A review of radio observations of comets

Snyder, L. E.

doi:10.1016/0019-1035(82)90026-4

Cited by 20 publications

(6 citation statements)

References 57 publications

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“…There is a long history of observations of cometary radio continuum. The majority of observations made at centimetric wavelengths were unsuccessful or matter of debate; see the reviews of Snyder (1982) and Crovisier and Schloerb (1991) for early observations. Even for the productive and dusty comet C/1995 O1 (Hale-Bopp), only a very weak thermal continuum was detected at 0.9 cm wavelength, attributed to thermal emission of cm-sized particles (Altenhoff et al, 1999).…”

Section: Radio Continuum Measurementsmentioning

confidence: 99%

Radio observations of Jupiter-family comets

Crovisier¹,

Biver²,

Bockelée‐Morvan³

et al. 2009

Planetary and Space Science

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Radio observations from decimetric to submillimetric wavelengths are now a basic tool for the investigation of comets. Spectroscopic observations allow us i) to monitor the gas production rate of the comets, by directly observing the water molecule, or by observing secondary products (e.g., the OH radical) or minor species (e.g., HCN); ii) to investigate the chemical composition of comets; iii) to probe the physical conditions of cometary atmospheres: kinetic temperature and expansion velocity. Continuum observations probe large-size dust particles and (for the largest objects) cometary nuclei. Comets are classified from their orbital characteristics into two separate classes: i) nearly-isotropic, mainly long-period comets and ii) ecliptic, short-period comets, the so-called Jupiter-family comets. These two classes apparently come from two different reservoirs, respectively the Oort cloud and the trans-Neptunian scattered disc. Due to their different history and - possibly - their different origin, they may have different chemical and physical properties that are worth being investigated. The present article reviews the contribution of radio observations to our knowledge of the Jupiter-family comets (JFCs). The difficulty of such a study is the commonly low gas and dust productions of these comets. Long-period, nearly-isotropic comets from the Oort cloud are better known from Earth-based observations. On the other hand, Jupiter-family comets are more easily accessed by space missions. However, unique opportunities to observe Jupiter-family comets are offered when these objects come by chance close to the Earth. About a dozen JFCs were successfully observed by radio techniques up to now. No obvious evidence for different properties between JFCs and other families of comets is found.Comment: Accepted for publication in Planetary and Space Science (special issue on Jupiter-family comets). 18 pages including 12 figures and 7 table

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Section: Radio Continuum Measurementsmentioning

confidence: 99%

Radio observations of Jupiter-family comets

Crovisier¹,

Biver²,

Bockelée‐Morvan³

et al. 2009

Planetary and Space Science

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“…The water production rate at perihelion, 1.0 × 10 31 s −1 , was taken from Colom et al (1999). The procedure originally developed by Snyder (1982) is used here to estimate the production rate Q(S i ) of species i from the observed beam-averaged column density N(S i )…”

Section: Upper Limits On Nh 3 Column Densitiesmentioning

confidence: 99%

Recent searches for the radio lines of NH₃ in comets

Hatchell

Bird

Tak

et al. 2005

A&A

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Abstract. Radio observations in the ammonia inversion lines of four comets, C/2001 A2 (LINEAR), 153P/Ikeya-Zhang, C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), were performed at the Effelsberg 100-m Radio Telescope during their respective close approaches to Earth. None of the four lowest energy metastable lines (J, K = J), J = 1-4, could be detected in these comets. We derive the following 3σ upper bounds on the NH 3 production rate , and comparing to the corresponding water production rates, percentage NH 3 abundances relative to H 2 O: Q(NH 3 ) < 1.9 × 10

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“…The aim of the present paper is to review the results of radio cometary observations and to discuss what may be learned from such studies in the future. Since several reviews of this topic for pre-Halley observations are available (Snyder 1982(Snyder , 1986Crovisier 1985;Schloerb and Gerard 1985), we will only summarize the results obtained during that period, and concentrate on more recent results.…”

Section: Introductionmentioning

confidence: 99%

The Study of Comets at Radio Wavelengths

Crovisier¹,

Schloerb²

1989

International Astronomical Union Colloquium

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Radio observations of comets complement studies at other wavelengths as well as providing certain kinds of unique information. Studies of continuum emission may probe the thermal emission of the nucleus and large-size dust particles. Spectroscopic observations of gas in the coma allow searches for parent molecular species that have no signatures in the optical spectral range. The 18-cm wavelength spectral lines of the OH radical now are relatively easy to detect, and observations of them permit long-term and short-term monitoring of the cometary gaseous output. Moreover, with the unique spectral resolution of radio techniques, aspects of the kinematics of the coma may be also studied, such as the gas expansion velocity and the anisotropy of gas production from the nucleus. In this review, we present recent results of cometary radio observations, and discuss what may be learned from such studies in the future.

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A review of radio observations of comets

Cited by 20 publications

References 57 publications

Radio observations of Jupiter-family comets

Radio observations of Jupiter-family comets

Recent searches for the radio lines of NH₃ in comets

The Study of Comets at Radio Wavelengths

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A review of radio observations of comets

Cited by 20 publications

References 57 publications

Radio observations of Jupiter-family comets

Radio observations of Jupiter-family comets

Recent searches for the radio lines of NH3 in comets

The Study of Comets at Radio Wavelengths

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Recent searches for the radio lines of NH₃ in comets