Search Publications
High-Precision VLBI Astrometric Observations of Radio-Emitting Stars for Detection of Extra-Solar Planets
Preston, Robert A.; Jones, Dayton L.; Lestrade, Jean-Francois +1 more
The displacement of a radio-emitting star around the barycenter of a possible planetary system can be measured by astrometric very long baseline interferometry (VLBI) observations. We have observed the radio-emitting starσ2 CrB at 8 epochs over 5 years by VLBI and fitted its 5 astrometric parameters to the observed coordinates. The post…
Progress report on the radial velocity measurement programme of Population II stars.
Bartkevičius, A.; Sperauskas, J.
The Population II radial velocity measurement programme was started in 1988 and was carried out during six observing runs. Metal-deficient stars, components of Population II visual binaries or common proper motion pairs, suspected radial velocity variables, HIPPARCOS programme stars are included into the observing programme. The measurements were …
Observations by ULYSSES of a pure electron event and its associated type III radio emission of 15 December 1990
Chaizy, P.; Pick, M.; Forsyth, R. +8 more
We describe an interplanetary electron event associated with a type III radio burst observed by Ulysses at 1.37 AU. This event was observed when the spacecraft crossed a region of strong compression between a fast and a slow solar wind stream, characterized by a relatively high density and a complex behaviour of the plasma density, magnetic field …
Multiwavelength observations of RV Tauri stars. IV. SX Centauri.
Evans, A.; Shenton, M.; Albinson, J. S. +6 more
We present ultraviolet, optical and infrared observations of the RV Tauri star SX Cen. From a fit of model atmospheres to the data we conclude that Z/Zsun_=0.033, that SX Cen has an extended atmosphere, and that the spectral types implied by the ultraviolet data close to deep minimum are consistent with those implied from optical spectr…
The Wind of EG Andromedae is not Dust Driven
Dgani, Ruth; Noriega-Crespo, Alberto; van Buren, Dave
The symbiotic star EG Andromedae has recently been the subject of several studies investigating its wind properties. Late-type giants are usually considered to have winds driven by radiation pressure on dust. Indeed, the derived wind velocity for EG Andromedae is consistent with this model. We point out here that there is no appreciable dust opaci…
The abundance of carbon in three type I planetary nebulae.
Patriarchi, P.; Perinotto, M.
The three planetary nebulae of type I: IC 4673, Me 1-1, and M 1-7, have been observed with the IUE satellite and the chemical abundance of carbon was derived. For the sake of homogeneity, also the abundances of the other most abundant chemical elements have been redetermined using the best optical data from the literature. We have found C/O equal …
LM1-64: a high excitation planetary nebula with WR nucleus in the LMC.
Torres-Peimbert, S.; Ruiz, M. T.; Peña, M. +1 more
The authors present optical and UV spectra of the planetary nebula LM1-64 in the LMC. This is a high excitation planetary nebula which shows evidence of having a WC central star. Broad and complex stellar emission at λ4650 (due to C III and C IV) is detected in the optical spectrum. The authors have measured all the emission line fluxes available …
Active Galactic Nuclei. V. X-Ray Variability and the Black Hole Cluster Paradigm
Pacholczyk, A. G.; Stoeger, W. R.
A random superposition of elementary luminosity bursts of rectangular or triangular shape produces X-ray luminosity flicker curves characterized by features corresponding to those observed in the X-ray- variable Seyfert galaxies and other active galactic nuclei. Such luminosity events could be produced by accretion processes resulting from tidal d…
The Latest Spectral Peregrinations of Rx-Puppis
Ivison, R. J.; Seaquist, E. R.
We present centimetre- and millimetre-wave continuum measurements of the symbiotic binary system RX Puppis. These suggest that RX Pup has returned to a state of low excitation after more than a decade of activity. Although the overall optical brightness has not altered substantially during the past two years, recent low-resolution ultraviolet and …
A Search for Ultraviolet Circumstellar Gas Absorption Features in alpha Piscis Austrinus (Fomalhaut), A Possible beta Pictoris--like System
Kondo, Yoji; Cheng, K. -P.; Bruhweiler, Fred C.
Archival high-dispersion International Ultraviolet Explorer (IUE) spectra have been used to search for circumstellar gas absorption features in alpha PsA (A3 V), a nearby (6.7 pc) proto-planetary system candidate. Recent sub-millimeter mapping observations around the region of alpha PsA indicate a spatially resolved dust disk like the one seen aro…