Results 21 to 30 of about 165,947,395 (159)

A Solar Analog Model for Decrease in Far Ultraviolet Irradiance Under a Grand Minimum

open access: yesEarth and Space Science, Volume 13, Issue 9, September 2026.
Abstract Solar analog field stars having a range of magnetic activity can provide an estimate of solar spectral irradiance (SSI) variability relevant to understanding the Sun's influence on terrestrial climate. This approach is particularly useful for far ultraviolet (FUV) irradiance that cannot be observed from the Earth surface.
D. Lubin, C. Melis, D. Tytler
wiley   +1 more source

Cosmic Ray Anisotropy Generated by the June 22nd 2015 Interplanetary Events

open access: yesJournal of Geophysical Research: Space Physics, Volume 131, Issue 9, September 2026.
Abstract On 22 June 2015, the near Earth interplanetary space was perturbed by a series of high‐speed streamers and interplanetary coronal mass ejections associated with an active region and two low‐latitude coronal holes. The interaction of these disturbances gave rise to the complex solar wind structure observed at 1 au.
A. Lara, K. P. Arunbabu, T. Niembro
wiley   +1 more source

Astronomy & Astrophysics (CAUCASUS)-VOLUME 4

open access: yes, 2018
The IV volume of Journal “Astronomy & Astrophysics (Caucasus)” was dedicated to the 110th Anniversary of Academician Victor Hambardzumyan. AcademicianVictor Hambardzumyan President of International Union of Astronomy (in 1961 – 1964 and 1966 – 72 ...
(CAUCASUS), Astronomy & Astrophysics
core   +1 more source

Collisionless Shocks: Contemporary State After Three Quarters of a Century of Research

open access: yesReviews of Geophysics, Volume 64, Issue 3, September 2026.
Abstract The collisionless shock research started in the late 1950s. Since then, plenty of data have been accumulated due to the large number of missions in the heliosphere, providing in situ measurements of the fields and particles. The quality of these measurements has vastly improved, especially in the last two decades.
M. Gedalin   +2 more
wiley   +1 more source

Applications of the IGIMF-theory to the astrophysics of galaxies

open access: yes, 2010
The functional form of the galaxy-wide stellar initial mass function is of fundamental importance for understanding galaxies. So far this stellar initial mass function has been assumed to be identical to the IMF observed directly in star clusters. But because stars form predominantly in embedded groups rather than uniformly distributed over the whole ...
Pflamm-Altenburg, Jan   +2 more
openaire   +2 more sources

Studies of Seyfert galaxies in Fesenkov Astrophysical Institute

open access: yesCommunications of the Byurakan Astrophysical Observatory, 2020
This article provides an overview of the main research results of a large group of Seyfert galaxies, carried out at Fesenkov Astrophysical Institute (FAI) over the past 50 years. Spectral observations have been performed since 1970. At an early stage, a three cascade image-tube (UM-92) was used as a radiation receiver.
E. Denissyuk   +5 more
openaire   +1 more source

Optical polarimetry studies of Seyfert galaxies [PDF]

open access: yes, 1999
Optical imaging polarimetry has been performed on seven nearby Seyfert galaxies, three with face-on and four with edge-on host galaxies of various morphological classifications.
Felton, Michelle Ann
core  

Can Solar Cyclic Variability Mimic Extreme Solar Particle (Miyake) Events in Radiocarbon?

open access: yesJournal of Geophysical Research: Space Physics, Volume 131, Issue 9, September 2026.
Abstract Rapid, strong enhancements in Δ14 ${{\Delta }}^{14}$C in the Earth's atmosphere, known as Miyake events, rarely occurred over the past millennia, pointing to major radiation storms affecting Earth. They are produced by extreme solar particle events (ESPEs) and are separated by an order‐of‐magnitude gap in the strength from directly observed ...
Ilya Usoskin   +2 more
wiley   +1 more source

The Great Cosmic Silence: What Does the Fermi Paradox Tell About the Future of Humanity?

open access: yesGlobal Policy, Volume 17, Issue 4, Page 553-565, September 2026.
ABSTRACT This article examines how institutional time horizons shape the long‐term survival prospects of human technological civilisation. While research on global catastrophic and existential risks has expanded, the temporal structures of political‐economic institutions remain underexamined.
Heikki Patomäki
wiley   +1 more source

The 40K‐K dating system: 1. Improving data interpretation using new model calculations

open access: yesMeteoritics &Planetary Science, Volume 61, Issue 9, Page 2187-2200, September 2026.
Abstract The 40K‐K cosmic‐ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic 40K with the stable cosmogenic isotopes 39K and 41K. However, earlier applications relied on semi‐empirical production models and inconsistent analytical data sets, limiting their ...
Farshid Nozarian   +2 more
wiley   +1 more source

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