Untitled

Sonneborn, G. H.; Jenkins, Edward B.; Tripp, Todd M.; Wozniak, P.; Vidal‐Madjar, A.; Ferlet, R.; Sofia, U. J.

doi:10.1023/a:1002108723340

Cited by 34 publications

(56 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While high values of D/H (above 2 Â 10 À5 ) have been reported toward two distant targets, namely, 2 Vel (Sonneborn et al 2000) and Feige 110 (Friedman et al 2002), five low values of D/H (below 1 Â 10 À5 ) were also previously reported toward distant targets with Copernicus, IMAPS, or FUSE: Ori A (Laurent, Vidal-Madjar, Jenkins et al 1999), Sco (York 1983), h Car (Allen, Jenkins, &Snow 1992), andHD 191877 andHD 195965 (Hoopes et al 2003). Values of D/H below 1 Â 10 À5 were also measured in two Orion regions through ISO observation of HD (Bertoldi et al 1999;Wright et al 1999).…”

Section: Evidence For a Low Present-epoch D/hmentioning

confidence: 96%

The Deuterium‐to‐Oxygen Ratio in the Interstellar Medium

Hébrard¹,

Moos²

2003

ApJ

View full text Add to dashboard Cite

Because the ionization balances for H i, O i, and D i are locked together by charge exchange, the deuterium-to-oxygen ratio, D/O, is an important tracer for the value of the D/H ratio and for potential spatial variations in the ratio. As the D i and O i column densities are of similar orders of magnitude for a given sight line, comparisons of the two values will generally be less subject to systematic errors than comparisons of D i and H i, which differ by about 5 orders of magnitude. Moreover, D/O is additionally sensitive to astration, because as stars destroy deuterium, they should produce oxygen. We report here the results of a survey of D/O in the interstellar medium performed with the Far Ultraviolet Spectroscopic Explorer. We also compare these results with those for D/N. Together with a few results from previous missions, the sample totals 24 lines of sight. The distances range from a few to $2000 pc and log N(D i) from $13 to $16 cm À2 . The D/O ratio is constant in the local interstellar medium out to distances of $150 pc and NðD iÞ ' 1 Â 10 15 cm À2 , i.e., within the Local Bubble. In this region of the interstellar space, we find D=O ¼ ð3:84 AE 0:16Þ Â 10 À2 (1 in the mean). The homogeneity of the local D/O measurements shows that the spatial variations in the local D/H and O/H must be extremely few, if any. A comparison of the Local Bubble mean value with the few D/O measurements available for low-metallicity quasar sight lines shows that the D/O ratio decreases with cosmic evolution, as expected. Beyond the Local Bubble, we detected significant spatial variations in the value of D/O. This likely implies a variation in D/H, as O/H is known to not vary significantly over the distances covered in this study. Our data set suggests a present-epoch deuterium abundance below 1 Â 10 À5 , i.e., lower than the value usually assumed, around 1:5 Â 10 À5 .

show abstract

Section: Evidence For a Low Present-epoch D/hmentioning

confidence: 96%

The Deuterium‐to‐Oxygen Ratio in the Interstellar Medium

Hébrard¹,

Moos²

2003

ApJ

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 73%

“…CH2DOH observed by Parise et al 2002; NH2D observed by Saito et al 2000 andHatchell 2003). These are remarkable results, given that the underlying abundance of deuterium in the local interstellar medium (ISM) is ∼10 −5 times lower than that of hydrogen (Linsky 1998;Sonneborn et al 2000).Such large enhancements in the abundances of deuterium-bearing molecules can either be due to gas-phase or to grain-surface fractionation. Grain-surface reactions are undoubtedly important in producing saturated species such as methanol, water, ammonia, and hydrogen sulphide.…”

