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

  title={The interstellar N2 abundance towards HD 124314 from far-ultraviolet observations},
  author={D. C. Knauth and B.-G. Andersson and Stephan R. McCandliss and H. Warren Moos},
The abundance of interstellar molecular nitrogen (N2) is of considerable importance: models of steady-state gas-phase interstellar chemistry, together with millimetre-wavelength observations of interstellar N2H+ in dense molecular clouds predict that N2 should be the most abundant nitrogen-bearing molecule in the interstellar medium. Previous attempts to detect N2 absorption in the far-ultraviolet or infrared (ice features) have hitherto been unsuccessful. Here we report the detection of… 

A low fraction of nitrogen in molecular form in a dark cloud

It is found that only a small fraction of nitrogen in the gas phase is molecular, with most of it being atomic, which explains the low N2 abundance in comets.

Submillimeter and Far-infrared Spectroscopy of Monodeuterated Amidogen Radical (NHD): Improved Rest Frequencies for Astrophysical Observations

Observations of ammonia in interstellar environments have revealed high levels of deuteration, and all its D-containing variants, including ND3, have been detected in cold prestellar cores and around

Photodissociation and chemistry of N2 in the circumstellar envelope of carbon-rich AGB stars

Context. The envelopes of asymptotic giant branch (AGB) stars are irradiated externally by ultraviolet photons; hence, the chemistry is sensitive to the photodissociation of N2 and CO, which are

Nitrogen hydrides in interstellar gas II. Analysis of Herschel/HIFI observations towards W49N and G10.6-0.4 (W31C)

As a part of the Herschel key programme PRISMAS, we have used the Herschel-HIFI instrument to observe interstellar nitrogen hydrides along the sight-lines towards eight high-mass star-forming regions

Vacuum ultraviolet photoabsorption spectroscopy of space-related ices: 1 keV electron irradiation of nitrogen- and oxygen-rich ices

Context. Molecular oxygen, nitrogen, and ozone have been detected on some satellites of Saturn and Jupiter, as well as on comets. They are also expected to be present in ice-grain mantles within

On the chemistry of hydrides of N atoms and O$^+$ ions

Previous work by various authors has suggested that the detection by Herschel/HIFI of nitrogen hydrides along the low-density lines of sight toward G10.6-0.4 (W31C) cannot be accounted for by


In this paper, we present the results of an observational search for gas phase urea [(NH2)2CO] observed toward the Sgr B2(N-LMH) region. We show data covering urea transitions from ∼100 GHz to 250

2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules

  • B. McGuire
  • Physics, Geology
    The Astrophysical Journal Supplement Series
  • 2022
To date, 241 individual molecular species, composed of 19 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. These molecules range in

Depletion of heavy nitrogen in the cold gas of star-forming regions

We investigate nitrogen-isotope fractionation in forming and evolving molecular clouds using gas-ice astrochemical simulations. We find that the bulk gas can become depleted in heavy nitrogen (15N)

Tracing the atomic nitrogen abundance in star-forming regions with ammonia deuteration

Partitioning of elemental nitrogen in star-forming regions is not well constrained. Most nitrogen is expected to be partitioned among atomic nitrogen (N I), molecular nitrogen (N 2 ), and icy



The Abundances of Solid N2 and Gaseous CO2 in Interstellar Dense Molecular Clouds

We present 2338-2322 cm-1 (4.277-4.307 μm) infrared spectra of a number of N2-containing mixed molecular ices and demonstrate that the strength of the infrared "forbidden" band due to the N≡N stretch

Potential Variations in the Interstellar N I Abundance

We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph observations of the weak interstellar N I λ1160 doublet toward 17 high-density sight lines [N(Htot) ≥

A survey of interstellar H I from L-alpha absorption measurements. II

The Copernicus satellite surveyed the spectral region near L alpha to obtain column densities of interstellar HI toward 100 stars. The distance to 10 stars exceeds 2 kpc and 34 stars lie beyond 1

On the Origin of the High-Ionization Intermediate-Velocity Gas toward HD 14434

We present Far-Ultraviolet Spectroscopic Explorer and Space Telescope Imaging Spectrograph observations of high-ionization interstellar absorption toward HD 14434 (l = 135.°1, b = -3.°8; d ~ 2.3

A survey of N2H+ in dense clouds: Implications for interstellar nitrogen and ion-molecule chemistry

Spectra of the N 2 H + J=1→0, J=3→2 and 15 NNH + and N 15 NH + J=1→0 rotational transitions have been obtained toward a sample of star-forming and cold dark clouds in the Galaxy. Toward the

The photodissociation and chemistry of interstellar CO

Recent work on the vacuum UV absorption spectrum of CO to the description of the photodissociation of interstellar CO and its principal isotopic varieties is discussed. The effects of line

H~3^+ and other species in the diffuse cloud towards Persei: A new detailed model

McCall et al. have recently shown that a large column density for the molecular ion H + 3 of 8 × 10 13 cm -2 exists in the classical diffuse cloud towards ζ Persei. They have used this observation to

Gas-phase chemistry in dense interstellar clouds including grain surface molecular depletion and desorption

We present time-dependent models of the chemical evolution of molecular clouds which include depletion of atoms and molecules onto grain surfaces and desorption, as well as gas-phase interactions. We

FUSE Measurements of Rydberg Bands of Interstellar CO between 925 and 1150 Å

We report the detection of 11 Rydberg bands of CO in FUSE spectra of the sight line toward HD 203374A. Eight of these electronic bands are seen in the interstellar medium for the first time. Our

Self-shielding in the solar nebula

Self-shielding in the solar nebula Variations in the abundance of isotopes of elements in primitive meteorites carry the record of chemical and nuclear processes that occurred during the formation of