BIMA Array Detections of HCN in Comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4)

Abstract

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) × 10 12 cm -2 and a production rate of Q(HCN) = (6.5 ± 2.2) × 10 26 s -1 , giving a production rate ratio of HCN relative to H 2 O 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) × 10 11 cm -2 and a production rate of Q(HCN) = (8.9 ± 4.7) × 10 25 s -1 , giving a production rate ratio of HCN relative to H 2 O of ∼(7.4 ± 3.9) × 10 -4 and relative to CN of ∼0.3 ± 0.2. For both comets, the production rates relative to H 2 O 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. © 2005, The American Astronomical Society. All rights reserved.