Supernovae: Why study them? What can they teach us about finding life beyond Earth?

Universe Today has recently investigated a myriad of scientific disciplines, including impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, meteorites, radio astronomy, extremophiles, organic chemistry, black holes, cryovolcanism, planetary protection, and dark matter, and what they can teach us about how we got here, where we’re going, and whether we might find life elsewhere in the universe.

Here, Universe Today discusses the explosive field of supernovae—plural for supernova—with Dr. Joseph Lyman, who is an assistant professor in the Astronomy and Astrophysics Group at the University of Warwick, regarding the importance of studying supernovae, the benefits and challenges, the most intriguing aspects about supernovae he’s studied throughout his career, what supernovae can teach us about finding life beyond Earth, and any advice he can offer upcoming students who wish to pursue studying supernovae. Therefore, what is the importance of studying supernovae?

“Supernovae really are a window into the universe at its most spectacular,” Dr. Lyman tells Universe Today. “We can’t hope to replicate their immense power with experiments here on Earth, and so they provide an invaluable means of studying what happens to matter under the most extreme conditions as stars explode. These conditions are so extreme that supernovae can create the most exotic objects we know of in the universe: neutron stars and black holes. Studying supernovae is therefore a means to study the production of these mysterious objects.”

Dr. Lyman continues, “Supernovae are also glimpses at our own origins. During these explosions, they release huge amounts of different elements, including oxygen, iron, calcium, into their environments – elements that would otherwise remain locked up in stars. It is the dispersal of such elements by supernovae that puts in motion the building blocks for the formation of planets, and, ultimately, life as we know it.”

The observations of supernovae occurring within our Milky Way Galaxy date back to 185 CE (Common Era) when Chinese astronomers during the Han dynasty observed a bright star that remained in the sky for approximately eight months, after which it faded away. While there has been speculation this observation was a comet despite the object remaining stationary, a 2006 study published in the Chinese Journal of Astronomy and Astrophysics concluded this observation was most likely a supernova after comparing records of the observation with comet observation records during the same time period.

While several more supernovae within our Milky Way Galaxy have been observed since that encounter, the most recent was observed on October 9, 1604, having since been identified as SN 1604. Because of this, astronomers have focused their attention on studying nebulae, which are remnants of supernovae that provide clues into the various elements and minerals that were ejected into space from the explosion, along with the star’s properties before it exploded. So, what are some of the benefits and challenges of studying supernovae?

Dr. Lyman tells Universe Today, “There is a captivating nature to studying an astrophysical phenomenon that is born, and then fades into nothing, right before your eyes. Unlike the unimaginably slow procession of most of the universe, supernova science, and that of other related transients, demands highly reactive modes of working, as astronomers scramble to gather telescopes resources and observations on chance discoveries.”

Dr. Lyman continues, “Studying one-off, dynamic objects is, however, also a huge challenge for these reasons. One can miss important clues on the nature of a supernova simply due to a bit of bad weather at an observatory. Some rare or fortuitous events we discover once per decade, or once per generation – the pressure is really then on to observe all we can about the object during its brief life, since once they’re gone, they’re gone.”

Despite the lack of supernovae observations within our Milky Way Galaxy occurring in the last several hundred years, astronomers have successfully observed countless supernovae flashes in other galaxies. This began in 1933 by the Swiss astronomer, Dr. Fritz Zwicky, who led a team of astronomers at Palomar Observatory in discovering 12 supernovae over a three-year period, with countless other supernovae outside the Milky Way being discovered to the present day. The most recent supernova was observed by NASA’s Hubble Space Telescope in 2018 when it observed an exploding star in the spiral galaxy NGC 2525, which is located approximately 70 million light-years from Earth.

Supernovae are classified into two types: Type I and Type II, with each being broken down into various subtypes based on their appearances or chemical compositions. Additionally, remnants of supernovae can become several types of celestial objects, including nebulae, neutron stars, or black holes, all depending on the size of the original star (progenitor) and the number of metals (metallicity) it was comprised of, as well. Therefore, what are the most intriguing aspects about supernovae that Dr. Lyman has studied throughout his career?

Dr. Lyman tells Universe Today, “A real highlight over the last decade has been the advent of new wide-field sky surveys that are capable now of detecting all manner of supernova types beyond the archetypal classes known about for many decades. The true diverse nature of supernovae, from extremely long-lived and hugely energetic ‘superluminous’ supernovae to fast-and-faint events, is now being revealed. With each new discovery, we are constantly re-evaluating our understanding of how stars evolve and die.”

As noted by Dr, Lyman, supernovae explosions release vast amounts of elements into the cosmos, nearly all of which are found on the Earth in some form or another, including living organisms such as humans. The elements he mentions are oxygen, iron, and calcium, all of which reside within our bodies and are essential for our very survival. Also, depending on the composition of the original star, other elements might include gold, uranium, lead, mercury, tin, silver, and zinc, the last of which is also essential for our survival and the others can be used for industrial purposes around the world. Given how some of these elements are found in our bodies, this falls in line with the famous quote by the American astronomer, Dr. Carl Sagan, who said, “We are made of star stuff.” Given these variables, what can supernovae teach us about finding life beyond Earth?

Dr. Lyman tells Universe Today, “Stars that explode as supernovae at the end of their lives are the nuclear fusion reactors of the universe that provide the elements essential for life. Their explosions seed the material used in the next generations of stars and planets. In this sense, supernovae have been crucial to our own existence, and life on Earth. We see supernovae, and the results of the ‘chemical enrichment’ of galaxies throughout the universe. So, in this sense, we already know the conditions needed to create Earth-like planets are not unique to our own position.”

Like all scientific endeavors, the study of supernovae involves a myriad of scientific disciplines, including astronomy, astrophysics, cosmology, nuclear physics, computer science, and chemistry, just to name a few. It is through constant collaboration and teamwork from scientists around the world that enables the study of supernovae to teach us about the formation and evolution of stars throughout the history of the universe and what it means regarding our place in all of it. Therefore, what advice does Dr. Lyman offer upcoming students who wish to pursue studying supernovae?

Dr. Lyman tells Universe Today, “Although we’ve known about supernovae for a century, it remains a very fast-moving research field and, perhaps more so than other astrophysics fields, new students may need to remain open to shifting focus and adapting in their study direction. Upcoming breakthroughs in observational facilities such as the Vera Rubin Observatory, as well as computational work now being able to routinely perform full 3D simulations of supernovae, make for an especially exciting time for the field. I see studying supernovae as a chance to enjoy the serendipity of the universe and see what new explosion it next throws at us to challenge our understanding.”

How will supernovae teach us about our place in the cosmos in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!