the age of our galaxy is up for debate can you believe it in the past we dated our galaxy at
11 billion years old but we may have been way off not much just a billion or two years
new studies of data recently released to the scientific community have shaken the
understanding of star dating as we know it welcome to Factnomenal and today we
are exploring how scientists are pinpointing the real birth of our very own galaxy the Milky Way
the discrepancy in the birth date of our galaxy is quite revolutionary information
this adjustment was brought to light by two scientists named Maosheng Xiang
and Hans-Walter Rix located in Heidelberg Germany at the Max Planck Institute for Astronomy or MPIA
Xiang and Rix were scouring through thousands of stars worth of data looking for something specific
these two men had to study a lot of scientific data that was transmitted to earth by
two immensely powerful telescopes to find the hidden truth about our galaxy's age
but can we blame the milky way come on we all get shy about getting older don't we
Xiang and Rix utilized two different methods as foundations of their study
one was china's large sky multi-object fiber spectroscopic telescope and the other was the
exquisitely detailed data transmitted from the European Space Agency's Gaia mission they combined
this data to look specifically at subgiant stars in the thick disk of our Milky Way fyi subgiants
are a particular type of star in a specific life stage these stars are in the phase of life right
before they transition into a red giant this period of time gives astronomers a precise
snapshot of the star's compositional makeup and it's the perfect time that can be used to study
the sub-giant more clearly compared to other phases of its life a sub-giant is an ideal
type of star to search for to put a birthday too one of the reasons that it is simpler to
date a sub-giant than other stars is because as a sub-giant the star is no longer producing any
energy of its own in the core thus it is easier to study with less variables and distractions
Xiang and Rix studied the brightness position and chemical composition of the sub-giants they did
this to be able to infer the ages of the stars in their selected cluster that they had chosen this
cluster was unique and found deep within the thick disk of the Milky Way more specifically than just
the brightness and position Xiang and Rix were looking at the metallicity of the stars as means
to categorize their subgiants metallicity is a complicated way to say make up of metals or gases
stars that have less metals and gases in them or with lower metallicity are considered to be the
older stars in our galaxy this is because when they were formed there were only a few elements
to choose from actually it was almost exclusively helium and hydrogen that were the only elements
available as building blocks in the early years so then if a star is found to have more diverse
metals in it or more than just the original two they are considered to be younger stars
scientists will study the makeup of stars and use their metallicity as a standard to start
describing them and what their ages are with this technique in mind our two scientists Xiang and
Rix continued to focus their eyes on a place in the Milky Way galaxy called the thick disk
the thick disk is a large cluster of thousands of stars and is exactly where our boys recently
discovered the sub-giants that changed everything they found that the sub-giant stars there have a
lower metallicity or older age than ever recorded this resulted in the age of the milky way galaxy
coming in at 13 billion years old instead of the 11 billion years as we had previously computed
to put that onto another timeline that means the Milky Way started to form as early as
0.8 billion years after the big bang Rix and Xiang's studies help to bring the creation of
the Milky Way into perspective and it also points to the oldest parts of our galaxy
the thick disk where the thousands of stars that were studied are is itself
one of the earliest parts of our galaxy to start forming at 0.8 billion years after the big bang
the thick disk was born first and its growth had begun to slow down after nearly 2 billion years
suddenly a dwarf galaxy called the Gaia Sausage Enceladus, GSE plowed into the thick disk causing
an enormous explosion of new stars and celestial matter to surge into our galaxy the Gaia sausage
was a small galaxy made up of a few billion stars and it was absorbed into the milky way after
the collision it got its name from the highly elongated orbit of its stars which resembled the
barbecue party favorite this merger of the Gaia sausage and the milky way was discovered in 2018
and has long been suspected of masking an older and original portion of our galaxy as GSE collided
with our galaxy the explosion of stars gave birth to a new and growing neighbor called the thin disk
when this collision took place and accelerated what has been called the second phase of galactic
evolution within the disks the night sky that we know and see was born the thin disc took front
end center from the thick disc as time went on and is now a huge blanket of stars that expands across
our night sky almost all of the stars that we see at night are part of the thin disc with its birth
the thin disc began to hide the older stars within the thick disk and thus mask the age
of our galaxy like a well done paint job can do on a classic vehicle this process of hiding old stars
behind bright new ones is no more a hindrance as our technology is advancing and our imaging
of space is getting more detailed and spectacular all of this excitement isn't even at its peak yet
this is because in June the Gaia Satellite is due to release another dataset and scientists
are hoping that it will cast even more light onto the dark mysteries of our galaxy the Milky
Way the Gaia Satellite's data is central to the discoveries made by ricks and Xiang the satellite
was created and deployed into space to send back precise positioning and brightness data of over
1.5 billion stars previously when trying to date a star astronomers were working within a range of 20
to 40 percent of uncertainty about the stellar age of the stars they were studying what that
means is that there was a 20 to 40 percent range in which they could be wrong on the exact date
according to Xiang with Gaia's brightness data we will be able to determine the age of a sub-giant
star to a few percent if you were to compare a gas within a few percent to the 20 to 40 percent
of uncertainty previously afforded to guesses we would take the new odds previously a scientist
could end up with results being off by one billion years and that would be totally normal as we
mentioned earlier scientists are using both the brightness and position as well as the chemical
makeup or metallicity of the star to pinpoint its age so the ability to explore this incredible data
in such detail has allowed them to get even closer to a real birthday for our galaxy than ever before
Timo Prusti a scientist for the Gaia Project stated that with each new analysis and data
release Gaia allows us to piece together the story of our galaxy in even more unprecedented detail
with the next release astronomers will be able to enrich the story with even more details
we have collected incredible amount of data already so we have more than 200 billion
astrometric measurements we have 45 billion photometric measurements and we have 4.4
billion spectra so Gaia has been extremely busy
the Gaia project is spearheading a lot of revolutionary data production
but another telescope that is preparing to help us view the thick disk and other parts of our galaxy
the telescope that is gearing up to challenge Gaia's influence in the scientific community
is the James Webb Space Telescope or JWST JWST is an infrared space telescope that
was launched into space on December 25th, 2021 it is now getting into position and preparing
to look far into the universe the telescope was created and launched to help us learn how stars
and planets have formed in the past as well as gather new data to see how they are forming now
scientists hope to use the JWST as well as Gaia's data to tell us more about that
dramatic collision of the sausage galaxy with our own Milky Way we are slowly getting more
and more opportunities to study and learn about the building blocks of our Milky Way
right now scientists lament the fact that it is easier to tell what is going to be happening
next to the stars in our universe rather than having the ability to tell what they have
already lived through astronomers are striving to have more powerful and advanced telescopes in
space to allow us to study and better plot the galaxy as we live in the middle of it
the growth in progress in the field of science is enabling us to send out
technology to corners of space that have been previously unexplored
we continue to expand the information that we know about the galaxy that we have always lived within
thank you for joining us to explore the stars with the astronomers here on our channel
tell us in the comments what wonderful images and discoveries you think will be made
with the next Gaia Satellite release and as always thanks for watching Factnomenal