Search Publications
HST observations of Cygnus A: circumnuclear effects of a powerful jet ?
Sparks, W. B.; Macchetto, F.; Miley, G. K. +1 more
We present 340nm continuum and [OII] line images of the nuclear region of the radio galaxy Cygnus A at 0".1 resolution. At this high resolution the northwestern of the two nuclear components is resolved into two separate, line emitting subcomponents, and the radio jet points accurately between them. This suggests that the radio jet has blasted a p…
HST observations of the core of globular cluster NGC 6397
Boksenberg, A.; Burgarella, D.; Barbieri, C. +17 more
The core of the nearby and very concentrated globular cluster NGC 6397 has been imaged through the f/96-F140W, f/48-F140W, f/96-F210M, and f/48-F220W ultraviolet filters of the Faint Object Camera on board the Hubble Space Telescope down to an ultraviolet limiting magnitude of ~19. The most interesting objects in the field of view are six very bri…
UV variability of IRAS 13224-3809, a rapidly X-ray variable far-infrared luminous galaxy.
Mas-Hesse, J. M.; Boller, Th.; Rodriguez-Pascual, P. M. +1 more
We have detected strong Lyα line variability in IRAS 13224-3809, a very luminous IRAS galaxy known to be a strong and rapidly variable soft X-ray emitter. While a relatively broad Lyα component (FWHM ~ 5000 km/s) remains essentially constant along three IUE observations performed between January and May 1993, the initially strong narrow core compo…
Soft and hard X-ray observations of 4U 1626-67
Mavromatakis, F.
The accreting binary pulsar 4U 1626-67 was detected in the soft X-rays by ROSAT in the course of the All-Sky survey at an average luminosity of 1.5 x 10^35^ d^2^_5 kpc_ erg/s, the lowest observed so far. The ROSAT spectrum is better fitted by a bremsstrahlung model rather than a blackbody spectrum. The source spectrum appears to be absorbed by a c…
HST observations of 3C 449: discovery of an extended nuclear disk and of possible optical jets.
Capetti, A.; Sparks, W. B.; Macchetto, F. +1 more
We present the results of HST observations of the radio-galaxy 3C 449. Observations were taken with the Faint Object Camera using the F372M and F342W filters both of which include the redshifted [OII]λλ3726, 3729 lines. Around the nucleus of 3C 449, we detected a ring with a projected diameter of 0.4" which corresponds to about 200 pc. Our analysi…
The expanding envelope of ζ Aurigae.
Baade, R.; Kirsch, T.
We redetermine the basic parameters of the circumstellar envelope of ζ Aur by means of the UV binary technique. The analysis consists of comparing IUE observations with theoretical profiles calculated with a newly developed 2-D radiative transfer code. We show that the B-type secondary causes an open HII region. The electron temperature and the io…
Evidence for ellipsoidal variations of the Be star binary HD 50123.
Sterken, C.; Vogt, N.; Mennickent, R.
On the basis of 8 years of photoelectric monitoring in the Stroemgren system we were able to establish that HD50123 is an interacting binary consisting of a B6Ve primary and an early K giant secondary which fills its Roche lobe. The orbital period is 28.601days. The secondary contributes considerably to the flux in the y and b bands, in which the …
Soft X-ray observations of EXO 2030+375
Mavromatakis, F.
The X-ray transient pulsar EXO 2030+375 was observed by ROSAT in November 1990 during the All-Sky survey. The observation took place very close to periastron passage and the source was clearly visible over an interval of two days. The average flux level suggests an active companion star although the ROSAT flux is lower than the observed flux in mo…
Ultraviolet variations in the spectrum of the visible central star of Abell 35.
Jasniewicz, G.; Lapierre, G.; Monier, R.
We report on simultaneous IUE and photometric observations carried out in March 1992 of the G8IV star BD-22 3467 located at the centre of the planetary nebula Abell 35. The main feature of the IUE low resolution spectra is a strong Mg II emission, which is common in fairly close binaries. Meanwhile no variations of the hot companion were detected …
A preliminary list of stars from TYCHO observations
Bastian, U.; van Leeuwen, F.; Petersen, C. +6 more
The final Tycho Catalog will be a major source of astrometric standard stars when it will be published, in 1997. While the Tycho positions with their full accuracy will only be available at the end of the data reduction, it is already possible to derive a preliminary list of about one million stars from the Tycho Input Catalogue (TIC) which have a…