Charge transfer 
 in collisions of O<sup>+</sup> with H and H<sup>+</sup> with O

Stancil, P. C.; Schultz, David; Kimura, Mineo; Gu, Jie; Hirsch, Gerhard; Buenker, R. J.

doi:10.1051/aas:1999419

Cited by 114 publications

(112 citation statements)

References 51 publications

Supporting

Mentioning

104

Contrasting

Order By: Relevance

“…The oxygen chemistry starts with the O( 3 P J ) + H + → O + ( 4 S) + H charge transfer process, where reaction rates are sensitive to the oxygen fine-structure level populations (Stancil et al 1999, and references therein). Indeed the charge transfer proceeds quickly when the O( 3 P 1 ) level (ΔE 12 /k = 228 K) is significantly populated, but it can be a slow proceess in cold gas where only the O( 3 P 2 ) ground-state level is populated (Spirko et al 2003).…”

Section: Pdr Modelsmentioning

confidence: 99%

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4

Gérin¹,

Luca²,

Black

et al. 2010

A&A

159

View full text Add to dashboard Cite

We report the detection of absorption lines by the reactive ions OH + , H 2 O + and H 3 O + along the line of sight to the submillimeter continuum source G10.6−0.4 (W31C). We used the Herschel HIFI instrument in dual beam switch mode to observe the ground state rotational transitions of OH + at 971 GHz, H 2 O + at 1115 and 607 GHz, and H 3 O + at 984 GHz. The resultant spectra show deep absorption over a broad velocity range that originates in the interstellar matter along the line of sight to G10.6−0.4 as well as in the molecular gas directly associated with that source. The OH + spectrum reaches saturation over most velocities corresponding to the foreground gas, while the opacity of the H 2 O + lines remains lower than 1 in the same velocity range, and the H 3 O + line shows only weak absorption. For LSR velocities between 7 and 50 km s −1 we estimate total column densities of N(OH + ) ≥ 2.5 × 10 14 cm −2 , N(H 2 O + ) ∼6 × 10 13 cm −2 and N(H 3 O + ) ∼4.0 × 10 13 cm −2 . These detections confirm the role of O + and OH + in initiating the oxygen chemistry in diffuse molecular gas and strengthen our understanding of the gas phase production of water. The high ratio of the OH + by the H 2 O + column density implies that these species predominantly trace low-density gas with a small fraction of hydrogen in molecular form.

show abstract

Section: Pdr Modelsmentioning

confidence: 99%

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4

Gérin¹,

Luca²,

Black

et al. 2010

A&A

159

View full text Add to dashboard Cite

show abstract

“…For transitions for which data were not available, we incorporated the formulation of Seaton (1962). Charge exchange rates with protons were obtained from Stancil et al (1998aStancil et al ( , 1998b, Lin et al (2005), and Stancil et al (1999), for C, N, and O, respectively. Collisional excitation and ionization by neutral H was assumed according to Kaulakys (1985) formula for Rydberg levels and neglected for lower levels.…”

Section: The C and O Nlte Calculationsmentioning

confidence: 99%

Semiempirical Models of the Solar Atmosphere. II. The Quiet‐Sun Low Chromosphere at Moderate Resolution

Fontenla

Balasubramaniam

Harder

2007

ApJ

View full text Add to dashboard Cite

We present a new, one-dimensional model of the solar atmosphere (called SRPM 305) at moderate angular resolution ($1 00 Y2 00 ). Key characteristics of the SRPM 305 model include (1) a minimum temperature of $3800 K at a gas pressure of $80 dyne cm À2 and (2) a rapid temperature rise above the temperature-minimum layer that results in substantial overionization of most elements when compared with LTE calculations. The model calculations reproduce the $4300 K minimum brightness temperature of the UV continuum ( between 1400Y1500 8) observed by SUMER and the $4400 K observed minimum radio-continuum brightness temperature (between wavelengths 0.01 and 100 mm). Neither the UV nor the radio continuum bear on the low-temperature minimum value because their broad intensity contribution functions cause the higher temperatures of the upper chromospheric layers to effectively hide the low minimum temperature region. The SRPM 305 model reproduces the observed intensities of CO lines at 4.466 m, at both the disk center and near the limb, by using C and O abundances consistent with recent literature low values. The model also reproduces observed intensities of C i spectral lines at 5381 and 8337 8, CH lines at about 4306 8, the CN band head at 3883 8, and the O i lines at 7772, 7774, and 7776 8, respectively. Using the SRPM 305 model, we find no significant abundance variations between the photosphere and the low chromosphere. Consequently, the single-component model presented here matches several apparently contradictory observations and thereby resolves the controversy about the temperature minimum value.

