Theoretical calculations of excited rovibrational levels of HD. Term values and transition probabilities of VUV electronic bands

Abgrall, H.; Roueff, E.

doi:10.1051/0004-6361:20053694

Cited by 39 publications

(39 citation statements)

References 29 publications

(59 reference statements)

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“…Another selection criterion was a high signal-to-noise ratio around the 1105.83 8 HD line. This line is 100 times weaker than the rest of the HD absorption features measured, all of which have similar oscillator strengths (HD f-values and wavelength data from Abgrall & Roueff 2006). In many cases this weak line's equivalent width is the only one falling on the linear portion of the COG, thus providing unambiguous information about the column density as Lacour et al (2005) found in their study.…”

Section: Observation and Data Reductionsupporting

confidence: 49%

A NewFUSESurvey of Interstellar HD

Snow¹,

Ross²,

Destree³

et al. 2008

Astrophysical Journal

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We have used archival FUSE data to complete a survey of interstellar HD in 41 lines of sight with a wide range of extinctions. This follow-up to an earlier survey was made to further assess the utility of HD as a cosmological probe; to analyze the HD formation process; and to see what trends with other interstellar properties were present in the data. We employed the curve-of-growth method, supported by line profile fitting, to derive accurate column densities of HD. We find that the N(HD)/2N(H 2 ) ratio is substantially lower than the atomic D/H ratio and conclude that the molecular ratio has no bearing on cosmology, because local processes are responsible for the formation of HD. Based on correlations with E(B À V ), H 2 , CO, and iron depletion, we find that HD is formed in the densest portion of the clouds; the slope of the log N (HD)/log N (H 2 ) correlation is greater than 1.0, caused by the destruction rate of HD declining more slowly than that of H 2 ; and, as a sidelight, that the depletions are density dependent.

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Section: Observation and Data Reductionsupporting

confidence: 49%

A NewFUSESurvey of Interstellar HD

Snow¹,

Ross²,

Destree³

et al. 2008

Astrophysical Journal

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“…The short tick marks indicate the position of the three H 2 -bearing components, the reddest of which also features CO and HD absorptions. The origin of the velocity scale for this figure and all following ones is defined at the position of the CO-bearing component at z abs = 2.68957. and oscillator strengths were taken from Morton & Noreau (1994) and Eidelsberg & Rostas (2003) for CO and from Abgrall & Roueff (2006) for HD. Updated wavelengths of H 2 Lyman and Werner bands were taken from Bailly et al (2010), with oscillator strengths from the Meudon group 1 , based on calculations described in Abgrall et al (1994).…”

Section: Discussionmentioning

confidence: 99%

A translucent interstellar cloud atz = 2.69

Noterdaeme¹,

Petitjean²,

Ledoux³

et al. 2010

A&A

129

147

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We present the analysis of a sub-damped Lyman-α system with neutral hydrogen column density, log N(H 0 ) (cm −2 ) = 20.0 ± 0.15 at z abs = 2.69 toward SDSS J123714.60+064759.5 (z em = 2.78). Using the VLT/UVES and X-shooter spectrographs, we detect H 2 , HD, and CO molecules in absorption with log N(H 2 , HD, CO) (cm −2 ) = 19.21 +0.13 −0.12 , 14.48 ± 0.05 and 14.17 ± 0.09 respectively. The overall metallicity of the system is super-solar ([Zn/H] = +0.34 relative to solar) and iron is highly depleted ([Fe/Zn] = −1.39), revealing metal-rich and dusty gas. Three H 2 velocity components spanning ∼125 km s −1 are detected. The strongest H 2 component, at z abs = 2.68955, with log N(H 2 ) = 19.20, does not coincide with the centre of the H i absorption. This implies that the molecular fraction in this component, f H 2 = 2N(H 2 )/(2N(H 2 )+N(H 0 )), is higher than the mean molecular fraction f H 2 = 1/4 in the system. We also found the Cl 0 associated with this H 2 component to have N(Cl 0 )/N(Cl + ) > 0.4, which points in the same direction. Cl 0 is tied to H 2 by charge exchange reactions, this means that the molecular fraction in this component is not far from unity. The kinetic temperature derived from the J = 0 and 1 rotational levels of H 2 is T = 108 +84 −33 K and the particle density derived from the C 0 ground-state fine structure level populations is n H0 ∼ 50-60 cm −3 . We derive an electronic density <2 cm −3 for a UV field similar to the Galactic one and show that the carbon-to-sulphur ratio in the cloud is close to the solar ratio. The size of the molecular cloud is probably smaller than 1 pc. Both the CO/H 2 = 10 −5 and CO/C 0 ∼ 1 ratios for f H 2 > 0.24 indicate that the cloud classifies as translucent, i.e., a regime where carbon is found both in atomic and molecular form. The corresponding extinction, A V = 0.14, albeit lower than the definition of a translucent sightline (based on extinction properties), is high for the observed H 0 column density. This means that intervening clouds with similar local properties but with higher column densities (i.e. larger physical extent) could be missed by current magnitudelimited QSO surveys. The excitation of CO is dominated by radiative interaction with the cosmic microwave background radiation (CMBR) and we derive T ex (CO) = 10.5 +0.8 −0.6 K when T CMBR (z = 2.69) = 10.05 K is expected. We measure N(HD)/2N(H 2 ) = 10 −5 . This is about 10 times higher than what is measured in the Galactic ISM for f H 2 = 1/4 but similar to what is measured in the Galactic ISM for higher molecular fractions. The astration factor of deuterium with respect to the primordial D/H ratio is only about 3. This can be the consequence of accretion of unprocessed gas from the intergalactic medium onto the associated galaxy. In the future, it will be possible to search efficiently for molecular-rich DLAs/sub-DLAs with X-shooter, but detailed studies of the physical state of the gas will still need UVES observations.

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“…[17][18][19] A radiative model includes the excitation by AS beams and the de-excitation by spontaneous emission ͑X 1 ⌺ g + ↔ B 1 ⌺ u + ͒ leading to a system of rate equations, which has been solved analytically. A fluorescence yield is calculated for each possible excitation taking into account the excitation rate, spontaneous and stimulated emission probabilities, optical properties of the spectrometer, and saturation effects.…”

Section: Methodsmentioning

confidence: 99%

Nonequilibrium rovibrational energy distributions of hydrogen isotopologues in an expanding plasma jet

Gabriel

Dungen

Schram

et al. 2010

The Journal of Chemical Physics

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State resolved densities of high rovibrationally excited hydrogen isotopologues H 2 , HD, and D 2 in the electronic ground state have been measured in a supersonically expanding plasma jet. The obtained state distributions differ substantially from thermal equilibrium. Moreover, the distributions are not the same for H 2 , HD, and D 2 indicating different formation and relaxation rates for each isotopologue. Mechanisms for this deviation from a Boltzmann distribution are given and compared to hydrogen reactions in other environments. The difference between the measured highest occupied rovibrational states in H 2 , HD, and D 2 is ascribed to an isotope effect in the dissociation process.

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Theoretical calculations of excited rovibrational levels of HD. Term values and transition probabilities of VUV electronic bands

Cited by 39 publications

References 29 publications

A NewFUSESurvey of Interstellar HD

A NewFUSESurvey of Interstellar HD

A translucent interstellar cloud atz = 2.69

Nonequilibrium rovibrational energy distributions of hydrogen isotopologues in an expanding plasma jet

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