Temporal evolution of the size and temperature of Betelgeuse’s extended atmosphere E. O’Gorman, G. M. Harper, A. Brown, E. F. Guinan, A. M. S. Richards, W. Vlemmings and R. Wasatonic A&A, 580 (2015) A101 Published online: 07 August 2015 DOI: 10.1051/0004-6361/201526136