Related papers: Detectability of neutral interstellar deuterium by…

Several years of neutral particle measurements by the NASA/IBEX mission have yielded direct observations of interstellar neutral helium and oxygen. The data indicate the presence of secondary neutral helium and oxygen, which are created…

We use high resolution spectra obtained with FUSE and STIS to obtain interstellar column densities of H I, D I, O I, S II, Fe II and P II toward the QSO HE 0226-4110 ( l = 253.4 deg , b = -65.77 deg). We obtain D/H = 21(+8, -6) ppm.…

This paper is one of three companion papers presenting the results of our in-depth analysis of the interstellar neutral helium (ISN He) observations carried out using the IBEX-Lo during the first six Interstellar Boundary Explorer (IBEX)…

Observations obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) have been used to determine the column densities of D I, O I, and N I along seven sight lines that probe the local interstellar medium (LISM) at distances from 37…

As the Galaxy evolves, the abundance of deuterium in the interstellar medium (ISM) decreases from its primordial value: deuterium is "astrated". The deuterium astration factor, f_D, the ratio of the primordial D abundance (the D to H ratio…

The IBEX-Lo instrument on the Interstellar Boundary Explorer (IBEX) mission measures interstellar neutral (ISN) helium atoms. The detection of helium atoms is made through negative hydrogen (H$^-$) ions sputtered by the helium atoms from…

To measure interstellar atomic deuterium abundances, we used the Interstellar Medium Absorption Profile Spectrograph (IMAPS) to obtain spectra of gamma2 Vel and zeta Pup over the wavelength interval 930-1150 A at a resolving power of…

In the early 1990s, contemporary interstellar dust penetrating deep into the heliosphere was identified with the in-situ dust detector on board the Ulysses spacecraft. Later on, interstellar dust was also identified in the data sets…

The Interstellar Boundary Explorer (IBEX) has been measuring fluxes of the Energetic Neutral Atoms (ENAs) using the IBEX-Hi (0.3 -- 6 keV) instrument since 2008. We have developed a numerical time-depended code to calculate globally…

Observations of deuterated species are useful in probing the temperature, ionization level, evolutionary stage, chemistry, and thermal history of astrophysical environments. The analysis of data from ALMA and other new telescopes requires…

Accurate measurements of interstellar deuterium abundances along lines of sight extending out to several hundred parsecs by FUSE and other instruments is making D/H a useful tool for understanding Galactic chemical evolution. We find that…

Interstellar neutral gas atoms penetrate the heliopause and reach 1~au, where they are detected by IBEX. The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in creation of…

Measurements of the upper atmosphere at ~100 km are important to investigate climate change, space weather forecasting, and the interaction between the Sun and the Earth. Atmospheric occultations of cosmic X-ray sources are an effective…

Because the ionization balances for HI, OI, and DI are locked together by charge exchange, D/O is an important tracer for the value of the D/H ratio and for potential spatial variations in the ratio. As the DI and OI column densities are of…

Observations show that the global deuterium-to-hydrogen ratio (D/H) in the local interstellar medium (ISM) is about 90% of the primordial ratio predicted by big bang nucleosynthesis. The high (D/H)$_{ISM}$ implies that only a small fraction…

Current measurements indicate that the deuterium abundance in diffuse interstellar gas varies spatially by a factor of ~4 among sightlines extending beyond the Local Bubble. One plausible explanation for the scatter is the variable…

We analyzed observations of interstellar neutral helium (ISN~He) obtained from the Interstellar Boundary Explorer (IBEX) satellite during its first six years of operation. We used a refined version of the ISN~He simulation model, presented…

The primordial abundance of deuterium (D/H) yields a measure of the density of baryons in the universe and is an important complement to determinations from cosmic microwave background (CMB) experiments. Indeed, the current small sample of…

While the abundance of elemental deuterium is relatively low (D/H ~ a few 1E-5), orders of magnitude higher D/H abundance ratios have been found for many interstellar molecules, enhanced by deuterium fractionation. In cold molecular clouds…

Hydrogen gas is the dominant component of the local interstellar medium. However, due to ionization and interaction with the heliosphere, direct sampling of neutral hydrogen in the inner heliosphere is more difficult than sampling the local…