Search Publications
Galactic globular clusters as a test for very-low-mass stellar models
Zoccali, M.; Piotto, G.; Cassisi, S. +2 more
We make use of the `Next Generation' model atmospheres of Allard et al. and Hauschildt, Allard & Baron to compute theoretical models for low- and very-low-mass stars for selected metallicities in the range Z=0.0002 to 0.002. On this basis, we present theoretical predictions covering the sequence of H-burning stars as observed in Galactic globu…
The cluster environments of the z~1 3CR radio galaxies
Best, P. N.
An analysis of the environments around a sample of 28 3CR radio galaxies with redshifts 0.6<z<1.8 is presented, based primarily upon K-band images down to K~20 taken using the UK Infrared Telescope (UKIRT). A net overdensity of K-band galaxies is found in the fields of the radio galaxies, with the mean excess counts being comparable to that …
Radio, optical and X-ray nuclei in nearby 3CRR radio galaxies
Hardcastle, M. J.; Worrall, D. M.
HST observations have shown that low-redshift 3CR radio galaxies often exhibit a point-like optical component positionally coincident with the GHz-frequency radio core. In this paper we discuss the correlation between the luminosities of the radio, optical and X-ray cores in these objects, and argue that all three components have a common origin a…
Clustering of galaxies around radio quasars at 0.5<=z<=0.8
Serjeant, Stephen; Lacy, Mark; Wold, Margrethe +1 more
We have observed the galaxy environments around a sample of 21 radio-loud, steep-spectrum quasars at 0.5<=z<=0.82, spanning several orders of magnitude in radio luminosity. The observations also include background control fields used to obtain the excess number of galaxies in each quasar field. The galaxy excess was quantified using the spat…
The distribution of bright OB stars in the Canis Major-Puppis-Vela region of the Milky Way
Kaltcheva, N. T.; Hilditch, R. W.
The picture of the young stellar groups in the Canis Major-Puppis-Vela (215 deg<l<275 deg) section of the Milky Way is studied and updated utilizing uvbyβ photometry of intrinsically luminous OB stars. We use all data from the literature to create a sample with 98per cent completeness to 9.5mag. The very dense low reddened OB association CMa…
Hubble Space Telescope observations of X-ray-selected active galactic nuclei
Schade, David J.; Boyle, B. J.; Letawsky, Michael
We report on the initial results of a comprehensive Hubble Space Telescope (HST) snapshot imaging survey of 76 low-redshift (z<0.15) X-ray-selected active galactic nuclei (AGN) in the Einstein Extended Medium Sensitivity Survey. This survey is expected to show no bias with respect to host galaxy types, and so is arguably one of the best availab…
The massive stellar content of the Hii region NGC 604 and its evolutionary state
Pérez, Enrique; González Delgado, Rosa M.
This paper analyses the integrated ultraviolet spectra taken with the International Ultraviolet Explorer (IUE) and optical ground-based spectra taken with the William Herschel Telescope (WHT) of the giant Hii region NGC 604. These data are complemented with ultraviolet (WFPC2 through F170W) and Hα (WFPC2 through F656N) images retrieved from the Hu…
The European Large Area ISO Survey - III. 90-µm extragalactic source counts
Genzel, R.; Danese, L.; Puget, J. -L. +17 more
We present results and source counts at 90µm extracted from the preliminary analysis of the European Large Area ISO Survey (ELAIS). The survey covered about 12deg2 of the sky in four main areas and was carried out with the ISOPHOT instrument onboard the Infrared Space Observatory (ISO). The survey is at least an order of magnitude…
Hubble Space Telescope imaging and ground-based spectroscopy of old nova shells - I. FH Ser, V533 Her, BT Mon, DK Lac and V476 Cyg
O'Brien, T. J.; Gill, C. D.
In this paper we report on the first five out of eleven observations in our programme of Hubble Space Telescope (HST) imaging of old nova shells. We present new WFPC2 images of the shells around FH Ser and V533 Her taken in the F656N (Hα+[Nii]) filter. We also show long-slit spectra taken using the William Herschel Telescope on La Palma for these …
The discovery of a low-mass, pre-main-sequence stellar association around γ Velorum
Jeffries, R. D.; Naylor, T.; Pozzo, M. +3 more
We report the serendipitous discovery of a population of low-mass, pre-main-sequence (PMS) stars in the direction of the Wolf-Rayet/O-star binary system γ2Vel and the Vela OB2 association. We argue that γ2Vel and the low-mass stars are truly associated and approximately coeval, and that both are at distances between 360 and 4…