1
00:00:00,000 --> 00:00:01,020
[MUSIC PLAYING]

2
00:00:01,020 --> 00:00:02,478
ANNA FREBEL: Have
you ever wondered

3
00:00:02,478 --> 00:00:06,120
how all the chemical
elements are made?

4
00:00:06,120 --> 00:00:09,420
Then join me as we are lifting
all the stardust secrets

5
00:00:09,420 --> 00:00:12,090
to understand the cosmic origin
of the chemical elements.

6
00:00:16,129 --> 00:00:19,020
We want to talk about the cosmic
origin of the chemical elements

7
00:00:19,020 --> 00:00:19,520
today.

8
00:00:28,280 --> 00:00:31,040
In order to understand where
the elements come from,

9
00:00:31,040 --> 00:00:34,410
we need to consider two
different components--

10
00:00:34,410 --> 00:00:37,090
one is nuclear physics
and one is astrophysics.

11
00:00:37,090 --> 00:00:39,260
When the nicely
combine, when we want

12
00:00:39,260 --> 00:00:42,500
to understand where the
chemical elements come from,

13
00:00:42,500 --> 00:00:44,695
and so let's look at
that in more detail.

14
00:00:44,695 --> 00:00:46,070
We have the nuclear
physics part.

15
00:00:49,790 --> 00:00:51,530
And we have astrophysics.

16
00:00:54,970 --> 00:00:57,070
And on the nuclear
physics side, we

17
00:00:57,070 --> 00:01:01,150
have two things that we want
to consider or learn about,

18
00:01:01,150 --> 00:01:06,320
namely how the light
elements are formed,

19
00:01:06,320 --> 00:01:10,210
light elements up to iron.

20
00:01:10,210 --> 00:01:15,010
And they are formed in
fusion processes in stars.

21
00:01:15,010 --> 00:01:19,650
Fusion processes.

22
00:01:19,650 --> 00:01:22,550
And so this is one.

23
00:01:22,550 --> 00:01:24,687
And then we have
also lots and lots

24
00:01:24,687 --> 00:01:26,270
of elements on the
periodic table that

25
00:01:26,270 --> 00:01:27,620
are heavier than iron.

26
00:01:27,620 --> 00:01:32,900
So how are the heavy
elements formed?

27
00:01:32,900 --> 00:01:35,780
That would be heavier than iron.

28
00:01:35,780 --> 00:01:37,495
And so they are made
in what's called

29
00:01:37,495 --> 00:01:39,410
a neutron-capture processes.

30
00:01:43,200 --> 00:01:48,460
And that's a really neat way
of making big heavy nuclei.

31
00:01:48,460 --> 00:01:51,270
And so these two
parts here together

32
00:01:51,270 --> 00:01:55,080
really explain how most of the
elements in the periodic table

33
00:01:55,080 --> 00:01:55,580
are made.

34
00:01:55,580 --> 00:01:57,038
And there are a
few extra processes

35
00:01:57,038 --> 00:01:58,450
that we will not consider.

36
00:01:58,450 --> 00:02:01,290
But this gets us almost there.

37
00:02:01,290 --> 00:02:04,650
Then we have the astrophysics,
because this is basically

38
00:02:04,650 --> 00:02:06,190
a lot of theory.

39
00:02:06,190 --> 00:02:08,400
And we need to put
this to the test.

40
00:02:08,400 --> 00:02:11,460
And one test that
the universe offers

41
00:02:11,460 --> 00:02:14,610
us is investigating
chemical evolution.

42
00:02:17,490 --> 00:02:20,100
Chemical evolution is that
the successive build up

43
00:02:20,100 --> 00:02:22,830
of heavy elements in
the universe with time,

44
00:02:22,830 --> 00:02:26,940
with cosmic time, over the
last 13.8 billion years.

45
00:02:26,940 --> 00:02:32,070
And we can observe
stars at different times

46
00:02:32,070 --> 00:02:36,300
and thus trace the signatures of
these nuclear sort of processes

47
00:02:36,300 --> 00:02:42,350
here and reconstruct how the
nuclear physics operated.

48
00:02:42,350 --> 00:02:44,730
That works particularly
well at early times

49
00:02:44,730 --> 00:02:47,040
when the universe was
a much less messy place

50
00:02:47,040 --> 00:02:48,190
than it is now.

51
00:02:48,190 --> 00:02:50,760
And so the second
portion here is

52
00:02:50,760 --> 00:02:55,230
going to be the oldest
stars because they

53
00:02:55,230 --> 00:02:58,470
are the tool for us
to really figure out

54
00:02:58,470 --> 00:03:01,860
how the elements were made
first in the universe.

55
00:03:01,860 --> 00:03:04,770
That allows us to again
obtain clean signatures

56
00:03:04,770 --> 00:03:07,720
of these processes there.

57
00:03:07,720 --> 00:03:11,940
And that's a very exciting and
timely avenue for us to study.

58
00:03:11,940 --> 00:03:13,590
And together with
the older stars,

59
00:03:13,590 --> 00:03:16,290
comes the concept of
stellar archeology.

60
00:03:20,200 --> 00:03:23,290
And that sort of
encompasses how we

61
00:03:23,290 --> 00:03:28,030
use stars that are still
available and shining today

62
00:03:28,030 --> 00:03:32,710
to study the early universe
when everything got started.

63
00:03:32,710 --> 00:03:35,950
And in order to study chemical
evolution with old stars,

64
00:03:35,950 --> 00:03:38,860
we actually need to use a
scientific method called

65
00:03:38,860 --> 00:03:40,640
spectroscopy.

66
00:03:40,640 --> 00:03:46,120
So we're also going to look
at spectroscopy and how

67
00:03:46,120 --> 00:03:50,860
that works, observing all the
little stellar little rainbows.

68
00:03:50,860 --> 00:03:54,000
And because we do that
with big telescopes,

69
00:03:54,000 --> 00:03:58,030
we're also going to look at what
it's like to use big telescopes

70
00:03:58,030 --> 00:04:00,590
and observing.

71
00:04:00,590 --> 00:04:02,920
Because all of
this work is based

72
00:04:02,920 --> 00:04:06,130
on astronomical observations
with the largest

73
00:04:06,130 --> 00:04:09,940
telescopes, mostly in Chile.

74
00:04:09,940 --> 00:04:14,610
And I will explain all these
different parts one by one.

75
00:04:14,610 --> 00:04:16,360
And then in the end,
we're going to put it

76
00:04:16,360 --> 00:04:19,030
all together to understand
the origin of the elements.

77
00:04:19,030 --> 00:04:21,480
[MUSIC PLAYING]