A survey of 39 comets using CCD spectroscopy

Fink, Uwe; Hicks, Michael

doi:10.1086/176938

Cited by 119 publications

(101 citation statements)

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“…Regarding carbon-chain species, the abundance of ethane and acetylene with respect to that of water, (∼0.6 and ∼0.3, respectively) is much the same for the three comets (Mumma et al 2001). The optical data obtained at ESO also allow us to compare Comet Lee with some of the comets presented in the surveys by A' Hearn et al (1995) and Fink & Hicks (1996). Comparison of the log of the production rates ratios CN OH and A f ρ OH for comet C/1999 H1 with the values for the restricted data set in Table 4 of A 'Hearn et al (1995) indicates that Comet Lee is similar to periodic comets 23P/Brorsen-Metcalf, 6P/d'Arrest or 2P/Encke and to long period comets such as Okazaki-Levy-Rudenko (C/1989 Q1), Thiele (C/1985 T1) or Sugano-Saigusa-Fujigawa (C/1983 J1).…”

Section: Discussionmentioning

confidence: 65%

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The gas and dust coma of Comet C/1999 H1 (Lee)

Lara¹,

Rodrigo²,

Tozzi³

et al. 2004

A&A

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Abstract. Comet Lee (C/1999 H1) was observed on June 6, 1999 when it was at r h = 0.98 AU and ∆ = 1.195 AU. The spectrophotometric observations, between 0.6 and 1 µm, were aimed at the detection of the CI( 1 D) doublet λλ 9823/9850 Å. The non-detection of these lines, with a 3σ flux upper limit of the order of 4.6 × 10 −17 erg cm −2 s −1 , confirms the CO depletion already noted by other authors. Several CN and NH 2 emission bands lie in that spectral range, making it possible to derive production rates for both species as ∼3.1 × 10 26 s −1 and 1.2 × 10 27 s −1 , respectively. The oxygen forbidden line at 6300 Å was used to obtain Q H 2 O = (1.22 ± 0.7) × 10 29 s −1 . Assuming that CN and NH 2 are directly produced by HCN and NH 3 , Comet Lee has a HCN/H 2 O ≈ 0.25% and NH 3 /H 2 O ≈ 1% at r h = 0.98 AU, in reasonable agreement with what has been found in other long-period comets. The structural analysis carried out on cometary images acquired with broad band R Bessel filter clearly displays two pairs of ion rays likely produced by the H 2 O + doublet at 6198 and 6200 Å, wavelengths covered by the bandpass filter. Identical features are found in the images acquired with the Gunn i filter. The dust brightness profiles in the east-west direction do not deviate from a ρ −m law (with 0.7 < m ≤ 1.2) as expected for a steady state model coma with a constant dust production rate and expanding at constant velocity. The dust production rate, as obtained from the A f ρ parameter, is ∼500 cm, which compared with the gas production rate classifies this comet as a dust poor one with relatively high (6.5-11.7) gas-to-dust mass ratio. Analysis of the normalized reflectivity gradient (i.e. continuum color) as a function of ρ indicates a slight reddening of the solid component in the coma at large cometocentric distances, whereas the average dust color within an aperture of 20 000 km, centered at the nucleus, is ∼9% per 1000 Å. Mie scattering computations applied to an ensemble of particles indicate that the dust coma is characterised by a relative broad size distribution with a typical mean size of 1 µm. These grains might be composed of a mixture of silicates and icy material.

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Section: Discussionmentioning

confidence: 65%

“…Similarly, of the 39 comets surveyed by Fink & Hicks (1996), comet C/1999 H1 resembles comets 73P/Schwassmann-Wachmann 3 or 2P/Encke in terms of CN to H 2 O relative abundance. Comparison of the NH 2 content versus H 2 O in the same database is more uncertain given the new results on the g-factors by Kawakita & Watanabe (2002).…”

Section: Discussionmentioning

confidence: 84%

The gas and dust coma of Comet C/1999 H1 (Lee)

Lara¹,

Rodrigo²,

Tozzi³

et al. 2004

A&A

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“…For this purpose we considered the findings of A 'Hearn et al (1995), Fink & Hicks (1996), Hanner & Hayward (2003), Schulz et al (2003), Sekanina (2003), Farnham & Schleicher (2005), and Hadamcik & LevasseurRegourd (2009). A'Hearn et al (1995 summarized the results of narrowband photometric data of 85 comets between 1976 and 1992.…”

