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The Hot Companion and Circumbinary Disk of the Be Star HR 2142
Gies, Douglas R.; Wang, Luqian; Peters, Geraldine J. +1 more
We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer (IUE) and ground-based Hα observations. We measured radial velocities for the Be star component from these spectra and computed a revised orbit. In order to search for th…
A New γ-Ray Loud, Eclipsing Low-mass X-Ray Binary
Strader, Jay; Udalski, Andrzej; Chomiuk, Laura +5 more
We report the discovery of an eclipsing low-mass X-ray binary at the center of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope γ-ray source 3FGL J0427.9-6704. Photometry from OGLE and the SMARTS 1.3 m telescope and spectroscopy from the SOAR telescope have allowed us to classify the system as an eclipsing low-mass X-ray binar…
Relativistic X-ray reverberation modelling of the combined time-averaged and lag-energy spectra in AGN
Chainakun, P.; Young, A. J.; Kara, E.
General relativistic ray tracing simulations of the time-averaged spectrum and energy-dependent time delays in active galactic nuclei (AGN) are presented. We model the lamp-post geometry in which the accreting gas is illuminated by an X-ray source located on the rotation axis of the black hole. The spectroscopic features imprinted in the reflectio…
The Fe II Emission in Active Galactic Nuclei: Excitation Mechanisms and Location of the Emitting Region
Garcia-Rissmann, A.; Sigut, T. A. A.; Rodríguez-Ardila, A. +2 more
We present a study of Fe II emission in the near-infrared region (NIR) for 25 active galactic nuclei (AGNs) to obtain information about the excitation mechanisms that power it and the location where it is formed. We employ an NIR Fe II template derived in the literature and find that it successfully reproduces the observed Fe II spectrum. The Fe I…
Suprathermal Electron Strahl Widths in the Presence of Narrow-band Whistler Waves in the Solar Wind
Fazakerley, A. N.; Maksimovic, M.; Alexandrova, O. +2 more
We perform the first statistical study of the effects of the interaction of suprathermal electrons with narrow-band whistler mode waves in the solar wind (SW). We show that this interaction does occur and that it is associated with enhanced widths of the so-called strahl component. The latter is directed along the interplanetary magnetic field awa…
Gravitational torques imply molecular gas inflow towards the nucleus of M 51
Meidt, S. E.; Schinnerer, E.; Leroy, A. K. +10 more
The transport of gas towards the centre of galaxies is critical for black hole feeding and, indirectly, it can control active galactic nucleus (AGN) feedback. We have quantified the molecular gas inflow in the central R< 1 kpc of M 51 to be 1 M⊙/yr, using a new gravitational torque map and the molecular gas traced by the Plateau de B…
Sun-to-Earth Characteristics of the 2012 July 12 Coronal Mass Ejection and Associated Geo-effectiveness
Möstl, Christian; Wang, Rui; Yang, Zhongwei +2 more
We analyze multi-spacecraft observations associated with the 2012 July 12 coronal mass ejection (CME), covering the source region on the Sun from the Solar Dynamics Observatory, stereoscopic imaging observations from the Solar Terrestrial Relations Observatory (STEREO), magnetic field characteristics from Mercury Surface, Space Environment, Geoche…
Subaru Telescope adaptive optics observations of gravitationally lensed quasars in the Sloan Digital Sky Survey
Terada, Hiroshi; Pyo, Tae-Soo; Oguri, Masamune +12 more
We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars and candidates (23 doubles, 1 quad, 1 possible triple, and 3 candidates) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid poin…
Discovery of a faint, star-forming, multiply lensed, Lyman-α blob
Grillo, C.; Balestra, I.; Rosati, P. +7 more
We report the discovery of a multiply lensed Lyman-α blob (LAB) behind the galaxy cluster AS1063 using the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The background source is at z = 3.117 and is intrinsically faint compared to almost all previously reported LABs. We used our highly precise strong lensing model to r…
Stellar Populations and Star Formation History of the Metal-poor Dwarf Galaxy DDO 68
Cignoni, M.; Tosi, M.; van der Marel, R. P. +6 more
We present the star formation history (SFH) of the extremely metal-poor dwarf galaxy DDO 68, based on our photometry with the Advanced Camera for Surveys. With a metallicity of only 12+{log}({{O}}/{{H}})=7.15 and a very isolated location, DDO 68 is one of the most metal-poor galaxies known. It has been argued that DDO 68 is a young system that sta…