Winner of the 2016 UNSW Bragg Student Prize for Science Writing, Marissa Petrakis, takes us on a journey to the supernovae.
The stars that illuminate the night sky are one of the most profound wonders of our world. These incandescent bodies spark a deep wonder across all aspects of our lives. We humans strive to know the world around us. We long to understand the magnitude of this world and our position in it across millions of galaxies. As quoted by Stephen Hawking, “Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what make the universe exist. Be curious”.
On clear nights, when the stars blaze brightly in the Southern Hemisphere, Australian astronomer Reverend Robert Evans carries his telescope onto the back porch of his home in the Blue Mountains and does an extraordinary thing. He searches for the flickers of dying stars, or supernova. Evans took up supernova hunting in 1955, and made his first official discovery in 1981, using a ten-inch Newtonian telescope he had assembled himself. When Evans first began observing galaxies in the late 1950’s fewer than 60 supernovae had ever been discovered. From 1995 to 1997 he was granted access to the Siding Spring Telescope at the Siding Spring Observatory (SSO) in NSW, where he made another three visual supernovae discoveries, ten thousand galaxy observations and spotted four supernovae on photographs at the SSO.
A supernova is simply a burst of intense radiation in a star, which happens approximately once every fifty years in our galaxy. Robert Evans is the world’s most successful individual hunter of supernovae, holding the current world record of 42 visual discoveries. As supernovae are spontaneous reactions that have the potential to occur anywhere in the presence of stars, Evans’ work relied exclusively on memorising starfield foregrounds and positions of around 1500 galaxies. His exceptional ability to recollect images and memories, often regarded as detailed and photographic, enabled him to detect changes by simply looking at them through his telescope. While supernovae burn for only a short period of time, their discovery is able to tell us remarkable things about how the universe began and what might happen to our universe in the future. Supernovae have shown scientists that we live in an expanding universe, which is growing at an ever-increasing rate. Scientists have also determined that supernovae play a key role in distributing elements throughout the universe. When a supernova explodes, it shoots elements and debris into space, much of which we now find on Earth.
On the night of August 4th 2005, Evans made his 40th visual discovery of a supernova. He spotted a new star in the spiral galaxy NGC 1559 using a 123-inch Newtonian reflector and his prodigious memory of star fields. “There’s something satisfying I think,” Evans says,” about the idea of light travelling for millions of years through space, and just at the right moment as it reaches Earth someone looks at the right bit of sky and sees it. It just seems right that an event of that magnitude should be witnessed.”
Supernovae do far more than simply impart a sense of wonder on all those who witness it. They come in several types, and of these, one in particular known as the 1a supernova is a fundamental benchmark that allows astronomers measure the brightness and distance of stars as well as the expansion rate of the universe.
Supernovae are also fundamental to the creation of the universe. According to the Big Bang Theory, around 13 billion years ago the universe consisted primarily of only hydrogen, helium and a small amount of lithium. Therefore, astronomers wanted to understand how heavy elements such as carbon, oxygen and iron, which are present everywhere in our lives, were produced. These elements, which are fundamental to life, have formed through supernovae explosions, during which they are released in shock waves. Through Evans’ incredible discoveries, astronomers have come to understand the significance of supernovae, as they have the ability to create planets, plants and people.
Our current understanding of cosmological issues in the world is enhanced through Evans’ extraordinary work and observations on supernovae. His work deals with questions about the origins of the universe, how it might end and what its general history is. Through discovering the ever-expanding frame of our world, the perception of our immediate surroundings is altered. We discover how small we really are, and how we are merely explorers of an infinitely expanding world. Supernovae not only determine the large scale of the cosmos, but they are key elements in understanding the foundation, evolution and future of our universe. When we look up, we can now truly understand the distance from here to the stars.
– Marissa Petrakis
Year 10, Meriden School