You’ve Been LIED TO by the North Star! Introduction and Information about Polaris
Drop everything and let me give you a really fun fact about the North Star to share with
your friends and family, in the hopes of sounding a little smarter and up to date in the science
field. Everything we know about this star has just been put under a huge question mark!
Polaris, also known as the North Star, has been guiding travelers for centuries in determining
the direction of north on Earth. This star is located in the constellation Ursa Minor,
commonly known as the Little Dipper. Thanks to its fixed position relative to the Earth's
rotation axis, Polaris remains almost directly above the North Pole throughout the night.
This makes it a reliable reference point for navigators, astronomers, and even
everyday stargazers who want to locate the North direction, since the beginning of civilization!
At the center of the Little Dipper, Polaris is part of a triple star system. It consists of
a primary star and two companions, which are much fainter and orbit around the main star.
The interesting aspect of Polaris that we will be focusing on is its pulsating nature. It
periodically varies in brightness, which can be clearly observed and determined by astronomers.
This characteristic is usually studied to gain insights into the distance of stars
and gain more information on the acceleration rate of the Universe.
These specifically rhythmic pulsating stars are called Cepheid variable stars.
Keep that in mind while watching the video! ---
What is Happening? Very recent studies have
shown that the pulsations of the star haven’t been showing exactly what we expected them to.
Its pulsations have been undergoing weird changes in the past 200 years,
and we only really noticed today! It seems like this is causing the science
community to no longer be able to agree neither on the size nor on the distance of Polaris from us!
Why? Well… because what we thought was a classical stable cepheid variable is actually changing its
periods many times throughout the years. It was known that Polaris had a strictly programmed
pulsating period of every 4 days. Meaning that every 4 days, Polaris would go on a full cycle of
being extremely bright and then extremely dark, etc… or at least that’s what we thought. Let’s
see this in more details… but before that, it is important to state the information regarding what
type of stars are orbiting our strangle Polaris. ---
Types of Stars Around It The Polaris I keep mentioning is the main star,
more professionally called Polaris AA. It is a yellow super giant, also called an F type star.
Astronomers seem to like putting simple letters on stars. Anyway,
Polaris is 5.5 times the mass of our dear Sun and it is our main focus because it is also the
famous Cepheid variable in the triplet. Moving on to one of the orbiting stars,
the closer one is called Polaris AB, and it is kinda similar in mass with our Sun. Polaris
AB revolves around Polaris AA in a pretty slow orbit with a period of approximately 29 years.
The last little orbiting star is one that is soo much further away from these two, that one
could wonder how it even ended up in this triple system. Anyway, can you imagine that it is 2400
astronomical units far away from the main star and orbits it with a period of 40 thousand years??
We expect that the distance of Polaris from the Earth is around 448 light years,
just for reference. ---
Direct Observations Here's the interesting part about Cepheid
variables- their total brightness is directly linked to their pulsation! It's like their own
little light show. So, if we look at these special stars that are really far away, we can actually
figure out exactly how far they are. How, you ask? Well, we can determine their total luminosity!
Recently, some smart folks decided to use the James Webb Space Telescope to take a closer
look at about 300 of these stars. Their goal was to confirm the distances to different galaxies and
see if they could solve the famous cosmic mystery known as the Hubble tension. This mystery has to
do with how the universe is expanding, how fast it’s going and it's been really bugging
scientists for a while now, trust me. Now, the James Webb Telescope is like the
Sherlock Holmes of space exploration. It's got all these fancy instruments to help us
investigate the mysteries of the universe. So, the scientists collected data from these Cepheid stars
and analyzed it with the help of the telescope. And guess what they found? The Hubble tension
is still hanging around like a pesky mosquito. It turns out, the universe isn't expanding at
the same rate everywhere you look. It's like a speed limit sign got all mixed up and confused.
But let's break it down a bit more. Imagine you're at a race, and all the runners are supposed to be
going at the same speed. But, when you actually watch them, some runners are going faster,
and some are going slower. It's chaos, right? Well, that's pretty much what's happening with
the expansion of the universe. The galaxies are like those runners, all going at different speeds.
So, what does this mean? It means that the Hubble tension is a real deal. It's
not just some fluke or mistake. Our universe is a bit wonky, and we still don't know why.
