These are images of three of the most distant supernovae known, discovered using the Hubble Space Telescope as a supernova search engine. The stars exploded back when the universe was approximately half its current age. The light is just arriving at Earth now. Supernovae are so bright they can be seen far away and far back in time. This allows astronomers to trace the expansion rate of the universe, and to determine how it is affected by the repulsive push of dark energy, an unknown form of energy that pervaded space.
The research team members are: Adam Riess and Louis-Gregory Strolger (STScI), John Tonry (Univ. of Hawaii), Stefano Casertano, Harry Ferguson and Bahram Mobasher (STScI), Peter Challis (Harvard-Smithsonian Center for Astrophysics), Alex Filippenko, Saurabh Jha, Weidong Li, Ryan Chornock (Univ. of California, Berkeley), Robert Kirshner (Harvard-Smithsonian Center for Astrophysics), Bruno Leibundgut (European Southern Observatory), Mark Dickinson, Mario Livio and Mauro Giavalisco (STScI), Charles Steidel (Caltech), Txitxo Benitez and Zlatan Tsvetanov (Johns Hopkins Univ.).