WEBVTT
1
00:00:00.720 --> 00:00:06.360
News of a star exploding in the night sky. A
2
00:00:06.400 --> 00:00:14.109
star called T, capital letter T, Corona Borealis. So this
3
00:00:14.130 --> 00:00:17.949
is a star in the constellation Corona Borealis. Corona Borealis
4
00:00:18.010 --> 00:00:22.850
from the Latin simply translates to Northern Crown. The system
5
00:00:22.890 --> 00:00:27.690
is about 2,600 light years away. So of course, anything
6
00:00:27.730 --> 00:00:32.810
we observe today already happened 2,600 years ago. In the
7
00:00:32.850 --> 00:00:36.049
northern hemisphere, we have Corona Borealis, and one of the
8
00:00:36.090 --> 00:00:45.859
stars in that constellation varies in brightness significantly, explosively. And
9
00:00:46.020 --> 00:00:52.219
so the way we identify variable stars in a constellation
10
00:00:52.240 --> 00:00:56.250
is we start lettering them from R. So this is
11
00:00:56.350 --> 00:01:02.070
T coronaborealis RST. It's the third discovered variable star in
12
00:01:02.109 --> 00:01:06.829
the constellation coronaborealis. Okay. It's been known for quite some
13
00:01:06.870 --> 00:01:11.420
time that this thing, the luminosity varies. And then one
14
00:01:11.450 --> 00:01:16.219
day it explosively varies on a level where if you
15
00:01:16.260 --> 00:01:19.519
didn't know it was in the sky and then it exploded,
16
00:01:19.799 --> 00:01:22.140
you would say, oh, there's a new star in the sky.
17
00:01:22.680 --> 00:01:26.030
A new star. What's Latin for new? Nova. That's Latin
18
00:01:26.069 --> 00:01:30.969
for new. So this category of variable star, this category
19
00:01:31.010 --> 00:01:37.950
of explosion has come to be known as Nova. So T-Coronavirus,
20
00:01:37.969 --> 00:01:41.659
what's going on? There's a red giant and a white
21
00:01:41.700 --> 00:01:45.879
dwarf and the white dwarf is dead. It's glowing from
22
00:01:45.959 --> 00:01:48.870
leftover heat from when it was an authentic star. The
23
00:01:48.989 --> 00:01:51.689
sun will die as a white dwarf. When the sun
24
00:01:51.810 --> 00:01:54.230
in five billion years sheds all of its outer layers,
25
00:01:54.310 --> 00:01:58.109
it will reveal a dense core, a dense core about
26
00:01:58.150 --> 00:02:00.750
the size of the earth. That will be a white
27
00:02:00.769 --> 00:02:04.879
dwarf that will slowly cool over the eons. But this
28
00:02:04.959 --> 00:02:08.379
white dwarf is in a binary orbiting system with the
29
00:02:08.439 --> 00:02:11.620
red giants and red giants like becoming bulbous and they
30
00:02:11.680 --> 00:02:15.039
keep expanding and expanding. And there is a balance point
31
00:02:15.870 --> 00:02:20.729
A literal balance point between these two objects where if
32
00:02:20.849 --> 00:02:25.120
the expanding gas crosses that balance point, it's a gravitational
33
00:02:25.159 --> 00:02:28.539
balance point, then it's no longer gravitationally bound to the
34
00:02:29.099 --> 00:02:32.199
red giant and it will fall into the white dwarf.
35
00:02:32.860 --> 00:02:38.969
So there's a gas transfer. And this transfer point, as
36
00:02:39.030 --> 00:02:41.849
the red giant gets larger and larger, there's what we
37
00:02:41.870 --> 00:02:46.159
call a lobe, an envelope of space around it. And
38
00:02:46.370 --> 00:02:50.030
it was first described mathematically by a fellow named Roche.
