A supernova discovered by an international group of astronomers, including Carnegie's Tom Holoien and Maria Drout, and led by the…
A supernova discovered by an international group of astronomers, including Carnegie’s Tom Holoien and Maria Drout, and led by the University of Hawaii Ben Shappee, gives an unprecedented look at the first moments of a violent crime star explosion. The light of the first hours of the explosion showed an unexpected pattern, which Carnegie’s Anthony Piro analyzed to reveal that the appearance of these phenomena is even more mysterious than previously thought.
Their findings are published in a trio of paper in The Astrophysical Journal and The Astrophysical Journal Letters .
Type Ia supernova is fundamental to our understanding of the cosmos. Their nuclear ovens are crucial to generating many of the elements around us, and they are used as cosmic rulers to measure distances across the universe. Despite their significance, the real mechanism that triggers a supernova explosion of type Ia has been uneven for decades.
It is therefore important to capture them in the act.
Astronomers have long been trying to get detailed information at the first moments of these explosions, hoping to figure out how these phenomena are triggered. This last occurred in February of this year with the discovery of a type Ia supernova called ASASSN-1
8bt (also known as SN 2018oh).
ASASSN-18bt was detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), an international network of telescopes with headquarters at Ohio State University, which routinely scans the sky for supernova and other cosmic explosions. NASA’s Kepler Space Telescope could simultaneously include additional data about this event. Kepler was designed to be extremely sensitive to small changes in the light of his mission to discover extra-solitary planets, so that it could get particularly detailed information about the explosion.
“ASASSN-18bt is the closest and brightest supernova yet to be observed by Kepler, so it offered a great opportunity to test the overwhelming theories of supernova formation,” says Shappee, the leading author of the discovery and early lightning paper and one of our Carnegie alumni.
Combining data from ASAS-SN, Kepler and Telescope around the world, the astronomers discovered that the ASASSN-18bt looked unusual in the first few days.
“Many supernovae show a gradual increase in the light they emit,” said Drout, jointly appointed at the University of Toronto. “But for this event you can clearly see that there is something unusual and exciting to happen at the beginning of time – an unexpected additional release.”
Type Ia supernova stems from the thermonuclear explosion of a white dwarf star – the dead core remains of a sun-like star after it has exhausted its nuclear fuel. Materials must be added to the white dwarf from a companion to trigger the explosion, but the nature of the companion star and how the fuel is transmitted has been discussed for a long time.
One possibility is that this extra light can be seen during the early days of supernova may be from the exploding white dwarf that collides with the companion. Although this was the original hypothesis, detailed comparisons with Pope’s theoretical modeling work showed that this additional light may have another, unexplained origin.
“Although the steep increase in ASASSN-18bt’s early brightness may indicate that the explosion collides with another star, our tracking data does not match predictions of how it should look,” Holoien says. “Other possibilities, such as an unusual distribution of radioactive Material in the exploded star is a better explanation of what we saw. More observations of ASASSN-18bt and earlier discoveries like this will hopefully help us differentiate between different models and better understand the origin of these explosions. “
” Nature always finds new ways to surprise us, and unique observations like this are good for motivating creative new approaches to how we think about these explosions, “added Piro.” As a theorist at Carnegie Observatories, it is so useful and inspiring to be right close to the observers who make these key measurements. “
This supports a hypothesis as evidenced by the Carnegie Supernova project, led by Maximilian Stritzinger ofAirhus University and led by Shappee and Piro, that there may be two different populations of type Ia supernovae – those showing early emissions and those who do not.
Thanks to ASAS-SN and next-generation surveys that now monitor the sky every night, astronomers will find even more new supernova and capture them at the explosion start. More of these events are found and studied, hopefully they will come across the solution to the long-term myth the mystery of how these star-shaped explosions come.
The researchers were supported by a NASA Hubble scholarship, Villum Foundation, the US National Science Foundation, NSFC, Research Corporation, NASA, David G. Price Fellowship for Astronomical Instrumentation, the Australian Research Council Center of Excellence for All Sky Astrophysics in 3 Dimensions, a sabbatical contribution from Aarhus University’s Faculty of Science and Technology, Gordon & Betty Moore Fation, Heising-Simons Foundation, Alfred P. Sloan Foundation, and David and Lucile Packard Foundation.