Search Publications
High-resolution optical and infrared spectroscopic observations of CIR X-1
Wu, Kinwah; Fender, Robert; Johnston, Helen M.
We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric Hα emission line has been in evidence for the past 20 years, although the shape of the line has changed significantly. We present an eccentric (e~0.7-0.9) l…
Thermal-infrared imaging of 3C radio galaxies at z~1
Simpson, Chris; Rawlings, Steve; Lacy, Mark
We present the results of a programme of thermal-infrared imaging of 19 z ~ 1 radio galaxies from the 3CR and 3CRR (LRL) samples. We detect emission at L' (3.8 µm) from four objects; in each case the emission is unresolved at 1-arcsec resolution. 15 radio galaxies remain undetected to sensitive limits of L' ~ 15.5. Using these data in tandem…
The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion
Whitelock, Patricia A.; Barba, Rodolfo; Hack, Warren +4 more
We present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aim of developing a reliable binary model for the system and identifying mechanisms responsible for its spectacular activity. The binary is composed of a long-period Mira variable surrounded by a thick dust shell and a hot ~ 0.8 M_su…
The 1995-96 decline of R Coronae Borealis: high-resolution optical spectroscopy
Hatzes, Artie P.; Lambert, David L.; Pandey, Gajendra +10 more
A set of high-resolution optical spectra of R CrB acquired before, during and after its 1995-96 decline is discussed. All of the components reported from earlier declines are seen. This novel data set provides new information on these components including several aspects not previously seen in declines of R CrB and other R Coronae Borealis stars. …
The anomalous intensities of helium lines in the quiet solar transition region
Jordan, C.; MacPherson, K. P.
Previous studies using observations made at low spatial and spectral resolution showed that the resonance lines of Hei and Heii are anomalously strong in the quiet Sun when compared with other transition region lines formed at similar temperatures. Here, the higher spatial and spectral resolution provided by the Coronal Diagnostic Spectrometer (cd…
Testing the FR I/BL Lac unifying model with HST observations
Capetti, Alessandro; Celotti, Annalisa
Hubble Space Telescope (HST) observations provide a novel way of testing unified models for FR I radio sources and BL Lac objects. The detection of extended dust discs in some radio galaxies provides information on their jet orientation. Given this, the strength of the compact nuclear sources of FR I and BL Lacs can be compared with model predicti…
200-µm ISO observations of NGC 6946: evidence for an extended distribution of cold dust
Bianchi, S.; Davies, J. I.; Evans, R. +2 more
We have used the Infrared Space Observatory (ISO) to obtain a resolved 200-µm image of the nearby spiral galaxy NGC 6946. We compare these observations with those made at 60 and 100 µm by the Infrared Astronomical Satellite (IRAS). Whereas IRAS mainly detected warm dust (T ~ 30 K) heated by star-forming regions, ISO detects an extended…
Observations and a model for the infrared continuum of Centaurus A
Lutz, D.; Sturm, E.; Alexander, D. M. +4 more
We present ISOSWS, ISOPHOT_S and 8-13µm observations of Centaurus A which show prominent PAH and silicate features. These and other data are used to construct a model for the infrared continuum. We find that, in a small nuclear aperture (~4arcsec, ~60pc), the spectral energy distribution is characteristic of emission from a starburst and dus…
Accretion shocks in T Tauri stars: diagnosis via semiforbidden ultraviolet line ratios
Lamzin, S. A.; Gomez de Castro, Ana I.
Numerical calculations of the structure of accretion shocks in T Tauri stars (TTSs) indicate that the C III]1909, O III]1661+1666 and Si III]1892 ultraviolet lines should have comparable intensities. We show how the density and the velocity of the accreted gas can be derived from these line ratios. We also indicate how these parameters can be used…
[Cii] 158-µm observations of a sample of late-type galaxies from the Virgo cluster
Metcalfe, L.; Völk, H. J.; Heinrichsen, I. +6 more
We have observed 19 Virgo cluster spiral galaxies with the Long Wavelength Spectrometer (LWS) onboard ESA's Infrared Space Observatory (ISO) obtaining spectra around the [Cii] 157.741-µm fine-structure line. These 19 galaxies are quiescent in star-forming activity compared with previous studies from airborne observatories, sample RC3 types 0…