mentioning

confidence: 77%

Modelling of Deuterium Chemistry in Star-Forming Regions

Roberts¹

2006

IAU

View full text Add to dashboard Cite

Several new multiply deuterated species have been detected over the past three years, including ND3 (van der Lis et al. 2002), CHD2OH, CD3OH (Parise et al. 2002, D2S (Vastel et al. 2003), HD + 2 (Vastel et al. 2004) and D2CS (Marcelino et al. 2005). In addition, mono-deuterated species have been observed with abundances >10% of their undeuterated analogues (e.g. CH2DOH observed by Parise et al. 2002; NH2D observed by Saito et al. 2000 andHatchell 2003). These are remarkable results, given that the underlying abundance of deuterium in the local interstellar medium (ISM) is ∼10 −5 times lower than that of hydrogen (Linsky 1998;Sonneborn et al. 2000).Such large enhancements in the abundances of deuterium-bearing molecules can either be due to gas-phase or to grain-surface fractionation. Grain-surface reactions are undoubtedly important in producing saturated species such as methanol, water, ammonia, and hydrogen sulphide. Water ice is observed to be abundant and ubiquitous throughout the ISM, and enhanced abundances of gas-phase NH 3, CH3OH, H2CO and H2S (among others) are observed in warmer regions around protostars where grain mantles have evaporated.Recent observational and theoretical evidence suggests that the deuterium fractionation in star-forming regions is set by gas-phase and grain-surface reactions during the cold, dense preprotostellar phase. For species which form on grain surfaces via H atom addition to CO, N, O and S, the deuterium fractionation on grains comes from the relative amounts of atomic D and H which are accreting from the gas. The observations of deuterated methanol and D2S require that the gas-phase atomic D/H ratio at the time the molecules formed was 0.1. This paper presents results from chemical models of the prestellar core phase of star formation, showing how this high atomic D/H ratio can be produced, and discusses how models can also be used to look at deuterium fractionation in the protostellar stages of star formation.

show abstract

“…To measure the total interstellar H i column density, we used the method of Jenkins (1971; see also Jenkins et al 1999 andSonneborn et al 2000). In brief, we constrained the H i column density using the Lorentzian wings of the Ly profile, which have optical depth at wavelength k given by (k) ¼ N (H i)(k) ¼ 4:26 ; 10 À20 N (H i)(k À k 0 ) À2 .…”

Section: Analysis Methodsmentioning

confidence: 99%

“…Precise measurements of D/ H in the local interstellar medium ( ISM ) were first made using Copernicus ( Rogerson & York 1973), the Hubble Space Telescope (HST; Linsky et al 1995), and IMAPS (Interstellar Medium Absorption Profile Spectrograph; Jenkins et al 1999;Sonneborn et al 2000). In the last several years many additional measurements of D/ H, D/O, D/ N, and related species, have been made using FUSE (Moos et al 2002;Wood et al 2004).…”

Section: Introductionmentioning

confidence: 99%

The Deuterium, Oxygen, and Nitrogen Abundance toward LSE 44

Friedman

Hébrard

Tripp

et al. 2006

ApJ

View full text Add to dashboard Cite

We present measurements of the column densities of interstellar D i, O i, N i, and H 2 made with the Far Ultraviolet Spectroscopic Explorer (FUSE ) and of H i made with the International Ultraviolet Explorer (IUE ) toward the sdO star LSE 44 [(l;. This target is among the seven most distant Galactic sight lines for which these abundance ratios have been measured. The H i column density was estimated by fitting the damping wings of interstellar Ly. The column densities of the remaining species were determined with profile fitting analyses and supplemented with curve-of-growth analyses for O i and H 2 . We find log N (D i) ¼ 15:87 AE 0:08, log N (O i) ¼

show abstract

Untitled

Cited by 34 publications

References 0 publications

The Deuterium‐to‐Oxygen Ratio in the Interstellar Medium

The Deuterium‐to‐Oxygen Ratio in the Interstellar Medium

Modelling of Deuterium Chemistry in Star-Forming Regions

The Deuterium, Oxygen, and Nitrogen Abundance toward LSE 44

Contact Info

Product

Resources

About