Results 81 to 90 of about 1,388 (238)
The formation of molecular hydrogen in the interstellar medium
, 2010 H2 is the most abundant molecule in the interstellar medium and forms on the surface of interstellar dust grains. Laboratory studies have been conducted of HD formation on a dust grain analogue, which is a highly-oriented pyrolytic graphite surface ...
Islam, F.
core
The Composition of Interstellar Molecular Clouds
, 1999 The published version is located at http://www.springerlink.com/content/r8t24w827755585q/We consider four aspects of interstellar chemistry for comparison with comets: molecular abundances in general, relative abundances of isomers (specifically, HCN and
Irvine, William M., William M. Irvine
core +1 more source
Production of atomic hydrogen by cosmic rays in dark clouds [PDF]
, 2018 Context. Small amounts of atomic hydrogen, detected as absorption dips in the 21 cm line spectrum, are a well-known characteristic of dark clouds. The abundance of hydrogen atoms measured in the densest regions of molecular clouds can only be explained ...
Caselli, P. +14 more
core +1 more source
Overtone Transition 2ν1 of HCO+ and HOC+: Origin, Radiative Lifetime, Collisional Quenching
ChemPhysChem, Volume 25, Issue 21, November 4, 2024.The C−H/O−H stretch vibration overtone of one of the simplest molecular ion isomeric systems HCO+/HOC+ is studied in a cryogenic ion trap experiment. Moreover, our comprehensive “zero background” method enables the determination of radiative lifetimes and select quenching reaction rates at the same time.
Miguel Jiménez‐Redondo +5 more
wiley +1 more source
A study of X-ray point sources in Heiles Clouds 1 and 2
Acta PolytechnicaStar formation takes place in the coldest parts of molecular clouds, beginning in the densest, collapsing regions of filaments. As pre-main sequence stars are luminous X-ray emitters, X-ray point sources can serve as effective tracers of YSOs.
Nóra Varga +2 more
doaj +1 more source
Natural Sciences, Volume 4, Issue 4, October 2024.Large free aromatic species, with up to 61 carbon atoms, were detected in grains of the Ryugu carbonaceous asteroid using ultra‐sensitive two‐step laser mass spectrometry. This discovery confirms the presence of large polycyclic aromatic hydrocarbons in the interstellar medium and provides new information on the formation and evolution of organic ...
Hassan Sabbah +3 more
wiley +1 more source
Isolated Black Holes as Potential PeVatrons and Ultrahigh-energy Gamma-Ray Sources
The Astrophysical Journal LettersThe origin of PeV cosmic rays (CRs) is a long-standing mystery, and ultrahigh-energy gamma-ray observations would play a crucial role in identifying it. Recently, LHAASO reported the discovery of “dark” gamma-ray sources that were detected above 100 TeV ...
Shigeo S. Kimura +4 more
doaj +1 more source
Novel algorithms for the understanding of the chemical cosmos
, 2015 Molecular data from the interstellar medium (ISM) contain information that holds the key to understanding our chemically controlled cosmos and to unlocking the secrets of our universe.
Makrymallis, A
core
Optical interstellar lines in dark clouds. II. K i and ultraviolet sodium lines [PDF]
, 1974 New observations of the K i and ultraviolet Na i interstellar lines are presented for some stars embedded in dense clouds and for a few supergiants. The new observations of weak lines, which are essentially unaffected by the adopted velocity distribution
Cohen, Judith G.
core
Meteoritics &Planetary Science, Volume 59, Issue 10, Page 2831-2850, October 2024.Abstract Samples of B‐type asteroid (101955) Bennu returned by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) spacecraft will provide unique insight into the nature of carbonaceous asteroidal matter without the atmospheric entry heating or terrestrial weathering effects associated with ...
A. N. Nguyen +7 more
wiley +1 more source