1. CIERA (Center For Interdisciplinary Exploration And Research In Astrophysics), 1800 Sherman Ave, Evanston, IL 60201, USA
2. Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
3. Niels Bohr International Academy, Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
4. Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
5. Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138, USA