Search Publications
The Cepheid period-luminosity zero-point from HIPPARCOS trigonometrical parallaxes
Catchpole, R. M.; Feast, M. W.
Hipparcos trigonometrical parallaxes of Cepheid variables are used to derive a zero-point for the period-luminosity (PL) relation. Adopting a slope from the Large Magellanic Cloud (LMC), the relation is found to be <M_V>=-2.81 log P-1.43. The standard error of the zero-point is 0.10 mag. Together with metallicity corrections this corresponds…
Cross-correlation characteristics of OB stars from IUE spectroscopy
Howarth, Ian D.; Prinja, Raman K.; Siebert, Kaj W. +1 more
We present a catalogue of homogeneous measures of the linewidth parameter, v_esin i, for 373 O-type stars and early B supergiants (including the separate components of 25 binary and three triple systems), produced by cross-correlating high-resolution, short-wavelength IUE spectra against a `template' spectrum of tauSco. We also tabulate terminal v…
Galactic kinematics of Cepheids from HIPPARCOS proper motions
Feast, Michael; Whitelock, Patricia
The Hipparcos proper motions of 220 Galactic Cepheids, together with relevant ground-based photometry, have been analysed. The effects of Galactic rotation are very clearly seen. Mean values of the Oort constants, A=14.82+/-0.84 km s^-1 kpc^-1, and B=-12.37+/-0.64 km s^-1 kpc^-1, and of the angular velocity of circular rotation at the Sun, Omega_o…
Observations of the Hubble Deep Field with the Infrared Space Observatory - V. Spectral energy distributions, starburst models and star formation history
Elbaz, D.; Danese, L.; Franceschini, A. +16 more
We have modelled the spectral energy distributions of the 13 Hubble Deep Field (HDF) galaxies reliably detected by the Infrared Space Observatory (ISO). For two galaxies the emission detected by ISO is consistent with being starlight or the infrared `cirrus' in the galaxies. For the remaining 11 galaxies there is a clear mid-infrared excess, which…
First results from HIPPARCOS trigonometrical parallaxes of Mira-type variables
van Leeuwen, F.; Whitelock, P. A.; Feast, M. W. +1 more
HIPPARCOS trigonometrical parallaxes are given for 16 pre-selected Mira variables. Linear diameters are derived for eight oxygen-rich Miras with known angular diameters. Comparison with pulsation theory shows that two of them (both with periods over 400d) are fundamental pulsators, while the others (all with periods of less than 400d) pulsate in a…
EUVE J0317-855: a rapidly rotating, high-field magnetic white dwarf
Christian, D. J.; Wickramasinghe, D. T.; Vennes, S. +2 more
Spectropolarimetric observations of the extreme-ultraviolet (EUV) source and high-field magnetic white dwarf EUVE J0317-855 (=RE J0317-853) in the wavelength range 4200-7200 A reveal a strongly structured circular polarization spectrum with a peak polarization of 8 per cent. The strongest features in the polarization spectrum are attributed to Hα …
A multiwavelength study of the Seyfert 1 galaxy MCG-6-30-15
Fabian, A. C.; Reynolds, C. S.; Celotti, A. +1 more
We present a multiwaveband spectroscopic study of the nearby Seyfert 1 galaxy MCG-6-30-15. New optical spectra from the Anglo-Australian Telescope are presented which clearly show the effects of dust extinction/reddening on both the emission-line spectrum and the non-stellar AGN continuum. The reddening is constrained to be in the range E(B-V)=0.6…
HST, radio and infrared observations of 28 3CR radio galaxies at redshift z~ - I. The observations
Best, P. N.; Longair, M. S.; Roettgering, H. J. A.
Hubble Space Telescope images are presented of a sample of 28 3CR radio galaxies with redshifts in the range 0.6<z<1.8, together with maps at comparable angular resolution of their radio structure, taken using the Very Large Array. Infrared images of the fields, taken with the United Kingdom InfraRed Telescope, are also presented. The optica…
Observations of the Hubble Deep Field with the Infrared Space Observatory - III. Source counts and P(D) analysis
Elbaz, D.; Danese, L.; Franceschini, A. +19 more
We present source counts at 6.7 and 15 µm from our maps of the Hubble Deep Field (HDF) region, reaching 38.6 muJy at 6.7 µm and 255 muJy at 15 mum. These are the first ever extragalactic number counts to be presented at 6.7 mum, and are three decades fainter than IRAS at 12 mum. Both source counts and a P(D) analysis suggest that we ha…
Kinematic ages of OB associations
Brown, A. G. A.; de Zeeuw, P. T.; Dekker, G.
Astrometric data from the HIPPARCOS mission include measurements of early-type stars in nearly all OB associations within 1kpc from the Sun, and are available as of 1996. In anticipation thereof we studied the determination of kinematic ages and initial sizes of OB associations. These studies have traditionally been done using proper motion data. …