Scientists at the University of Sheffield have used HiPERCAM, a high-speed, multicolor camera that is capable of taking more than 1000 images per second, to measure both the mass and the radius of an old star (also called a cool subdwarf star) for the first time. HiPERCAM is mounted on the Gran Telescopio Canarias (GTC), the world’s largest optical telescope, with a 10.4-m mirror diameter. HiPERCAM can take one picture every millisecond, in contrast to a traditional camera on a large telescope that can typically capture only one picture every few minutes. HiPERCAM’s speed enabled the scientists to measure the cool subdwarf star accurately. Artist’s impression of a binary star. Courtesy of Mark Garlick. The new camera can be used to take high-speed images of objects in the universe, enabling their rapid brightness variations, which are due to phenomena such as eclipses and explosions, to be studied in more detail. Data captured by the camera, taken in five different colors simultaneously, will allow scientists to study the remnants of dead stars such as white dwarfs, neutron stars, and black holes. Professor Vik Dhillon and researchers Steven Parsons and Stuart Littlefair from the University of Sheffield led the HiPERCAM project in partnership with the Science and Technology Facilities Council’s Astronomy Technology Centre (ATC) and the Instituto de Astrofisica de Canarias, along with researchers from the University of Warwick and Durham University. “Now we have been able to measure the size of the star, we can see it is in line with stellar structure theory,” Dhillon said. “These results would not have been possible with any other telescope. This not only proves stellar structure theory, but has also verified the potential of HiPERCAM.” The research was published in Nature Astronomy (https://doi.org/10.1038/s41550-019-0746-7).