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The symbiotic star CH Cygni - III. A precessing radio jet
Davis, R. J.; Eyres, S. P. S.; Bode, M. F. +3 more
VLA, MERLIN and Hubble Space Telescope imaging observations of the extended regions of the symbiotic system CH Cygni are analysed. These extensions are evidence of a strong collimation mechanism, probably an accretion disc surrounding the hot component of the system. Over 16 yr (between 1985 and 2001) the general trend is that these jets are seen …
The highly variable X-ray spectrum of the luminous Seyfert 1 galaxy 1H 0419-577
O'Brien, P. T.; Reeves, J. N.; Page, K. L. +1 more
An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 is presented. We find that the spectrum is well fitted by a power law of canonical slope and three blackbody components (to model the strong soft excess). The XMM-Newton data are compared and contrasted with observations by ROSAT in 1992 and by ASCA and BeppoSAX in 1996. We fin…
Chandra observations of the nucleus of M33
Rutledge, Robert E.; Dubus, Guillaume
The nearby galaxy M33 hosts the most luminous steady X-ray source in the Local Group. The high spatial resolution of Chandra allows us to confirm that this ultra-luminous X-ray source is within the nucleus and rule out at the 4.6σ level a previously proposed possible counterpart located 1 arcsec away. The X-ray spectrum is well fitted by a disc bl…
Spatially resolved STIS spectra of the gravitationally lensed broad absorption line quasar APM08279+5255: the nature of component C and evidence for microlensing
Lewis, Geraint F.; Pettini, Max; Ellison, Sara L. +4 more
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While gravitationally lensed quasars are expected to display an odd number of images, invariably systems are observed with an even number of quasars. For this, lensing galaxies must have very small core radii; this provides strong demagnification of one of the images. High-resolution imaging of the gravitationally lensed broad absorption…The Sunyaev-Zel'dovich effect as a cosmological discriminator
Diego, J. M.; Martínez-González, E.; Benitez, N. +2 more
We show how future measurements of the Sunyaev-Zel'dovich effect (SZE) can be used to constrain the cosmological parameters. We combine the SZ information expected from the Planck full-sky survey, N (S ), where no redshift information is included, with the N (z ) obtained from an optically identified SZ-selected survey covering less than 1 per cen…
µJy radio sources in the cluster MS1054-03
Franx, M.; van Dokkum, P. G.; Röttgering, H. J. A. +1 more
An extremely deep 5-GHz radio observation is presented of the rich cluster MS1054-03 at redshift 34 radio sources are detected down to a 6σ level of 32µJy, compared with about 25 expected from previous blank-field radio source count determinations; the sources giving rise to these excess counts lie predominantly within 2arcmin (~700kpc) of t…
Extreme X-ray variability in the luminous quasar PDS 456
O'Brien, P. T.; Reeves, J. N.; Pounds, K. A. +1 more
We present evidence from BeppoSAX and XMM-Newton of extreme X-ray variability in the high-luminosity radio-quiet quasar PDS 456, the most luminous known active galactic nucleus (AGN) at z < 0.3. Repeated X-ray flaring is found in PDS 456, over the duration of the 340-ks long BeppoSAX observation. The X-ray flux doubles in just 30 ks, whilst the…
Luminosity-metallicity relation for stars on the lower main sequence
Jimenez, Raul; Flynn, Chris; Kotoneva, Eira
We present a comparison of the predictions of stellar models with the luminosity of the lower main sequence (5.5 < MV < 7.3) using K dwarfs in the Hipparcos catalogue. The parallaxes of our comparison stars are known to better than 15 per cent and metallicities have been recently determined from photometry. A major advantage of ou…
Gamma-ray bursts in normal and extreme star-forming galaxies
Ramirez-Ruiz, Enrico; Blain, A. W.; Trentham, Neil
We discuss how gamma-ray burst (GRB) optical afterglows and multiwavelength observations of their host galaxies can be used to obtain information about the relative amounts of star formation happening in optical and submillimetre galaxies. That such an analysis will be possible follows from the currently favoured idea that GRBs are closely linked …
First XMM-Newton observations of strongly magnetic cataclysmic variables - II. Timing studies of DP Leo and WW Hor
Cropper, Mark; Ramsay, Gavin; Much, Rudi +5 more
XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables, DP Leo and WW Hor, continuously for three orbital cycles each. Both systems were in an intermediate state of accretion. For WW Hor we also obtained optical light curves with the XMM-Newton Optical Monitor and from ground-based observations. Our analysis of the X-ray and …