It's like trying to solve a Rubik's cube that keeps changing colors every time you turn it.
Even though the Hubble tension is a bit frustrating, it's also exciting.
It means there's still so much we have to learn about the universe we live in.
--- Something is Weird!
Recently, the observations from Polaris have added a new twist to the story.
Astronomers have been keeping tabs on it and have noticed some interesting things.
Back in 1911, they figured out that Polaris is a pulsating star. But what's really fascinating
is that over the course of the 20th century, the period of its pulsations has been slowly
increasing. It's like the star is taking longer and longer to complete one full pulsation.
However, the total amplitude, or the size of the brightness change, has been getting smaller.
It's like the star is becoming less flamboyant with its pulsations.
But here's where it gets even weirder. Between 1963 and 1965,
something unexpected happened. The pulsations actually reversed for those years, and nobody
knows why. It's like Polaris decided to flip the script and confuse everyone. This phenomenon
has been ongoing for more than a century, with the pulsations gradually intensifying,
although the increase is not significant. At present, the only hypothesis we have is that
Polaris comprises three stars in a system. It is possible that one of the stars is influencing the
primary star, causing it to pulsate at slightly varying intervals and with reduced intensity.
Nonetheless, this is merely speculation, and we have yet to establish a concrete explanation.
But hold on, because there's more. In the last few years, things have taken an even stranger turn.
You thought we were done, didn’t you. Nope! Around 2010, instead of the period continuing
to increase, it started to decrease. It's like Polaris decided to change its mind and
confuse us even more. And in the 1990s, the pulsations became so small that they almost
disappeared completely. It was like the star was playing a disappearing act on us.
All of these changes were measured using something called radial velocity, which looks at the total
velocity of the star by analyzing its red shift and blue shift. Scientists have collected nearly
4,000 measurements over the past 60 years. And based on these measurements, the amplitude of the
changes seems to be coming down. It's like Polaris is slowly calming down and becoming more stable.
So, what does all of this mean? Well, right now, we don't have all the answers. But like
I gave you a little hint about it earlier, we do have some possible explanation to this
mess. ---
Possible Causes We Know Of As we get into the intricacies,
it becomes a little apparent that the cause lies within the orbital dynamics at play. Let's take
a closer look at the enigmatic situation. To quickly recap, our attention is drawn to
the main star, which happens to be accompanied by a neighboring star that orbits it every 29 years.
This celestial companion could be holding a key role in this. It influences over the upper layers
of the primary star, causing subtle shifts in their positions. The eccentric nature of their
orbit amplifies these effects, particularly when the stars draw closer to each other.
This celestial rendezvous occurs every 29 years, possibly triggering significant
changes in the orbital dynamic of the two stars. Curiously, such a scenario also poses a challenge
for astronomers seeking to chart a more precise and accurate orbit of the entire star system. The
intricacies of these celestial motions make it incredibly challenging to map their paths with
great precision. ---
Consequences However, this new
finding presents a huge problem. As I mentioned earlier, Cepheid variables are commonly used to
accurately determine distances, because of their unchanging nature. But now we have discovered that
these Cepheid variables are influenced by their partner stars, and to a greater extent
than previously thought. This is something we need to be aware of because it could be distorting our
measurements of distances to galaxies that are far away. In simpler terms, this phenomenon could be
causing errors in our understanding of the expansion of the universe,
also known as the Hubble tension. To gain a better understanding of what exactly is happening here
and whether this could be the reason behind the discrepancies we observe, further study is needed.
These recent revelations have opened up a new avenue of investigation.
It is important to delve deeper into the changes occurring in the well-known star, Polaris. What is
causing these changes remains a mystery, as nobody currently possesses the answers. Cool stuff huh?
--- Outro
In conclusion, the discovery of how Cepheid variables are influenced by their
partner stars has raised concerns regarding the accuracy of distance measurements. This phenomenon
could potentially skew our understanding of the expansion of the universe and the Hubble tension.
Therefore, it is crucial that we dedicate more
research to studying this phenomenon in order to gain a clearer understanding of the situation. The
changes observed in Polaris present an intriguing mystery that scientists are eager to solve, and
you my friend, have something cool to impress your friends with.
Thanks for watching, and we'll see you in the next video, where we'll explore more
fascinating developments of our world! Don’t forget to like, subscribe to our
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