Search Publications
The nature of the intranight variability of radio-quiet quasars
Siemiginowska, A.; Czerny, B.; Gupta, A. C. +1 more
We select a sample of 10 radio-quiet quasars with confirmed intranight optical variability and with available X-ray data. We compare the variability properties and the broad-band spectral constraints to the predictions of intranight variability by three models: (i) irradiation of an accretion disc by a variable X-ray flux, (ii) an accretion disc i…
Coronal loop oscillations and diagnostics with Hinode/EIS
Taroyan, Y.; Bradshaw, S.
Context: Standing slow (acoustic) waves commonly observed in hot coronal loops offer a unique opportunity to understand the properties of the coronal plasma. The lack of evidence for similar oscillations in cooler loops is still a puzzle.
Aims: The high cadence EIS instrument on board recently launched Hinode has the capability to detect wave …
Cosmological models in scalar tensor theories of gravity and observations: a class of general solutions
Piedipalumbo, E.; Demianski, M.; Rubano, C. +1 more
Aims: We study cosmological models in scalar tensor theories of gravity with power-law potentials as models of an accelerating universe.
Methods: We consider cosmological models in scalar tensor theories of gravity that describe an accelerating universe and study a family of inverse power-law potentials, for which exact solutions of the Einste…
Asteroid 2867 Steins. II. Multi-telescope visible observations, shape reconstruction, and rotational state
Jorda, L.; Lamy, P. L.; Colas, F. +14 more
Context: Asteroid 2867 Steins is the first target of the Rosetta space mission with a flyby scheduled in September 2008.
Aims: An early physical characterization is needed to optimize the flyby parameters and the science operations, and to maximize the scientific return. The aim of this article is to characterize the shape and rotational state…
A Comparison of Solar Open Field Regions Found by Type III Radio Bursts and the Potential Field Source Surface Model
DeRosa, Marc L.; Nitta, Nariaki V.
For heliophysics research and applications, the potential field source surface (PFSS) model is often employed to extrapolate the photospheric magnetic field to the corona. In an attempt to evaluate the performance of the PFSS model, we compare the computed footpoints of the heliospheric magnetic field with the locations of flares associated with t…
Supernova Remnants in the AKARI IRC Survey of the Large Magellanic Cloud
Onaka, Takashi; Ita, Yoshifusa; Seok, Ji Yeon +9 more
We present a near- to mid-infared study of supernova remnants (SNRs) using the AKARI IRC Survey of the Large Magellanic Cloud (LMC). The LMC survey observed about a10 square degree area of the LMC in five bands centered at 3, 7, 11, 15, and 24 µm using the Infrared Camera (IRC) aboard AKARI. The number of SNRs in the survey area is 21, which…
Non-thermal bremsstrahlung from supernova remnants and the effect of Coulomb losses
Vink, Jacco
Aims: We investigate the shape of the electron cosmic ray spectrum in the range up to ~1000 keV, assuming that the acceleration process at the shock results in a power law in momentum, and that downstream of the shock the spectrum is affected by Coulomb interactions with background electrons only.
Methods: In the non-relativistic regime one ca…
Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause
Pierrard, V.; Glassmeier, K. H.; Blomberg, L. G. +4 more
A case study of a poloidal ULF pulsation near the dayside plasmapause is presented based on Cluster observations of magnetic and electric fields. The pulsation is detected close to the magnetic equatorial plane at L shells L=[4.4, 4.6] and oscillates with a frequency of f=23 mHz. Investigating the wave energy flux reveals the standing wave nature …
On the morphology of sigma-drop galaxies
Knapen, J. H.; Comerón, S.; Beckman, J. E.
Context: Local reductions of the stellar velocity dispersion in the central regions of galaxies are known as sigma-drops (σ-drops). Knowing the origin of these features can lead to better understanding of inner galactic dynamics.
Aims: We present a sample of 20 σ-drop galaxies matched with a control sample of galaxies without σ-drop in order t…
Environmental effects on the globular cluster blue straggler population: a statistical approach
Moretti, A.; Piotto, G.; de Angeli, F.
Context: Blue stragglers stars (BSS) constitute an ubiquitous population of objects whose origin involves both dynamical and stellar evolution.
Aims: In this paper we study the properties of a catalogue of BSS extracted from an homogeneous sample of 56 Galactic globular clusters (GC) observed with Wide-Field Planetary Camera 2 on board of Hubb…