39
00:02:50.949 --> 00:02:55.409
So it fills his Roche lobe and the gas crosses
40
00:02:55.530 --> 00:03:00.849
over and lands gently on the white dwarf. So now
41
00:03:00.870 --> 00:03:04.389
we have hydrogen on the surface of a white dwarf
42
00:03:05.430 --> 00:03:11.050
and this continues and it accumulates and it continues. As
43
00:03:11.110 --> 00:03:16.189
that continues, the pressure builds Because the white dwarf is
44
00:03:16.229 --> 00:03:19.560
basically solid matter, all right? And you have gas falling
45
00:03:19.590 --> 00:03:21.680
on it. At the base of the gas, the pressure
46
00:03:21.719 --> 00:03:27.319
is growing and the temperature is growing. Well, this is
47
00:03:27.340 --> 00:03:32.419
an unstable situation because eventually there's enough gas pressure down
48
00:03:32.620 --> 00:03:40.590
on that hydrogen layer that it ignites. Spontaneous thermonuclear fusion. Well,
49
00:03:40.610 --> 00:03:42.729
the sun is doing that in its core every second
50
00:03:42.770 --> 00:03:45.669
of every day. But if you do that on your surface,
51
00:03:46.449 --> 00:03:51.930
you will blow out all of the gas that was there, catastrophically,
52
00:03:52.509 --> 00:03:57.340
because it is uncontained. This is what is visibly a
53
00:03:57.680 --> 00:04:02.479
nova seen in the night sky. Now, here's what's cool. T.
54
00:04:02.539 --> 00:04:07.000
corona borealis has been repeating this every 80 years. We
55
00:04:07.039 --> 00:04:12.039
have evidence of this going back centuries. What's the evidence?
56
00:04:12.340 --> 00:04:16.420
Every time it explodes, there's a gas layer moving slowly
57
00:04:16.480 --> 00:04:20.350
away from the system. We have deep photos from specialized
58
00:04:20.379 --> 00:04:26.250
telescopes that reveal these shells of gas offering a record
59
00:04:26.269 --> 00:04:30.410
of all the previous times this has gone Nova. So
60
00:04:30.509 --> 00:04:32.589
this happened long ago, but the light is only now
61
00:04:32.649 --> 00:04:38.110
just reaching us. So the brightness reaches about magnitude two
62
00:04:38.149 --> 00:04:43.600
and a half. And that's astronomer lingo for about the
63
00:04:43.639 --> 00:04:47.579
brightness of the North Star is about magnitude two and
64
00:04:47.600 --> 00:04:50.579
a half. Many people think the North Star is bright
65
00:04:50.720 --> 00:04:53.680
and distinct in the night sky, but it's not. It's
66
00:04:53.720 --> 00:04:57.420
just not. Like, get over it. The North Star is
67
00:04:57.480 --> 00:04:59.740
not in the top 10. It's not even in the
68
00:04:59.779 --> 00:05:03.980
top 40. The North Star is the 49th brightest star
69
00:05:04.019 --> 00:05:06.680
in the night sky. So this nova is not something
70
00:05:06.720 --> 00:05:11.930
that will grab your attention. Walking down the street. That's not, no,
71
00:05:11.990 --> 00:05:14.610
it's not that we're going to have arsenals of telescopes
72
00:05:14.689 --> 00:05:16.970
trained on this object because the last time it blew,
73
00:05:17.509 --> 00:05:19.470
we didn't have that many telescopes in the world. It
74
00:05:19.550 --> 00:05:23.029
certainly weren't space telescopes. So this will be the best
75
00:05:23.129 --> 00:05:28.060
studied Nova there ever was simply because of its timing
76
00:05:28.519 --> 00:05:32.339
and its brightness. So even though there's 50 or so,
77
00:05:32.959 --> 00:05:37.430
nobody discovered each year, some of them are repeating. This one, T.
78
00:05:37.639 --> 00:05:41.310
coronae borealis, is one of the brightest, simply because of
79
00:05:41.350 --> 00:05:44.490
how close it is to us relative to the others.
