The Hubble Space Telescope has been in operation for an astonishing 28 years, and during this
time it has imaged some spectacular sights of our galaxy and beyond.
It truly is a marvel of technology, and has helped improve our knowledge of the universe
we live in no end.
This includes understanding the many different types of stars in our galaxy, in various stages
of their development.
In this episode, we are going to have a look at some of the most special and peculiar stars
it has seen, and believe me when I say some of these are simply breath-taking!
35. HH 34.
This amazing sight, found near the Orion Nebula, is a Herbig-Haro object or an emission jet
from an extremely young star that is still in the earliest stages of its formation.
You can see the star here, still tucked inside this molecular cloud.
The Orion Nebula is one of the closest HII nebulae, or star forming regions to us, which
means we can see stars in the process of being formed reasonably close-up.
The star is releasing this extremely hot jet of gas from one of its poles, which speeds
through space at hundreds to thousands of kilometres per second.
Eventually this jet hits colder material, heating it up, which is what you can see here
at the bottom left.
For astronomical standards, this is a very short-lived event, only lasting a few thousand
years.
36.
More stars in the process of being formed, this is XZ Tauri and its neighbour stars HL
Tauri and V1213 Tauri.
To me, this image is one of the most mind blowing images Hubble has ever taken, the
birth of stars taken against the backdrop of a dark molecular cloud.
Let’s have a look at what is going on!
This is XZ Tauri, a star system containing two stars about the distance of our Sun and
Pluto apart.
For reasons unknown to scientists, these stars have ejected a huge bubble of hot gas seen
here.
This bubble is expanding at a rapid rate, as seen over the course of 5 years.
This over here, is HL Tauri, another very young T-Tauri star.
This star has a protoplanetary disk surrounding it, meaning planets are likely still in the
process of forming here.
It’s also ejecting another Herbig-Haro object, number 150, shooting over in this direction.
And lastly we find V1213 Tauri, a variable star with a spectacular disk surrounding it.
At a side on angle to us, the disk obscures the view of the star itself. But its reflected
light comes off the surrounding gases and HH 30, the Herbig-Haro objects shooting off
in both directions away from the star.
An amazing image, found near the Taurus constellation.
37.
OK, just one more protostar.
HH 24.
The star itself is again hidden away behind the blanket of the molecular cloud it is surrounded
and being fed by, but what is clearly evident is the lightsabre like jet of gas being blasted
away from the star in both directions.
It shares a lot of similarities to the other Herbig-Haro objects in this episode, but the
image itself is so impressive nonetheless.
This protostar is also found near the Orion nebula.
38.
LL Pegasi.
We’re moving on now to stars near the end of their lives.
Nope, not this bright star, but rather this dark and mysterious spiral next to it.
This is one of the most perfect geometrical objects formed in space.
But what is it?
This is actually a pre-planetary nebula, basically a massive star found behind all this dust
in the centre is shedding some of its mass, potentially before it erupts into a planetary
nebula.
The difference between a pre-planetary nebula and a planetary nebula is that a preplanetary
nebula is a reflection nebula, meaning it is illuminated by light reflecting off it,
whereas a planetary nebula consists of extremely hot ionised atoms, which produces
its own light.
In this image, the material forming the spiral is moving at 50,000kph, and by combining this
speed with the distance between the layers, it is estimated to produce a ring roughly
every 800 years.
They believe this is directly related to the fact that this is a binary star system, the
orbital period of which is thought to also be 800 years.
This means the spiral is a result of the orbital motion between the two stars as one sheds
its mass.
39.
Another preplanetary nebula is HD 44179, a unique nebula with a rectangular, or X shape!
This nebula is really hard to see from a ground telescope due to the Earth’s atmosphere,
and is one of the situations where having Hubble is space really useful.
This preplanetary nebula has really baffled scientists, who don’t know the exact mechanics
of how this structure formed.
But there is evidence that this is due to another close binary star system, with a star
about the mass of our Sun shedding its mass before it turns into a white dwarf.
It’s the remaining white dwarf that will eventually radiate UV light, ionising the
ejected gases to become a planetary nebula.
40.
Let’s have a look at a completely different type of star with RS Puppis.
This bright star at the centre of the image is our focus in this image, and there is something
very unusual about this star.
It is a variable star, known as a Cepheid Variable.
This means it varies in brightness by a factor of 5 once every 40 or so days.
Because this star is surrounded by a beautiful dust structure, we can see the variable nature
of this star through a “light-echo”.
Light travels extremely fast, but it still takes a long time to get across astronomical
distances.
This means we can see the procession of light travelling away from the star, with some rings
being dark as the star was dimmer, and some rings being brighter as the star brightened!
Hubble imaged RS Puppis over a 5-week period, and you can actually see this light echo pulsing.
All in all, a ghostly yet beautiful image.
41.
AG Carinae.
This star is another variable star, but it is one of the brightest in the Milky Way.
Because it is so bright, it is also short lived, as it is shedding its mass through
solar winds at an incredible rate, and at speeds of up to 7 million kph.
Much of the surrounding material around this star is part of the ejected mass of the star,
being further sculpted by the solar winds as you can see.
One day this star will become a Wolf-Rayet star, a type of star millions of times more
luminous than our Sun.
However, it’s so hot that it isn’t visible to the naked eye, much of its output is in
the ultraviolet!
42.
NGC 4993.
So far, all the stars we have looked at have been found in our own galaxy, outside the
galaxy, individual stars are pretty hard to observe...
Typically.
But sometimes cataclysmic events happen in other galaxies that are so big that we can
observe it millions of light years away.
And this is what happened with NGC 4993, where something even more spectacular than a supernova
happened, a kilonova.
In August 2017, LIGO detected gravitational waves from the collision of two neutron stars,
and within 12 hours the source of these gravitational waves had been discovered.
Considering is it so bright and evident 140 million light years away, I can’t imagine
what it would have been like from within the same galaxy.
These neutron stars will have combined to form a black hole, and the resultant kilonova
explosion will have emitted electromagnetic radiation in every frequency, from radio waves
to gamma rays.
Interestingly, it is believed that these neutron stars colliding could be the main source of
heavier elements such as gold in the universe.
It that is true, it gives your jewellery a bit of a new perspective!
Are you inspired to learn more about stars but have no idea where to start?
Protostars, neutron stars and black holes can appear daunting at first without a prior
knowledge to astronomy, but fret no more.
A good place to start learning the logic and theory behind science is Brilliant.
They have a bunch of courses teaching you how to think like a scientist.
Each course is interactive and breaks up complicated concepts into bite-sized chunks to make sure
you actually absorb the information, a strategy which I find very helpful for myself!
Try Brilliant out for free today by using the link brilliant.org/astrum.
Then, if you like what you see, the first 200 people that used that link will get 20%
off the annual Brilliant premium subscription!
Well sadly that’s all we have time for today.
If you’re new to the channel and like what you see, you’ll love my other videos too!
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All the best, and see you next time.