It took 12.8 billion years for its light to reach us. Since the universe is about 13.7 billion years old, we see a star that existed 900 million years after the beginning. Until this discovery, made using the Hubble Space Telescope (HST), the oldest single star we had ever seen, it was about four billion years after the beginning of the universe, so this discovery took us a huge step back in time. We have identified many galaxies as old as, or possibly older than, this recently discovered star, each containing billions of stars. However, these stars are so densely packed that even Hubble cannot separate them into individuals. The resolution or the ability to distinguish detail depends on the size of the lens or mirror that creates the image. To see a single star in such a distant galaxy would require an extremely large lens. Coincidentally, in this case, one was available. One of the predictions that emerged from Einstein’s work on relativity was the possibility of a “gravitational lens”. Bulky objects bend light, focusing it to form an image, just as curved lenses do. There happens to be a large cluster of galaxies between us and this star, which acts as a lens, increasing the magnification and resolution of the Hubble Telescope thousands of times. Of course, a convenient concentration of galaxies will not be a perfect lens. However, this star falls in one of the best parts of the image, so we can see the star as an individual, and not just as a member of a dense multitude of billions, visible only as a glowing cloud. The discoveries were admired by JRR Tolkien’s writings and they named the star Earendel, or “Dawn Star”, from an elite sailor in “Silmarillion”. Long ago, the universe consisted almost entirely of hydrogen and helium. All the other elements needed to create planets (and us) are the waste from the production of energy by many generations of stars. When Earedel was formed, there were almost no such elements. The concentration of this debris mixed with hydrogen and the sun from which a star is formed has a dramatic effect on the star. Current theory suggests that these stars were more massive than the stars we see around us now. However, even a small increase in mass dramatically increases the brightness of a star and the rate at which it consumes fuel. Arendel and his brothers had masses probably hundreds of times the mass of the sun. The result is that they glowed incredibly loudly for perhaps a million or two years, before they ran out of fuel, collapsed and exploded. The next generations created the universe we see around us today with everything to create planets, people and, hopefully, a bunch of aliens. It is very unlikely that Arendel will be the oldest star in the universe. With generations of hot, bright, large stars passing at a rate of one every two million years, there could be several generations of previous stars. This star was located because it was in the right place for a cluster of galaxies to focus its light gravitationally in the direction of the Hubble Telescope. The search for older stars is not just a record search. The farthest back in time we can see is 380,000 years after the Big Bang, the age of cosmic microwave background radiation. At that point, the universe became completely dark, with large clouds of hydrogen and helium. Then, at some point, the first stars formed, and there was light. When did these first stars form? How was? We have many ideas, but ideas are not facts. At what point in the history of the universe did the planets and life become possible? This is a big part of understanding our place in the universe, and just as important if we are alone. ————— Jupiter, Venus, Mars and Saturn line up low at dawn. It is in order of increasing brightness. The moon will be full moon on April 16. Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory near Penticton.
