Chemical and physical properties of gas jets in comets: II. Modeling OH, CN and C2 jets in Comet C/1995 O1 (Hale–Bopp) one month after perihelion

We present an analysis of OH, CN, and C2 jets observed in Comet Hale–Bopp during April 22–26, 1997. We conclude that an extended source, which peaks in productivity after a certain amount of time has passed after being released from the nucleus (8.5, 2.5, and 42.6×104 s42.6×104 s, respectively) is responsible for the observed coma jet morphology in all three species. Sub-micron organic grains are the favored explanation for the extended source. Our models indicate that this extended source produces approximately 40% of the OH, 50% of the C2, and 75% of the CN. The balance for each species is created by a diffuse nuclear gas source. Compared with the nuclear gas source and normalized to the CN abundance, the composition of the extended source is depleted in OH by a factor of ∼6, and depleted in C2 by a factor of ∼2. The existence of anti-sunward jets do not require production of radicals throughout the cometary night. Instead, our model demonstrates that active areas exposed to near-twilight conditions throughout the comet's rotational period can produce the observed anti-sunward morphology.