Search Publications
The solar ultraviolet spectrum from 1200 Å to 1560 Å: a radiometric comparison between SUMER/SOHO and SOLSTICE/UARS
Wilhelm, K.; Curdt, W.; Schühle, U. +3 more
After short descriptions of the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrometer onboard SOHO (the Solar and Heliospheric Observatory) and the SOLSTICE (Solar-Stellar Irradiance Comparison Experiment) spectrometer on UARS (the Upper Atmosphere Research Satellite), a radiometric comparison is carried out of solar irradiance …
Evolved, single, slowly rotating ... but magnetically active. The G8-giant HR 1362 = EK Eridani revisited
Strassmeier, K. G.; Henry, G. W.; Hall, D. S. +1 more
We rediscuss the unusual case of the slowly rotating late-type giant HR 1362, which exhibits a very unusual high level of magnetic activity. New BVRI photometry from two robotic telescopes from 1991 through 1998 together with previously published photometric data gives a very precise photometric period of 306.9+/-0.4 days. With the aid of high-res…
Vertical motion and expansion of the Gould Belt
Comerón, F.
The kinematics of the Gould Belt is considered taking into account its orientation in space and the motions of its member stars parallel and perpendicular to the galactic plane. An analysis of Hipparcos data for these stars, complemented with published radial velocities, shows that there is a mild gradient along the galactic plane in the velocity …
ISO spectroscopy of shocked gas in the vicinity of T Tauri
Spinoglio, L.; van Dishoeck, E. F.; Tielens, A. G. G. M. +2 more
We present the results of ISO SWS and LWS spectroscopy of the young binary system T Tau. The spectrum shows absorption features due to H_2O ice, CO_2 ice, gas-phase CO and amorphous silicate dust, which we attribute to the envelope of T Tau S. We derive an extinction of A_V = 17.4m +/- 0.6m towards this source. Detected emission lines from H i ari…
ISO. Monitoring the mass loss of a very late Helium flash star
Blommaert, J. A. D. L.; Asplund, M.; Kimeswenger, S. +3 more
We present ISOCAM observations of Sakurai's object (V4334 Sgr) covering the wavelength range of 4 to 15 mu m in seven filters. The photometry shows that in the period from February 1997 to February 1998 the flux over the whole wavelength range has increased by a factor of about ten. Combined with ground-based data we conclude that this increase is…
New Zr II oscillator strengths and the zirconium conflict in the HgMn star chi LUPI
Leckrone, D. S.; Sikström, C. M.; Lundberg, H. +4 more
Lifetimes on the sub-nanosecond scale for the levels v(2) D_{3/2}, v(2) F_{3/2} and v(2) F_{5/2} in the 4d5s5p configuration in Zr II have been measured, using the method of laser-induced fluorescence. Combined with branching fractions obtained with the Lund Ultraviolet (UV) Fourier Transform Spectrometer (FTS), experimental oscillator strengths h…
Center-to-limb variation of the solar oscillation. New results from MDI data
Schmidt, W.; Stix, M.; Wöhl, H.
{Using 17 hours of full-disk MDI Doppler data we have investigated the center-to-limb variation of the oscillatory wave spectrum of the solar photosphere. Power distributions in the k_hnu -plane are calculated for fields of 20(deg) x 20(deg) on the Sun, centered at every 10(deg) heliographic latitude. From the center-to-limb variation of the power…
The ``Papillon'' nebula: a compact H bt II blob in the LMC resolved by it HST
Heydari-Malayeri, M.; Charmandaris, V.; Zinnecker, H. +2 more
We present high spatial resolution HST imaging of the LMC compact {H ii} region N159-5. This high excitation blob is revealed to be a ``papillon'' or butterfly-shaped ionized nebula with the ``wings'' separated by { ~ },2''.3 (0.6 pc). Two subarcsecond features resembling a ``smoke ring'' and a ``globule'' are detected in the wings, the origin of …
The absolute magnitudes of RR Lyrae stars from BT HIPPARCOS parallaxes parallaxes
Salaris, M.; Groenewegen, M. A. T.
Using the method of ``reduced parallaxes'' for the Halo RR Lyrae stars in the hipparcos catalogue we derive a zero point of 0.77 +/- 0.26 mag for an assumed slope of 0.18 in the M_V-[Fe/H] relation. This is 0.28 magnitude brighter than the value Fernley et al. (1998a) derived by employing the method of statistical parallax for the identical sample…
Infrared spectra of young stars in Chamaeleon
Henning, Th.; Lemke, D.; Pfau, W. +2 more
We present infrared spectra covering the wavelength ranges 3.1-5.0 mu m and 5.8-11.6 mu m for 9 young stars located in the Chamaeleon I dark cloud. The spectra were taken with the spectrophotometer of ISO (ISOPHOT-S). The spectra of three stars which illuminate reflection nebulae are dominated by the series of strong emission features generally as…