SpaceTime Series 27 Episode 18
*Revealing Dark Matter through Lopsided Galaxies
A groundbreaking study unveils how asymmetric galaxies could be the key to unlocking the mysteries of dark matter, the elusive substance that dominates the universe's matter content and binds galaxies together.
*Virgin Galactic's 2024 Space Tourism Triumph
Virgin Galactic soars into the new year with a successful space tourism flight, reaching the fringes of space and marking a milestone for commercial space travel.
*Reflecting on the SunRISE-3 Mission
We revisit the ambitious SunRISE-3 mission, which despite its untimely end, aimed to launch the largest telescope ever on a balloon to peer into the sun's mysterious chromosphere.
*Skywatch – Orion's Splendor and Betelgeuse's Fate
The February night skies offer a spectacle with the constellation Orion taking center stage, the Horsehead Nebula in view, and the red supergiant Betelgeuse nearing its explosive end as a supernova.
Join us as we explore these cosmic tales and more on SpaceTime with Stuart Gary.
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00:00:00
This is SpaceTime series 27 episode 18 for broadcast on the
00:00:04
ninth of February 2024. Coming up on SpaceTime claims that
00:00:09
lopsided Galaxies could shed new light on dark matter Virgin
00:00:14
Galactic undertakes its first space tourism flight for 2024.
00:00:18
And we look back at the ill fated SunRISE three mission
00:00:21
which was launching the biggest telescope ever to fly on a
00:00:24
balloon. All that and more coming up on space time.
00:00:30
Welcome to space time with Stuart Gary.
00:00:49
A new study suggests that lopsided Galaxies are providing
00:00:53
astronomers with new clues about a mysterious invisible substance
00:00:57
called dark matter. Scientists have no idea what dark matter
00:01:01
is, but we can see its gravitational influence on
00:01:04
normal so called baric matter.
00:01:06
The stuff stars, planets, houses people, trees, dogs, cats and
00:01:11
cars are made out of dark matter appears to hold Galaxies
00:01:15
together. It stops them flinging apart as they rotate and there's
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a lot of it, it makes up at least three quarters of all the
00:01:22
matter in the universe. And that 's really disconcerting if
00:01:26
you're a scientist, it means that you know nothing about the
00:01:29
majority of the stuff that makes up the universe.
00:01:32
The new study suggests that astronomers can measure
00:01:35
properties of dark matter by the so called proper motion of
00:01:38
Galaxies across space. The prerequisite is to find a galaxy
00:01:43
in the universe that moves relative to dark matter.
00:01:46
Now, since everything in the universe is in motion, and since
00:01:49
there's a great deal of dark matter in the universe, it's not
00:01:52
really difficult to find these Galaxies, heavy objects like
00:01:56
Galaxies attract all types of matter, whether it's dark matter
00:02:00
or the more visible matter that we encounter on a daily basis.
00:02:04
Now, we know dark matter interacts only gravitationally
00:02:07
with normal matter. So as dark matter moves past the galaxy,
00:02:11
the galaxy begins to pull the dark matter particles towards
00:02:15
it. However, the change of the speed direction of the particle
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takes time and before the trajectory curves towards the
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galaxy, they're already managing to pass the galaxy.
00:02:26
So the dark matter particles aren't entering the galaxy
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instead they're moving behind the galaxy. Therefore, the
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density of matter back there increases. And this should lead
00:02:35
to a slowdown of the galaxy, a phenomenon known as dynamical
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friction. Now, the strength of dynamical friction in turn
00:02:42
depends on how quickly dark matter particles pass the
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galaxy.
00:02:46
That is how long the galaxy is time to change the trajectory of
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the dark matter particles. When the particles are passing
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slowly, the density of matter increases close to the galaxy
00:02:56
causing it to slow down more as the dark matter particles move
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past the galaxy.
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The gravity field of the galaxy affects the particles of matter
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creating an over density behind the galaxy. Now, this over
00:03:09
density slows down the galaxy and distorts shape and that
00:03:13
could be a clue to dark matter. Now, finding these lopsided
00:03:17
Galaxies isn't difficult because they make up about 30% of all
00:03:20
the Galaxies in the universe.
00:03:21
So there are lots of them out there. Trouble is the lopsided
00:03:25
shape of the galaxy isn't always caused by dynamical friction.
00:03:29
Other factors include Galaxies that were formed asymmetrically
00:03:32
through galactic cannibalism or mergers.
