BIMA array detections of HCN in comets linear (C/2002 T7) and NEAT (C/2001 Q4)

We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) array. With a 25.″4×20.″3 synthesized beam around comet LINEAR and using a variable temperature and outflow velocity (VTOV) model, we found an HCN column density of 〈N_T〉 = (6.4 ±2.1) × 10¹² cm^-2 and a production rate of Q(HCN) = (6.5 ± 2.2) × 10²⁶ s^-1, giving a production rate ratio of HCN relative to H₂O of ∼(3.3 ± 1.1) × 10 ^-3 and relative to CN of ∼4.6 ± 1.5. With a 21.″3 × 17.″5 synthesized beam around comet NEAT and using a VTOV model, we found an HCN column density of 〈NT〉 = (8.5 ± 4.5) × 10¹¹ cm^-2 and a production rate of Q(HCN) = (8.9 ± 4.7) × 10²⁵ s^-1, giving a production rate ratio of HCN relative to H₂O of ∼(7.4 ± 3.9) × 10 ^-4 and relative to CN of ∼0.3 ± 0.2. For both comets, the production rates relative to H₂O are similar to those found in previous comet observations. For comet LINEAR, the production rate relative to CN is consistent with HCN being the primary parent species of CN, while for comet NEAT it is too low for this to be the case.