Hogerheijde, Michiel R. and de Pater, Imke and Wright, Melvin and Forster, J. R. and Snyder, L. E. and Remijan, A. and Woodney, L. M. and A'Hearn, M. F. and Palmer, Patrick and Kuan, Y.-J and Huang, H.-C. and Blake, Geoffrey A. and Qi, Chunhua and Kessler, Jacqueline and Liu, S.-Y. (2004) Combined BIMA and OVRO Observations of Comet C/1999 S4 (LINEAR). Astronomical Journal, 127 (4). pp. 2406-2412. ISSN 0004-6256 http://resolver.caltech.edu/CaltechAUTHORS:20120918-154219610
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We present results from an observing campaign of the molecular content of the coma of comet C/1999 S4 (LINEAR) carried out jointly with the millimeter arrays of the Berkeley-Illinois-Maryland Association (BIMA) and the Owens Valley Radio Observatory (OVRO). Using the BIMA array in autocorrelation ("single-dish") mode, we detected weak HCN J = 1–0 emission from comet C/1999 S4 (LINEAR) at 14 ± 4 mK km s^(-1) averaged over the 143" beam. The 3 days over which emission was detected, 2000 July 21.9–24.2, immediately precede the reported full breakup of the nucleus of this comet. During this same period, we find an upper limit for HCN J = 1–0 of 144 mJy beam^(-1) km s^(-1) (203 mK km s^(-1)) in the 9" × 12" synthesized beam of combined observations of BIMA and OVRO in cross-correlation ("imaging") mode. Together with reported values of HCN J = 1–0 emission in the 28" IRAM 30 m beam, our data probe the spatial distribution of the HCN emission from radii of 1300 to 19,000 km. Using literature results of HCN excitation in cometary comae, we find that the relative line fluxes in the 12" × 9", 28", and 143" beams are consistent with expectations for a nuclear source of HCN and expansion of the volatile gases and evaporating icy grains following a Haser model.
|Additional Information:||© 2004 American Astronomical Society. Received 2001 October 10; accepted 2004 January 2. We are indebted to the staffs of the Owens Valley and Hat Creek Radio Observatories for providing excellent support during the observations. Wilson Hoffman and Steve Scott are especially thanked for creating and maintaining the software required to track fast-moving targets such as this comet. The research of M. R. H. in Berkeley was supported by the Miller Institute for Basic Research in Science. This work was partially funded by NASA NAG 5-4292, NAG 5-4080, NAG 5-8708, and NGT 5-0083, NSF AST 96-13998, AST 96-13999, AST 96-13716, AST 96-15608, and AST 99-81363, Taiwanese grants NSC 86-2112-M-003-T and 89-2112-M-003-004, and the Universities of Illinois, Maryland, and California, Berkeley. We greatly thank the referee, D. Bockelée-Morvan, for providing constructive criticism of our paper and pointing out ways in which to significantly improve our analysis.|
|Subject Keywords:||comets: individual (C/1999 S4 (LINEAR)); radiative transfer; radio lines: solar system; techniques: interferometric|
|Official Citation:||Combined BIMA and OVRO Observations of Comet C/1999 S4 (LINEAR) Michiel R. Hogerheijde et al. 2004 The Astronomical Journal 127 2406|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||19 Sep 2012 15:27|
|Last Modified:||26 Dec 2012 16:12|
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