The Spatial Distribution of Gaseous Atomic Sodium in the Comae of Comets: Evidence for Direct Nucleus and Extended Plasma Sources

Combi, M. R.; DiSanti, M. A.; Fink, Uwe

doi:10.1006/icar.1997.5832

Cited by 58 publications

(50 citation statements)

References 46 publications

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“…1). Sodium emission in comet spectra has been previously observed in other comets (e.g., Combi, DiSanti, & Fink 1997)-in Hale-Bopp by several groups (Cremonese 1997; Cremonese et al 1997;Brown et al 1998;Kawakita & Fujii 1998;Rauer et al 1998; and in Hyakutake ). In comet Hale-Bopp, source regions for the observed Na may be located in the nucleus and a region distributed around the nucleus Rauer et al 1998;Kawakita & Fujii 1998).…”

Section: Observationsmentioning

confidence: 63%

Unidentified Molecular Bands in the Plasma Tail of Comet Hyakutake (C/1996 B2)

Wyckoff

Heyd

Fox

1999

The Astrophysical Journal

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Unidentified molecular emission bands first observed in optical spectra of the plasma tail of comet Halley (1P/1982 U1) have been discovered in pure ion tail spectra ( Å , ) of comet Dl ∼ 4700-6300 l/Dl ∼ 1000-4400 Hyakutake (C/1996 B2) and three other recent comets (Nakamura-Nishimura-Machholz P/1994 N1, Austin C/1989 X1, and Brorsen-Metcalf 32P/1989 N1), but not in comet Hale-Bopp (C/1995 O1). The strengths of the bands near 4940, 5310, and 6000 Å are correlated among the comets observed, indicative that the unidentified bands arise from a single molecular species. The bands have an asymmetric spatial distribution that extends in the antisolar direction, resembling molecular ions observed in comet plasma tails. Thus, the source of the unidentified bands is probably a single species of molecular ions. Of known laboratory molecular ion spectra, none can be attributed to the unidentified cometary emission bands. The absence of the unidentified ions in the tail of Hale-Bopp may be explained by a parent species of the unidentified ions that mimics the coma dynamics and photochemistry of H 2 O more closely than CO. This is inferred from the large tail CO ϩ /H 2 O ϩ ratio observed in Hale-Bopp, which arises from the comet's large production rate that extends the ionopause and coma collision zone. Our observations provide evidence that the source region for the ions in plasma tails of comets lies external to the magnetic field-free ionopause.

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Section: Observationsmentioning

confidence: 63%

Unidentified Molecular Bands in the Plasma Tail of Comet Hyakutake (C/1996 B2)

Wyckoff

Heyd

Fox

1999

The Astrophysical Journal

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“…Different mechanisms of ejection from the dust grains, such as photo-sputtering or solar wind sputtering, have been suggested; but according to Ip and Jorda (1998), these two mechanisms should be not efficient enough to explain the observed ejection rate from comet Hale-Bopp. Therefore, other mechanisms have been suggested, such as the impact of very small dust grains (smaller than 100 Å) on the dust grains (Ip & Jorda 1998) or an ionic parent for the Na observed emission (Combi et al 1997). The latter solution has been however rejected by Brown et al (1998), who found that such a possibility would produce sodium velocities that contradict the observed ones and could not explain a sodium tail that is spatially distinct from the ionic tail.…”

Section: Introductionmentioning

confidence: 99%

Comet McNaught C/2006 P1: observation of the sodium emission by the solar telescope THEMIS

Leblanc

Fulle

Ariste³

et al. 2008

A&A

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“…A recent analysis of three Sodium in Comet Hale-Bopp was observed using the Lick Observatory 0.6-m coudé auxiliary telescope coupled such comets has suggested that in these cases, sodium is produced from both a nuclear source and a more extended to the Hamilton Echelle Spectrometer (Vogt 1988) on 8 and 10 April 1997 (Table 1). For each exposure, the nucleus source with a distribution reminiscent of the plasma tail (Combi et al 1997).…”

Section: Introductionmentioning

confidence: 99%

“…

fering initial interpretations suggested that the sodium tail came from a plasma source (Combi et al 1997), from so-

suggests that the intensities and velocities of sodium in Hale-Observations of the velocity distribution of cometary Bopp can be explained if 55% of the observed sodium is pro-sodium give important clues into the source and dynamics duced at the nucleus, the remaining 45% is produced in an of the sodium. For example, velocities measured from specextended source, and the sodium is accelerated by solar radia-tra obtained far from the nucleus at the location of the tion pressure.

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mentioning

confidence: 99%