The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations

Knauth, D. C.; Andersson, B. G.; McCandliss, Stephan R.; Moos, H. W.

doi:10.1038/nature02614

Cited by 111 publications

(93 citation statements)

References 23 publications

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“…0 transition of 92.2 GHz in line with Turner's observations. It took until 2004 before near-IR, electronic bands were linked to N 2 , [36] but this claim has been disputed by some. In any case, the protonated CO and N 2 molecules were observed in the 1970s and owe their initial detections to quantum chemistry.…”

Section: Quantum Chemistry In Astrochemical Detectionmentioning

confidence: 99%

“…Additionally, the most common isotope of argon on Earth is 40 Ar originating from the decay of potassium found in seawater. In the greater universe on the other hand, 40 Ar is less than 0.01% of the argon atoms with 36 Ar and 38 Ar making up the most common isotopes. 36 Ar is very expensive to use in laboratory experiments on Earth, but changing the mass of the argon atom in a quantum chemical input file is straightforward.…”

Section: Terrestrially Unstable Molecules Charged Species and Radicalsmentioning

confidence: 99%

“…In the greater universe on the other hand, 40 Ar is less than 0.01% of the argon atoms with 36 Ar and 38 Ar making up the most common isotopes. 36 Ar is very expensive to use in laboratory experiments on Earth, but changing the mass of the argon atom in a quantum chemical input file is straightforward. Quantum chemistry once more shows its value in being able to predict properties for such species that are not easily physically studied.…”

Section: Terrestrially Unstable Molecules Charged Species and Radicalsmentioning

confidence: 99%

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Quantum astrochemical spectroscopy

Fortenberry

2016

Int J of Quantum Chemistry

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In this review, the origins of astrochemistry and the initial applications of quantum chemistry to the discovery of new molecules in space are discussed. Furthermore, more recent successes and failures of quantum astrochemistry are explored. Finally, the application of quantum chemistry to the chemical study of space is driving developments in large-scale computational science. Consequently, cloud computing and large molecule computations are discussed. Astrochemistry is a natural application of quantum chemistry. The ability to analyze routinely and completely the structural, spectroscopic, and electronic properties of any given molecule, regardless of its laboratory stability, make this tool a necessary component for astrochemical analysis. The sizes of the computations scaling with the number of electrons and degrees-of-freedom can become limiting, but proper choices of methods can provide unique insights. The chemistry of the Earth is a small snapshot of the chemistries available in the universe at large, and the flexibility inherent within computation make quantum chemistry an excellent driver of new knowledge in fundamental molecular science as well as in astrophysics.

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Section: Quantum Chemistry In Astrochemical Detectionmentioning

confidence: 99%

Section: Terrestrially Unstable Molecules Charged Species and Radicalsmentioning

confidence: 99%

Section: Terrestrially Unstable Molecules Charged Species and Radicalsmentioning

confidence: 99%

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Quantum astrochemical spectroscopy

Fortenberry

2016

Int J of Quantum Chemistry

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“…N 2 is well studied at various locations within our solar system through its electronic transitions at ultraviolet wavelengths (e.g., Strobel 1982;Meier et al 1991;Wayne 2000;Liang et al 2007) and a detection in interstellar space has been claimed through UV absorption lines in a diffuse cloud toward the bright background star HD 124314 (Knauth et al 2004). In dense clouds well shielded from UV radiation, most nitrogen is expected to exist as N 2 (e.g., Herbst & Klemperer 1973;Woodall et al 2007) but can only be detected indirectly through the protonated ion N 2 H + (Turner 1974;Herbst et al 1977) or its deuterated form N 2 D + .…”

