Related papers: Systematic Theoretical Study on the Interstellar C…
The physical conditions of the earliest environment of high-mass star formation are currently poorly understood. To that end, we present observations of the carbon chain molecules HC$_5$N , CCS, and HC$_7$N in the 22-25 GHz band towards 12…
The study of the physical and chemical properties of gas infall motion in the molecular clumps helps us understand the initial stages of star formation. We used the FTS wide-sideband mode of the IRAM 30-m telescope to observe nine infall…
Chemical abundances in the X-ray halos (also known as the intracluster medium, ICM) of clusters and groups of galaxies can be measured via prominent emission line features in their X-ray spectra. Elemental abundances are footprints of…
The determination of chemical abundances constitutes a fundamental requirement for obtaining a complete picture of a star. Particularly in massive stars, CNO abundances are of prime interest, due to the nuclear CNO-cycle and various mixing…
The increasing number of observations towards different environments in the Milky Way, as well as theoretical and experimental works, are improving our knowledge of the astrochemical processes in the interstellar medium (ISM). In this…
(Abridged) The Central Molecular Zone (CMZ) of the Milky Way exhibits extreme conditions, including high gas densities, elevated temperatures, enhanced cosmic-ray ionization rates, and large-scale dynamics. Large-scale molecular surveys…
A non-LTE analysis of C I lines at 1.068-1.069 micron was carried out for selected 46 halo/disk stars covering a wide metallicity range (-3.7 <[Fe/H]< +0.3), based on the spectral data collected with IRCS+AO188 of the Subaru Telescope, in…
Our main purpose is to estimate the effect of assuming uniform density on the line-of-sight in PDR chemistry models, compared to a more realistic distribution for which total gas densities may well vary by several orders of magnitude. A…
Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the…
We present ISO LWS observations of the proto-planetary nebula CRL 618, a star evolving very fast to the planetary nebula stage. In addition to the lines of 12CO, 13CO, HCN and HNC, we report on the detection of H2O and OH emission together…
In this paper we study the oxygen chemistry in the C-rich circumstellar shells of IRC+10216. The recent discoveries of oxygen bearing species (water, hydroxyl radical and formaldehyde) toward this source challenge our current understanding…
We report the first detection in the interstellar medium of $N$-cyanomethanimine (H$_2$CNCN), the stable dimer of HCN of highest energy, and the most complex organic molecule identified in space containing the prebiotically relevant NCN…
As building blocks of dust, rocky planets, and even complex life, the chemical elements heavier than hydrogen (H) and helium (He) - called "metals" in astronomy - play an essential role in our Universe and its evolution. Up to Fe and Ni,…
There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…
The chemical inventory of planets is determined by the physical and chemical processes that govern the early phases of star formation. The aim is to investigate N-bearing complex organic molecules towards two Class 0 protostars (B1-c and…
Based on the spectrum fitting method applied to CI 5380, NI 7486, and OI 6156-8 lines, we determined the abundances of C, N, and O for 100 mostly A-type main-sequence stars (late B through early F at 11000K>Teff>7000K) comprising normal…
We present a study of the abundances and physical conditions in the interstellar gas toward the heavily reddened star HD 192639 [E_(B-V) = 0.64], based on analysis of FUSE and HST/STIS spectra covering the range from 912 to 1361 A. This…
Icy interstellar dust grains are a source of complex organic molecule (COM) production, although their formation mechanisms are debated. Laboratory experiments show that atomic C deposited onto interstellar ice analogs can react with…
Bipolar outflows constitute some of the best laboratories to study shock chemistry in the interstellar medium. A number of molecular species have their abundance enhanced by several orders of magnitude in the outflow gas, likely as a…
Although carbon is, together with oxygen and nitrogen, one of the most important elements in the study of galactic chemical evolution its production sites are still poorly known and have been much debated (see e.g. Gustafsson et al. 1999;…