Search Publications
On the radial distribution of white dwarfs in the Galactic globular cluster omega Cen
Prada Moroni, P. G.; Degl'Innocenti, S.; Marchetti, E. +14 more
We present deep and accurate photometry (F435W, F625W, F658N) of the Galactic Globular Cluster omega Cen collected with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). We identified ≈ 6,500 white dwarf (WD) candidates and compared their radial distribution with that of Main Sequence (MS) stars. We found a mild evid…
Study of waves in the magnetotail region with cluster and DSP
Balogh, A.; Zhang, T. L.; Klecker, B. +6 more
The study of the neutral sheet is of fundamental importance in understanding the dynamics of the Earth’s magnetosphere. From the earliest observation of the magnetotail, it has been found that the neutral sheet frequently appears to be in motion due to changing solar wind conditions and geomagnetic activity. Multiple crossings of the neutral sheet…
Distribution of coronal heating in a solar active region
Gontikakis, C.; Contopoulos, I.; Dara, H. C.
Aims: We investigate the distribution of heating of coronal loops in a non-flaring solar active region, using a simple electrodynamic model: the random displacements of the loop footpoints, caused by photospheric plasma motions, generate electric potential differences between the footpoints and, as a result, electric currents flow along the loops,…
Multi-instrument observations of a large scale Pc4 pulsation
Lucek, E. A.; Yeoman, T. K.; Clausen, L. B. N. +1 more
On 7 November 2005 various ground based and spaced based instruments registered five wave packets with frequencies in the Pc4 range. The most prominent of the five wave packets was observed in ground based magnetometer data spanning almost all latitudes on the dayside magnetosphere. The propagation from the dayside into the tail is deduced from Po…
Observations of anomalous transport of energetic electrons in the heliosphere
Perri, S.; Zimbardo, G.
We study the propagation of energetic particles, accelerated by interplanetary shock waves, upstream of the shock, considering the possibility of having anomalous transport. The theoretical treatment of the anomalous transport is developed via the propagator formalism, considering that in the case of a superdiffusive transport the propagator has p…
Large-Scale Coronal Density and Abundance Structures and Their Association with Magnetic Field Structure
Raymond, John C.; Riley, Pete; Li, Jing +1 more
We construct subsynoptic maps of the ultraviolet-line fluxes, electron density, and elemental abundances for an east limb corona at 1.63 solar radii from 2000 September 20 to October 1. The data, covering position angles of 85°-126°, were taken from the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SO…
Spatial and Temporal Noise in Solar EUV Observations
Delouille, V.; Hochedez, J. -F.; Chainais, P.
Solar telescopes will never be able to resolve the smallest events at their intrinsic physical scales. Pixel signals recorded by SOHO/(CDS, EIT, SUMER), STEREO/SECCHI/ EUVI, TRACE, SDO/AIA, and even by the future Solar Orbiter EUI/HRI contain an inherent "spatial noise" since they represent an average of the solar signal present at subpixel scales…
Spectroscopic distances of 28 nearby star candidates
Stecklum, B.; Jahreiß, H.; Meusinger, H. +1 more
Aims: Twenty eight hitherto neglected candidates for the Catalogue of Nearby Stars (CNS) were investigated to verify their classification and to improve their distance estimates. All targets had at least a preliminary status of being nearby dwarf stars based on their large proper motions and relatively faint magnitudes. Better photometric and/or s…
Gravi-Magnetic Rotators in Cataclysmic Binary Stars
Andronov, I. L.
Various astrophysical processes are reviewed, which take place in the classical, asynchronous and intermediate polars, as well as the results of their theoretical and observational investigations according to the international program ``Inter-Longitude Astronomy''. The uniqueness of the class of polars is the largest arbitrary influence of the mag…
New flare model using recent measurements of the solar ultraviolet irradiance
Chamberlin, Phillip C.; Woods, Thomas N.; Eparvier, Francis G.
The solar photon output from the Sun, which was once thought to be constant, varies considerably over time scales from seconds during solar flares to years due to the solar cycle. This is especially true in the wavelengths shorter than 190 nm. These variations cause significant deviations in the Earth and space environment on similar time scales, …