Search Publications
Hydrodynamics of photoionized columns in the Eagle Nebula, M 16
Ward-Thompson, D.; Whitworth, A. P.; Williams, R. J. R.
We present hydrodynamical simulations of the formation, structure and evolution of photoionized columns, with parameters based on those observed in the Eagle Nebula. On the basis of these simulations we argue that there is no unequivocal evidence that the dense neutral clumps at heads of the columns were cores in the pre-existing molecular cloud. …
A photometric study of the ages and metallicities of early-type galaxies in A 2218
Smith, G. P.; Smail, Ian; Fruchter, A. S. +4 more
We present deep optical and near-infrared imaging of the rich cluster A2218 at z=0.17. Our optical imaging comes from new multicolour Hubble Space Telescope WFPC2 observations in the F450W (B450), F606W (V606) and F814W (I814) passbands. These observations are complemented by deep near-infrared, Ks-band …
Solar-cycle variation of the sound-speed asphericity from GONG and MDI data 1995-2000
Howe, R.; Hill, F.; Schou, J. +3 more
We study the variation of the frequency splitting coefficients describing the solar asphericity in both GONG and MDI data, and use these data to investigate temporal sound-speed variations as a function of both depth and latitude during the period 1995-2000 and a little beyond. The temporal variations in even splitting coefficients are found to be…
Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10
Smartt, S. J.; Crowther, P. A.; Dufton, P. L. +5 more
We present high quality spectroscopic data for two massive stars in the OB 10 association of M31, OB 10-64 (B0 Ia) and OB 10-WR1 (WC6). Medium resolution spectra of both stars were obtained using the ISIS spectrograph on the William Herschel Telescope. This is supplemented with Hubble Space Telescope STIS UV spectroscopy and Keck I HIRES data for …
Testing the hypothesis of the morphological transformation from field spiral to cluster S0
Smail, Ian; Kodama, Tadayuki
Hubble Space Telescope observations of distant clusters have suggested a steep increase in the proportion of S0 galaxies between clusters at high redshifts and similar systems at the present day. It has been proposed that this increase results from the transformation of the morphologies of accreted field galaxies from spirals to S0s. We have simul…
Kinematics from spectroscopy with a wide slit: detecting black holes in galaxy centres
Binney, James; Maciejewski, Witold
We consider long-slit emission-line spectra of galactic nuclei when the slit is wider than the instrumental point spread function, and the target has large velocity gradients. The finite width of the slit generates complex distributions of brightness at a given spatial point in the measured spectrum, which can be misinterpreted as coming from addi…
A new method for ISOCAM data reduction - I. Application to the European Large Area ISO Survey Southern Field: method and results
Aussel, H.; Pozzi, F.; Danese, L. +7 more
We develop a new data reduction technique for ISOCAM LW data and apply it to the European Large Area ISO Survey (ELAIS) LW3 (15-µm) observations in the southern hemisphere (S1). This method, known as LARI technique and based on the assumption of the existence of two different time-scales in ISOCAM transients (accounting for either fast or sl…
The phenomenology of solar-cycle-induced acoustic eigenfrequency variations: a comparative and complementary analysis of GONG, BiSON and VIRGO/LOI data
Chaplin, W. J.; Elsworth, Y.; Appourchaux, T. +2 more
We use high-quality helioseismic data collected by three different observational programmes during the declining phase of activity cycle 22,Q7 and a substantial portion of the rising phase of the current cycle (23), to study the phenomenological nature of the cycle-induced (centroid) eigenfrequency variations. We have analysed the frequency depend…
Hubble Space Telescope photometry of globular clusters in the Sombrero galaxy
Forbes, Duncan A.; Brodie, Jean P.; Larsen, Søren S.
We explore the rich globular cluster (GC) system of the nearby Sa galaxy M104, the `Sombrero' (NGC 4594), using archive Wide Field Planetary Camera 2 data. The GC colour distribution is found to be bimodal at the >99 per cent confidence level, with peaks at (V-I)0=0.96+/-0.03 and 1.21+/-0.03. The inferred metallicities are very simil…
The symbiotic star CH Cygni - I. Non-thermal bipolar jets
Davis, R. J.; Eyres, S. P. S.; Bode, M. F. +4 more
Very Large Array surface brightness and spectral index maps of the evolving extended emission of the triple symbiotic star CH Cygni are presented. These are derived from observations at 4.8, 8.4 and 14GHz between 1985 and 1999. The maps are dominated by thermal emission around the central bright peak of the nebula, but we also find unambiguous non…