Search Publications
Hubble Space Telescope observations of globular cluster systems along the Hubble sequence of spiral galaxies
Strader, Jay; Minniti, Dante; Kissler-Patig, Markus +3 more
We have studied the globular cluster systems of seven giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers the Hubble types Sa to Sc, allowing us to study the variation of the properties of globular cluster systems along the Hubble sequence. The photometry reaches ~1.5 mag beyond the turn-over ma…
Mass limits for the progenitor star of supernova 2001du and other Type II-P supernovae
Smartt, S. J.; Benetti, S.; Maund, J. R. +3 more
The supernova SN 2001du was discovered in the galaxy NGC 1365 at a distance of 19+/-2Mpc, and is a core-collapse event of Type II-P. Images of this galaxy, of moderate depth, have been taken with the Hubble Space Telescope approximately 6.6 yr before discovery and include the supernova position on the WFPC2 field of view. We have observed the supe…
XMM-Newton and the Pleiades - I. Bright coronal sources and the X-ray emission from intermediate-type stars
Briggs, K. R.; Pye, J. P.
We present results of X-ray spectral and timing analyses of solar-like (spectral types F5-K8) and intermediate-type (B4-F4) Pleiads observed in a 40-ks XMM-Newton EPIC exposure, probing X-ray luminosities (LX) up to a factor 10 fainter than previous studies using the ROSAT PSPC. All eight solar-like members have `quasi-steady'LX
Hubble Space Telescope imaging and ground-based spectroscopy of old nova shells - II. The bipolar shell of the slow nova HR Del
O'Brien, T. J.; Harman, D. J.
We present Hubble Space Telescope (HST) WFPC2 imaging of HR Del in filters centred on the lines of Hα, [N II] and [O III], with corresponding William Herschel Telescope (WHT) ISIS slit spectroscopy for the lines of Hα, Hβ, [N II] and [O III]. The data show that the ejected shell of HR Del is composed of many small bright knots. These are distribut…
Photometric redshifts in the Hubble Deep Fields: evolution of extinction and the star formation rate
Rowan-Robinson, Michael
Photometric redshifts are studied with a template approach using data from the Hubble Deep Field (HDF) North and South. The problem of aliasing in photometric redshift estimates is investigated in some detail and found not to be a significant problem if at least four photometric bands are available. The performance of the approach presented here a…
A simultaneous XMM-Newton and BeppoSAX observation of the archetypal broad line Seyfert 1 galaxy NGC 5548
Perola, G. C.; Matt, G.; Reeves, J. N. +3 more
We report the spectral analysis of a long XMM-Newton observation of the well-studied, moderate luminosity broad line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3-10 keV) spectrum can be well fitted by a power law of photon index Γ~ 1.75, together with reflection. The only feature in the ha…
The origin of the Fe K features in Markarian 205 and Markarian 509
Page, M. J.; Salvi, N. J.; Davis, S. W.
We examine the 3-10 keV EPIC spectra of Mrk 205 and 509 to investigate their Fe K features. The most significant feature in the spectra of both objects is an emission line at 6.4 keV. The spectra can be adequately modelled with a power law and a relatively narrow (σ < 0.2 keV) Fe Kα emission line. Better fits are obtained when an additional Gau…
The Tully-Fisher relation of cluster spirals at z= 0.83
Aragón-Salamanca, Alfonso; Hjorth, Jens; Milvang-Jensen, Bo +2 more
We present the rest-frame B-band Tully-Fisher relation for a sample of 8 cluster spiral galaxies at z= 0.83 and 19 field spirals at z= 0.15-0.90 based on Very Large Telescope (VLT) spectroscopy and Hubble Space Telescope (HST) photometry. No strong difference is detected between the cluster and the field galaxies, but we find some evidence that th…
Circumstellar features in hot DA white dwarfs
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +1 more
We present a phenomenological study of highly ionized, non-photospheric absorption features in high spectral resolution vacuum ultraviolet spectra of 23 hot DA white dwarfs. Prior to this study, four of the survey objects (Feige 24, REJ 0457-281, G191-B2B and REJ 1614-085) were known to possess these features. We find four new objects with multipl…
The high frequency power spectrum of Markarian 766
Vaughan, S.; Fabian, A. C.
An analysis is presented of the power spectrum of X-ray variability of the bright Seyfert 1 galaxy Mrk 766 as observed by XMM-Newton. Over the 0.2-10 keV energy range the power spectral density (PSD) is well-represented by a power-law with a slope of αlow~ 1 at low frequencies, breaking to a slope of αhi= 2.8+0.2