00:03:35
However, astronomers can usually detect the difference because of
00:03:38
the existence of the remains of the other galaxy's nucleus or
00:03:41
because of a larger stellar halo. Now, galactic lopsidedness
00:03:45
can also be caused by a constant inflow of gas. So to measure the
00:03:50
velocities of dark matter, astronomers really need a
00:03:52
lopsided galaxy that is as isolated from other Galaxies as
00:03:56
possible.
00:03:57
Only then, could you be sure that nothing's happened to it
00:04:00
over a long period of time other than the passage of dark matter.
00:04:04
This is space time still to come. Virgin Galactic's first
00:04:09
near space flight for 2024. And we look back at the ill fated
00:04:13
SunRISE three mission, all that and more still to come on space
00:04:18
time.
00:04:34
Virgin Galactic's undertaken a successful first flight for the
00:04:37
New Year with its rocket powered space plane carrying four space
00:04:41
tourists to the edge of space from its New Mexico spaceport,
00:04:45
the galactic six mission reached an apogee or maximum altitude of
00:04:49
88.83 kilometers.
00:04:51
Now, that's still well short of the 100 kilometer high carbon
00:04:54
line which marks the internationally recognized start
00:04:56
of space. But it's about as high as the spaceship two s seem to
00:05:00
be able to fly after being released from its twin fuselage
00:05:04
mother ship the VMS Eve high above the New Mexico desert.
00:05:07
The blue and white delta winged rocket plane VSS Unity quickly
00:05:11
fired up its hybrid rocket engine and accelerated
00:05:14
vertically reaching mach 2.98 as it climbed to the edge of space
00:05:19
after reaching apogee and allowing passengers to
00:05:22
experience several minutes of weightlessness.
00:05:24
Unity began its re entry glide back down to Earth eventually
00:05:28
landing on the same runway from which it had taken off 56
00:05:31
minutes earlier attached to its eve mother ship. Meanwhile,
00:05:35
ongoing development is continuing on Virgin Galactic's
00:05:38
next generation of delta class space planes.
00:05:41
They're expected to start test flights next year and enter
00:05:44
service carrying passengers by 2026. Virgin Galactic says its
00:05:48
next flight to the edge of space is expected to include a mix of
00:05:52
both researchers and space tourists. We'll keep you
00:05:55
informed this space time. Still to come.
00:06:00
We look back at the SunRISE three mission to send the
00:06:03
largest telescope ever mounted on the balloon into the
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stratosphere and the spectacular constellation of Orion and the
00:06:10
nearby massive ticking time bomb of battle girls are among the
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highlights of the February Night skies on Skywatch.
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course, we'll include the details in the show notes and on
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our website. And now it's back to our show.
00:08:34
You're listening to space time with Stuart Garry.
00:08:39
Back in July 2022 the Max Planck Institute's SunRISE three solar
00:08:44
observatory high altitude balloon borne telescope made a
00:08:47
premature landing just hours after its launch. The mission
00:08:52
had been designed to carry the largest telescope ever launched
00:08:55
on a balloon high into the stratosphere.
00:08:58
A gondola loaded with scientific instruments was attached to a 6
00:09:02
m tall helium filled balloon. The mission would observe the
00:09:06
sun from an altitude of 35 kilometers where it's above more
00:09:10
than 99 per cent of the Earth's atmosphere. This would provide a
00:09:13
clearer, less distorted image than possible from the ground
00:09:16
where different temperatures cause different layers of air to
00:09:20
refract light differently.
00:09:21
The atmosphere is so thin that air turbulence doesn't obscure
00:09:25
the view. And the drier air at this altitude also allows the
00:09:29
wider spectrum of wavelengths to reach the telescope compared to
00:09:32
the fairly narrow band visible from the ground SunRISE.
00:09:36
Three was designed to undertake a multi day flight, collecting
00:09:39
unique measurements from a layer of the sun more than 2000
00:09:43
kilometers thick extending from just below the sun's visible
00:09:46
surface. That's the photosphere all the way to the upper Chromos
00:09:50
sphere. A highly dynamic layer between the photosphere and the
00:09:54
sun's outer atmosphere.
00:09:55
The corona. Even after decades of research, astronomers still
00:09:59
find the sun's Chromos sphere, a mysterious region of the sun's
00:10:03
atmosphere. It experiences an enormous temperature jump from a
00:10:07
comparatively moderate 6000 °C at the surface up to 200
00:10:12
degrees Celsius further up.
