相关论文: HD molecules at high redshift: A low astration fac…

Observations of damped Ly-alpha absorbers (DLA) indicate that the fraction of hydrogen in its neutral form (HI) is significant by mass at all redshifts. This gas represents the reservoir of material that is available for star formation at…

Aims. We measure the deuterium fraction, RD, and the CO-depletion factor, fd, toward a number of starless and protostellar cores in the L1688 region of the Ophiuchus molecular cloud complex and search for variations based upon environmental…

We study the physical conditions in DLAs, using a sample of 33 systems toward 26 QSOs acquired for a recently completed survey of H_2 by Ledoux et al. (2003). We use the column densities of H_2 in different rotational levels, together with…

Theory predicts, and observations confirm, that the column density ratio of a molecule containing D to its counterpart containing H can be used as an evolutionary tracer in the low-mass star formation process. Since it remains unclear if…

The metallicity in portions of high-redshift galaxies has been successfully measured thanks to the gas observed in absorption in the spectra of quasars, in the Damped Lyman-alpha systems (DLAs). Surprisingly, the global mean metallicity…

Observations of star forming environments revealed that the abundances of some deuterated interstellar molecules are markedly larger than the cosmic D/H ratio of 10-5. Possible reasons for this pointed to grain surface chemistry. How- ever,…

We study the molecular gas content of 24 star-forming galaxies at $z=3-4$, with a median stellar mass of $10^{9.1}$ M$_{\odot}$, from the MUSE Hubble Ultra Deep Field (HUDF) Survey. Selected by their Lyman-alpha-emission and H-band…

High redshift DLA systems suggest that the relative abundances of elements might be roughly solar, although with absolute abundances of more than two orders of magnitude below solar. The result comes from observations of the [SII/ZnII]…

The standard interstellar ratio of deuterium to hydrogen (D/H) atoms is $\sim 1.5 \times 10^{-5}$. However, the deuterium fractionation is in fact found to be enhanced, to different degrees, in cold, dark cores, hot cores around massive…

We report a further analysis of the ratio of deuterium to hydrogen (D/H) using HST spectra of the z=0.701 Lyman limit system towards the QSO PG1718+481. Initial analyses of this absorber found it gave a high D/H value, 1.8 - 3.1 \times…

Observations of deuterium fractionation in the solar system, and in interstellar and circumstellar material, are commonly used to constrain the formation environment of volatiles. Toward protoplanetary disks, this approach has been limited…

Tracing molecular hydrogen content with carbon monoxide in low-metallicity galaxies has been exceedingly difficult. Here we present a new effort, with IRAM 30-m observations of 12CO(1-0) of a sample of 8 dwarf galaxies having oxygen…

Proximate molecular quasar absorbers (PH2) are an intriguing population of absorption systems recently uncovered through strong H2 absorption at small velocity separation from the background quasars. We performed a multi-wavelength…

We present a detailed analysis of three extremely strong intervening DLAs (log N(HI)>=21.7) observed towards quasars with VLT/UVES. We measure overall metallicities of [Zn/H]~-1.2, -1.3 and -0.7 at respectively zabs=2.34 towards SDSS…

We present the first high-resolution (6.2 to 7.7 km/s FWHM) spectra of the APM BR J0307-4945 quasar at z_em = 4.73 obtained with UVES on the 8.2m VLT Kueyen telescope. We focus our analysis on a damped Ly-alpha (DLA) system at z_abs = 4.466…

Deuterium-to-hydrogen (D/H) enrichments in molecular species provide clues about their original formation environment. The organic materials in primitive solar system bodies have generally higher D/H ratios and show greater D/H variation…

To interpret H_2 quasar absorption line observations in Damped Ly-alpha clouds (DLAs), we model the H_2 spatial distribution within a DLA. Based on numerical simulations of disk structures with parameters similar to those derived for such…

Deuterium fractionation is known to enhance the [DCO+]/[HCO+] abundance ratio over the D/H elemental ratio of about 1e-5 in the cold and dense gas typically found in pre-stellar cores. We report the first detection and mapping of very…

Deuteration of hydrocarbon material, including polycyclic aromatic hydrocarbons (PAHs), has been proposed to account for the low gas-phase abundances of D in the interstellar medium. JWST spectra of four star-forming regions in M51 show an…

The Lyman decrement associated with the cumulative effect of HI in QSO absorption systems along the line of sight provides a distinctive feature for identifying galaxies at z>2.5. The Hubble Deep Field (HDF) observations offer the…