Section: Introductionmentioning

confidence: 99%

Photodissociation of interstellar N₂

Heays

Visser

et al. 2013

A&A

138

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Context. Molecular nitrogen is one of the key species in the chemistry of interstellar clouds and protoplanetary disks, but its photodissociation under interstellar conditions has never been properly studied. The partitioning of nitrogen between N and N 2 controls the formation of more complex prebiotic nitrogen-containing species. Aims. The aim of this work is to gain a better understanding of the interstellar N 2 photodissociation processes based on recent detailed theoretical and experimental work and to provide accurate rates for use in chemical models. Methods. We used an approach similar to that adopted for CO in which we simulated the full high-resolution line-by-line absorption + dissociation spectrum of N 2 over the relevant 912-1000 Å wavelength range, by using a quantum-mechanical model which solves the coupled-channels Schrödinger equation. The simulated N 2 spectra were compared with the absorption spectra of H 2 , H, CO, and dust to compute photodissociation rates in various radiation fields and shielding functions. The effects of the new rates in interstellar cloud models were illustrated for diffuse and translucent clouds, a dense photon dominated region and a protoplanetary disk. Results. The unattenuated photodissociation rate in the Draine (1978, ApJS, 36, 595) radiation field assuming an N 2 excitation temperature of 50 K is 1.65 × 10 −10 s −1 , with an uncertainty of only 10%. Most of the photodissociation occurs through bands in the 957-980 Å range. The N 2 rate depends slightly on the temperature through the variation of predissociation probabilities with rotational quantum number for some bands. Shielding functions are provided for a range of H 2 and H column densities, with H 2 being much more effective than H in reducing the N 2 rate inside a cloud. Shielding by CO is not effective. The new rates are 28% lower than the previously recommended values. Nevertheless, diffuse cloud models still fail to reproduce the possible detection of interstellar N 2 except for unusually high densities and/or low incident UV radiation fields. The transition of N → N 2 occurs at nearly the same depth into a cloud as that of C + → C → CO. The orders-of-magnitude lower N 2 photodissociation rates in clouds exposed to black-body radiation fields of only 4000 K can qualitatively explain the lack of active nitrogen chemistry observed in the inner disks around cool stars. Conclusions. Accurate photodissociation rates for N 2 as a function of depth into a cloud are now available that can be applied to a wide variety of astrophysical environments.

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“…Nevertheless, it has not have been observed directly for a long time (neither in absorption nor emission). The first direct observation of molecular nitrogen in the interstellar media was achieved at far-ultraviolet absorption towards the HD 124314 star with the help of the Far Ultraviolet Spectroscopic Explorer (FUSE) (Knauth et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Laboratory spectroscopic studies of the collisions between slow H⁺, H₂⁺, H₃⁺ions and molecular nitrogen

Werbowy

Pranszke

2011

A&A

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Luminescence in the 275-470 nm spectral region was observed in the collisions of H + , H + 2 , and H + 3 with N 2 in the 10-1000 eV projectile energy range. For all the systems, a luminescent charge exchange leads to the electronically excited states of N + 2 (B 2 Σ u ) and N 2 (C 2 Π u , G 2 Δ g ). Computer simulation of the spectra was used to estimate relative cross sections for the reactions, as well as the temperatures corresponding to population distributions of vibrational and rotational levels of the products. The vibrational temperatures of the products for the H + 2 +N 2 and H + 3 +N 2 collision systems are found to be changing significantly with the projectile velocity, increasing from 1500 K at the lowest projectile velocities (≤50 km s −1 ) and going through a maximum (15 000 K) at about 80 km s −1 , to decrease rapidly with increasing velocity, down to 3000 K. The H + +N 2 collision system, however, does not show a similar increase in temperature. The increase in vibrational temperature indicates that, for velocities in the 50-1000 km s −1 range, the charge transfer process is the non-Franck-Condon type, a model that assumes a change in the internuclear distance of target molecule by the incident ion before electron capture occurs. This vibrational temperature dependency could be used to infer the ion velocity producing the observed emission of N + 2 . Also we found no evidence of any formation of excited NH molecules in these reactions.

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The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations

Cited by 111 publications

References 23 publications

Quantum astrochemical spectroscopy

Quantum astrochemical spectroscopy

Photodissociation of interstellar N₂

Laboratory spectroscopic studies of the collisions between slow H⁺, H₂⁺, H₃⁺ions and molecular nitrogen

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The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations

Cited by 111 publications

References 23 publications

Quantum astrochemical spectroscopy

Quantum astrochemical spectroscopy

Photodissociation of interstellar N2

Laboratory spectroscopic studies of the collisions between slow H+, H2+, H3+ions and molecular nitrogen

Contact Info

Product

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Photodissociation of interstellar N₂

Laboratory spectroscopic studies of the collisions between slow H⁺, H₂⁺, H₃⁺ions and molecular nitrogen