Search Publications

A study of lambda Bootis type stars in the wavelength region beyond 7000 Å

Kamp, I.; Paunzen, E.; Wiesemeyer, H. +1 more

The group of lambda Bootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. One of the theories to explain the abundance pattern of these stars involves circumstellar or interstellar matter around the objects. Hence…

The Wilson-Bappu effect: A tool to determine stellar distances

Pasquini, L.; Ortolani, S.; Pace, G.

Wilson & Bappu (\cite{orig}) have shown the existence of a remarkable correlation between the width of the emission in the core of the K line of Ca II and the absolute visual magnitude of late-type stars.

Here we present a new calibration of the Wilson-Bappu effect based on a sample of 119 nearby stars. We use, for the first time, width m…

Common overabundance of ³He in high-energy solar particles

Torsti, J.; Kocharov, L.; Laivola, J.

Solar energetic particle (SEP) observations of the ERNE instrument (the Energetic and Relativistic Nuclei and Electron experiment) onboard the Solar and Heliospheric Observatory enable measurements of the ³He intensity in the high-energy range, >15 MeV nucleon^-1, with a good statistical resolution. We report an overview of…

Photospheric flows measured with TRACE II. Network formation

Roudier, T.; Krijger, J. M.

We analyse a 7 d (167 h) sequence of TRACE white-light images with 1 arcsec angular resolution taken at 1 min cadence. The TRACE resolution and the fast cadence allows us to produce maps of the horizontal flow fields with high angular (1 arcsec) and temporal resolution (5 min). The field of view of 128arcsec x 128arcsec (~93 Mm x 93 Mm) covers app…

The corona of V390 Aurigae (HD 33798)

Gondoin, P.

V390 Aurigae (HD 33798) is a rapidly rotating, lithium rich, late-type giant whose distinctive characteristics include a high X-ray luminosity observed by the XMM-Newton space observatory. Series of lines of highly ionized Fe and several Lyman lines of hydrogen-like ions and triplet lines of helium-like ions are visible in the reflection grating s…

CDS/SoHO multi-line observation of a solar active region: Detection of a hot stable loop and of a cool dynamic loop

Peres, G.; Reale, F.; Di Giorgio, S.

We analyze a space-, time- and spectral-resolved SoHO/CDS observation of the evolution of an active region over a time lapse of approximately three hours in various spectral lines emitted in the interval of temperature 1.3 x 10⁴ < T < 2.5 x 10⁶ K. We identify and characterize two structures of interest: a longer coronal…

First results from TOO observations of the Aql X-1 field with INTEGRAL

Lutovinov, A.; Molkov, S.; Grebenev, S.

We present results of observations of the Aql X-1 field performed in March-April 2003 with the INTEGRAL observatory. This TOO (Target Of Opportunity) INTEGRAL observations was initiated upon receiving an indication from the ASM/RXTE that the source started an outburst. Thirteen X-ray sources were detected by the INTEGRAL imagers, JEM-X and IBIS, d…

Neutron-induced nuclear reactions and degradation in germanium detectors

Cordier, B.; Jean, P.; von Ballmoos, P. +15 more

We have measured cross sections of neutron-induced nuclear reactions leading to the delayed production of gamma -ray lines similar to the ones of astrophysical interest. Conclusions were drawn concerning the expected background in the ²⁶Al 1809 keV line and the ⁷Be 478 keV line in SPI. The neutron-induced degradation of Ge de…

Status of the Integral/IBIS telescope modeling and of the response matrices generation

Goldoni, P.; Malaguti, G.; Bird, A. J. +8 more

The main objective of the IBIS modeling activities is the generation of the IBIS spectral response matrices. This generation has been done step by step by firstly constructing a ``calibrated model" of each IBIS sub-system. A ``calibrated model" is defined as a GEANT Monte-Carlo model, further checked by intensive corresponding calibration. These c…

Observation of GRB 030131 with the INTEGRAL satellite

Pian, E.; Frontera, F.; Hurley, K. +13 more

A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted ~ 150 s, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS ins…