Section: Comparison With Previous Perihelion Passagesmentioning

confidence: 99%

“…A'Hearn et al (1995 summarized the results of narrowband photometric data of 85 comets between 1976 and 1992. Fink & Hicks (1996) reported the analysis of 39 objects obtained from spectral measurements from 1985 to 1993. Hanner & Hayward (2003) observed 81P in the thermal infrared during 1997.…”

Section: Comparison With Previous Perihelion Passagesmentioning

confidence: 99%

Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

Bertini

Barbieri

et al. 2012

A&A

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Context. The Jupiter-family comet 81P/Wild 2, target of the NASA Stardust mission, is very important in the context of the studies of pristine objects in the solar system. First, it was only recently deflected into the present orbit, having spent at least 300 yr at higher heliocentric distance prior to the orbital change in 1974. It is therefore likely that the comet experienced a recent activation with consequent low alteration of its original material. Second, it is the only comet whose coma material was brought back to Earth for laboratory analysis. We observed the object between 2010 February 9 and September 9 for a total of 11 nights during the 2010 perihelion passage. Aims. The goals of the campaign were the characterization of the comet's dust activity and the comparison with previous apparitions to derive hints on the secular behavior of the object. Methods. Broadband R-and I-images were acquired using three instruments: ALFOSC, CAMELOT, and TCP. The first one is mounted at the Nordic Optical Telescope on La Palma, while the second and the third are mounted at the Instituto de Astrofisica de Canarias 0.82-m telescope on Tenerife. We analyzed the presence and variability of dust structures in the coma with image-enhancing techniques, the radial profile of the dust brightness, and we measured the dust production rate and the dust reddening. Results. We found evidence of a long-lasting sunward fan and anti-solar tail activity throughout all our observations up to a heliocentric distance of 2.42 AU. A f ρ measurements suggest a pre-perihelion peak of the activity, caused by a seasonal effect, plus two post-perihelion outbursts. Both spatial and A f ρ radial profiles indicate a steady-state coma at nucleocentric distances greater than ∼1000-2000 km. The color analysis reveals a moderately reddened dust with a 6-9%/1000 Å reddening, consistent with the current picture of cometary dust. The second outburst emitted dust with lower reddening. Conclusions. The comparison with previous perihelion passages points toward a recurrent main activity always driven by the same areas on the nucleus, producing dust with similar characteristics and in similar coma structures in different years. Our A f ρ measurement at the longest heliocentric distance suggests the comet was less dust-productive in 2010, pointing toward a possible secular aging of the object and its activity. The change of dust colors during the unusual second outburst suggests that an internal part of the nucleus has different physical properties compared with those that produce the recurrent main activity, pointing toward a heterogeneous comet.

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“…We must therefore estimate the water production rate of each comet at the heliocentric distance of the observations to calculate a m . We checked several large data sets, namely Festou (1990), A'Hearn et al (1995, Fink & Hicks (1996), Crovisier et al (2002), and only found data for three of our comets in the second article, namely 4P/Faye, 10P/Tempel 2 and 59P/Kearns-Kwee. This article tabulates the OH production rates at specified heliocentric distances (Table III of A'Hearn et al 1995).…”

Section: Dust Production Ratementioning

confidence: 99%

Properties of the nuclei and comae of 13 ecliptic comets from Hubble Space Telescope snapshot observations

Lamy

Tóth

Weaver

et al. 2009

A&A

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Context. Knowledge of the size distribution of cometary nuclei and, more generally, of their physical properties is important for constraining models of the formation and evolution of the Solar System. Aims. We report on our on-going effort to determine the ensemble properties of comets based on our success in detecting the nuclei of active comets with the Hubble Space Telescope (HST). Methods. During cycle 8 (July 1999 to June 2000), we observed 13 ecliptic comets with the planetary camera 2 through at least two filters (V and R) and up to four (B, V, R, I) for the brightest ones. The ∼30 min of HST observational time devoted to each comet did not permit a proper determination of light curves, so our "snapshot" observations yield effective radii, not shapes. In our present sample, eight out of thirteen nuclei have sub-kilometer radii. The average color of the observed nuclei is (V − R) = 0.52 ± 0.04, which is significantly redder than the Sun. We determined the dust activity parameter A f ρ of their coma in the R band, and estimated the dust production rates. The average reflectivity gradient of the dust comae of six comets is S [670, 792 nm] = 15.2 ± 2.3% per kÅ.

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A survey of 39 comets using CCD spectroscopy

Cited by 119 publications

References 0 publications

The gas and dust coma of Comet C/1999 H1 (Lee)

The gas and dust coma of Comet C/1999 H1 (Lee)

Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

Properties of the nuclei and comae of 13 ecliptic comets from Hubble Space Telescope snapshot observations

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