80
00:05:44.790 --> 00:05:49.449
The rest are discovered by telescopes and special surveys intended
81
00:05:49.490 --> 00:05:52.689
and designed to make just such discoveries. Again, why do
82
00:05:52.709 --> 00:05:56.470
they recur? Because once you have the explosion, we start
83
00:05:56.490 --> 00:05:59.629
the cycle all over again. The red giant spills out
84
00:05:59.649 --> 00:06:03.069
of its roche lobe and layers hydrogen gas and some
85
00:06:03.110 --> 00:06:07.399
helium until it hits that threshold once again. The fact
86
00:06:07.420 --> 00:06:13.079
that this repeats every 80 years means, yeah, that's a
87
00:06:13.199 --> 00:06:17.300
once-in-a-lifetime event. We've all heard people describe eclipses that way,
88
00:06:17.540 --> 00:06:25.470
once-in-a-lifetime event. Well, that's just BS. Baloney sandwich. Because there's
89
00:06:25.509 --> 00:06:28.149
an eclipse, a total solar eclipse, somewhere in the world
90
00:06:28.269 --> 00:06:30.670
every two and a half years or so. They're simply
91
00:06:30.730 --> 00:06:34.370
not coming to you that often, but they're coming to Earth.
92
00:06:34.850 --> 00:06:41.540
more often than the Olympics. So there's another kind of
93
00:06:41.740 --> 00:06:46.139
object out there where you have a binary system, once again,
94
00:06:46.160 --> 00:06:50.790
a red giant and a white dwarf. And if the
95
00:06:50.889 --> 00:06:55.589
white dwarf is already near a different kind of threshold
96
00:06:55.649 --> 00:07:01.160
in mass, a threshold first calculated by the brilliant Indian
97
00:07:01.220 --> 00:07:07.519
astrophysicist Subrahmanyan Chandrasekhar, He noted that if you have a
98
00:07:08.000 --> 00:07:10.959
white dwarf that's near a limit, what limit is that?
99
00:07:11.259 --> 00:07:16.980
About 1.4 times the mass of the sun. And you
100
00:07:17.240 --> 00:07:21.560
drop some more material on it, oh, it's no longer
101
00:07:21.639 --> 00:07:26.720
just let's explode the outer surface. The entire star, white dwarf,
102
00:07:27.199 --> 00:07:33.839
goes unstable. And it collapses and becomes a supernova. These
103
00:07:33.899 --> 00:07:39.490
are way brighter than Novi. Novi, that's plural, Latin plural, N-O-V-A-E.
104
00:07:40.209 --> 00:07:43.029
Way brighter. And we see them in the sky, and
105
00:07:43.050 --> 00:07:46.529
so what else could we do but call them super Novi?
106
00:07:47.689 --> 00:07:50.060
And they're kind of related because there's a mass transfer,
107
00:07:50.100 --> 00:07:52.220
but one is way brighter than the other because one
108
00:07:52.259 --> 00:07:55.279
is the catastrophic death of the white dwarf, and the
109
00:07:55.319 --> 00:07:58.279
other one is just sort of puffing, not puffing, it's
110
00:07:58.300 --> 00:08:02.629
still explosive, but it's way tamer. than what goes on
111
00:08:02.670 --> 00:08:05.850
in a supernova. Supernova you can see halfway across the universe.
112
00:08:06.389 --> 00:08:08.509
That's how bright they are. They're as bright as the
113
00:08:08.550 --> 00:08:12.800
entire galaxy in which they explode. This nova, we are
114
00:08:12.819 --> 00:08:17.519
at a safe distance, 2,600 light years. You can sleep
115
00:08:17.620 --> 00:08:20.500
well at night knowing life on Earth will not end
116
00:08:21.120 --> 00:08:28.389
from that. That's what's up with that. T. coronae borealis,
117
00:08:29.389 --> 00:08:31.620
an exploding star in a sky near you.