00:10:14
And in the layers above this, the temperature rises to over a
00:10:17
million degrees Celsius, a multitude of processes that
00:10:21
scientists still don't fully understand but could involve a
00:10:23
lot of magnetic reconnection occur up in the Chromos and
00:10:27
supply the corona with energy.
00:10:29
Now, in concert, these processes not only generate the incredibly
00:10:33
high temperatures of the corona but also facilitate violent
00:10:36
eruptions in which the sun repeatedly hurdles particles and
00:10:40
radiation into space in the solar wind. SunRISE. Three was
00:10:45
equipped with a 1 m telescope.
00:10:47
The largest balloon borne telescope ever launched at its
00:10:50
gondola carried three scientific instruments, an ultraviolet
00:10:54
spectra polarimeter, an imager, a visible light imaging
00:10:58
polarization spectrometer and a near infrared polarization
00:11:02
spectrometer. These allowed the mission to study the sun in a
00:11:06
wide range of wavelengths.
00:11:09
The three instruments were fed by way of two support devices,
00:11:13
an image stabilization and light distribution system which
00:11:16
supplies the telescope's images to the scientific instruments
00:11:19
and a correlation tracker and wavefront sensor which monitors
00:11:22
the vibration or image blur of the telescope in real time,
00:11:26
compensating is needed to obtain the highest possible resolution
00:11:30
images of the sun in the.
00:11:32
Build up to the mission's launch technical and scientific teams
00:11:35
from Germany, Spain, Japan and the United States prepared the
00:11:39
complicated electronics and optical instruments of the
00:11:41
mission and conducted a series of exhausting mission
00:11:45
rehearsals.
00:11:46
The team were greeted by driving snow and icy temperatures of
00:11:49
down to minus 15 °C when they arrived at the launch site at
00:11:54
Sweden's estranged Space Center near Karuna, which isn't far
00:11:57
from the Arctic circle. Launching from the Arctic circle
00:12:01
involves a considerable logistical effort.
00:12:03
But for the scientific success of the mission, the remote
00:12:06
launch site in the far north was crucial since the sun does not
00:12:11
set beyond the Arctic circle during the northern summer
00:12:13
SunRISE too could record observational data around the
00:12:16
clock as it flew. After a series of delays due to logistical
00:12:21
issues and bad weather. The 6 m tall balloon was eventually
00:12:24
launched.
00:12:25
However soon after its launch, scientists found they were in
00:12:29
trouble, unable to correctly aim the telescope towards the sun
00:12:33
that made it impossible to obtain any observational data.
00:12:36
And so the mission was terminated just hours after it
00:12:40
began, the observatory landed safely on uninhabited Swedish
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territory not far from the border with Norway.
00:12:47
The only good news was that the scientific instrument package
00:12:50
was left largely intact by the landing. This third ill fated
00:12:55
flight followed two highly successful early emissions back
00:12:58
in 2009 and 2013. It was a valiant effort ultimately ending
00:13:04
in failure. This report from the Max Planck Foundation.
00:13:08
Earth's atmosphere has always been a challenge for ground
00:13:11
based solar observation turbulence in the air obstructs
00:13:15
our view and ultraviolet light does not reach the Earth's
00:13:18
surface to fully utilize our fine tuned instruments. We need
00:13:22
to surmount almost all of our atmosphere and enter the
00:13:25
stratosphere. We've built a tele to direct sunlight into our
00:13:29
instruments and a gondola to carry and guide them.
00:13:33
We've integrated it all together to work as one and conducted
00:13:36
extensive tests in preparation for its flight on a
00:13:39
stratospheric balloon. Our goal is to better understand our star
00:13:43
's capricious nature and its effects on Earth. However, it's
00:13:47
not easy to investigate the sun.
00:13:49
The only information get from the sun is encoded in sunlight.
00:13:52
That is why we engineer unique instruments that extract
00:13:56
different information from sunlight. An important part of
00:13:59
our preparations takes place in laboratories that are kept
00:14:02
meticulously free from dirt and dust. Even the smallest dust
00:14:06
particles on our instruments may have a negative impact on the
00:14:09
quality of our data.
00:14:10
This is space time and time now to turn our eyes to the skies
00:14:30
and check out the celestial sphere for February on Skywatch.
00:14:34
February is the second month of the year in the Julian and
00:14:38
Gurian calendars. It's also the shortest month of the year and
00:14:41
the only one which is a length less than 30 days.
