A Tiny Ancient Star Reveals Our Galaxy’s True Age


As we gaze up at the night sky, while standing far from the interfering glare of bright city lights, we can see our Milky Way Galaxy stretching from horizon to horizon like a sparkling starlit smile–telling us that we are only a small part of something vast, ancient, and mysterious. Astronomers have long thought that our Galaxy is very old. Indeed, scientists have proposed that it may be almost as old as the Universe itself. In November 2018, astronomers using the Gemini Observatory announced that they have discovered a tiny tattle-tale star that is likely the oldest known star dwelling in the disk of our Milky Way. Despite its unimpressive size, this diminutive star could play a disproportionate role in our scientific understanding of the true age and history of our Galaxy. The ancient star also sheds new light on the mysterious conditions that existed in the newborn Universe soon after its birth in the Big Bang almost 14 billion years ago.

The Gemini Observatory is composed of twin 8.1-meter diameter optical/infrared telescopes that can together scan the entire sky. Gemini North and Gemini South are situated at two separate locations in Hawaii and Chile, respectively.

The tiny tattle-tale star has a very interesting story to tell. It is old, small, and most importantly composed of elements very similar to those that formed in the Big Bang. In order to host a star like this, the disk of our Milky Way could very well be up to three billion years older than previously thought. Our Galaxy’s age has been calculated to be approximately 13.51 billion years, while our Universe is thought to be about 13.8 billion years old.

“Our Sun likely descended from thousands of generations of short-lived massive stars that have lived and died since the Big Bang. However, what’s most interesting about this star is that it had perhaps only one ancestor separating it and the beginnings of everything,” commented Dr. Kevin Schlaufman in a November 5, 2018 Gemini Observatory Press Release. Dr. Schlaufman is of Johns Hopkins University in Maryland, and lead author of this study published in the November 5, 2018 issue of The Astrophysical Journal.

The Big Bang theory suggests that the first generation of stars were composed almost entirely of hydrogen and helium. The Big Bang birth of the Universe formed only the lightest of atomic elements–hydrogen, helium, and small quantities of lithium (Big Bang Nucleosynthesis). All atomic elements heavier than helium–termed metals by astronomers–were created by the stars in their nuclear-fusing furnaces (Stellar Nucleosynthesis). Alternatively, in the case of the heaviest atomic elements of all–such as gold and uranium–in the powerful and fiery supernovae blasts that heralded the explosive demise of massive stars (Supernova Nucleosynthess). 바카라사이트

When stars perish, their stellar material is recycled to be used in the formation of new baby stars. Newborn stars receive–as their legacy from earlier generations of stars–all of the elder stars newly forged heavier atomic elements. The oxygen you breathe, the iron in your blood, the calcium in your bones, the sand beneath your feet, the water that you drink, were all formed in the nuclear-fusing hearts of the Universe’s myriad stars.

Astronomers refer to stars which are depleted of atomic elements heavier than helium as low metallicity stars. “But this one has such low metallicity it’s known as an ultra metal poor star–this star may be one in ten million,” Dr. Schlaufman continued to explain in the Gemini Observatory Press Release.

The birth of the first generation of stars is one of the most fascinating mysteries haunting cosmologists. The most ancient stars are believed to have ignited as early as 100 million years after the Big Bang. However, the first stars to form in the Universe were unlike the stars we know today. This is because they formed directly from the pristine primordial gases churned out in the Big Bang itself. These primordial gases were primarily hydrogen and helium, and these two lightest of atomic elements are believed to have gravitationally pulled themselves together to form ever tighter and tighter knots. The cores of the first generation of protostars to emerge in our ancient Universe first caught fire within the mysterious dark and frigid hearts of these extremely cold dense knots of pristine ancient gases–which ultimately collapsed under their own relentless, heavy gravitational pull. The first stars did not form the same way or even from the same elements as stars do now. The first stars are referred to as Population III stars. Our own Sun is a member of the youngest stellar generation, and is classified as a Population I star. Sandwiched between the youngest and oldest stellar generations are the Population II stars.

 


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