Search Publications
An analysis of the Ap binary HD 81009
Wade, G. A.; Bohlender, D. A.; Mathys, G. +3 more
We present a detailed investigation of the orbit, component characteristics and magnetic field of the single spectrum (SB1), visual Ap binary HD 81009. By simultaneously modeling new and archival radial velocity measurements and new and archival speckle interferometric measurements (obtained with the CHARA array) we obtain a unique model of the or…
Orbital period variation in close binaries from radial velocity data and magnetic activity cycles. I. AR Lacertae: The test case
Lanza, A. F.; Frasca, A.
We check the possibility of detecting orbital period changes in non-eclipsing close binaries by means of spectroscopic orbit determinations. In order to test our method, we selected the eclipsing binary AR Lacertae for which the spectroscopically determined epochs of superior conjuctions can be compared with those provided by the light minima phot…
The bright 175 mu m knots of the Andromeda galaxy
Lemke, D.; Haas, M.; Schmidtobreick, L.
Discrete far-infrared (FIR) sources of M 31 are identified in the ISO 175 mu m map and characterized via their FIR colours, luminosities and masses in order to reveal the nature of these knots. With our spatial resolution of 300 pc at M 31's distance, the FIR knots are clearly seen as extended objects with a mean size of about 800 pc. Since this a…
Decaying post-flare loops system observed by SOHO/CDS and Yohkoh/SXT
Heinzel, P.; Fludra, A.; Varady, M.
The results of an analysis of joint SOHO/CDS and Yohkoh/SXT observations of a decaying post-flare loops system with a rapid time evolution are presented. The loop system was a remnant of a small single loop flare (GOES class C2.9). Using the CDS raster taken in several EUV lines with different formation temperatures and a temperature sensitive lin…
ORFEUS II echelle spectra: on the influence of iron-group line blanketing in the Far-UV spectral range of hot subdwarfs
Deetjen, J. L.
We present an analysis of the subdwarf O star Feige 67 with a fully metal-line blanketed NLTE model atmosphere based on high-resolution Far-UV (912-2000 Å) and Near-UV (2000-3400 Å) spectra from new ORFEUS II echelle observations and the IUE final archive. The Far- UV spectra are heavily blanketed by iron and nickel lines, preventing the detection…
Solar equatorial plasma rotation: a comparison of different spectroscopic measurements
Schmidt, W.; Wöhl, H.
We present solar equatorial rotation velocities measured with two different spectral lines (Fe I 557.6 nm and Ni I 676.8 nm) and two different spectrometers at the German Vacuum Tower Telescope (VTT) on Tenerife. The `classical' sidereal solar equatorial rotation velocity of about 2000 m/s has been confirmed. The results are compared with those fr…
Shaping of elliptical planetary nebulae. The influence of dust-driven winds of AGB stars
Höfner, Susanne; Reimers, Christian; Dorfi, Ernst A.
We calculated a model to investigate the shaping of a PN morphological group, i.e. elliptical PNe, in terms of the so-called Interacting Winds Model. The angle-dependent mass loss generated by a dust driven wind due to a slow rotation of the AGB star is an effective way for the shaping of PNe. The matter which is more concentrated in the equatoria…
Spectroscopic confirmation of a white dwarf companion to the B star 16 Dra
Barstow, M. A.; Burleigh, M. R.
Using an Extreme Ultraviolet Explorer (EUVE) spectrum, we confirm the identification of a white dwarf companion to the B9.5V star 16 Dra (HD150100), and constrain its surface temperature to lie between 29,000 K and 35,000 K. This is the third B star + white dwarf non-interacting Sirius-type binary to be confirmed, after y Pup (HR2875, HD59635) and…
Vertical motions in the disk of NGC 5668 as seen with optical Fabry-Perot spectroscopy
Battaner, E.; Jiménez-Vicente, J.
We have observed the nearly face-on spiral galaxy NGC 5668 with the TAURUS II Fabry-Perot interferometer at the William Herschel Telescope using the Hα line to study the kinematics of the ionized gas. From the extracted data cube we construct intensity, velocity and velocity dispersion maps. We calculate the rotation curve in the innermost 2 arcmi…
Kinematics and morphology of the narrow-line region in the Seyfert galaxy NGC 1386
Dietrich, M.; Wagner, S. J.; Rossa, J.
We present a high spatial and spectral resolution 2-D echelle spectrogram of the Narrow-Line Region in the Seyfert 2 galaxy