Search Publications
The optical counterpart of the ultraluminous X-ray source NGC 5204 X-1
Knigge, C.; Roberts, T. P.; Lira, P. +1 more
We use archival HST/WFPC2 V- and I-band images to show that the optical counterpart to the ultraluminous X-ray source NGC 5204 X-1, reported by Roberts et al., is composed of two sources separated by 0.5 arcsec. We have also identified a third source as a possible counterpart, which lies 0.8 arcsec from the nominal X-ray position. Point spread fun…
The dual dust chemistries of planetary nebulae with [WCL] central stars
Barlow, M. J.; Liu, X. -W.; Cohen, Martin +1 more
The rather rare class of central stars of planetary nebulae that show very low-excitation Wolf-Rayet spectra has been a subject of great interest, particularly in the infrared, since its discovery in the late 1960s. Further peculiarities have been found with the advent of infrared spectroscopy from ISO. Notably, these objects simultaneously betray…
Surface abundances of light elements for a large sample of early B-type stars - II. Basic parameters of 107 stars
Lambert, David L.; Lyubimkov, Leonid S.; Rostopchin, Sergey I. +1 more
Effective temperatures Teff, surface gravities logg and interstellar extinctions AV are found for 107 B stars. Distances d of the stars, which are based on the derived Teff, logg and AV values, show good agreement with those obtained from the Hipparcos parallaxes. Comparing the Teff and logg v…
Observations of hyperluminous infrared galaxies with the Infrared Space Observatory: implications for the origin of their extreme luminosities
McMahon, Richard; Verma, Aprajita; Rowan-Robinson, Michael +1 more
We present 7-180 µm photometry of a sample of hyperluminous infrared galaxies (HyLIGs) obtained with the photometer and camera mounted on the Infrared Space Observatory. We have used radiative transfer models of obscured starbursts and dusty torii to model their spectral energy distributions (SEDs). We find that IRAS F00235+1024, IRAS F14218…
The effect of lensing on the identification of SCUBA galaxies
Ivison, R. J.; Smail, Ian; Blain, A. W. +1 more
Spectroscopic surveys of submillimetre(submm)-selected sources have uncovered optically bright galaxies at z<~ 1 close to the positions of several submm sources. Naive statistical analyses suggest that these galaxies are associated with the submm emission. However, in some cases, it is difficult to understand this association given the relative…
Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009
Martin, P. G.; Harrington, J. P.; Balick, B. +8 more
We present new Hubble Space Telescope (HST)/WFPC2 imagery and STIS long-slit spectroscopy of the planetary nebula NGC 7009. The primary goal was to obtain high spatial resolution of the intrinsic line ratio [OIII] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (tA…
Testing the line-driven disc wind model: time-resolved ultraviolet spectroscopy of IX Vel and V3885Sgr
Knigge, C.; Long, K. S.; Proga, D. +2 more
To confront the predictions of the most recent line-driven disc wind models with observational evidence, we have obtained Hubble Space Telescope (HST ) STIS (1180-1700Å) echelle spectra of the nova-like variables IX Vel and V3885Sgr at three epochs. The targets were observed in time-tag mode for ~2000s on each occasion, allowing us to study the sp…
Giant low surface brightness haloes in distant radio galaxies: USS0828+193
Pentericci, L.; Humphrey, A.; Villar-Martín, M. +5 more
We present results on the spectroscopic study of the ionized gas in the high-redshift radio galaxy USS0828+193 at z= 2.57. Thanks to the high signal-to-noise (S/N) ratio of the emission lines in the Keck spectrum, we have been able to perform a detailed kinematic study by means of the spectral decomposition of the emission line profiles. This stud…
Observations of the Hubble Deep Field South with the Infrared Space Observatory - II. Associations and star formation rates
Oliver, Seb; Elbaz, David; Franceschini, Alberto +15 more
We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15µm with the ISOCAM instrument on board the Infrared Space Observatory (ISO ). We find reliable optical/near-infrared associations for 32 of the 35 sources detected in this field by Oliver et al. (Paper I): eight of them are…
An XMM-Newton observation of Ton S180: constraints on the continuum emission in ultrasoft Seyfert galaxies
Brandt, W. N.; Vaughan, S.; Fabian, A. C. +3 more
We present an XMM-Newton observation of the bright, narrow-line, ultrasoft type 1 Seyfert galaxy Ton S180. The 0.3-10 keV X-ray spectrum is steep and curved, showing a steep slope above 2.5 keV (Γ~ 2.3) and a smooth, featureless excess of emission at lower energies. The spectrum can be adequately parametrized using a simple double power-law model.…