00:14:44
The month is 28 days in common years and 29 in leap years was a
00:14:49
quadrennial 29th day being caught a leap day. This
00:14:53
additional day, every fourth year is needed to keep the
00:14:55
calendar year synchronized with the astronomical year because
00:14:59
seasons and astronomical events don't repeat in whole numbers of
00:15:02
days, calendars that have the same number of days in each year
00:15:06
tend to drift over time with respect to the event.
00:15:09
The year is supposed to track by inserting an additional day
00:15:12
every fourth year. This drift can be corrected.
00:15:15
The extra days occur in years which are multiples of four,
00:15:18
with the exception of years divisible by 100 but not by 400.
00:15:23
Similarly, in the lunar Solar Hebrew Calendar, Adar Ale 1/13
00:15:28
month is added seven times every 19 years to the 12 lunar months
00:15:32
in its common years in order to keep its calendar from also
00:15:35
drifting through the seasons.
00:15:37
And the Baha calendar ali day is added whenever it's needed. In
00:15:41
order to ensure that the following year begins on the
00:15:43
vernal equinox, the length of the day is also occasionally
00:15:47
changed by the insertion of leap seconds in a co ordinated
00:15:50
universal time or UTC more often referred to as GMT or Greenwich.
00:15:55
Meantime, this is needed because of the variability in Earth's
00:15:58
rotational period. But unlike leap days, leap seconds aren't
00:16:03
introduced on a regular schedule since the variability in the
00:16:06
length of the day is not entirely predictable.
00:16:09
Ok. Let's turn our attention to the sky now. And throughout most
00:16:13
of February sky watchers in the southern hemisphere may be lucky
00:16:16
enough to catch sight of the occasional meteor associated
00:16:19
with the alpha and beta centauri meteor showers.
00:16:22
As their names suggest they appear to radiate out from the
00:16:26
direction of the constellation Centaurus as two separate
00:16:29
streams. Although they rarely produce more than one or two
00:16:32
Meteors per hour, they usually peak around February the eighth
00:16:36
and to see them at their best, you really should be looking
00:16:39
towards the east a few hours before dawn.
00:16:42
Ok, looking north now and high in the sky is the famous
00:16:46
constellation of Orion. The Hunter Orion is one of the best
00:16:50
known and most recognized constellations in the sky. In
00:16:54
Greek mythology, Orion was the son of a Gorgon and Poseidon who
00:16:58
was also known as Neptune, the God of the sea.
00:17:00
In Roman mythology, Orion was a mighty but egotistical and
00:17:04
conceited Hunter who once boasted that his skill would
00:17:07
allow him to kill all the world 's animals. So the Earth goddess
00:17:11
Gaia sent Scorpius the Scorpion to kill him and save the
00:17:14
animals. Orion was stung in the shoulder.
00:17:18
But then the healer of Uscis intervened to save him and crush
00:17:21
the Scorpion. Both Orion and the Scorpion were then placed in the
00:17:25
heavens to play out the story each year with Scorpius rising
00:17:28
in the east as the defeated Orion sets in the west.
00:17:32
Now, a variation of this fable speaks of Orion getting a little
00:17:35
bit too close to Artemis, the goddess of chastity. Now, her
00:17:39
brother Apollo didn't approve of this relationship and tricked
00:17:43
Artemis into testing her skill by shooting an arrow at a
00:17:46
distant speck on the ocean.
00:17:48
What Artemis didn't know was that that speck was actually
00:17:51
Orion swimming to escape the giant Scorpion created to kill
00:17:55
him. When Artemis discovered what she had done, she placed
00:17:58
Orion's body in the sky as the stars we see today. Similar
00:18:03
variations to this story appear in other cultures including
00:18:06
ancient Egypt where Orion is known as Osiris, the God of the
00:18:09
underworld and of regeneration.
00:18:11
The very earliest depiction that 's been linked to the
00:18:14
constellation Orion is a prehistoric mammoth ivory
00:18:17
carving found in a cave in the Arch Valley in West Germany. In
00:18:21
1979 archaeologists have estimated that it would have
00:18:25
been fashioned somewhere between 70 years ago.
00:18:30
The distinctive pattern of Orion has been recognized in numerous
00:18:33
cultures around the world including ancient Babylonian
00:18:36
star catalogs dating back to the late bronze age Orion is easily
00:18:40
identified by its rectangle of four stars surrounding a central
00:18:44
trio of stars in a row which form Orion's belt and hanging
00:18:49
from the belt are the stars which make up the sword of
00:18:52
Orion.
