Results 41 to 50 of about 200,990 (159)

Nucleosynthesis Predictions and High-Precision Deuterium Measurements

Universe, 2017
Two new high-precision measurements of the deuterium abundance from absorbers along the line of sight to the quasar PKS1937–1009 were presented. The absorbers have lower neutral hydrogen column densities (N(HI) ≈ 18 cm − 2 ) than for previous ...
Signe Riemer-Sørensen, Espen Sem Jenssen   +1 more
doaj   +1 more source

Chemical abundances of LINER galaxies – nitrogen abundance estimations

Monthly Notices of the Royal Astronomical Society
ABSTRACT In this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3600 – 10 000 Å) of 40 LINERs from the Mapping Nearby Galaxies (MaNGAs) survey were considered.
C B Oliveira, Â. C. Krabbe, O. L. Dors, I. A. Zinchenko, J. A. Hernández-Jiménez, M. V. Cardaci, G. F. Hägele, Gabriele S Ilha   +7 more
openaire   +3 more sources

The solar wind heavy ion composition in the ascending phases of the solar cycles 23 and 25

Frontiers in Astronomy and Space Sciences
The approximately 11-year solar cycle has been shown to impact the heavy ion composition of the solar wind, even when accounting for streams of differing speeds; however, the heavy ion composition observed between the same specific phases of a past solar
D. T. Carpenter, S. T. Lepri, L. Zhao, R. M. Dewey, J. M. Raines, S. Livi, S. Livi, A. B. Galvin, L. M. Kistler   +8 more
doaj   +1 more source

High-Resolution Spectroscopy of Cool Carbon-Rich and Metal-Poor Star HD 209621

Open Astronomy, 2012
Element abundances for HD 209621 obtained earlier display significant discrepancies, especially in the case of CNO and neutron-capture elements. Therefore we performed a detailed analysis of chemical composition of this star using a new high-resolution ...
Matrozis E., Začs L., Barzdis A.
doaj   +1 more source

Viruses in aquatic ecosystems: important advancements of the last 20 years and prospects for the future in the field of microbial oceanography and limnology

Advances in Oceanography and Limnology, 2010
Over the last two decades, viruses in aquatic systems have been observed to modify, influence and control aquatic systems. Since the determination decades ago that viruses were abundant in aquatic ecosystems, researchers have demonstrated that viruses ...
Stéphan Jacquet, Takeshi Miki, Rachel Noble, Peter Peduzzi, Steven Wilhelm   +4 more
doaj   +1 more source

Bewertung und Verbesserung der Biodiversität in landwirtschaftlichen Gebieten unter besonderer Berücksichtigung von Vogelarten als Bioindikatoren

Julius-Kühn-Archiv, 2013
Agricultural landscapes have crucial functions for biodiversity conservation. Contrary to the goals of biodiversity protection the habitat functions and the biological diversity are deteriorating, especially in arable areas.
Hoffmann, Jörg, Wiegand, Ina, Wittchen, Udo, Ehlert, Sigrid, Berger, Gert, Pfeffer, Holger   +5 more
doaj   +1 more source

Ba Isotope Ratio in CEMP-s and CEMP-rs Stars as a Signature of s-Process and i-Process

Galaxies
We present a spectroscopic analysis of three carbon-enhanced metal-poor (CEMP) stars of type CEMP-s and CEMP-rs and determine their non-local thermodynamic equilibrium (NLTE) abundances of Ba and the fractions of the odd Ba isotopes (Fodd). We found Fodd
Tatyana Sitnova, Lyudmila Mashonkina
doaj   +1 more source

The stellar origins of 96Zr excesses in presolar graphites from the Murchison meteorite

Astronomy & Astrophysics
Context. Zirconium-96 is a stable isotope that can be synthesized under different neutron-rich nucleosynthetic conditions. Astrophysical models predict its production to occur in various stellar environments: from low-to-intermediate-mass asymptotic ...
Pal I., Jadhav M., Shulaker D. Z., Raiwa M., Savina M. R., Bouillion H., Pignatari M., Roberti L., Lugaro M., Szányi B., Karakas A., Denissenkov P., Herwig F., Dory C. J., Gyngard F., Kita N., Amari S.   +16 more
doaj   +1 more source

Asymmetrical thermonuclear supernovae triggered by the tidal disruption of white dwarfs

Astronomy & Astrophysics
In a dense star cluster core, a tidal disruption event (TDE) of a white dwarf (WD) can occur if the WD passes within the tidal radius of an intermediate-mass black hole (IMBH).
Vynatheya Pavan, Dessart Luc, Ryu Taeho, Pakmor Rüdiger   +3 more
doaj   +1 more source

The impact of the carbon fusion rate on the properties of superbursts

Astronomy & Astrophysics
Context. Superbursts are very energetic explosions in the crust of neutron stars in low-mass X-ray binaries (LMXBs). These are triggered by unstable carbon burning at T ≤ 109 K.
Nava-Callejas M., Goriely S., Chamel N.
doaj   +1 more source