Search Publications
Misleading results from low-resolution spectroscopy: From galaxy interstellar medium chemistry to cosmic star formation density
Flores, H.; Hammer, F.; Gruel, N. +2 more
Low resolution spectroscopy (R=150) from the Canada-France-Redshift Survey (CFRS) revealed intriguing properties for low redshift galaxies (z ≤0.3): nearly half of their spectra show prominent Hα emission lines, but no Hβ emission line and barely detected [O II] λ3727, and [O III] λ5007 lines. We call these objects ``CFRS Hα-single" galaxies and h…
X-ray variability of the Narrow Line Seyfert 1 Galaxy PKS 0558-504
Arévalo, P.; Brinkmann, W.; Gliozzi, M. +1 more
We present results from several XMM-Newton observations of the radio-loud Narrow-line Seyfert 1 galaxy (NLS1) PKS 0558-504. We find evidence for strong and persistent X-ray variability, both on short and long time-scales. On short time scales of ⪆2 hours the source varies smoothly by 15-20%; long-term variations by a factor ⪆2 could not be resolve…
Detection of Saturnian X-ray emission with XMM-Newton
Schmitt, J. H. M. M.; Ness, J. -U.; Robrade, J.
The giant planet Saturn was observed by XMM-Newton in September 2002. We present and analyse these XMM-Newton observations and compare our findings to the Chandra observations of Saturn. Contamination of the XMM-Newton data by optical light is found to be severe in the medium and thin filters, but with the thick filter all optical light is suffici…
STIS observations of FLIERs in NGC 7662
Balick, B.; Corradi, R. L. M.; Patriarchi, P. +1 more
We observed the planetary nebula NGC 7662 with STIS on board the HST to investigate the physical conditions in the microstructures within the nebula at high spatial resolution and to closely examine the physical conditions in FLIERs. We aim to reveal spectroscopic differences in small scale structures moving at about the same velocity as the surro…
Dynamics of the fast solar tachocline. II. Migrating field
Forgács-Dajka, E.
We present detailed numerical calculations of the fast solar tachocline based on the assumption that the dynamo field dominates over the dynamics of the tachocline. In the present paper of the series, we focus on three shortfalls of the earlier models. First, instead of the simple oscillating dipole poloidal field we study the more general magneti…
The field surrounding NGC 7603: Cosmological or non-cosmological redshifts?
López-Corredoira, M.; Gutiérrez, C. M.
We present new observations of the field surrounding the Seyfert galaxy NGC 7603, where four galaxies with different redshifts - NGC 7603 (z=0.029), NGC 7603B (z=0.057) and two fainter emission line galaxies (z=0.245 and z=0.394) - are apparently connected by a narrow filament, leading to a possible case of anomalous redshift. The observations com…
Properties and nature of Be stars Dra. XXIII. Long-term variations and physical properties of κ Dra.
Harmanec, P.; Hadrava, P.; Krtička, J. +9 more
We present an analysis of new spectroscopic observations of the bright Be star
Analysis of Ulysses data: Radiation pressure effects on dust particles
Krüger, H.; Grün, E.; Wehry, A.
The objective of this paper is to illustrate the influence of the radiation pressure and the electromagnetic force on dust particles in interplanetary space. Between 1990 and 2001 62 so-called β-meteoroids (β describes the ratio of the radiation pressure force to gravity) were detected as dust particles coming from the inner solar system on hyperb…
The August 11th, 1999 CME
Koutchmy, S.; Baudin, F.; Bocchialini, K. +5 more
We present here a set of observations, space borne and ground based, at different wavelengths, of the solar corona at and after the time of the total solar eclipse of August 11{th}. It is used to consider some unusual features of the coronal dynamics related to a limb Coronal Mass Ejection (CME) observed after the total eclipse. The complementary …
Variations of the hard X-ray footpoint asymmetry in a solar flare
Siarkowski, M.; Falewicz, R.
We analysed hard and soft X-ray observations from the SXT and HXT instruments on the Yohkoh satellite of an X5.3 class flare of 25 August 2001. The most prominent features of this flare are: a fast (450 km s-1), hard (up to 90 keV) and compact X-ray moving feature, two clear footpoint sources, and loop-top emission between them. The Yoh…