Results 21 to 30 of about 601,537 (357)
The Evolution of Massive Helium Stars, Including Mass Loss [PDF]
Astrophysical Journal, 2019 The evolution of helium stars with initial masses in the range 1.6–120 is studied, including the effects of mass loss by winds. These stars are assumed to form in binary systems when their expanding hydrogenic envelopes are promptly lost just after ...
S. Woosley
semanticscholar +1 more source
Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions [PDF]
, 2001 New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features.
Randall K. Smith +3 more
semanticscholar +1 more source
Astrophysical detection of the helium hydride ion HeH+ [PDF]
Nature, 2019 During the dawn of chemistry1,2, when the temperature of the young Universe had fallen below some 4,000 kelvin, the ions of the light elements produced in Big Bang nucleosynthesis recombined in reverse order of their ionization potential.
R. Güsten +9 more
semanticscholar +1 more source
Helium in the Atmosphere [PDF]
Nature, 1898 THE discovery of helium lines in the spectrum of neon, by Mr. E. C. C. Baly, will necessitate a modification of the views we have expressed in our communication to the British Association at Bristol. We there estimated the density of neon at 9.6, allowing for the presence of a certain proportion of argon unavoidably left in the neon.
Ramsay, William, Travers, Morris W.
+10 more sources
Neonatal Applications of Heliox: A Practical Review
Frontiers in Pediatrics, 2022 Heliox is a mixture of helium and oxygen that may be utilized as an alternative to air-oxygen during the ventilatory support in the neonate. Special physical properties of Heliox, particularly low density, allow for improved gas flow and diffusion. First
Tomasz Szczapa +2 more
doaj +1 more source
Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b [PDF]
Science, 2018 Helium escaping from hot gas giants Many gas giant exoplanets orbit so close to their host star that they are heated to high temperatures, causing atmospheric gases to escape.
L. Nortmann +27 more
semanticscholar +1 more source
The European Physical Journal D, 2013 Using a configuration-interaction variational method, we accurately compute the reduced, single-electron von Neumann entropy for several low-energy, singlet and triplet eigenstates of helium atom. We estimate the amount of electron-electron orbital entanglement for such eigenstates and show that it decays with energy.
Giuliano Benenti +3 more
openaire +5 more sources
Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet [PDF]
Science, 2018 Helium escaping from hot gas giants Many gas giant exoplanets orbit so close to their host star that they are heated to high temperatures, causing atmospheric gases to escape.
R. Allart +12 more
semanticscholar +1 more source
Post-merger evolution of double helium white dwarfs and distribution of helium-rich hot subdwarfs [PDF]
, 2021 The mergers of double helium white dwarfs are believed to form isolated helium-rich hot subdwarfs. Observation shows that the helium-rich hot subdwarfs can be divided into two subgroups based on whether the surface is carbon-rich or carbon-normal. But it is not clear whether this distribution directly comes from binary evolution.
arxiv +1 more source
The ionization of helium by neutral helium atoms [PDF]
Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1946 A method is described for investigating the ionization produced in helium by collisions between quasi-stationary atoms—that is, atoms possessing only therm al velocities—and a beam of neutral helium atoms with kinetic energy less than 100 eV. Ionization is shown to begin when the kinetic energy of the bombarding atoms is twice as great as the minimum ...
Frank Horton, Dorothy M. Millest
openaire +3 more sources