4U 1957+11 IS ONE OF THE FEW PERSISTENTLY ACTIVE BLACK HOLE CANDIDATES. ALTHOUGH WE DO NOT KNOW ITS MASS DISTANCE OR INCLINATION THE FACT THAT IT IS APPARENTLY ALWAYS IN A THERMAL-DOMINATED STATE WITH EXTREMELY HIGH DISK TEMPERATURE.
$46,993FY2020National Aeronautics and Space AdministrationNASA
Washington University, The