Lecture 2 (cont’d): In the Beginning: Origins of the Elements

1. The Periodic Table: elements and isotopes2. Synthesis of elements in the Early Universe

3. Stars: making the “elements of life”

4. We are made of star stuff.

2

Millenium Run, Springel et al. 2006

* LIFE & CULTURE * JANUARY 29, 2011

If You Don't Like This Universe…Brian Greene and David Gelernter discuss alternate realities, like a cosmos with a Jets-Bears Super Bowl

Electron Orbits in Atoms

The Periodic Table

The Periodic Table

Electron Orbits in Atoms

Electron Orbits in AtomsPlots of electron density shapes of 1s, 2p and 3d orbitals:

The Periodic Table

… in terms of electron subshells:

The Periodic Table

… the elements of Earth life:

Looking Back into the Past

HotDenseSmooth

ColdThinClumpy

Looking Back into the Past

NASA’s WMAP mission mapped the sky in microwaves

Looking Back into the Past

False-color map of thetemperature fluctuationsseen by measured byWMAP.

This pattern appears tobe random, but it is the superposition of wavesof different size. It islike a fingerprint.

The pattern seen isconsistent only if 75% ofH and 25% of Heconstitute the gas.

Stars like our Sun expand and disperse their envelopes

It takes 3 to 10 Ga for thethe synthesis of light and heavyelements in these stars.Their envelopes are rich in heavyelements - yet, especially inC, N, and O. Eventually new stars are formedfrom this gas.

How do we know that ?a) We see the signaturesof these newly synthesized elements in their light.

The most massive stars end their thermonuclear cycles as Supernovae

Supernova 1994D:the bright explosion of astar in the outskirts of adistant galaxy.

During the explosion, in a matter of minutes, hours anddays, large quantities of iron and other heavy elements are synthesized.

The most massive stars end their thermonuclear cycles as Supernovae

During the explosion, in a matter of hours and days, large quantities of iron andother heavy elements aresynthesized.

How do we know that ?a) We see the signatures in the light from the explosion;b) Computer models reproduce measured isotopic ratios in SolarSystem objects and other stars.

We are made of star stuff

By mass -• Human body: H = 10%, He = 0%, C = 18%, N = 3%, O = 65%, Ca = 2%, Fe = 0.004%.

• Earth’s crust: H = 1 %, He = 0%, C = 2%, N = 0%, O = 47%, Si = 26%, Ca = 3%, Fe = 5%

• Sun & stars: H = 71%, He = 27%, all other elements = 2% (with O most abundant).

The Periodic Table

… the elements of Earth life:

Main points to take home:

1) Elements: def. by protons in atom (90 stable); Isotopes: def. by neutrons in atom (266 stable); The Periodic Table of the Elements allows the analytical description of all species of mineral or biological origin.

2) There are 2 main sources of their origin:a) H, He, & Li were synthesized ~13.7 Ga ago

in the Early Universe;b) stars transform H & He into all the rest.

3) Planets and life are here thanks to many past generations of stars.

The Periodic Table

We are made of star stuff

By mass -• Human body: H = 10%, He = 0%, C = 18%, N = 3%, O = 65%, Ca = 2%, Fe = 0.004%.• Plants: H = 10%, He = 0%, C = 3%, N = 0.3%, O = 79%, Ca = 0.1%, Fe = 0.02%.• Earth’s crust: H = 1 %, He = 0%, C = 2%, N = 0%, O = 47%, Si = 26%, Ca = 3%, Fe = 5%• Sun & stars: H = 71%, He = 27%, all other elements = 2% (with O most abundant).