Massive star mergers and the recent transient in NGC4490: a more massive cousin of V838 Mon and V1309 Sco

Nathan Smith, Jennifer E. Andrews, Schuyler D. Van Dyk, Jon C. Mauerhan, Mansi M. Kasliwal, Howard E. Bond, Alexei V. Filippenko, Kelsey I. Clubb, Melissa L. Graham, Daniel A. Perley, Jacob Jencson, John Bally, Leonardo Ubeda, Elena Sabbi