1
00:00:00.720 --> 00:00:06.360
News of a star exploding in the night sky. A
2
00:00:06.400 --> 00:00:14.109
star called T, capital letter T, Corona Borealis. So this
3
00:00:14.130 --> 00:00:17.949
is a star in the constellation Corona Borealis. Corona Borealis
4
00:00:18.010 --> 00:00:22.850
from the Latin simply translates to Northern Crown. The system
5
00:00:22.890 --> 00:00:27.690
is about 2,600 light years away. So of course, anything
6
00:00:27.730 --> 00:00:32.810
we observe today already happened 2,600 years ago. In the
7
00:00:32.850 --> 00:00:36.049
northern hemisphere, we have Corona Borealis, and one of the
8
00:00:36.090 --> 00:00:45.859
stars in that constellation varies in brightness significantly, explosively. And
9
00:00:46.020 --> 00:00:52.219
so the way we identify variable stars in a constellation
10
00:00:52.240 --> 00:00:56.250
is we start lettering them from R. So this is
11
00:00:56.350 --> 00:01:02.070
T coronaborealis RST. It's the third discovered variable star in
12
00:01:02.109 --> 00:01:06.829
the constellation coronaborealis. Okay. It's been known for quite some
13
00:01:06.870 --> 00:01:11.420
time that this thing, the luminosity varies. And then one
14
00:01:11.450 --> 00:01:16.219
day it explosively varies on a level where if you
15
00:01:16.260 --> 00:01:19.519
didn't know it was in the sky and then it exploded,
16
00:01:19.799 --> 00:01:22.140
you would say, oh, there's a new star in the sky.
17
00:01:22.680 --> 00:01:26.030
A new star. What's Latin for new? Nova. That's Latin
18
00:01:26.069 --> 00:01:30.969
for new. So this category of variable star, this category
19
00:01:31.010 --> 00:01:37.950
of explosion has come to be known as Nova. So T-Coronavirus,
20
00:01:37.969 --> 00:01:41.659
what's going on? There's a red giant and a white
21
00:01:41.700 --> 00:01:45.879
dwarf and the white dwarf is dead. It's glowing from
22
00:01:45.959 --> 00:01:48.870
leftover heat from when it was an authentic star. The
23
00:01:48.989 --> 00:01:51.689
sun will die as a white dwarf. When the sun
24
00:01:51.810 --> 00:01:54.230
in five billion years sheds all of its outer layers,
25
00:01:54.310 --> 00:01:58.109
it will reveal a dense core, a dense core about
26
00:01:58.150 --> 00:02:00.750
the size of the earth. That will be a white
27
00:02:00.769 --> 00:02:04.879
dwarf that will slowly cool over the eons. But this
28
00:02:04.959 --> 00:02:08.379
white dwarf is in a binary orbiting system with the
29
00:02:08.439 --> 00:02:11.620
red giants and red giants like becoming bulbous and they
30
00:02:11.680 --> 00:02:15.039
keep expanding and expanding. And there is a balance point
31
00:02:15.870 --> 00:02:20.729
A literal balance point between these two objects where if
32
00:02:20.849 --> 00:02:25.120
the expanding gas crosses that balance point, it's a gravitational
33
00:02:25.159 --> 00:02:28.539
balance point, then it's no longer gravitationally bound to the
34
00:02:29.099 --> 00:02:32.199
red giant and it will fall into the white dwarf.
35
00:02:32.860 --> 00:02:38.969
So there's a gas transfer. And this transfer point, as
36
00:02:39.030 --> 00:02:41.849
the red giant gets larger and larger, there's what we
37
00:02:41.870 --> 00:02:46.159
call a lobe, an envelope of space around it. And
38
00:02:46.370 --> 00:02:50.030
it was first described mathematically by a fellow named Roche.
