Results 111 to 120 of about 52,001 (350)

Helium Abundance at the Galactic Center

The Astrophysical Journal, 1974
We suggest that the low abundance of ionized helium in H II regions at the galactic center can be explained by selective absorption of helium-ionizing photons by dust within the ionized gas. This model requires an extrapolation to 500 A of the rapid increase of the extinction measured between 1500 A and 1000 A with the Copernicus satellite, and it ...
M. Jura, E. L. Wright
openaire   +1 more source

Understanding Degradation Mechanisms in Water‐In‐Salt Electrolyte. Part 2: Impact of the Electrochemical Parameters on the Cycling Behavior of LiFePO4 versus TiS2

Batteries &Supercaps, EarlyView.
Cycling water‐in‐salt batteries involves complex degradation processes that require multiprobe analysis. Using online electrochemical mass spectrometry (OEMS), postmortem X‐ray photoemission spectroscopy (XPS) (including hard‐XPS), and scanning electron microscopy (SEM), the degradation mechanisms are examined in composite electrodes (TiS2 and LiFePO4)
Célia Doublet, Théo Faverge, Vincent Martin, Hiram Castillo Michel, Jean‐Pascal Rueff, Marian Chatenet, Lauréline Lecarme, Claire Villevieille   +7 more
wiley   +1 more source

Theoretical Diagnostics for Narrow-line Regions of Active Galactic Nuclei

The Astrophysical Journal
Gas metallicity, ionization parameter, and gas pressure can affect the observed ratios of specific strong emission lines within galaxies. While the theoretical strong lines diagnostics for gas metallicity, ionization parameters, and gas pressure in star ...
Peixin Zhu, Lisa J. Kewley, Ralph S. Sutherland   +2 more
doaj   +1 more source

Early evolutionary history of the seed

Biological Reviews, EarlyView.
ABSTRACT The seed is an essential stage in the life history of gymnospermous and angiospermous plants, facilitating both their survival and dispersal. We reappraise knowledge of the evolutionary history of the gymnospermous seed, from its origin in the late Devonian through to the well‐known end‐Permian extinctions – an interval encompassing the ...
Richard M. Bateman, Alan R. T. Spencer, Jason Hilton   +2 more
wiley   +1 more source

Dual‐Mode Thio‐MacMillan Organocatalysts: Stereoselective Diels–Alder Reactions or Sacrificial Self‐Cyclization to N‐Bridged Bicyclic Lactams

Chemistry – A European Journal, EarlyView.
The study of the Diels–Alder reaction of cinnamaldehyde and cyclopentadiene, catalyzed by chiral imidazolidine‐4‐thiones, led to the discovery of a highly regio‐ and stereoselective Michael‐addition and consecutive ring closure. Here, the imidazolidine‐4‐thione not only catalytically activates cinnamaldehyde but also participates as the nucleophile to ...
Marian S. R. Ebeling, Luca V. Parziale, Marc Sachsenhauser, Christoph J. B. Seifert, Nathalie J. Kurrle, Oliver Trapp   +5 more
wiley   +1 more source

Chemical Abundances of M and G Dwarfs in the Hyades and Coma Berenices Open Clusters from APOGEE Spectra

The Astrophysical Journal
Open clusters are one of the best astrophysical laboratories we have available for stellar astrophysics studies. This work presents metallicities and individual abundances for 14 M dwarfs and six G dwarfs from two well-known open clusters: Hyades and ...
Deusalete Vilar, Diogo Souto, Katia Cunha, Anderson Andrade-Silva, Verónica Loaiza-Tacuri, Fábio Wanderley, Verne V. Smith, Vinicius Grilo, Cintia F. Martinez, Bárbara Rojas-Ayala, Zachary Way   +10 more
doaj   +1 more source

The Gaia-ESO survey: Open clusters as tracers of galactic chemical evolution

Astronomy & Astrophysics
Aims. We investigate the formation and evolutionary trajectory of the Milky Way’s inner and outer galactic regions using stars from open clusters in the Gaia-ESO OC survey. Methods. Using numerical simulations from Chempy, we leveraged Markov chain Monte
Boucher K., Worley C. C., Gilmore G., Stonkutė E., Magrini L., Drazdauskas A., Bragaglia A., Tautvaišienè G., Bensby T., Jiménez-Esteban F., Martell S., Randich S., Damiani F.   +12 more
doaj   +1 more source

Is the Sun Embedded in a Typical Interstellar Cloud?

, 2008
The physical properties and kinematics of the partially ionized interstellar material near the Sun are typical of warm diffuse clouds in the solar vicinity.
A. Czechowski, A.C. Cummings, A.C. Cummings, B. Flynn, B.D. Savage, B.E. Wood, B.E. Wood, C. Heiles, C.S. Bowyer, C.S. Weller, D.E. Welty, E. Gruen, E. Möbius, E. Salerno, E.B. Jenkins, J. Tinbergen, J. Vallerga, J.D. Slavin, J.L. Han, J.L. Linsky, J.M. Ajello, J.P. Simpson, K. Cheng, L.A. Marschall, L.M. Haffner, L.M. Haffner, M. MacLow, M. Witte, M. Wolleben, N. Lehner, N.V. Pogorelov, P. Frisch, P. Routly Jr., P.B. Lucke, P.C. Frisch, P.C. Frisch, P.C. Frisch, P.C. Frisch, P.C. Frisch, P.C. Frisch, P.M. Gondhalekar, Priscilla C. Frisch, R. Crutcher, R. Lallement, R. Lallement, R. Ratkiewicz, R. Shetty, R.J. Rand, R.J. Reynolds, R.J. Reynolds, S. Redfield, S. Redfield, S. Redfield, S.M. Kahn, T.F. Adams, T.J. Linde, V. Piirola, V.V. Izmodenov   +57 more
core   +1 more source

Phosphorus Enrichment by ONe Novae in the Galaxy

The Astrophysical Journal Letters
Recent observations have shown that [P/Fe] in the Galactic stars decreases with increasing [Fe/H] for [Fe/H] ≳ − 1 whereas it is almost subsolar for [Fe/H] ≲ −2. These [P/Fe] trends with [Fe/H] have not been well reproduced by previous theoretical models
Kenji Bekki, Takuji Tsujimoto
doaj   +1 more source

STRONTIUM ABUNDANCES IN COOL DWARF STARS OF GALACTIC THIN AND THICK DISKS

Odessa Astronomical Publications, 2016
We revise the strontium abundances in FGK stars with metallicities ranging from −1.0 < [Fe/H] < +0.3. The observed stars belong to the substructures of the Galaxy thick and thin discs.
T. I. Gorbaneva, T. V. Mishenina
doaj   +1 more source