Search Publications
On the Anomalous Red Giant Branch of the Globular Cluster ω Centauri
Sterken, C.; Prada Moroni, P. G.; Degl'Innocenti, S. +17 more
We present three different optical and near-infrared (NIR) data sets for evolved stars in the Galactic globular cluster ω Centauri. The comparison between observations and homogeneous sets of stellar isochrones and zero-age horizontal branches provides two reasonable fits. Both of them suggest that the so-called anomalous branch has a metal-interm…
On the Fractal Structure of Solar Supergranulation
Singh, Jagdev; Paniveni, U.; Krishan, V. +1 more
We employ fractal analysis to study the complexity of supergranulation structure using the Solar and Heliospheric Observatory (SOHO) dopplergrams. Our data consists of 200 visually selected supergranular cells, for which we find a broad, slightly asymmetric dispersion in the size distribution, with the most probable size around 31.9 Mm. From the a…
Very Large Array and SOHO Observations of Type I Noise Storms, Large-Scale Loops and Magnetic Restructuring in the Corona
Willson, Robert F.
Very Large Array (VLA) observations at 91-cm wavelength are combined with data from the SOHO EIT, MDI and LASCO and used to study the evolving coronal magnetic environment in which Type I noise storms and large-scale coronal loops occur. On one day, we have shown the early evolution of a coronal mass ejection (CME) in projection in the disk by tra…
Spatial Distribution and North-South Asymmetry of Coronal Bright Points from Mid-1998 to Mid-1999
Temmer, M.; Vršnak, B.; Wöhl, H. +5 more
Full-disc full-resolution (FDFR) solar images obtained with the Extreme Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) were used to analyse the centre-to-limb function and latitudinal distribution of coronal bright points. The results obtained with the interactive and the automatic method, as well as for…
Is the Bursting Radio Source GCRT J1745-3009 a Double Neutron Star Binary?
Treves, A.; Possenti, A.; Turolla, R.
GCRT J1745-3009 is a peculiar transient radio source in the direction of the Galactic center. It was observed to emit a series of ~1 Jy bursts at 0.33 GHz, with a typical duration of ~10 minutes and at apparently regular intervals of ~77 minutes. If the source is indeed at the distance of the Galactic center, as seems likely, we show that its obse…
Energetic particle fluxes in the exterior cusp and the high-latitude dayside magnetosphere: statistical results from the Cluster/RAPID instrument
Asikainen, T.; Mursula, K.
In this paper we study the fluxes of energetic protons (30 4000 keV) and electrons (20 400 keV) in the exterior cusp and in the adjacent high-latitude dayside plasma sheet (HLPS) with the Cluster/RAPID instrument. Using two sample orbits we demonstrate that the Cluster observations at high latitudes can be dramatically different because the satell…
Flare X-Ray Observations of AB Doradus: Evidence of Stellar Coronal Opacity
Mathioudakis, M.; Keenan, F. P.; Matranga, M. +1 more
X-ray spectra of the late-type star AB Dor obtained with the XMM-Newton satellite are analyzed. AB Dor was particularly active during the observations. An emission measure reconstruction technique is employed to analyze flare and quiescent spectra, with emphasis on the Fe XVII 15-17 Å wavelength region. The Fe XVII 16.78 Å/15.01 Å line ratio incre…
A nightside source of Saturn's kilometric radiation: Evidence for an inner magnetosphere energy driver
Gurnett, D. A.; Kurth, W. S.; Cecconi, B. +5 more
During Cassini's orbit insertion about Saturn, the spacecraft passed within 1.4 Rs of the planet passing from dayside into the nightside region. During this nightside passage, the onboard Radio and Plasma Wave (RPWS) instrument surprisingly detected Saturn kilometric radiation (SKR). Prior to this encounter, it was believed that SKR ori…
Large-scale activity in solar eruptive events of October November 2003 observed from SOHO/EIT data
Grechnev, V. V.; Chertok, I. M.
Large-scale solar disturbances associated with powerful flares and coronal mass ejections (CMEs) during two passages of a grand system of three active regions in October November 2003 are analyzed using data obtained with the SOHO/EIT EUV telescope. Dimmings (transient coronal holes) and, to a lesser extent, coronal waves (traveling emitting front…
Stagnation Flow in Thin Streamer Boundaries
Nerney, Steven; Suess, Steven T.
Slow solar wind is believed to arise in the legs or near the cusp of streamers, inside the brightness boundary. In an earlier study, we used an analytic model of flow in this layer to analyze the effect of the magnetic field on the geometry of the flow. That study successfully described those conditions that can lead to a decrease of the flow spee…