39
00:02:50.949 --> 00:02:55.409
So it fills his Roche lobe and the gas crosses
40
00:02:55.530 --> 00:03:00.849
over and lands gently on the white dwarf. So now
41
00:03:00.870 --> 00:03:04.389
we have hydrogen on the surface of a white dwarf
42
00:03:05.430 --> 00:03:11.050
and this continues and it accumulates and it continues. As
43
00:03:11.110 --> 00:03:16.189
that continues, the pressure builds Because the white dwarf is
44
00:03:16.229 --> 00:03:19.560
basically solid matter, all right? And you have gas falling
45
00:03:19.590 --> 00:03:21.680
on it. At the base of the gas, the pressure
46
00:03:21.719 --> 00:03:27.319
is growing and the temperature is growing. Well, this is
47
00:03:27.340 --> 00:03:32.419
an unstable situation because eventually there's enough gas pressure down
48
00:03:32.620 --> 00:03:40.590
on that hydrogen layer that it ignites. Spontaneous thermonuclear fusion. Well,
49
00:03:40.610 --> 00:03:42.729
the sun is doing that in its core every second
50
00:03:42.770 --> 00:03:45.669
of every day. But if you do that on your surface,
51
00:03:46.449 --> 00:03:51.930
you will blow out all of the gas that was there, catastrophically,
52
00:03:52.509 --> 00:03:57.340
because it is uncontained. This is what is visibly a
53
00:03:57.680 --> 00:04:02.479
nova seen in the night sky. Now, here's what's cool. T.
54
00:04:02.539 --> 00:04:07.000
corona borealis has been repeating this every 80 years. We
55
00:04:07.039 --> 00:04:12.039
have evidence of this going back centuries. What's the evidence?
56
00:04:12.340 --> 00:04:16.420
Every time it explodes, there's a gas layer moving slowly
57
00:04:16.480 --> 00:04:20.350
away from the system. We have deep photos from specialized
58
00:04:20.379 --> 00:04:26.250
telescopes that reveal these shells of gas offering a record
59
00:04:26.269 --> 00:04:30.410
of all the previous times this has gone Nova. So
60
00:04:30.509 --> 00:04:32.589
this happened long ago, but the light is only now
61
00:04:32.649 --> 00:04:38.110
just reaching us. So the brightness reaches about magnitude two
62
00:04:38.149 --> 00:04:43.600
and a half. And that's astronomer lingo for about the
63
00:04:43.639 --> 00:04:47.579
brightness of the North Star is about magnitude two and
64
00:04:47.600 --> 00:04:50.579
a half. Many people think the North Star is bright
65
00:04:50.720 --> 00:04:53.680
and distinct in the night sky, but it's not. It's
66
00:04:53.720 --> 00:04:57.420
just not. Like, get over it. The North Star is
67
00:04:57.480 --> 00:04:59.740
not in the top 10. It's not even in the
68
00:04:59.779 --> 00:05:03.980
top 40. The North Star is the 49th brightest star
69
00:05:04.019 --> 00:05:06.680
in the night sky. So this nova is not something
70
00:05:06.720 --> 00:05:11.930
that will grab your attention. Walking down the street. That's not, no,
71
00:05:11.990 --> 00:05:14.610
it's not that we're going to have arsenals of telescopes
72
00:05:14.689 --> 00:05:16.970
trained on this object because the last time it blew,
73
00:05:17.509 --> 00:05:19.470
we didn't have that many telescopes in the world. It
74
00:05:19.550 --> 00:05:23.029
certainly weren't space telescopes. So this will be the best
75
00:05:23.129 --> 00:05:28.060
studied Nova there ever was simply because of its timing
76
00:05:28.519 --> 00:05:32.339
and its brightness. So even though there's 50 or so,
77
00:05:32.959 --> 00:05:37.430
nobody discovered each year, some of them are repeating. This one, T.
