A Blue Supergiant Star (image) NASA/Goddard Space Flight Center Caption A blue supergiant star, illustrated here, may be the most likely source of ultra-long gamma-ray bursts like GRB 130925A, which last hours rather than seconds. These stars contain about 20 times the sun's mass and may reach sizes large enough to span Jupiter's orbit. Credit NASA's Goddard Space Flight Center/S. Wiessinger Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.