We Were Wrong About the Origins of Our Galaxy

 

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 Science Reads 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