00:18:53
To those of our listeners in the southern hemisphere Orion
00:18:55
appears to be upside down with the sword on his belt pointing
00:18:59
upwards.
00:19:00
And if you look really, really carefully, you'll notice that
00:19:03
the middle star in the sword looks a bit fuzzy. That's
00:19:07
because it's not a star, but rather a huge star forming
00:19:10
region that is messier 42 or M 42. The Great Nebula in Orion
00:19:16
located some 1344 light years away.
00:19:20
M 42 is the nearest large star forming region to Earth
00:19:23
containing hundreds of newly forming stars and proto stars. A
00:19:28
light year is about 10 trillion kilometers. The distance a
00:19:32
photon can travel in a year at 300 kilometers per second,
00:19:35
the speed of light in a vacuum and the ultimate speed limit of
00:19:38
the universe, the Orion Nebula is more than 24 light years
00:19:41
across and it contains as much mass as 2000 suns.
00:19:46
It's one of the most scrutinized and photographed objects in the
00:19:49
night sky and is among the most intensely studied celestial
00:19:53
features Orion Nebula has revealed much about the process
00:19:57
of how stars and planetary systems are formed from
00:19:59
collapsing molecular gas and dust clouds.
00:20:02
By studying M 42 astronomers have directly observed
00:20:06
protoplanetary discs, brown dwarfs intense and turbulent
00:20:10
motions of gas and the f ionizing effects of nearby
00:20:14
massive stars in the nebula.
00:20:16
The Orion Nebula contains a very young open cluster known as
00:20:20
trapezium due to the asterism of its four primary stars. The
00:20:24
trapezium itself is the component of the much larger
00:20:27
Orion Nebula cluster. An association of around 2800 stars
00:20:32
within a diameter of just 20 light years.
00:20:36
The brightest star in the constellation of Orion is the
00:20:39
semi regular variable red super giant Betel Girs, which
00:20:42
represents the Scorpion's Sting on Orion's shoulder, currently
00:20:46
known as Betel Girs and commonly referred to by the public as
00:20:50
beetle juice.
00:20:50
Don't say it three times the names of birth tortured
00:20:53
mispronunciations of the original Arabic name IPT Yazar,
00:20:57
meaning the hand of the big man, the big man being Orion. The
00:21:00
Hunter located some 643 light years away. Begs is the ninth
00:21:05
brightest star in the night sky and it's big, really big.
00:21:10
In fact, red giants like begs are among the largest stars in
00:21:14
the universe, at least in terms of volume. Although they're by
00:21:17
no means the most massive or luminous calculations of Betel G
00:21:21
's mass range from slightly under 10 to a little over 20
00:21:25
times that of the sun and it shines with some 100 times
00:21:29
the sun's brightness.
00:21:31
If it were placed at the location of our sun at the
00:21:34
center of our solar system, its visible surface would extend
00:21:37
almost as far out as Jupiter engulfing the orbits of the
00:21:40
planets Mercury Venus, Earth and MARS, as well as the main
00:21:44
asteroid belt.
00:21:45
Pal GS began its life around 10 million years ago as a spectral
00:21:49
type O or B blue star astronomers describe stars in
00:21:53
terms of spectral types, a classification system based on
00:21:57
temperature and characteristics. The hottest, most massive and
00:22:00
most luminous stars are known as spectra type O blue stars.
00:22:05
They're followed by spectra type B, blue white stars.
00:22:08
Then spectra type A white stars, spectral type f, whitish yellow
00:22:12
stars, spectra type G, yellow stars. That's where our sun fits
00:22:16
in. Then there are spectra type K orange stars and the coolest
00:22:20
and least massive stars are spectral type M red stars often
00:22:24
referred to as red dwarfs.
00:22:26
Each spectral classification system is also subdivided using
00:22:29
a numeric digit to represent temperature with zero being the
00:22:32
hottest and nine being the coolest. And then a Roman
00:22:35
numerals added to represent luminosity, put them all
00:22:38
together and our sun is officially classified as A G two
00:22:43
V or G 25 yellow dwarf star.
00:22:46
Also included in the stellar classification system are
00:22:49
spectral types LT and Y which are assigned to failed stars
00:22:53
known as brown dwarfs, some of which were actually born as
00:22:56
spectral type M red stars but became brown dwarfs after losing
00:23:00
some of their mass, brown dwarfs fitted all category between the
00:23:03
largest planets which are about 13 times the mass of Jupiter and
00:23:07
the smallest spectra type m red dwarf stars which are between 75
00:23:11
and 80 times the mass of Jupiter or about 0.08 solar masses.