show abstract

“…6.3, it includes H 0 , whose contribution comes from the equilibrium condition O + /O 0 0.82 × (H + /H 0 ), valid for O 0 > O + , i.e. in the nebular regions affected by the O + + H 0 ← → O 0 + H + reaction (Williams 1973;Stancil et al 1999).…”

Section: Equatorial Moustachesmentioning

confidence: 99%

The 3-D ionization structure of NGC 6818: A Planetary Nebula threatened by recombination

Benetti

Ragazzoni

Sabbadin

et al. 2003

A&A

View full text Add to dashboard Cite

Abstract. Long-slit NTT+EMMI echellograms of NGC 6818 (the Little Gem) at nine equally spaced position angles, reduced according to the 3-D methodology introduced by Sabbadin et al. (2000a,b), allowed us to derive: the expansion law, the diagnostics and ionic radial profiles, the distance and the central star parameters, the nebular photo-ionization model, the 3-D reconstruction in He II, [O III] and [N II], the multicolor projection and a series of movies. The Little Gem results to be a young (3500 years), optically thin (quasi-thin in some directions) double shell (M ion 0.13 M ) at a distance of 1.7 kpc, seen almost equatorial on: a tenuous and patchy spherical envelope (r 0.090 pc) encircles a dense and inhomogeneous tri-axial ellipsoid (a/2 0.077 pc, a/b 1.25, b/c 1.15) characterized by a hole along the major axis and a pair of equatorial, thick moustaches. NGC 6818 is at the start of the recombination phase following the luminosity decline of the 0.625 M central star, which has recently exhausted the hydrogen shell nuclear burning and is rapidly moving toward the white dwarf domain (log T * 5.22 K; log L * /L 3.1). The nebula is destined to become thicker and thicker, with an increasing fraction of neutral, dusty gas in the outermost layers. Only over some hundreds of years the plasma rarefaction due to the expansion will prevail against the slower and slower stellar decline, leading to a gradual re-growing of the ionization front. The exciting star of NGC 6818 (m V 17.06) is a visual binary: a faint, red companion (m V 17.73) appears at 0.09 arcsec in PA = 190 • , corresponding to a separation ≥150 AU and to an orbital period ≥1500 years.

show abstract

Charge transfer in collisions of O⁺ with H and H⁺ with O

Cited by 114 publications

References 51 publications

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4

Semiempirical Models of the Solar Atmosphere. II. The Quiet‐Sun Low Chromosphere at Moderate Resolution

The 3-D ionization structure of NGC 6818: A Planetary Nebula threatened by recombination

Contact Info

Product

Resources

About

Charge transfer in collisions of O+ with H and H+ with O

Cited by 114 publications

References 51 publications

Interstellar OH+, H2O+and H3O+along the sight-line to G10.6–0.4

Interstellar OH+, H2O+and H3O+along the sight-line to G10.6–0.4

Semiempirical Models of the Solar Atmosphere. II. The Quiet‐Sun Low Chromosphere at Moderate Resolution

The 3-D ionization structure of NGC 6818: A Planetary Nebula threatened by recombination

Contact Info

Product

Resources

About

Charge transfer in collisions of O⁺ with H and H⁺ with O

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4

Interstellar OH⁺, H₂O⁺and H₃O⁺along the sight-line to G10.6–0.4