Search Publications
The nature and origin of Seyfert warm absorbers
Page, M. J.; Branduardi-Raymont, G.; Blustin, A. J. +2 more
We collate the results of recent high resolution X-ray spectroscopic observations of 23 AGN, and use the resulting information to try to provide answers to some of the main open questions about warm absorbers: where do they originate, what effect do they have on their host galaxies, and what is their importance within the energetics and dynamics o…
Lower mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
Bouret, J. -C.; Hillier, D. J.; Lanz, T.
We have analyzed the far-ultraviolet spectrum of two Galactic O4 stars, the O4If+ supergiant HD 190429A and the O4V((f)) dwarf HD 96715, using archival FUSE and IUE data. We have conducted a quantitative analysis using the two NLTE model atmosphere and wind codes, tlusty and cmfgen, which incorporate a detailed treatment of NLTE metal line blanket…
On stars with weak winds: the Galactic case
Schaerer, D.; Martins, F.; Hillier, D. J. +3 more
We study the stellar and wind properties of a sample of Galactic O dwarfs to track the conditions under which weak winds (i.e. mass loss rates lower than 10-8 M⊙ yr-1) appear. The sample is composed of low and high luminosity dwarfs including Vz stars and stars known to display qualitatively weak winds. Atmosphere …
Disentangling the composite continuum of symbiotic binaries. I. S-type systems
Skopal, A.
We describe a method of disentangling the composite, 0.12-5 µm continuum of symbiotic binaries. The observed SED is determined by the IUE/HST archival spectra and flux-points corresponding to the optical UBVRI and infrared JHKLM photometric measurements. The modeled SED is given by superposition of fluxes from the cool giant, hot stellar sou…
Molecular hydrogen emission from protoplanetary disks
Nomura, H.; Millar, T. J.
We have modeled self-consistently the density and temperature profiles of gas and dust in protoplanetary disks, taking into account irradiation from a central star. Making use of this physical structure, we have calculated the level populations of molecular hydrogen and the line emission from the disks. As a result, we can reproduce the observed s…
Integrated spectrum of the planetary nebula NGC 7027
Barlow, M. J.; Zhang, Y.; Liu, X. -W. +2 more
We present deep optical spectra of the archetypal young planetary nebula (PN)
HST/ACS Lyman α imaging of the nearby starburst ESO 338-IG04
Östlin, G.; Hayes, M.; Mas-Hesse, J. M. +3 more
ESO 338-IG04 (Tololo 1924-416) is a well-known, luminous (MV = -19.3) Blue Compact Galaxy in the local universe. Its complex morphology indicates a recent merger and/or close interaction, and it contains a central young starburst with compact star clusters of ages ≲ 40 Myr. The galaxy was imaged using the Advanced Camera for Surveys onb…
The mass of the black hole in 3C 273
Paltani, S.; Türler, M.
In this paper we apply the reverberation method to determine the mass of the black hole in 3C 273 from the Lyα and Civ emission lines using archival IUE observations. Following the standard assumptions of the method, we find a maximum-likelihood estimate of the mass of 6.59× 10^9 M_⊙, with a 1σ confidence interval 5.69{-}8.27× 109 M_⊙. …
Strong dust processing in circumstellar discs around 6 RV Tauri stars. Are dusty RV Tauri stars all binaries?
Waters, L. B. F. M.; Dominik, C.; Dejonghe, H. +2 more
We present extended Spectral Energy Distributions (SEDs) of seven classical RV Tauri stars, using newly obtained submillimetre continuum measurements and Geneva optical photometry supplemented with literature data. The broad-band SEDs show a large IR excess with a black-body slope at long wavelengths in six of the seven stars, R Sct being the noti…
A far UV study of interstellar gas towards HD 34078: High excitation H2 and small scale structure
Le Petit, F.; Roueff, E.; Andersson, B. -G. +5 more
To investigate the presence of small scale structure in the spatial distribution of H2 molecules we have undertaken repeated FUSE UV observations of the runaway O9.5V star, HD 34078. In this paper we present five spectra obtained between January 2000 and October 2002. These observations reveal an unexpectedly large amount of highly exci…