78
00:05:37.639 --> 00:05:41.310
coronae borealis, is one of the brightest, simply because of
79
00:05:41.350 --> 00:05:44.490
how close it is to us relative to the others.
80
00:05:44.790 --> 00:05:49.449
The rest are discovered by telescopes and special surveys intended
81
00:05:49.490 --> 00:05:52.689
and designed to make just such discoveries. Again, why do
82
00:05:52.709 --> 00:05:56.470
they recur? Because once you have the explosion, we start
83
00:05:56.490 --> 00:05:59.629
the cycle all over again. The red giant spills out
84
00:05:59.649 --> 00:06:03.069
of its roche lobe and layers hydrogen gas and some
85
00:06:03.110 --> 00:06:07.399
helium until it hits that threshold once again. The fact
86
00:06:07.420 --> 00:06:13.079
that this repeats every 80 years means, yeah, that's a
87
00:06:13.199 --> 00:06:17.300
once-in-a-lifetime event. We've all heard people describe eclipses that way,
88
00:06:17.540 --> 00:06:25.470
once-in-a-lifetime event. Well, that's just BS. Baloney sandwich. Because there's
89
00:06:25.509 --> 00:06:28.149
an eclipse, a total solar eclipse, somewhere in the world
90
00:06:28.269 --> 00:06:30.670
every two and a half years or so. They're simply
91
00:06:30.730 --> 00:06:34.370
not coming to you that often, but they're coming to Earth.
92
00:06:34.850 --> 00:06:41.540
more often than the Olympics. So there's another kind of
93
00:06:41.740 --> 00:06:46.139
object out there where you have a binary system, once again,
94
00:06:46.160 --> 00:06:50.790
a red giant and a white dwarf. And if the
95
00:06:50.889 --> 00:06:55.589
white dwarf is already near a different kind of threshold
96
00:06:55.649 --> 00:07:01.160
in mass, a threshold first calculated by the brilliant Indian
97
00:07:01.220 --> 00:07:07.519
astrophysicist Subrahmanyan Chandrasekhar, He noted that if you have a
98
00:07:08.000 --> 00:07:10.959
white dwarf that's near a limit, what limit is that?
99
00:07:11.259 --> 00:07:16.980
About 1.4 times the mass of the sun. And you
100
00:07:17.240 --> 00:07:21.560
drop some more material on it, oh, it's no longer
101
00:07:21.639 --> 00:07:26.720
just let's explode the outer surface. The entire star, white dwarf,
102
00:07:27.199 --> 00:07:33.839
goes unstable. And it collapses and becomes a supernova. These
103
00:07:33.899 --> 00:07:39.490
are way brighter than Novi. Novi, that's plural, Latin plural, N-O-V-A-E.
104
00:07:40.209 --> 00:07:43.029
Way brighter. And we see them in the sky, and
105
00:07:43.050 --> 00:07:46.529
so what else could we do but call them super Novi?
106
00:07:47.689 --> 00:07:50.060
And they're kind of related because there's a mass transfer,
107
00:07:50.100 --> 00:07:52.220
but one is way brighter than the other because one
108
00:07:52.259 --> 00:07:55.279
is the catastrophic death of the white dwarf, and the
109
00:07:55.319 --> 00:07:58.279
other one is just sort of puffing, not puffing, it's
110
00:07:58.300 --> 00:08:02.629
still explosive, but it's way tamer. than what goes on
111
00:08:02.670 --> 00:08:05.850
in a supernova. Supernova you can see halfway across the universe.
112
00:08:06.389 --> 00:08:08.509
That's how bright they are. They're as bright as the
113
00:08:08.550 --> 00:08:12.800
entire galaxy in which they explode. This nova, we are
114
00:08:12.819 --> 00:08:17.519
at a safe distance, 2,600 light years. You can sleep
115
00:08:17.620 --> 00:08:20.500
well at night knowing life on Earth will not end
116
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from that. That's what's up with that. T. coronae borealis,
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an exploding star in a sky near you.
