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X-Ray Spectral Properties of Seyfert I Galaxy LEDA 168563
Fabian, Andrew C.; Tsuruta, Sachiko; Liebmann, Andrew C. +2 more
Interesting among possible mechanisms responsible for X-ray emission from active galactic nuclei (AGNs) is ionized relativistic reflection (IRR). Since it arises close to the central black hole it can test strong gravity. Its characteristic features include a high energy Compton hump, a broad Fe Kα line, and a soft excess. Therefore, using the Swi…
The Catalogues Analysis of Stars Equatorial Coordinates and B-Magnitude of the FON Project
Andruk, V. M.; Akhmetov, V. S.; Protsyuk, Yu. I. +1 more
FON project was expected a catalogue of stellar positions and B magnitude of Northern sky from combination six astronomical observatories of the former USSR were equipped with the same wide-angle astrographs: Goloseevo (Ukraine), Zvenigorod, Zelenchuk (Russia), Abastumani (Georgia), Kitab (Uzbekistan) and HisorAO (Tajikistan). This paper has been …
A Hubble Space Telescope imaging study of four FeLoBAL quasar host galaxies
Vestergaard, M.; Fan, X.; Lawther, D.
We study the host galaxies of four Iron Low-Ionization Broad Absorption-line Quasars (FeLoBALs), using Hubble Space Telescope imaging data, investigating the possibility that they represent a transition between an obscured active galactic nucleus (AGN) and an ordinary optical quasar. In this scenario, the FeLoBALs represent the early stage of merg…
Herschel-PACS photometry of faint stars for sensitivity performance assessment and establishment of faint FIR primary photometric standards
Balog, Z.; Müller, T. G.; Klaas, U. +3 more
Aims: Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright (≲2.5 Jy) to faint (≳5 mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise dependence with flux and time, and compare the results with predictions from the Herschel exposure…
Study on the Curvature and Gradient of the Magnetic Field in Earth's Cusp Region Based on the Magnetic Curvature Analysis Method
Rong, Zhaojin; Shen, Chao; Xiao, Chao +2 more
This paper uses the multiple-point magnetic measurements from the Cluster mission to investigate the curvature and gradient of the magnetic field as well as their relations with the current density inside the cusp region under different interplanetary magnetic field (IMF) conditions. From two event studies, it is shown that the curvature radius of…
A Statistical Study of Ionospheric Boundary Wave Formation at Venus
Zhang, Tielong; Futaana, Yoshifumi; Frahm, Rudy A. +3 more
Previous missions to Venus have revealed that encounters with plasma irregularities of atmospheric origin outside the atmosphere are not uncommon. A number of mechanisms have been proposed to discuss their origins as well as their roles in the atmospheric evolution of Venus. One such mechanism involves an ionopause with a wavelike appearance. By u…
Studies of Modern Star Catalogs Based on Photoelectric Observations of Lunar Occultations of Stars
Churkin, K. O.; Andreev, A. O.; Nefedyev, Yu. A. +2 more
An important area of investigation in astronomy is the relationship between fundamental and dynamical coordinate systems. Valuable material for such studies is provided by photoelectric occultation observations of stars by the Moon, which can provide high precision of detecting rapidly occurring processes and have been carried out over a long time…
Dating the Tidal Disruption of Globular Clusters with GAIA Data on Their Stellar Streams
Loeb, Abraham; Bose, Sownak; Ginsburg, Idan
The Gaia mission promises to deliver precision astrometry at an unprecedented level, heralding a new era for discerning the kinematic and spatial coordinates of stars in our Galaxy. Here, we present a new technique for estimating the age of tidally disrupted globular cluster streams using the proper motions and parallaxes of tracer stars. We evolv…
Faint γ-ray sources at low redshift: the radio galaxy IC 1531
Vignali, C.; Grandi, P.; Siemiginowska, A. +6 more
We present a multiwavelength study of IC 1531 (z = 0.02564), an extragalactic radio source associated with the γ-ray object 3FGL J0009.9 - 3206 and classified as a blazar of uncertain type in the Third Fermi-Large Area Telescope AGN catalog (3LAC). A core-jet structure, visible in radio and X-rays, is enclosed within a ∼220 kpc wide radio structur…
Measurement of coronal properties of Seyfert galaxies from NuSTAR's hard X-ray spectrum
Stalin, C. S.; Rani, Priyanka
Precise measurement of the coronal properties of Active Galactic Nuclei (AGN) requires the availability of high signal-to-noise ratio data covering a wide range of X-ray energies. The Nuclear Spectroscopic Telescope Array (NuSTAR) which is highly sensitive to earlier missions in its operational energy range of 3–79 keV, allows us to arrive at prec…