00:23:16
Red super giants are fascinating objects. After spending billions
00:23:21
of years fusing hydrogen into helium in their core. A star's
00:23:24
core hydrogen supply eventually runs out and the balancing act
00:23:28
between nuclear fusion pushing outwards and gravity, pushing
00:23:32
inwards stops with gravity winning the entire mass of the
00:23:37
star then comes crashing down on the core.
00:23:40
This causes a dramatic increase in the co pressure and
00:23:43
consequently temperature things get hot enough to trigger what's
00:23:46
called a helium flash. This causes the core helium which is
00:23:50
being created in the star to begin fusing into carbon and
00:23:53
oxygen.
00:23:54
At the same time, the hydrogen rich region around the stellar
00:23:58
core has now moved out into that region where the temperatures
00:24:01
and pressures are high enough for hydrogen fusion into helium
00:24:04
to commence in a shell around the core.
00:24:06
Now, as all this is going on, the increasing core temperature
00:24:09
results in an increasing level of luminosity. And the resulting
00:24:13
radiation pressure from the shell burning causes the outer
00:24:16
diffuse gaseous envelope of the star to expand to hundreds of
00:24:19
times its previous radius.
00:24:21
And as the now bloated star's Chromos sphere or visible
00:24:25
surface moves further away from its core, it cools down, turning
00:24:29
redder. Hence, the star has become a red giant, small stars
00:24:33
like the sun eventually lose their outer envelopes completely
00:24:37
which continue expanding outwards as planetary nebula.
00:24:40
This ultimately exposes the star 's white hot stellar core as a
00:24:44
white dwarf, she is then left to slowly cool down over the eons
00:24:48
of time. However, stars with masses more than around eight
00:24:52
times that of the sun experience a very different fate.
00:24:56
Unlike the sun, their fusion cycle doesn't end with helium in
00:24:59
the core, fusing into carbon and oxygen, they have enough mass to
00:25:03
fuse carbon and oxygen in their core into progressively heavier
00:25:06
and heavier elements through a different process. While the
00:25:09
shell burning around the core also fuses progressively heavier
00:25:13
and heavier elements, carbon, nitrogen, oxygen, neon
00:25:17
magnesium, silicon, sulfur, nickel and eventually iron.
00:25:21
These stars have become super giants, eventually they'll
00:25:25
explode as core collapse supernovae ending up as either
00:25:29
super dense strange objects called neutron stars or even
00:25:33
stranger objects called black holes, singularities of infinite
00:25:37
density and zero volume where the laws of physics, the science
00:25:41
understands them no longer apply.
00:25:43
It's too early to tell whether be goes ultimate fate will be as
00:25:47
a neutron star or black hole as a red super giant. Bet Gs is
00:25:52
reaching the end of its life and it's expected to explode as the
00:25:55
core collapse or type two supernova any day.
00:25:58
Now, of course, in astronomical terms, any day now could mean
00:26:02
tomorrow or it could mean a million years from now when it
00:26:05
does explode. Bet girls will temporarily outshine all the
00:26:09
other stars in our galaxy and it will be clearly visible in the
00:26:12
daytime sky on Earth.
00:26:14
The last star to be seen by humans to go supernova in our
00:26:17
galaxy was Tyko star that was in 1572. And that was before the
00:26:22
invention of the telescope diagonally opposite, be girls
00:26:26
marking. Orion's left foot is the blues super giant star
00:26:30
Rigel, the second rider star in the constellation Orion Rigel's
00:26:34
part of a triple or possibly quadruple star system with three
00:26:37
or four small companion stars.
00:26:40
The primary star Rigel A is located some 863 light years
00:26:44
away and is about 23 times the mass of the sun.
00:26:47
The star's already exhausted its core hydrogen supply and it's
00:26:51
swollen out to between 79 and 115 times the sun's radius and
00:26:56
is somewhere between 100 and 299 times as luminous like
00:27:02
Bet G it's now fusing progressively heavier and
00:27:05
heavier elements in its core, meaning it too will soon go
00:27:08
supernova. Rully pulsates quasi periodically and is classified
00:27:13
as an alpha sign. Variable star.
00:27:16
Alpha Sydney variables are variable blue or white super
00:27:19
giant stars which exhibit non radial pulsations, meaning some
00:27:23
areas of the star's surface are contracting while others are
00:27:26
expanding. This causes irregular variations in brightness due to
00:27:31
beating of multiple pulsation periods.
