Observations of HCN, HNC, and NH<sub>3</sub>in Comet Hale‐Bopp

Hirota, Tomoya; Yamamoto, Satoshi; Kawaguchi, Kentarou; Sakamoto, Akihiro; Ukita, Nobuharu

doi:10.1086/307507

Cited by 39 publications

(25 citation statements)

References 14 publications

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“…The upper energy of each hyperfine component and the beam efficiency are 4.3 K and 0.48, respectively. The obtained production rate is lower than the value of (1.7±0.3)×10 28 molecule s −1 at r h = 0.98 AU (Hirota et al 1999), probably because of the larger heliocentric distance in the present observation. When we investigate the heliocentric distance dependence of Q(HCN) from the data of Biver et al (1999), Q(HCN) at r h = 1.26 AU was calculated to be 6.9 × 10 27 molecule s −1 .…”

Section: Resultscontrasting

confidence: 83%

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Ikeda

Kawaguchi

Takakuwa

et al. 2002

A&A

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Abstract.We have observed 9 rotational lines of methanol in comet Hale-Bopp (1995 O1) using the 45-m radio telescope at Nobeyama Radio Observatory in the frequency range 36-104 GHz. The observed transitions have upper state rotational energy levels of E u = 7-159 K. Assuming the Haser model for density distribution, we estimated the excitation temperature and the production rate to be T ex = 81 ± 8 K and Q(CH 3 OH) = (1.2 ± 0.1) × 10 29 molecule s −1 , respectively. We also observed the HCN J = 1−0 line at 88 GHz to derive the HCN production rate. We compared the production rate of CH 3 OH with that of HCN and that of other molecules whose production rates have been determined previously. The abundance ratio Q(CH 3 OH)/Q(X) is estimated to be in the range 3-121, where X denotes HCN, HNC, H 2 CO, CS and CH 3 CN. When we compare these abundance ratios with those in interstellar clouds: the bipolar flow L1157 B1/B2, the star-forming region SgrB2(M) and the dark cloud TMC-1, they are close to the values in L1157 B1/B2 or in SgrB2(M). We found that the abundance ratio Q(CH 3 OH)/Q(H 2 O) was similar to solid methanol ratio relative to water ice in interstellar medium. These results support the hypothesis that cometary nuclei are formed from dust grains outside of the primordial solar nebula so that the grain composition of the nebula remains in cometary nuclei.

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Section: Resultscontrasting

confidence: 83%

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Ikeda

Kawaguchi

Takakuwa

et al. 2002

A&A

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“…They were then definitely detected in C/1996 B2 (Hyakutake) (Palmer et al 1996) and C/1995 O1 (Hale-Bopp) (Bird et al 1997;Hirota et al 1999) and tentatively detected in 153P/Ikeya-Zhang (Bird et al 2002;Hatchell et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Ammonia and other parent molecules in comet 10P/Tempel 2 fromHerschel/HIFI and ground-based radio observations

Biver

Crovisier

Bockelée‐Morvan

et al. 2012

A&A

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The Jupiter-family comet 10P/Tempel 2 was observed during its 2010 return with the Herschel Space Observatory. We present here the observation of the J K (1 0 -0 0 ) transition of NH 3 at 572 GHz in this comet with the Heterodyne Instrument for the Far Infrared (HIFI) of Herschel. We also report on radio observations of other molecules (HCN, CH 3 OH, H 2 S and CS) obtained during the 1999 return of the comet with the CSO telescope and the JCMT, and during its 2010 return with the IRAM 30-m telescope. Molecular abundances relative to water are 0.09%, 1.8%, 0.4%, and 0.08% for HCN, CH 3 OH, H 2 S, and CS, respectively. An abundance of 0.5% for NH 3 is obtained, which is similar to the values measured in other comets. The hyperfine structure of the ammonia line is resolved for the first time in an astronomical source. Strong anisotropy in the outgassing is present in all observations from 1999 to 2010 and is modelled to derive the production rates.

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“…HCN has been extensively studied around several comets, including comet P/Halley (Despois et al 1986), comet Hyakutake (C/1996 B2) (e.g., Mumma et al 1996;Lis et al 1997;Womack et al 1997;Biver et al 1999a), comet Hale-Bopp (C/1995 O1) (e.g., Fitzsimmons & Cartwright 1996;Wright et al 1998;Hirota et al 1999;Irvine et al 1999;Magee-Sauer et al 1999;Ziurys et al 1999;Veal et al 2000;Snyder et al 2001;Woodney et al 2002), and comet LINEAR (C/1999 S4) (Bockelée-Morvan et al 2001;Hogerheijde et al 2004). Veal et al (2000) made some of the first interferometric observations of HCN in comet Hale-Bopp.…”

Section: Introductionmentioning

confidence: 99%

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

Friedel

Remijan

Snyder

et al. 2005

ApJ

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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 25B4 ; 20B3 synthesized beam around comet LINEAR and using a variable temperature and outflow velocity ( VTOV) model, we found an HCN column density of hN T i ¼ (6:4 AE 2:1) ; 10 12 cm À2 and a production rate of Q(HCN) ¼ (6:5 AE 2:2) ; 10 26 s À1 , giving a production rate ratio of HCN relative to H 2 O of $(3:3 AE 1:1) ; 10 À3 and relative to CN of $4:6 AE 1:5. With a 21B3 ; 17B5 synthesized beam around comet NEAT and using a VTOV model, we found an HCN column density of N T h i ¼ (8:5 AE 4:5) ; 10 11 cm À2 and a production rate of Q(HCN) ¼ (8:9 AE 4:7) ; 10 25 s À1 , giving a production rate ratio of HCN relative to H 2 O of $(7:4 AE 3:9) ; 10 À4 and relative to CN of $0:3 AE 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.

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Observations of HCN, HNC, and NH₃in Comet Hale‐Bopp

Cited by 39 publications

References 14 publications

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Ammonia and other parent molecules in comet 10P/Tempel 2 fromHerschel/HIFI and ground-based radio observations

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

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Observations of HCN, HNC, and NH3in Comet Hale‐Bopp

Cited by 39 publications

References 14 publications

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Multi-transitional observations of methanol in Comet Hale-Bopp (1995 O1)

Ammonia and other parent molecules in comet 10P/Tempel 2 fromHerschel/HIFI and ground-based radio observations

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

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Observations of HCN, HNC, and NH₃in Comet Hale‐Bopp