Aug 6, 2020
Artist's interpretation of supernova 2019ehk. The star shed gas (in purple) right before the explosion and then created calcium-rich material (in orange). Credit: Aaron M. Geller.
A research team led by scientists at Northwestern University has examined a calcium-rich supernova with X-ray imaging, which provided an unprecedented glimpse into the star during its last month of life and final explosion.
The supernova named SN 2019ehk was discovered on April 28, 2019, by an amateur viewing galaxy Messier 100, a spiral galaxy located 55 million light years from Earth.
University of California Santa Barbara graduate student Daichi Hiramatsu was the first to trigger the space telescope Swift to study SN 2019ehk in the X-ray and ultraviolet light frequencies. Hiramatsu works at Las Cumbres Observatory with staff scientist Dr. Andy Howell. LCO observations were critical in monitoring the long-term evolution of this supernova.
The worldwide follow-up operation moved so quickly that the supernova was observed just 10 hours after explosion. The X-ray emission detected with Swift only lingered for five days and then completely disappeared.
“In the world of transients, we have to discover things very, very fast before they fade,” said Professor Raffaella Margutti. “Initially, no one was looking for X-rays. Daichi noticed something and alerted us to the strange appearance of what looked like X-rays. We looked at the images and realized something was there. It was much more luminous than anybody would have ever thought. There were no preexisting theories that predicted calcium-rich transients would be so luminous in X-ray wavelengths.”