Search Publications
Are There Field-Free Gaps near τ = 1 in Sunspot Penumbrae?
Solanki, S. K.; Borrero, J. M.
The vertical stratification of the magnetic field strength in sunspot penumbrae is investigated by means of spectropolarimetric observations at high spatial resolution from the Hinode spacecraft. Assuming that the magnetic field changes linearly with optical depth we find that, in those regions where the magnetic field is more inclined and the Eve…
A magnetic null geometry reconstructed from Cluster spacecraft observations
Escoubet, C. P.; Dandouras, I.; Glassmeier, K. -H. +15 more
This paper reports for the first time the identification of a magnetic structure around a magnetic null in a magnetic reconnection region in the magnetotail. Magnetic reconnection is one of the fundamental processes in astrophysical and solar-terrestrial plasmas. Though the concept of reconnection has been studied for many years, the process that …
INTEGRAL and Swift/XRT observations of the SFXT IGR J16479-4514: from quiescence to fast flaring activity
Masetti, N.; Bird, A. J.; Ubertini, P. +6 more
Context: The fast X-ray transient IGR J16479-4514 is known to display flares typically lasting a few hours. Recently, its counterpart has been identified with a supergiant star, therefore the source can be classified as a member of the newly discovered class of Supergiant Fast X-ray Transients (SFXTs); specifically, it is the one with the highest …
Abundance variations and first ionization potential trends during large stellar flares
Nordon, R.; Behar, E.
Context: In the solar corona, elements of low first ionization potential (FIP ⪉ 10 eV) are enriched relative to their abundances in the photosphere, while high-FIP abundances remain unchanged. This was labeled as the Solar FIP effect. High-resolution X-ray spectroscopy has revealed that active stellar coronae show an opposite effect, which was lab…
The properties of penumbral microjets inclination
Katsukawa, Y.; Jurčák, J.
Aims: We investigate the dependence of penumbral microjets inclination on the position within penumbra.
Methods: The high cadence observations taken on 10 November 2006 with the Hinode satellite through the Ca II H and G-band filters were analysed to determine the inclination of penumbral microjets. The results were then compared with the incl…
Observations of recurrent cosmic ray decreases during solar cycles 22 and 23
Gómez-Herrero, R.; Heber, B.; Müller-Mellin, R. +5 more
During solar cycle 22, the modulation of several hundred MeV galactic cosmic rays (GCRs) by recurrent and transient cosmic ray decreases was observed by the Ulysses spacecraft on its descent towards the solar south pole. In solar cycle 23, Ulysses repeated this trajectory segment during a similar phase of the solar cycle, but with opposite heliosp…
The environments of SLACS gravitational lenses
Auger, M. W.
We report on an investigation of the environments of the Sloan Lens ACS Survey (SLACS) sample of gravitational lenses. The local and global environments of the lenses are characterized using Sloan Digital Sky Survey (SDSS) photometry and, when available, spectroscopy. We find that the lens systems that are best modelled with steeper than isotherma…
Modeling of Solar Wind in the Coronal Funnel with Mass and Energy Supplied at 5 Mm
Tu, C. -Y.; Marsch, E.; He, J. -S.
The origin of the solar wind is a long-standing issue in both observational and theoretical studies. To understand how and where in the solar atmosphere the mass and energy of the solar wind are supplied is very important. Previous observation suggests a scenario in which the fast solar wind originates at heights above 5 Mm in the magnetically ope…
Speckle observations with PISCO in Merate: IV. Astrometric measurements of visual binaries in 2005
Scardia, M.; Prieur, J. -L.; Pansecchi, L. +6 more
We present relative astrometric measurements of visual binaries made during the second semester of 2005, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. The purpose of this long term program is to impro…
Measuring supermassive black holes with gas kinematics. II. The LINERs IC 989 , NGC 5077 , and NGC 6500
Marconi, A.; Capetti, A.; de Francesco, G.
We present results from a kinematical study of the gas in the nucleus of a sample of three LINER galaxies, obtained from archival HST/STIS long-slit spectra. We found that, while for the elliptical galaxy NGC 5077, the observed velocity curves are consistent with gas in regular rotation around the galaxy's center, this is not the case for the two …