ﻻ يوجد ملخص باللغة العربية
We present new measurements of the interstellar gas-phase oxygen abundance along the sight lines towards 19 early-type galactic stars at an average distance of 2.6 kpc. We derive O {small I} column densities from {it HST}/STIS observations of the weak 1355 AA intersystem transition. We derive total hydrogen column densities [N(H {small I})+2N(H$_2$)] using {it HST}/STIS observations of lya and {it FUSE} observations of molecular hydrogen. The molecular hydrogen content of these sight lines ranges from f(H$_2$) = 2N(H$_2$)/[N(H {small I})+2N(H$_2$)] = 0.03 to 0.47. The average $<H_{tot}/E_{B-V}>$ of 6.3$times10^{21}$ cm$^{-2}$ mag$^{-1}$ with a standard deviation of 15% is consistent with previous surveys. The mean oxygen abundance along these sight lines, which probe a wide range of galactic environments in the distant ISM, is 10$^6$ oh = $408 pm 13$ (1 $sigma$ in the mean). %$({rm O/H})_{gas} = 408 pm 14$(1 $sigma$). We see no evidence for decreasing gas-phase oxygen abundance with increasing molecular hydrogen fraction and the relative constancy of oh suggests that the component of dust containing the oxygen is not readily destroyed. We estimate that, if 60% of the dust grains are resilient against destruction by shocks, the distant interstellar total oxygen abundance can be reconciliated with the solar value derived from the most recent measurements %by Holweger and by Allende Prieto, Lambert & Asplund: of 10$^6$ oh$_odot$ = 517 $pm$ 58 (1 $sigma$). We note that the smaller oxygen abundances derived for the interstellar gas within 500 pc %by Meyer, Cardelli & Jura or from nearby B star surveys are consistent with a local elemental deficit.
The azimuthal variation of the HII region oxygen abundance in spiral galaxies is a key observable for understanding how quickly oxygen produced by massive stars can be dispersed within the surrounding interstellar medium. Observational constraints on
Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New atomic models of O and Ni are used to perform Non-Local Thermodynamic Equilibrium (NLTE) calculations w
Oxygen is the third most abundant element in the universe, but its chemistry in the interstellar medium is still not well understood. In order to critically examine the entire oxygen budget, we attempt here initially to estimate the abundance of atom
We construct maps of the oxygen abundance distribution across the disks of 88 galaxies using CALIFA data release 2 (DR2) spectra. The position of the center of a galaxy (coordinates on the plate) were also taken from the CALIFA DR2. The galaxy inclin
We have derived oxygen abundances for 8 galaxies from the Survey of HI in Extremely Low-mass Dwarfs (SHIELD). The SHIELD survey is an ongoing study of very low-mass galaxies, with M$_{rm HI}$ between 10$^{6.5}$ and 10$^{7.5}$ M$_{odot}$, that were de