Lyman-alpha observations of comet Hyakutake with SWAN on SOHO

Bertaux, Jean-Loup; Costa, J.; Quémerais, Éric; Lallement, R.; Kyrölä, E.; Schmidt, W.; Summanen, T.; Mäkinen, T.; Goukenleuque, C.

doi:10.1016/s0032-0633(97)00179-7

Cited by 42 publications

(29 citation statements)

References 5 publications

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“…For the exceptionally bright and nearby comet C/1996 B2 (Hyakutake) Hubble Space Telescope (HST) spectroscopy detected the Ly-α emission, as the relative velocity (54 km s −1 ) of the comet was sufficient to Doppler shift it away from the background (Combi et al 1998). Observations with small field-of-view (FOV), like HST, are difficult to interpret directly because the innermost coma is optically thick to Lyman-α (Combi et al 1998), so most observations have been very wide field like sounding rockets and the SOHO SWAN all-sky Lyman-α camera (Bertaux et al 1998;Mäkinen et al 2001;Combi et al 2011b). Because the H coma can cover 10 or more degrees of the sky, background stars can become a serious limitation, especially for fainter comets.…”

Section: Uv/visible Emission Featuresmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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Section: Uv/visible Emission Featuresmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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“…For a few dates we have also determined values with a fast solar wind model. For comparison we have added the results obtained from observations at longer wavelength, namely the observation of Lα by SOHO/SWAN by Bertaux et al (1998) and the radio observation of the 18-cm line of OH by Gérard et al (1998). The agreement is rather good.…”

Section: Comet Hyakutakementioning

confidence: 99%

The morphology of cometary X-ray emission

Wegmann¹,

Dennerl²,

Lisse³

2004

A&A

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Abstract. X-ray emission from comets is generated by charge exchange of heavy solar wind ions in a high ionization state with the neutral particles of the cometary coma. We use model calculations and theoretical considerations to study the morphology of the emission. The emission is located in a bowl-shaped region on the subsolar side of the nucleus. We derive several length scales. By comparison with hydrodynamic scales we find that the maximum emission comes from inside the bow shock. The size of the emission region depends on the size of the cometary coma, i.e., mainly on the gas production, while the intensity depends mainly on the energy content of the heavy ions in the solar wind flow. This dependence allows a determination of the gas production of the comet and the heavy ion energy flux from a statistical study of the observed spatial distribution of X-ray photons. Here we apply this procedure to X-ray observations from comets C/1996 B2 (Hyakutake), C/1990 K1 (Levy), 2P/Encke and C/2000 WM1 (LINEAR). The gas production rates determined by our method agree very well with those obtained by other methods. The variability of the emission documented in several recorded outbursts correlates with the solar wind proton density.

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“…The primary mission of the SWAN instrument on SOHO is to examine the global distribution of the solar wind by monitoring its effect on the Ly-α emission from the neutral hydrogen atoms streaming through the Solar System from the interstellar medium. The SWAN instrument and the first results have been described in detail by Bertaux et al (1995Bertaux et al ( , 1997, and the observations of the Ly-α coma of Comet Hyakutake (1996 B2) have been described by Bertaux et al (1998). For completeness we provide here a brief summary of the instrument and observational methods as they were applied to the observations of Comet Hale-Bopp.…”

Section: Observationsmentioning

confidence: 99%

“…The solar UV photodissociation chain of water, OH and H 2 produces a large spatially extended coma of atomic hydrogen (H) which, for a bright comet, far outshines the IPM in Ly-α. The SWAN instrument, therefore, is an ideal instrument for observing the brightness, distribution, and development of the H Ly-α comae of comets (Bertaux et al 1998). These measurements then serve as an ideal tracer of cometary water production.…”

Section: Introductionmentioning

confidence: 99%