Spatial distribution of H2O+ in comet P/Halley

DiSanti, M. A.; Fink, Uwe; Schultz, A.

doi:10.1016/0019-1035(90)90205-n

Cited by 23 publications

(10 citation statements)

References 19 publications

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“…The water cation is found in naturally occurring plasmas, for instance, in the Earth's ionosphere [1,2], in comet tails [3,4], and in several regions of the interstellar medium [5][6][7][8]. In these plasmas water ions participate in reactions that influence the thermal and chemical properties of the environment as formulated in several model chemistries [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Harbo

Dziarzhytski²,

Domesle

et al. 2014

Phys. Rev. A

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The decay of metastable states of the water radical cation H 2 O + has been observed in an experiment that combines photofragment momentum imaging and electrostatic ion-beam trapping in a crossed-beam geometry. Photoabsorption of 532-nm laser light from a fast beam of H 2 O + is observed to yield fragmentation into both OH 0 + H + and OH + + H 0 . Using coincident photofragment momentum imaging, the initial state of the observed photofragmentation is associated with low vibrational levels of the second excitedB 2 B 2 state of H 2 O + , dissociating via absorption onto a repulsive part of theÃ 2 A 1 state. Electrostatic ion trapping in the laser interaction region is used to follow the photofragment intensity as a function of time and to determine the lifetime of the metastable states to be τB 2 B 2 = 198 ± 11 μs.

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Section: Introductionmentioning

confidence: 99%

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Harbo

Dziarzhytski²,

Domesle

et al. 2014

Phys. Rev. A

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“…The water cation H 2 O + occurs in several natural environments where molecular gas is exposed to ionizing radiation. It has been directly observed in the upper atmosphere [1] and in the tails of several comets [2][3][4][5][6][7] through its emission spectrum in the visible (vis) range; these observations have been used to indirectly identify the presence of neutral water in comets, since H 2 O molecules themselves do not show a vis emission spectrum. Recently, the astrophysical importance of H 2 O + has been highlighted by several observations of both H 2 O + and other oxygen hydride ions (OH + and H 3 O + ) using the Herschel Space Observatory [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Photolysis of water-radical ions H2O+in the xuv: Fragmentation through dicationic states

et al. 2013

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The photofragmentation of the water cation H 2 O + through dicationic states has been studied at 35.0 ± 0.2 nm (35.4 ± 0.3 eV) and 21.8 ± 0.2 nm (56.8 ± 0.5 eV) with a crossed ion-photon beams experiment at the free electron laser FLASH. The dissociation of the dications is found to be similar at the two wavelengths and to proceed into O 0 + 2H + , OH + + H + , and O + + H 2 + , with determined ratios σ OH + +H + /σ O + +H 2 + = 4.2 ± 0.3 and σ OH + +H + /σ O 0 +2H + > 0.7. The measured kinetic-energy releases for these processes are consistent with three-body breakup (O 0 + 2H +) occurring mainly through the 2 3 A and 2 1 A states of H 2 O 2+ and two-body breakup (OH + + H +) occurring through X 3 A , 1 3 A , and 1 1 A states of H 2 O 2+ , as predicted in a recent theoretical study [Gervais et al., J. Chem. Phys. 131, 024302 (2009)]. In addition to the kinetic-energy releases, we also report on fragment correlation in the three-body channel where the two protons carry the major part of the released momentum.

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“…In the remainder of this paper, all distances and velocities cited will be deprojected in this manner. tions of the cometary ionosphere does not extend very far toward the Sun in typical periodic comets (McCarthy et al 1987;DiSanti et al 1990; Ip et al 1985). Thus it is a small technical triumph to observe the H 2 0+ velocities on the Sun side.…”

Section: Introduction and Observationsmentioning

confidence: 99%

Kinematics of the ion tail of comet P/Swift-Tuttle

Spinrad¹,

Brown²,

Johns³

1994

The Astronomical Journal

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We have obtained long-slit high resolution spectra of the H 2 0+ 6199 A complex in the near tail of comet P/Swift-Tuttle. The observations were made using the Hamilton echelle spectrometer fed by the Lick Observatory 0.6 m coude auxiliary telescope. For most of our observations, the spectral slit was aligned along the Sun-tail axis and the cometary nucleus was placed at one end of the slit, giving us spectra having the spatial and spectral resolution needed to measure the radial velocity and velocity dispersion continuously down the cometary tail out to a distance of 4X llf km. The radial velocities confirm the earlier more restricted observations by Rauer & Jockers [Icarus, 102, 117 (1993)] and by Wyckoff & Lindholm (1994) showing that the tail motions are indeed bulk flows in the antisolar direction. Out to 3Xllf km in the tail typical bulk flows are at a speed of-30 km s-1. The velocity dispersion, (ur), of the H 2 0+ lines follows a pattern that is quite systematic; ur is smallest near the cometary nucleus, and steadily increases down the tail. The highest velocity dispersions are found ahead of the nucleus and off the tail axis. These velocity dispersions are equivalent to ion temperatures ranging from 10 5 to 10 6 K. We note a clear anticorrelation between the H 2 0+ line intensities (related to the ion density) and the bulk flow and dispersion velocities; direct mass loading of the solar wind by the observed water ions may be responsible. We discuss several approximate equipartition methods used to infer local magnetic fields induced by the interaction of the cometary ions with the solar wind particle/field stream. Typical fields derived are near 50 nT. The measured tailward accelerations are consistent with this order of magnitude B field.

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Spatial distribution of H2O+ in comet P/Halley

Cited by 23 publications

References 19 publications

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Lifetime of low vibrational levels of the metastableB̃2B2state ofH2O+<

Photolysis of water-radical ions H2O+in the xuv: Fragmentation through dicationic states

Kinematics of the ion tail of comet P/Swift-Tuttle

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