Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies

C. Cardamone, K. Schawinski, M. Sarzi, S. Bamford, N. Bennert, C.M. Urry, C. Lintott, W. Keel, J. Parejko, R.C. Nichol, D. Thomas, D. Andreescu, P. Murray, M.J. Raddick, A. Slosar, A. Szalay, J. Vandenberg