00:27:34
The pulsations are likely caused by ion oy variations and
00:27:37
typically have periods ranging from several days to a few
00:27:40
weeks. Raja's companion star RL B is some 500 times fainter than
00:27:46
the super giant and it's only visible with a telescope RB
00:27:50
itself is a spectroscopic binary system comprising two main
00:27:54
sequence blue white stars.
00:27:56
Main sequence stars are those happily fusing hydrogen into
00:28:00
helium in their core. And spectroscopic binaries are
00:28:03
double star systems orbiting each other so closely and at
00:28:06
such an angle that they can only be visually separated at least
00:28:09
from our viewpoint on Earth by the spectroscopic signatures.
00:28:13
The two stars making up Rigel B are estimated to be 3.9 and 2.9
00:28:18
times the mass of the sun respectively. And one of those
00:28:21
stars RL BB itself, maybe a binary, it appears to have a
00:28:26
very close visual companion rigl C of almost identical
00:28:29
appearance.
00:28:31
The third brightest star in Orion is Bellatrix Orion's left
00:28:35
shoulder. It's a spectral type B main sequence blue star with
00:28:39
about 8.6 times the mass and six times the radius of the sun
00:28:43
bellatrix is located about 250 light years away.
00:28:47
It has an estimated age of approximately 25 million years.
00:28:51
Now, that's old enough for a star of this mass to have
00:28:53
consumed much of the hydrogen in its core and begin the process
00:28:57
of evolving away off the main sequence into a blue giant.
00:29:01
One of the most stunning nebula in Orion is the spectacular
00:29:05
horsehead nebula B I 33. The horsehead is a dark nebula
00:29:09
located just south of the star Al attack, which is the furthest
00:29:13
east on Orion's belt and is part of the much larger Orion
00:29:16
molecular cloud complex located around 1500 light years away.
00:29:21
The horsehead nebula was first recorded in 1888. It's one of
00:29:25
the most identifiable nebulae simply because of the shape of
00:29:28
its swirling clouds of dark dust and gas, which really does bear
00:29:32
an incredible resemblance to a horse's head to the west of
00:29:37
Orion's belt. You'll see a V shaped grouping of stars which
00:29:40
represent the head of Taurus.
00:29:41
The bull who in Greek mythology was changed by the God Zeus to
00:29:46
carry Princess Europa to crete. The V is also part of a large
00:29:50
open star cluster known as the Hyades. One of Tour's eyes is
00:29:54
the giant orange star called Aran or the follower, which is
00:29:58
located at around 65 light years away and has about 1.5 times the
00:30:02
mass of the sun.
00:30:04
Aldebaran is thought to contain a number of Jupiter sized
00:30:07
planets.
00:30:08
Abras already evolved off the main sequence having exhausted
00:30:12
its core hydrogen fuel supply. It follows the Pleiades or seven
00:30:16
sisters. A spectacular open star cluster to the northwest of the
00:30:20
V located in the constellation. Tourist. The pleads is one of
00:30:24
the nearest and youngest open star clusters to Earth located
00:30:28
just 443 light years away.
00:30:30
There's a story in Greek mythology which tells us that
00:30:33
Orion fell in love with the seven sisters and pursued them
00:30:36
for a long time. Eventually Zeus turned both Orion and the pleads
00:30:41
into stars.
00:30:42
Interestingly, a similar story is told in the Aboriginal
00:30:45
dreamtime culture of the Great Victoria Desert region, near Old
00:30:49
Deer in Outback, South Australia. Orion's described as
00:30:52
a young male Hunter who chases but never catches the plead who
00:30:56
are a group of seven young women in Orion's right hand is a club
00:31:00
filled with magic fire and represented by the red giant
00:31:03
star begs.
00:31:04
However, the pleads older sister represented by the Hades Star
00:31:08
cluster taunts Orion standing in front of him, she defensively
00:31:12
lifts her foot, which is the star older Baran and is also
00:31:15
full of fire magic and this causes Orion great humiliation,
00:31:19
putting out his fire and allowing the seven sisters to
00:31:22
escape.
00:31:23
Now, one of the interesting facts about this ancient
00:31:25
dreamtime story is that it accurately describes the
00:31:28
variability of battles which brightens and fades over a 400
00:31:32
day period.
