相关论文: Nitrogen Fractionation in External Galaxies
The 18O/17O ratio of the Solar System is 5.2 while that of the interstellar medium (ISM) and young stellar objects is ~4. This difference cannot be explained by pollution of the Sun's natal molecular cloud by 18O-rich supernova ejecta…
We investigate the evolution of the metallicity of the intergalactic medium (IGM) with particular emphasis on its spatial distribution. We propose that metal enrichment occurs as a two step process. First, supernova (SN) explosions eject…
We interpret the peculiar super-solar nitrogen abundance recently reported by the James Webb Space Telescope observations for GN-z11 ($z=10.6$) using our state-of-the-art chemical evolution models. The observed CNO ratios can be…
Molecular nitrogen is one of the key species in the chemistry of interstellar clouds and protoplanetary disks and the partitioning of nitrogen between N and N2 controls the formation of more complex prebiotic nitrogen-containing species.…
The Central Molecular Zone (CMZ) contains most of the mass of our Galaxy but its star formation rate is one order of magnitude lower than in the Galactic disc. This is likely related to the fact that the bulk of the gas in the CMZ is in a…
Aims: We aim to understand the fragmentation as well as the disk formation, outflow generation and chemical processes during high-mass star formation on spatial scales of individual cores. Methods: Using the IRAM Northern Extended…
Understanding the nucleosynthetic origin of nitrogen and the evolution of the N/O ratio in the interstellar medium is crucial for a comprehensive picture of galaxy chemical evolution at high-redshift because most observational metallicity…
We conduct a statistical analysis of the factors responsible for the variation in the ionization parameter (U) of high-redshift star-forming galaxies based on medium resolution JWST/NIRSpec observations obtained by the Cosmic Evolution…
Clouds of high infrared extinction are promising sites of massive star/cluster formation. A large number of cloud cores discovered in recent years allows investigation of possible evolutionary sequence among cores in early phases. We have…
We employ analytical and numerical chemical evolution models to study observed trends in abundance ratios involving carbon, nitrogen, and oxygen. Several sets of published stellar yields for both intermediate-mass and massive stars are…
N$_2$ plays a profound role in supporting processes on the surface and in the atmosphere of Pluto, yet the origin of Pluto's N$_2$ remains a mystery. However, this may begin to change as the $^{14}$N/$^{15}$N ratio of N$_2$ was recently…
We discuss the evolution of oxygen, carbon and nitrogen in galaxies of different morphological type by adopting detailed chemical evolution models with different star formation histories (continuous star formation or starbursts). We start…
This brief review will discuss the current knowledge on the origin and evolution of the nitrogen atmospheres of the icy bodies in the solar system, particularly of Titan, Triton and Pluto. An important tool to analyse and understand the…
The chemical evolution of distant galaxies cannot be assessed from observations of individual stars, in contrast to the case of nearby galaxies. On the other hand, the study of the interstellar medium (ISM) offers an alternative way to…
Carbon isotope fractionation of CO has been reported in the disk around TW Hya,where elemental carbon is more abundant than elemental oxygen ([C/O]$_{\rm elem}$> 1). We investigated the effects of the [C/O]$_{\rm elem}$ ratio on carbon…
Measurements of the isotopic abundances in meteoritic amino acids have found enhancements of $^2$H/H, $^{15}$N/$^{14}$N, and $^{13}$C/$^{12}$C in the amino acids in the meteorites studied. We show that they are consistent with the…
We report the first detection of C$^{15}$N in diffuse molecular gas from a detailed examination of CN absorption lines in archival VLT/UVES spectra of stars probing local diffuse clouds. Absorption from the C$^{15}$N isotopologue is…
Many investigations of star formation rates (SFRs) in galaxies have explored details of dust obscuration, with a number of recent analyses suggesting that obscuration appears to increase in systems with high rates of star formation. To date…
New infrared absorption measurements of oxygen isotope ratios in CO gas from individual young stellar objects confirm that the solar system is anomalously high in its 18O/17O ratio compared with extra-solar oxygen in the Galaxy. We show…
We present 33\,GHz photometry of 103 galaxy nuclei and extranuclear star-forming complexes taken with the Green Bank Telescope (GBT) as part of the Star Formation in Radio Survey (SFRS). Among the sources without evidence for an AGN, and…