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The XXL Survey. XLIII. The quasar radio loudness dichotomy exposed via radio luminosity functions obtained by combining results from COSMOS and XXL-S X-ray selected quasars
Smolčić, V.; Pierre, M.; Leslie, S. +13 more
We studied a sample of 274 radio and X-ray selected quasars (XQSOs) detected in the COSMOS and XXL-S radio surveys at 3 GHz and 2.1 GHz, respectively. This sample was identified by adopting a conservative threshold in X-ray luminosity, LX [2-10 keV] ≥ 1044 erg s-1, selecting only the most powerful quasars. A number…
Modelling of 35-d superorbital cycle of B and V light curves of IMXB HZ Her/Her X-1
Klochkov, D.; Bikmaev, I. F.; Wilms, J. +13 more
The X-ray binary Her X-1 consists of an accreting neutron star and the optical component HZ Her. The 35-d X-ray superorbital variability of this system is known, since its discovery in 1972 by the Uhuru satellite and is believed to be caused by forced precession of a warped accretion disc tilted to the orbital plane. We argue that the observed fea…
CzeV1731: The unique doubly eclipsing quadruple system
Wolf, M.; Gazeas, K.; Mašek, M. +14 more
We report the discovery of the relatively bright (V = 10.5 mag), doubly eclipsing 2+2 quadruple system CzeV1731. This is the third known system of its kind, in which the masses are determined for all four stars and both the inner and outer orbits are characterized. The inner eclipsing binaries are well-detached systems moving on circular orbits: p…
Wide-field study of the peculiar globular cluster system hosted by the field lenticular NGC 1172
Salinas, Ricardo; Gómez, Matías; Caso, Juan Pablo +2 more
We present a wide-field study of the globular cluster system (GCS) of the field lenticular galaxy NGC 1172, based on observations from Gemini Multi-Object Spectrograph/Gemini (optical), FourStar/Magellan (NIR), and archival data from ACS/Hubble Space Telescope (optical). This analysis covers the full extension of the GCS, and results in a value of…
The phenomenon of shape evolution from solar-driven outgassing for analogues of small Kuiper belt objects
Rezac, L.; Li, J. -Y.; Zhao, Y. +1 more
One of the key findings of the Rosetta mission to the Jupiter-family comet 67P/Churyumov-Gerasimenko was its peculiar bi-lobed shape and its apparent Northern/Southern hemispheric dichotomy in large-scale morphology. This has re-ignited scientific discussions on the topic of the origin, evolution and age of the nucleus. In this work, we conduct a …
The Kinematic Evolution of Erupting Structures in Confined Solar Flares
Cheng, X.; Ding, M. D.; Huang, Z. W.
In this Letter, we study the kinematic properties of ascending hot blobs associated with confined flares. Taking advantage of high-cadence extreme-ultraviolet images provided by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we find that for the 26 events selected here, the hot blobs are first impulsively accelerated out…
Low-mass Group Environments Have No Substantial Impact on the Circumgalactic Medium Metallicity
Charlton, Jane C.; Kacprzak, Glenn G.; Churchill, Christopher W. +4 more
We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at $\langle {z}_{\mathrm{abs}}\rangle =0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/COS and from Keck/HIRES or the Very Large Telescope/UVES, we measure column…
In the Quest for Cosmic Rotation
Korotky, Vladimir A.; Masár, Eduard; Obukhov, Yuri N.
This paper analyzes the problem of global rotation in general relativity (GR) theory. Simple cosmological models with rotation and expansion are presented, which give a natural explanation of the modern values of the acceleration parameter at different red shifts without involving the concepts of "dark energy" and "dark matter". It is shown that d…
Onthe changes in the physical properties of the ionized region around the Weigelt structures in η Carinae over the 5.54-yr spectroscopic cycle
Gull, T. R.; Corcoran, M. F.; Hillier, D. J. +3 more
We present HST/STIS observations and analysis of two prominent nebular structures around the central source of η Carinae, the knots C and D. The former is brighter than the latter for emission lines from intermediate- or high-ionization potential ions. The brightness of lines from intermediate- and high-ionization potential ions significantly decr…
Pulsation in the white dwarf HE 1017-1352: confirmation of the class of hot DAV stars
Kepler, S. O.; Romero, Alejandra D.; Antunes Amaral, L. +3 more
We report the detection of periodic variations on the $T_\mathrm{eff}\simeq 32\, 000$ K DA white dwarf star HE 1017-1352. We obtained time series photometry using the 4.1-m Southern Astrophysical Research telescope on three separate nights for a total of 16.8 h. From the frequency analysis, we found four periods of 605, 556, 508, and 869 s with si…