The shell of QU Vulpeculae at 2.2 microns, Hα, and 3.6 centimeters

Observations of the classical nova QU Vul (1984) were carried out in the infrared, optical, and radio regimes between days 3791 and 4262 after discovery. For the first time a spatial extension of the shell around QU Vul could be unambiguously established from our IR and optical observations. At 2.2 μm, a shell size of about 0″.S was found, which corresponds to a linear diameter of (4.5 ± 0.4) × 10¹⁶ cm on day 4124 assuming QU Vul is 3.6 kpc distant. The mass of the shell is (4 ± 1.5) × 10^-4 M_⊙ with the assumption that a free-free emission process is the dominant emission mechanism in the shell. This shell mass is larger than found for any nova.