Search Publications
Variability of the EUV quiet Sun emission and reference spectrum using SUMER
Kretzschmar, M.; Lilensten, J.; Aboudarham, J.
This paper aims to build a quiet Sun EUV reference spectrum from the SOHO - SUMER database. We make use of 750 quiet Sun spectra spread over a large range of solar activity. They are carefully calibrated both in terms of frequency and intensity. The data do not show any noticeable variations versus the solar activity. This allows us to build a qui…
ISO deep far-infrared survey in the ``Lockman Hole''. III. Catalogs and source counts at 90 & 170 µm
Sanders, D. B.; Kawara, K.; Taniguchi, Y. +7 more
We present the catalogs and source counts for the C90 (reference wavelength of 90 µm) and C160 (170 µm) bands, which were extracted from our analysis of an ISO deep far-infrared survey conducted as part of the Japan/UH ISO cosmology project. The total survey area is ∼0.9 deg2 in two fields within the Lo…
Radio observations of HD 93129A: The earliest O star with the highest mass loss?
Benaglia, P.; Koribalski, B.
We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities …
X-ray emitting class I protostars in the Serpens dark cloud
Preibisch, T.
We analyze a set of three individual XMM-Newton X-ray observation of the Serpens dark cloud. In addition to the 45 sources already reported in the analysis of the first of these XMM-Newton observations by Preibisch (\cite{Preibisch2003), the complete combined data set leads to the detection of X-ray emission from four of the 19 known class I proto…
Complexity of magnetic structures: Flares and cycle phase dependence
Meunier, N.
A long data set of MDI/SOHO full-disk magnetograms is analyzed to provide a large sample of active regions. The objective is to study the variations of the fractal dimension of these structures on different time scales: in relation to their activity level (spots, flares) and during the solar cycle. First, the variations of the fractal dimension of…
Photospheric and stellar wind variability in ɛ Ori (B0 Ia)
Stahl, O.; Rivinius, Th.; Orlando, S. +4 more
We provide direct observational evidence for a link between photospheric activity and perturbations in the dense inner-most stellar wind regions of the B supergiant star ɛ Ori. The results, which are relevant to our understanding of the origin of wind structure, are based on a multi-spectral line analysis of optical time-series data secured in 199…
Solar type II and type IV radio bursts observed during 1998-2000 with the ARTEMIS-IV radiospectrograph
Hillaris, A.; Preka-Papadema, P.; Moussas, X. +9 more
A catalogue of the type II and type IV solar radio bursts in the 110-687 MHz range, observed with the radio spectrograph ARTEMIS-IV operated by the University of Athens at Thermopylae, Greece from 1998-2000 is presented. These observations are compared with the LASCO archives of Coronal Mass Ejections and the Solar Geophysical Reports of solar fla…
Flare observation of the Sun as a star by SUMER/SOHO in the hydrogen Lyman continuum
Vial, J. -C.; Wilhelm, K.; Curdt, W. +3 more
During the execution of the programme ``Sun as a star'', while the SUMER (Solar Ultraviolet Emission of Emitted Radiation)/SOHO (SOlar and Heliospheric Observatory) slit was collecting the scattered radiation from the telescope mirror far away from the solar disk image, a class X5.3/3b flare erupted on the solar disk, on 25 August 2001. During the…
Temperature dependence of the Lyman α line wings in cool hydrogen-rich white dwarf atmospheres. Application to ZZ Ceti white dwarf spectra
Kielkopf, J. F.; Allard, N. F.; Loeillet, B.
Theoretical Lyman α absorption profiles show a significant dependence on temperature of the H2 satellite at 1600 Å, whereas the H2+ satellite at 1400 Å remains unchanged. The use of opacities calculated with different approximations concerning the electric dipole transition moment (constant, dependent on interatomi…
RX J1821.6+6827: A cool cluster at z = 0.81 from the ROSAT NEP survey
Böhringer, H.; Wolter, A.; Briel, U. G. +3 more
We present an analysis of the properties of the cluster of galaxies RX J1821.6+6827, or NEP 5281, at a redshift z= 0.816 ±0.001. RX J1821.6+6827 was discovered during the optical identification of the X-ray sources in the North Ecliptic Pole (NEP) region of the ROSAT All-Sky Survey and it is the highest redshift cluster of galaxies of the NEP surv…