00:31:33
The play at seven sisters story is remarkably similar to legends
00:31:37
found in many other cultures around the world and which
00:31:40
haven't had any contact with each other for tens of thousands
00:31:43
of years. The play at seven brighter stars can be seen with
00:31:46
the unaided eye, hence the seven sisters nickname. But this
00:31:50
spectacular open star cluster actually consists of more than
00:31:53
100 stars.
00:31:55
Now, if you follow Ryan's Belt to the east. It brings you to
00:31:58
Sirius, one of the nearest and brightest stars in the sky
00:32:02
located just 8.7 light years away. Sirius is a binary star
00:32:06
system with a spectral type, a white star orbited by a white
00:32:10
dwarf. It's the brightest star in the constellation Canis
00:32:14
major.
00:32:14
The Great dog in Greek mythology, Sirius was the dog
00:32:18
star and the canine companion of Orion, the Hunter to the ancient
00:32:22
Egyptians, C was known as the God Anubis lord of the
00:32:25
underworld, who had the head of the dog and who invented
00:32:28
embalming the funeral rites and who guided one through the
00:32:32
underworld to judgment where he attended the scales during the
00:32:35
weighing of the heart to determine one's fate in the
00:32:37
afterlife.
00:32:39
Later, Anubis was replaced by Osiris as lord of the
00:32:41
underworld. Sirius also represented the God Isis and
00:32:45
ancient Egyptians initially based their calendar on the star
00:32:48
's yearly motion across the sky.
00:32:51
Now, if you look high in the southern sky in February, you'll
00:32:54
see the star Canopus.
00:32:55
A white super giant located 330 light years away, the second
00:33:00
brightest star in the night sky after Sirius in Greek mythology,
00:33:04
Canopus was the helmsman of the Greek King Menelaus and the
00:33:08
brightest star in the constellation Carina, which
00:33:10
represents the keel of the boat used by Jason and the Argonauts
00:33:14
in their quest for the golden fleece located nearby are the
00:33:18
vessel's sails represented by the constellation Vela and the
00:33:21
roof of the boat's rear cabin or poop deck, which is represented
00:33:24
by the constellation p also in the southern skies.
00:33:28
This time of year, you'll see the large and small Magellanic
00:33:31
clouds which are two dwarf Galaxies orbiting our own
00:33:35
galaxy. The milky way, the Magellanic clouds were known as
00:33:38
Polynesians and Maori and served as import navigation markers.
00:33:43
They're named in honor of the Portuguese Navigator Ferdinand
00:33:46
Magellan, who was the first European to cite them during the
00:33:48
first circumnavigation of the Earth.
00:33:50
Between 1519 and 1522 Magellan himself didn't complete the
00:33:55
circumnavigation. He was killed in the Philippines during the
00:33:58
battle of Mactan. Right now, the large Magellanic cloud is
00:34:02
located almost directly overhead and is about 100 and 63
00:34:06
light years away. Although it looks like an irregular dwarf
00:34:09
galaxy, astronomers have classified it as a disrupted
00:34:12
barred spiral.
00:34:13
It's around 14 light years in diameter and contains about
00:34:17
10 billion times the mass of the sun located slightly lower into
00:34:21
the west. You'll see the small Magellanic cloud which is
00:34:24
located around 200 light years away. It's classified as
00:34:28
an irregular dwarf galaxy about 7000 light years wide with about
00:34:32
7 billion times the mass of the sun.
00:34:35
Astronomers speculate that it too was once a bad spiral
00:34:38
galaxy, but it become disrupted by the gravitational tidal
00:34:41
perturbations of the milky way turning to the planets now and
00:34:46
Jupiter is in the northwest of areas on February the 16th, the
00:34:50
crescent moon will be to the right or north of Jupiter. So
00:34:53
it'll be easier to spot right now.
00:34:55
Saturn is low in the west in Aquarius at the start of the
00:34:58
month and is about to disappear below the horizon, turning to
00:35:02
the morning stars or more accurately, the morning planets
00:35:05
and mercury started a month off low in Sagittarius in the South
00:35:08
East, but he is now moving into Capricorn.
00:35:11
Venice is also in the east, moving from Sagittarius to
00:35:14
Capricorn during the middle of the month, Venice, of course, is
00:35:17
easy to see as the morning star because it's the brightest
00:35:20
object in the night sky other than the moon. And the red
00:35:24
planet MARS is also making a morning appearance this time of
00:35:27
year, moving east from Sagittarius to Capricorn during
00:35:30
the middle of the month. And that is Skywatch for February.
00:35:50
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