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NH 3 in comets

NH 3 in comets. Jennifer Hatchell (Exeter, ex-MPIfR). with. Mike Bird (RAIUB) William Sherwood (MPIfR) Wilhelm Altenhoff (MPIfR) Floris van der Tak (MPIfR) Karl Menten (MPIfR). Motivation. - NH 3 along with CO 2 and H 2 O is a constituent of cometary ices.

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NH 3 in comets

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  1. NH3 in comets Jennifer Hatchell (Exeter, ex-MPIfR) with Mike Bird (RAIUB) William Sherwood (MPIfR) Wilhelm Altenhoff (MPIfR) Floris van der Tak (MPIfR) Karl Menten (MPIfR)

  2. Motivation - NH3 along with CO2 and H2O is a constituent of cometary ices. -Nitrogen chemistry in early solar nebula poorly understood (N2, NH3 and N balance) - Spin temperature (from ortho/para ratio) implies formation temperature of ices

  3. Radio observations Photo: William Sherwood

  4. Previous radio detections NH3 /H2O C/1983 D IRAS-Araki-Alcock (Altenhoff et al. 1983) C/1996 B2 Hyakutake (Palmer et al. 1996, Green Bank) C/1995 O1 Hale-Bopp (Butler et al. 2002, Green Bank) C/1995 O1 Hale-Bopp (Hirota et al. 1999, Nobeyama) C/1995 O1 Hale-Bopp (Bird et al. 1997, Effelsberg) 6% 0.3% 1.8% 1.0-1.8% Direct detection Halley (Allen et al. 1987; Meier et al. 1994, Giotto) 0.1-2%

  5. Optical detections of NH2 (daughter) OPR 3.33 Spin temp. 28K Spin temp. 30K NH3 /H2O = 0.5% C/1999 S4 LINEAR (Kawakita et al. 2001) C/1995 O1 Hale-Bopp & 153P/Ikeya-Zhang (Kawakita et al. 2004) Kawakita et al. 2002 reanalysis of earlier NH2 data Infrared detections of NH3 (lines often overlap with atmospheric absorptions) C/2002 T7 NH3 near 3 microns (Magee-Sauer et al. 2002) NH3 /H2O = ???

  6. Targets 2001,2002,2004 C/2002 C1 (Ikeya-Zhang) (153P) C/2001 A2 (NEAT) 2002 2001 Images: T.Vsoske, T.Lovejoy, S.Kim, and M.Jäger/G.Rheman C/2001 Q4 (NEAT) C/2002 T7 (LINEAR) 2004

  7. OH 1665/1667 MHz

  8. NH3 24 GHz

  9. NH3 24 GHz NH3 /H2O <= 0.5%

  10. Conclusions NH3 / H2O variable, 0.3-1.5% NH3 / H2O <= 0.5% in many comets: Halley and Hale-Bopp may have been exceptional Consistency between radio / optically derived ratios

  11. Upcoming comet missions Deep Impact (NASA) 9P/Tempel 1 launch date Jan 12 2005 Impactor + cameras July 4 2005 Philae (lander) Rosetta (ESA) 67 P/Churyumov-Gerasimenko launched 2 March 2004 Lander 2014 Rosetta

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