Professor, Department of Mechanical Engineering, Sharif University of Technology (2011--)

Associate Professor, Department of Mechanical Engineering, Sharif University of Technology (2005-2011)

Astrophysics Visiting Member, Institute for Advanced Study, Princeton, NJ (Second Semester 2010)

Astrophysics Visiting Member, Institute for Advanced Study, Princeton, NJ (Fall 2007)

Non-Resident Researcher, School of Astronomy, IPM, Tehran, Iran (2007-2010)

Research Fellow, Department of Mathematics, Florida State University, Tallahassee, FL (2002-2004)

Associate Professor, Institute for Advanced Studies in Basic Sciences, IASBS (2001-2002)

Assistant Professor, IASBS (1998-2001)

Visiting Scientist, Leiden Observatory, Leiden, The Netherlands (summer 2000)