composition varies in different areas of the universe. Our solar system makes a nice model.[Re - the Cosmic Rays have enhanced abundances for Li, Be, B, and Sc, Ti, V, Cr, Mn. Also, the solar system has a deficit of Li, Be, and B beyond the abundance in the universe.]
22“O que existe ali?”(Desenvolvido por Stacie Kreitman, Falls Church, VA)Uma atividade em sala de aula demonstra as diferentes composições elementares dos diferentes objetos no universo.Demonstra como nós estimamos as abundâncias.Allow minutes for the activity.Participants are given bottles which model the elemental composition of the Sun, the interstellar medium, carbonaceous Chondrites (meteorite), the earth’s atmosphere, and the elements formed in a supernova explosion. Participants are also given a key as to what element each substance represents, and the abundances in each substance.Give 1 bottle to each group of After they’ve all had time to determine what they have, have each group say what they have and how they determined that.The activity includes a “mystery” bottle with a substance not listed on the key. Those groups should first share what they think the composition is. Then the entire audience can attempt to determine what the substance is.See for the activity.
23Top 10 Elementos no Corpo Humano Elemento por % átomos10. Magnésio (Mg) %9. Cloro (Cl) %8. Sódio (Na) %7. Enxofre (S) %6. Fósforo (P) %5. Cálcio (Ca) %4. Nitrogênio (N) %3. Carbono (C) %2. Oxigênio (O) %1. Hidrogênio (H) %Source:Element Symbol % NotesOxygen O 65.0 Water; organic compoundsCarbon C 18.5 Organic compoundsHydrogen H 9.5 Water; organic compoundsNitrogen N 3.2 Part of all protein moleculesCalcium Ca 1.5 Bones/teeth; clotting; hormonesPhosphorous P 1.0 Nucleic acids/ATP; bones/ teethSulfur S 0.3 Component of many proteinsChlorine Cl 0.2 Water movement between cellsSodium Na 0.2 Water balance; extracellular fluidMagnesium Mg 0.1 Muscle contraction and nervesIodine I <0.1 Production of thyroid hormoneIron Fe <0.1 Basic component of hemoglobinElements that make up less than 0.1% of the body are “trace elements”, like:Some trace elements are:cobalt copper fluorinemanganese silicon zinc Nickel
24Nós precisamos apenas da luz ! Análise EspectralNem sempre nós conseguimos uma amostra de um determinado pedaço do Universo.Nós precisamos apenas da luz !
25Análise Espectral Cada elemento um único sinal espectral: Determinado pelo arranjo dos elétrons.Linhas de emissão ou absorção surgem a partir do re-arranjo dos elétrons nos diferentes níveis de energia.Composition is usually determined through spectroscopy. Each element gives off a unique “signature” of specific wavelengths of light, which we see as bright lines in its spectrum.By measuring the relative intensities of the lines from different elements, we can determine their abundance in an object being observed.The optical spectrum of H shows the Balmer lines - transitions to/from the n=2 electron shell. From red to blue, this spectrum shows H-alpha (transition from n=3 to n=2), H-beta (transition from n=4), H-gamma (transition from n=5), and H-delta (faintly).We’re used to seeing these spectra. What if you could hear them ?Hidrogênio
26Nickelodeon Atividade de Classe (Desenvolvido por Shirley Burris, Nova Scotia)Dispunha um arco-íris de cores sobre um teclado de pianoEntão, “toque” um elementoHidrogênioPrint a colored spectrum, cut it into strips, and lay the strips on the keys of a musical keyboard.Then put down the emission spectrum of an element, and line up the lines with the keys.Then play the element.
27Mais Elementos Musicais Agora toque outro elemento:HélioCarbonoE outroPlay helium. Go back and play H again, and ask them to listen for the difference. The difference arises from the yellow-green line.After you play carbon, note that you can play the elements either as chords (as we did) or as individual notes up the scale. Also note that you can place the spectrum any where you want, but around middle C is usually best.The chords won’t sound familiar, which is good, because you want participants (and students) to listen for the differences (rather than for something they recognize).
28Adquirindo Água com as Mãos OxigênioHidrogênioYou can now combine elements, either to create molecules or to create the substances we analyzed in the bottles.E agora teremos ...Água
29Sua Conexão Cósmica com os Elementos? Check out the website at the bottom of this slide for this presentation and more activities and materials. The web site contains an on-line version of the booklet which accompanies these materials, and a link to an order form for requesting a hard copy of the poster and booklet.So we have pondered this question, and hopefully we have some better ideas about the answer. And if you need further inspiration … (next slide)
30Conexões CósmicasPara fazer uma torta de maçã do nada, você deverá primeiro inventar o universo.Carl Sagan