the eye the universe in my pocket observatory les étoiles

2
1 2 4 3 3 3 3 When the Universe was very dense and hot (T = 10 12 K), shortly after the Big Bang*, it contained only elementary particles of matter (quarks, electrons, neutrinos) and ‘grains’ of light called photons. As they cooled, the quarks combined into protons and neutrons in equal amounts. But as the temperature dropped, most neutrons turned into protons which are less massive. When the temperature fell below 10 9 K, there were 7 protons for every neutron. Neutrons and protons then combined to form nuclei . The most stable nucleus that could be formed at that time was helium. All the available neutrons were used to form helium, giving one helium nucleus for every 12 hydrogen nuclei at the end of the primordial epoch. * see tuimp 12 Hydrogen and helium 5 12 Num. of protons Solar system Earth’s crust Human body H 1 70.5 0.14 9.5 He 2 27.5 - - C 6 0.30 0.030 18.5 N 7 0.11 0.005 3.2 O 8 0. 96 46.6 65 Si 14 0.065 27.7 0.00002 S 16 0.040 0.050 0.3 Ca 20 0.006 3.6 1.5 Fe 26 0.117 5.0 0.006 Mass percentage of the chemical elements in different locations From the Big Bang to us BANG ! Winds, collisions, explosions Some of the elements formed in stars are ejected into the interstellar medium while the rest are locked up forever in the ‘stellar corpses’ that are white dwarfs, neutron stars and black holes. Stars with a mass of less than 8 times that of the Sun disperse their outer layers in a peaceful manner, ejecting nitrogen, carbon and some elements heavier than iron. The more massive stars end their life in a spectacular explosion, a supernova, and expel carbon, oxygen, neon, magnesium and silicon, among others. Other heavy elements, such as gold and uranium require a very high density of neutrons to form, and this is more likely to happen in neutron star collisions. 9 8 Composite image of the Cat’s Eye planetary nebula. This object results from several episodes of stellar winds emanating from the central star which is now in the process of becoming a white dwarf. The Cat’s Eye planetary nebula. (Credit: R. Corradi with the NOT telescope). G292.0 + 1.8: A supernova remnant coming from a star of great mass which ejected a lot of oxygen, magnesium and neon into the interstellar medium. G292.0+1.8 in X-rays. Credit : NASA/CXC/SAO . Representation of the collision of two neutron stars. Gold, uranium and other heavy elements in the Universe are believed to have formed during such an event. Artist view (Dana Berry, SkyWorks Digital). Proton : formed of three elementary particles, the quarks. It has a positiv e electric charge and its mass is 1.672 649 × 10 -24 g. Neutron: also formed of three quarks but does not have an electric charge. Its mass is 1.674 93 × 10 -24 g. Electron: particle of negative electric charge, whose mass is about 1/2000of that of the proton. Hydrogen: the lightest of the elements. It consists of a proton and an electron. Helium: the lightest stable element after hydro- gen. It consist of an particle and 2 electrons. 4 It was George Gamow, in an article with Alpher and Bethe in 1948, who proposed the theory of the formation of primordial hydrogen and helium. In this article, the authors further argued that all the other elements were also formed in the Big Bang by successively adding neutrons. But on this point they were wrong. p p p p p n n n n n n p n proton neutron deuterium tritium a particle One process of helium formation From stars to living beings Before becoming part of a living being, elements must pass through many stages that are still poorly understood. First there is the formation of clouds of molecules and dust, in which stars are born. While still very young, these stars are surrounded by a protoplanetary disk, made up of clumps of dust and ice. It is from this disk material that planets are formed. Their chemical composition differs according to the distance from the star: The smaller the distance, the easier it is for the volatile elements to dissipate. It also depends on the planets' mass: The smaller the mass, the easier it is for the lighter particles to escape. As the planet forms, a segregation of elements occurs so that the core has a different composition from the crust. Finally, it is from the materials in the crust that living beings are formed. 13 Quiz Answer on overleaf What is the origin of gold ? Grażyna Stasińska Paris Observatory The Universe in my pocket ES-001 No. 14 Les étoiles et moi We come from the stars +

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Page 1: The Eye The Universe in my pocket Observatory Les étoiles

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✃ 3 ✁ 3

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13

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Le

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+

Page 2: The Eye The Universe in my pocket Observatory Les étoiles

Ou

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te

llar

en

erg

y" in

19

31

. Ha

ns

Be

th

e B

ide

nt

ified

in

19

38

an

d 1

93

9 t

he

tw

om

ec

ha

nis

ms

th

at

tra

ns

form

hy

dro

ge

nin

to

he

lium

in s

ta

rs.

Fre

d H

oy

le s

ho

we

din

19

46

ho

w t

he

e

lem

en

ts

are

sy

nt

he

siz

ed

from

hy

dro

ge

n.

Ma

rga

ret

an

d G

eo

ffrey

Bu

rbid

ge

, Willia

m

Fo

wle

r an

d F

red

Ho

yle

B2

FH

pu

blis

he

din

1

95

7 t

he

irv

ery

de

ta

iled

art

icle

"Sy

nt

he

sis

of t

he

ele

me

nt

sin

st

ars

" an

d, t

he

sa

me

ye

ar, A

las

ta

ir Ca

me

ron

Cp

ub

lish

ed

"Nu

cle

ar

rea

ct

ion

sin

st

ars

an

d n

uc

leo

ge

ne

sis

".

