Search Publications
Integral field spectroscopy of the radio galaxy 3C 171
Durret, F.; Petitjean, P.; Márquez, I. +1 more
We have performed integral field spectroscopy of the radio galaxy {3C 171} (redshift z=0.238) with the TIGER instrument at the Canada France Hawaii telescope in the Hβ -[OIII]4959-5007 wavelength region. We present the reconstructed Hβ and [OIII] images and compare them to the HST and radio maps. We discuss the variations of the [OIII]/Hβ line rat…
Rotational modulation and flares on RS CVn and BY Dra stars. XX. Photometry and spectroscopy of CC Eri in late 1989
Amado, P. J.; Doyle, J. G.; Mathioudakis, M. +4 more
The active flaring binary CC Eri was studied via multi-wavelength observations involving multi-based photometry and ground- and space-based spectroscopy. Combining early spectroscopic data with the present implies an orbital period of P=1.5615 days. Furthermore, the spectroscopic data suggests spectral types of K7 and M3 for the system. The optica…
Spiral and irregular galaxies in the Hubble Deep Field North. Comparison with early types and implications for the global SFR density
Rodighiero, G.; Franceschini, A.; Granato, G. L. +2 more
We analyze a morphologically-selected complete sample of 52 late-type (spiral and irregular) galaxies in the Hubble Deep Field North with total K-magnitudes brighter than K=20.47 and typical redshifts z ~ 0.5 to 1.4. This sample exploits in particular the ultimate imaging quality achieved by HST in this field, allowing us to clearly disentangle th…
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…