On the possibility of nitrous oxide (N2O) as a cometary parent molecule in Comet 1P/Halley

Abstract

Nitrous oxide as a possible parent molecule in Comet 1P/Halley is discussed in light of in situ measurements and theoretical considerations. Hitherto undiscussed in cometary context, N2O could be a trace parent molecule with Q(N2O)/Q(H2O) ~ 2 x 10-4 in Comet 1P/Halley. Having a photo lifetime >105 s at 1 au heliocentric distance during solar minimum conditions and with a gas outflow speed of 0.85 km s-1 in the coma of Comet 1P/Halley, N2O could reach into the tail of comet where it dissociates into N2 and O. In this scenario, N2O acts as a camouflage for N2 and may help solve the puzzle of the presence of N+2 ions only in the tail of Comet 1P/Halley