Search Publications
New online database of symbiotic variables: Symbiotics in X‑rays
Merc, J.; Gális, R.; Wolf, M.
Symbiotic variable stars belong to an interesting class of interacting binary systems. Since the beginning of this century, the systematic search for these objects has begun, and such surveys have led to discoveries of many new objects and dozens of candidates in the Milky Way and the Local Group. As the latest catalogue of symbiotic binaries is a…
Decade‑long X‑ray observations of HESS J0632+057
Santangelo, Andrea; Pühlhofer, Gerd; Chernyakova, Maria +1 more
We present the results of a decade of X‑ray observations of the gamma ray loud binary HESS J0632+057 and interpret the available broadband data in view of the system geometry and emission mechanisms. We have performed an analysis of all X‑ray data available to date from Swift, XMM‑Newton, Chandra, NuSTAR, and Suzaku. We refine the orbital period o…
Observations of X‑ray reverberation around black holes
Ponti, G.; De Marco, B.
The X‑ray emission from accreting black hole (BH) systems displays strong variability. Short reverberation lags are expected between the primary hard X‑ray continuum and the reprocessed disk emission. These lags depend on light‑travel distances, thus offering the opportunity to map the geometry of the innermost accretion flow. X‑ray reverberation …
The nonlinear X‑ray/ultraviolet relation in active galactic nuclei: Contribution of instrumental effects on the X‑ray variability
Lusso, E.
We have recently demonstrated that the nonlinear relation between ultraviolet and X‑ray luminosity in quasars is very tight (with an intrinsic dispersion of ∼0.2 dex), once contaminants (e.g., dust reddening, X‑ray absorption), variability, and differences in the active galactic nuclei physical properties are taken into account. This relation has …
On the possibilities of classical nova identifications among historical Far Eastern guest star observations
Hoffmann, Susanne M.; Vogt, Nikolaus; Tappert, Claus
More than 100 guest star observations have been obtained by Chinese, Korean, Japanese, and Vietnamese astronomers between ∼600 BCE and ∼1690 CE. Comparing the coordinates from the information given in old texts for eight supernova recoveries with modern supernova remnant positions, we estimate the typical positional accuracy of the order of 0.3–7°…
Catalog of equatorial coordinates and B‑magnitudes of the Kitab's part of the FON project
Andruk, V.; Yuldoshev, Q.; Relke, H. +3 more
We present a catalog of stars with equatorial coordinates α and δ and B‑magnitudes of stars for the Kitab's section of the FON project (FON‑Kitab). The photographic plates of the FON project were exposed on the double telescope Double Zeiss Astrograph (DAZ, D/F = 40/300, 69″/mm) at the Kitab observatory of the Republic of Uzbekistan. A total of 19…
Galaxy rotation curve from classical Cepheids
Gnaciński, Piotr
The galaxy rotation curve is usually assumed to be flat. However, some galaxies have rotation curves that are lower than the flat rotation curve. In our galaxy, the Keplerian rotation of interstellar clouds in the galactic longitude l = 135° was observed. We use a kinematic approach to derive the rotational velocity of classical Cepheids. The rota…
The new 4‑m robotic telescope
Rebolo, R.; Steele, I. A.; Harvey, E. +9 more
We present a project to build a 4‑m‑diameter telescope (New Robotic Telescope [NRT]) with fully robotic operation. The telescope will be sited at the Observatory of Roque de los Muchachos in the island of La Palma (Spain). When it enters into operation in 5 years' time, it will be likely the largest robotic telescope in the world. This, in conjunc…
The complex phenomena of young stellar objects revealed by their X‑ray variability
Reale, F.; Sciortino, S.; Pillitteri, I. +1 more
X‑ray observations of young stellar objects (YSOs) have shown several complex phenomena at work. In recent years, a few X‑ray programs based on long, continuous, and, sporadically, simultaneous coordinated multiwavelength observations have paved the way to our current understanding of the physical processes at work, which very likely regulates the…
Tidal disruption events: Past, present, and future
Motch, C.; Komossa, S.; Lira, P. +6 more
The tidal disruption of a star by a nuclear supermassive black hole was predicted in the 1970s and first confirmed by soft X‑ray flares seen from quiescent galaxies in the ROSAT all‑sky survey. We report here on the discovery of a new candidate tidal disruption event, 1RXS J075908.8 + 074835, from the ROSAT bright source catalog, which faded by a …