Search Publications
Insights from multi-wavelength observations during high and low states of non-magnetic CVs
Szkody, Paula
Close binaries containing a white dwarf accreting from a disk that receives material from a late stellar companion show an interesting variety of behaviors that depend on their accretion rates and the changes in this rate. The highest accretion rates are evident during the bright states of novalikes, as well as the superoutbursts of the shortest p…
NLTE spectral analysis of the intermediate helium-rich subdwarf B star CPD-20°1123
Löbling, L.
Subdwarf B (sdB) stars are core helium-burning stars with stratified atmospheres. Their atmospheres are dominated by hydrogen (H) while the helium (He) and metal abundances are shaped by an interplay of gravitational settling and radiative levitation. However, a small fraction of these show spectra dominated by He I absorption lines. In between th…
Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern hemisphere
Metcalfe, Nigel; Shanks, Tom; Ansarinejad, Behzad +1 more
The integrated Sachs-Wolfe (ISW) effect probes the late-time expansion history of the Universe, offering direct constraints on dark energy. Here, we present our measurements of the ISW signal at redshifts of $\bar{z}=0.35$ , 0.55, and 0.68, using the cross-correlation of the Planck cosmic microwave background temperature map with ∼0.5 million lumi…
Observation of Disturbed Plasma Structures in the Environment of the Sun and Near-Earth Space with Radio Sounding and Local Measurements
Bird, M. K.; Efimov, A. I.; Lukanina, L. A. +3 more
An experiment on radio sounding of the circumsolar plasma by signals from the Mars Express spacecraft in 2013 was carried out in the period from March 4 through May 31. The investigated characteristics were the frequency of signals in the centimeter and decimeter ranges and the differential frequency. A number of events were recorded in which the …
New CCD photometry and light curve analysis of two WUMaBinaries: 1SWASP J133417.80+394314.4 and V2790 Orion
El-Depsey, M. H.; Hassan, I. A.; Shokry, A. +5 more
We present a new multicolor CCD photometry and light curve analysis of two eclipsing binary systems, 1SWASP J133417.80 + 394314.4 and V2790 Orion. The photometric solutions for both binaries were carried out using the updated version of the Wilson- Devinney code. The results showed that first systems is A- type W UMa with mass ratios q = 0.158 whi…
Accuracy of magnitudes in pre‑telescopic star catalogs
Hoffmann, Susanne M.; Protte, Philipp
Historical star magnitudes from catalogs by Ptolemy (137 AD), al‑Sūfī (964), and Tycho Brahe (1602/27) are converted to the Johnson V‑mag scale and compared to modern‑day values from the HIPPARCOS catalog. The deviations (or "errors") are tested for dependencies on three different observational influences. The relation between historical and moder…
The Composition, Excitation, and Physical State of Atomic Gas in the Debris Disk Surrounding 51 Oph
Jenkins, Edward B.; Gry, Cécile
We measured 304 absorption features in the ultraviolet and visible spectra of the star 51 Oph, which is known to have a debris disk with a high inclination. We analyzed the relative populations of atoms in excited fine-structure and metastable levels that are maintained by optical pumping and collisional excitation by electrons, and we found that …
The fractal nature as new frontier in microstructural characterization and relativization of scale sizes within space
Arnold, Walter; Mitic, Vojislav V.; Lazovic, Goran +3 more
Today in the age of advanced ceramic civilization, there are a variety of applications for modern ceramics materials with specific properties. Our up-to date research recognizes that ceramics have a fractal configuration nature on the basis of different phenomena. The key property of fractals is their scale-independence. The practical value is tha…
The fate of O+ ions observed in the plasma mantle: particle tracing modelling and cluster observations
Nilsson, Hans; Gunell, Herbert; Slapak, Rikard +5 more
Ion escape is of particular interest for studying the evolution of the atmosphere on geological timescales. Previously, using Cluster-CODIF data, we investigated the oxygen ion outflow from the plasma mantle for different solar wind conditions and geomagnetic activity. We found significant correlations between solar wind parameters, geomagnetic ac…
Two New Rapidly Rotating ON Stars Found with LAMOST
Howarth, Ian D.; Li, Guang-Wei
The ON stars are a rare subtype of O stars of uncertain origin. We report two new, rapidly rotating ON stars found in data acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. LS I +61 28 is an ON8.5 Vn dwarf with a projected equatorial rotational velocity of {V}{{e}}\sin I≃ 298 {km} {{{s}}}-1, while H…