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We have studied a sample of more than 25 000 young stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The relative errors of their parallaxes do not exceed 10\%. The selection of stars belonging to active…

Astrophysics of Galaxies · Physics 2020-08-26 O. I. Krisanova , V. V. Bobylev , A. T. Bajkova

We consider $f(R)$ modified gravity theory incorporating the chameleon mechanism to address galactic dynamics. By employing the metric formalism and utilizing a conformal transformation, we simplify the field equations and describe the…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Gayatri Mohan , Umananda Dev Goswami

In this manuscript we present a new approach for the numerical solution of the Galactic Cosmic Ray propagation problem. We introduce a method using advanced contemporary numerical algorithms while retaining the general complexity of other…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Ralf Kissmann

Despite centuries of rigorous theoretical and observational research, the origin and acceleration mechanism of Galactic Cosmic Rays (GCRs) remain a mystery. In 1949, Fermi proposed a diffusive shock acceleration model that includes a…

High Energy Astrophysical Phenomena · Physics 2023-03-16 Anil Raghav , Kalpesh Ghag , Omkar Dhamane , Zubair Shaikh , Ankush Bhaskar , Utsav Panchal

In this paper we outline the considerations required in order to select a target star system for the Icarus interstellar mission. It is considered that the maximum likely range for the Icarus vehicle will be 15 light-years, and a list is…

Astrophysics of Galaxies · Physics 2011-06-07 I. A. Crawford

We present an implementation-oriented relativistic modeling framework for high-precision GNSS processing consistent with the IAU-adopted Barycentric and Geocentric Celestial Reference Systems (BCRS/GCRS) and their associated time scales…

General Relativity and Quantum Cosmology · Physics 2026-01-13 Slava G. Turyshev , Yoaz E. Bar-Sever , William I. Bertiger

Initial discovery of CRs dates back to a century ago (1912). Their identification as particles rather than radiation dates to about 20 years later and in 20 more years also the first suggestion that they were associated with SNRs was in…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Elena Amato

Galactic Cosmic Rays (GCRs) have to travel through the heliosphere before they interact with the Earth's atmosphere. During this, they are deflected by the Sun's magnetic field, causing variations in this field to imprint on the flux,…

The Sixth Catalogue of Fundamental Stars (FK6) combines the ground-based astrometric data of the basic fundamental stars, obtained over more than two centuries and summarized in the FK5, with the observations of the HIPPARCOS astrometry…

Astrophysics · Physics 2007-05-23 R. Wielen , H. Schwan , C. Dettbarn , H. Jahreiss , H. Lenhardt

An important contribution to the gamma-ray emission of our Galaxy is the Galactic Diffuse emission. We present specific developments within the PICARD code for modeling of Galactic cosmic ray propagation that are relevant for the…

High Energy Astrophysical Phenomena · Physics 2017-01-26 Felix Niederwanger , Olaf Reimer , Ralf Kissmann , Richard Tuffs

Evolution of the mass function (MF) and radial distribution (RD) of the Galactic globular cluster (GC) system is calculated using an advanced and a realistic Fokker-Planck (FP) model that considers dynamical friction, disc/bulge shocks and…

Astrophysics · Physics 2009-11-13 Jihye Shin , Sungsoo S. Kim , Koji Takahashi

We extend the bimetric description of the Universe to a five-dimensional framework. Starting from Souriau's work (1964) we use two Robertson-Walker metrics with an extra term corresponding to the additional Kaluza fifth dimension. This…

General Physics · Physics 2008-12-08 Jean Pierre Petit , Gilles d'Agostini

The transition from galactic to extragalactic cosmic rays is discussed. One of critical indications for transition is given by the Standard Model of Galactic cosmic rays, according to which the maximum energy of acceleration for iron nuclei…

Astrophysics · Physics 2007-10-20 V. Berezinsky

Much has been learned about Galactic cosmic rays in the past decade: On the observational side, the spectra of cosmic ray nuclei have been directly measured with high precision, resolving chemical composition up to TV rigidities. At even…

High Energy Astrophysical Phenomena · Physics 2025-12-05 Philipp Mertsch

We use 20 years of astrometric data from the RECONS program on the CTIO/SMARTS 0.9-m to provide new insight into multiple star systems in the solar neighborhood. We provide new and updated parallaxes for 210 systems and derive nine…

Solar and Stellar Astrophysics · Physics 2020-12-09 Eliot Halley Vrijmoet , Todd J. Henry , Wei-Chun Jao , Serge B. Dieterich

Stellar rotation periods can be determined by observing brightness variations caused by active magnetic regions transiting visible stellar disk as the star rotates. The successful stellar photometric surveys stemming from the Kepler and…

Solar and Stellar Astrophysics · Physics 2020-10-28 E. M. Amazo-Gomez , A. I. Shapiro , S. K. Solanki , G. Kopp , M. Oshagh , T. Reinhold , A. Reiners

We present the results of 16 years of monitoring stellar orbits around the massive black hole in center of the Milky Way using high resolution NIR techniques. This work refines our previous analysis mainly by greatly improving the…

Astrophysics · Physics 2011-02-11 S. Gillessen , F. Eisenhauer , S. Trippe , T. Alexander , R. Genzel , F. Martins , T. Ott

We present Infrared Space Observatory (ISO) observations of fine structure lines toward the Radio Arc region, close to Sgr A, in the Galactic center region (GCR). The ionization at large scale is dominated by the clusters of massive stars…

Astrophysics · Physics 2009-11-07 N. J. Rodriguez-Fernandez , J. Martin-Pintado , P. de Vicente

The Classical Coordinate System is geometrical by nature with time being an external variable. Constructing a classical coordinate system employs a point-like signal with infinite speed. In Special Relativity Theory the speed is limited but…

General Physics · Physics 2007-05-23 M. F. Yagan

We discuss the region of transition between galactic and extragalactic cosmic rays. The exact shapes and compositions of these two components contains information about important parameters of powerful astrophysical sources and the…

Astrophysics · Physics 2008-11-26 Todor Stanev