Search Publications
HD 50975: a yellow supergiant in a spectroscopic binary system
Sperauskas, J.; Raudeliūnas, S.; Začs, L. +2 more
Context. Recent detection of a yellow supergiant star as a possible progenitor of a supernova has posed serious questions about our understanding of the evolution of massive stars.
Aims: The spectroscopic binary star HD 50975 with an unseen hot secondary was studied in detail with the main goal of estimating fundamental parameters of both com…
The most compact bright radio-loud AGN—I. A new target sample selected for the space VLBI
Frey, Sándor; An, Tao; Wu, Xiaocong
We investigated the archival ground-based VLBI images of the extragalactic radio sources included in both the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck catalogues, and selected 49 bright and compact sources as potential targets for space Very Long Baseline Interferometry (VLBI) observations at mm wavelengths. These sources have a …
Orbital Signatures from Observed Light Curves of Blazars
Mangalam, A.; Mohan, P.
Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical models based on this view. Thes…
Kinematic analysis of stellar radial velocities by the spherical harmonics
Tsvetkov, A. S.; Vityazev, V. V.; Trofimov, D. A.
A method for a kinematic analysis of stellar radial velocities using spherical harmonics is proposed. This approach does not depend on the specific kinematic model and allows both low-frequency and high-frequency kinematic radial velocity components to be analyzed. The possible systematic variations of distances with coordinates on the celestial s…
Predicting the characteristics of thunder on Titan: A framework to assess the detectability of lightning by acoustic sensing
Petculescu, Andi; Kruse, Roland
The search for lightning is an important item on the agenda for the future exploration of Titan. Thunder, as a direct lightning signature, can be used, together with electromagnetic signals, to corroborate and quantify lightning. Using Cassini-Huygens data and model predictions, the main characteristics of thunder produced by a potential 20 km clo…
A high-resolution image of the inner shell of the P Cygni nebula in the infrared [Fe II] line
Boutsia, K.; Arcidiacono, C.; Ragazzoni, R. +11 more
Using the adaptive optics system of the Large Binocular Telescope, we have obtained near-infrared camera PISCES images of the inner shell of the nebula around the luminous blue variable star P Cygni in the [Fe II] emission line at 1.6435 µm. We have combined the images in order to cover a field of view of about 20 arcsec around P Cygni, thus…
Strong lensing analysis of PLCK G004.5-19.5, a Planck-discovered cluster hosting a radio relic at z = 0.52
Sifón, Cristóbal; Hughes, John P.; Barrientos, L. Felipe +2 more
Context. The recent discovery of a large number of galaxy clusters using the Sunyaev-Zel'dovich (SZ) effect has opened a new era on the study of the most massive clusters in the Universe. Multiwavelength analyses are required to understand the properties of these new sets of clusters, which are a sensitive probe of cosmology.
Aims: We aim for…
Multiwavelength Observations of AB Doradus
Johnston-Hollitt, M.; Budding, E.; Slee, O. B. +1 more
We have observed the bright, magnetically active multiple star AB Doradus in a multiwavelength campaign centring around two large facility allocations in November 2006 and January, 2007. Our observations have covered at least three large flares. These flares were observed to produce significant hardening of the X-ray spectra during their very init…
A Change in the Solar He II EUV Global Network Structure as an Indicator of the Geo-Effectiveness of Solar Minima
Gurman, J. B.; Didkovsky, L.
Solar activity during 2007 - 2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor (SEM), one of instruments on the Charge Element and Isotope Analysis System (CELIAS) on board the Solar and Hel…
Circumferential graben and the structural evolution of Alba Mons, Mars
McGovern, Patrick J.; Öhman, Teemu
Alba Mons is a unique, very extensive but shallow volcanotectonic construct in northern Tharsis, Mars. Numerous models have been presented to explain the formation of Alba Mons and its most characteristic feature, a wristwatch-like pattern of radial and circumferential graben. We used a wide selection of topographic datasets to characterize the fa…