AB

C

B2F

H6

p

p

p

p

pp

ppp

n

n

n

nnn

nn

nn

nn

np p

n

p

nn

pp

pp

Be

ryll

ium

-8

Ca

rbo

n-1

2

α p

art

icle

α p

art

icle

α p

art

icle

hy

dro

ge

n

he

liu

m

carb

on

ox

yg

en

sili

con

iro

n

Ca

rbo

n

form

at

ion

fro

m

th

ree

he

liu

mn

uc

lei

Dia

gra

mo

f t

he

on

ion

st

ruc

tu

re o

f a

ma

ss

ive

s

ta

r a

t t

he

en

d o

f it

se

vo

lut

ion

.Ea

ch

lay

er

ha

s a

dif

fere

nt

co

mp

os

itio

n. E

lem

en

ts

he

av

ier

th

an

iro

na

re p

rod

uc

ed

by

ne

ut

ron

ca

pt

ure

.

Th

e c

os

mic

od

ys

se

y o

f t

he

ele

me

nt

s

On

ce

re

lea

se

din

to

th

e in

te

rst

ell

ar

me

diu

m, t

he

ele

me

nt

sb

eg

ina

lon

g

jou

rne

ya

cro

ss

th

e g

ala

xie

s, b

efo

reb

ein

gt

rap

pe

dd

uri

ng

th

e f

orm

at

ion

o

f n

ew

st

ars

. Th

us

, su

cc

es

siv

e

ge

ne

rat

ion

so

f s

ta

rs b

ec

om

ein

cre

as

ing

lyri

ch

in c

arb

on

, nit

rog

en

, o

xy

ge

na

nd

ot

he

re

lem

en

ts

.

Th

e jo

urn

ey

of

th

ee

lem

en

ts

th

rou

gh

th

e in

te

rst

ell

ar

me

diu

m c

an

be

ve

ryt

ort

uo

us

, wit

hp

ert

urb

at

ion

s li

nk

ed

to

co

llis

ion

s b

et

we

en

ga

lax

ies

. E

lem

en

ts

rele

as

ed

du

rin

gs

up

ern

ov

a

ex

plo

sio

ns

ca

ne

ve

nm

ak

ein

cu

rsio

ns

in

to

th

e in

te

rga

lac

tic

me

diu

m, a

nd

fi

na

lly

en

d u

p in

ot

he

rg

ala

xie

s.

In f

ac

t, r

ec

en

tn

um

eri

ca

ls

imu

lat

ion

s s

ug

ge

st

th

at

ma

ny

of

th

e e

lem

en

ts

pre

se

nt

in t

he

Mil

ky

Wa

yc

am

e f

rom

ot

he

rg

ala

xie

s.

11

10

Th

e s

ym

bo

lsin

dic

at

et

he

ab

un

da

nc

eo

f o

xy

ge

n(r

ed

wh

ere

ab

un

da

nt

, blu

ew

he

res

ca

rce

).

Cre

dit

: Ló

pe

z-S

án

ch

ez

(AA

O/M

QU

) & K

ori

ba

lski

(CS

IRO

).

Th

e g

ala

xie

s N

GC

15

12

a

nd

NG

C 1

51

0 s

ee

nin

u

ltra

vio

let

lig

ht

. B

rig

ht

a

rea

s a

re r

eg

ion

sw

he

res

ta

rs h

av

e r

ec

en

tly

form

ed

.C

red

it: G

AL

EX

(N

AS

A)

NG

C 1

51

2

NG

C 1

51

0

Th

e v

ery

ho

t a

nd

de

ns

e c

ore

of

a s

ta

r p

rovi

de

sid

ea

lco

nd

itio

ns

fo

r p

rod

uc

ing

larg

er

an

d la

rge

rn

uc

lei.

Fir

st

, hy

dro

ge

na

to

ms

co

mb

ine

to

fo

rmh

eliu

m. T

his

co

rre

sp

on

ds

to

th

e lo

ng

es

tp

ha

se

in t

he

life

of

a s

ta

r. A

lmo

st

all

of

th

e s

ta

rs w

es

ee

sh

inin

gg

et

th

eir

en

erg

yfr

om

th

isp

roc

es

s.

On

ce

th

e h

yd

rog

en

isu

se

du

p, t

he

he

lium

co

rec

on

de

ns

es

an

d it

st

em

pe

rat

ure

ris

es

.Th

en

th

e h

eliu

mn

uc

leif

us

e in

g

rou

ps

of

th

ree

to

fo

rmc

arb

on

, wh

ileh

yd

rog

en

co

nt

inu

es

to

pro

du

ce

he

lium

in

th

e o

ut

er

lay

ers

of

th

e s

ta

r.

He

avi

er

nu

cle

iare

th

en

fo

rme

d, b

y f

urt

he

ra

dd

itio

ns

of 𝛼

pa

rtic

les

in d

iffe

ren

tla

ye

rs. I

f t

he

st

ar

ism

as

siv

e e

no

ug

h, t

his

pro

ce

ss

co

nt

inu

es

un

til

th

e c

ore

ism

ad

e

of

iro

n, t

he

mo

st

st

ab

le e

lem

en

t.

Nu

cle

ihe

avi

er

th

an

iro

na

re c

rea

te

du

nd

er

dif

fere

nt

co

nd

itio

ns

by

th

e a

dd

itio

n o

f n

eu

tro

ns

.

Fu

sio

n in

st

ars

7

+