Search Publications
On the relationship between shift and intensity of ultraviolet lines in coronal holes and the quiet Sun
Solanki, S. K.; Schühle, U.; Rüedi, I. +1 more
We study the relationship between wavelength shifts and intensities of chromospheric, transition-region and coronal ultraviolet emission lines in polar coronal holes and in the normal quiet Sun using SUMER data. Within coronal holes almost all the lines showing the network and formed above 30 000 K show a correlation between blueshifts and brightn…
Long-term photometry of the Wolf-Rayet stars WR 137, WR 140, WR 148, and WR 153
Altmann, M.; Panov, K. P.; Seggewiss, W.
In 1991, a long term UBV-photometry campaign of four Wolf-Rayet stars was started using the 60 cm telescope of the National Astronomical Observatory Rozhen, Bulgaria. Here we report on our observational results and discuss the light variations. The star WR 137 was observed during 1991 - 1998. No indications of eclipses were found, though random li…
Clustering of galaxies at faint magnitudes
Freudling, W.; Fynbo, J. U.; Möller, P.
Significant uncertainties exist in the measured amplitude of the angular two-point correlation function of galaxies at magnitudes I~26 and fainter. Published results from HST and ground-based galaxy catalogs seem to differ by as much as a factor of 3, and it is not clear whether the correlation amplitude as a function of magnitude increases or dec…
New infrared object in the field of the SMC cluster NGC 330
Sauvage, M.; Tanabé, T.; Vansevičius, V. +1 more
We report ISO (Infrared Space Observatory) observations of a new infrared source discovered in the vicinity of the young populous cluster NGC 330 in the Small Magellanic Cloud. The object was observed with ISOCAM at 4.5, 6.75 and 11.5 mu m and shows a prominent mid-infrared excess, indicating the presence of a dust shell. The available observation…
The Hipparcos, Tycho, TRC, and ACT catalogues --- A whole sky comparison of the proper motions
Hoogerwerf, R.; Blaauw, A.
We present a whole sky comparison of the proper motions contained in the Hipparcos Catalogue, the Tycho Catalogue, the Tycho Reference Catalogue (TRC), and the Astrographic Catalogue plus Tycho Reference Catalogue (ACT). The catalogues are compared in the 20 declination zones defined by the original Carte du Ciel project. We find that (1) the prop…
The nature of the DAB white dwarf HS 0209+0832
Reimers, D.; Wolff, B.; Jordan, S. +1 more
The DAB white dwarf
The nearby M-dwarf system Gliese 866 revisited
Franz, O. G.; Leinert, Ch.; Jahreiß, H. +3 more
We present an improved orbit determination for the visual pair in the M-dwarf triple system
IRAS 03201+5459: a C-rich AGB star with silicate absorption
Szczerba, R.; Jiang, B. W.; Deguchi, S.
IRAS 03201+5459 is a late-type star with a circumstellar envelope according to its IRAS color. It has no identification at optical or near-infrared wavelengths. A full ISO-SWS spectrum between 2.3 and 43 mu m was taken at a resolution of about ~ 300 to investigate its nature. The spectrum shows the 9.7 mu m feature in absorption, usually seen in O…
No QPO time lags from Sco X-1 as seen with EXOSAT: a comparison with Cyg X-2
Kuulkers, Erik; van der Klis, Michiel; Lamb, Frederick K. +2 more
We have measured the phase-delay and rms amplitude spectra of Cyg X-2 and Sco X-1. Using EXOSAT data from the normal branch of Cyg X-2 we confirm earlier (Ginga) results, showing that at an energy near 6 keV there is both a minimum in the quasi-periodic oscillations QPO rms amplitude spectrum and a 150deg phase jump in the QPO phase-del…
Long-duration cosmic ray modulation from a Sun-Earth L1 orbit
Harrison, R. A.; Pike, C. D.
We analyse cosmic ray hits impacting the detector system of the Coronal Diagnostic Spectrometer aboard the Solar and Heliospheric Observatory spacecraft. These observations allow us to study the modulation of cosmic rays over a 4 year period (1996-2000) running from solar minimum to maximum, from a Sun-Earth L1 Lagrangian orbit. The modulation, at…