Search Publications
Multi-wavelength Behaviour of III Zw2
Wu, Kinwah; Mason, Keith O.; Salvi, Nikita +2 more
III Zw2 was observed with XMM-Newton in July 2000. Its X-ray spectrum can be described by a power law of photon index Γ~1.7 with a Gaussian line at 6.7KeV. There is no significant evidence of intrinsic absorption within the source or of a soft X-ray excess. Multi-wavelength light curves over a period of 25 years show related variations from the ra…
UBV Photometry of the Massive Eclipsing Binary TT Aur
Demircan, O.; Saygaç, A. T.; Özdemir, S. +5 more
UBV observations of the massive binary system TT Aur were carried out mainly at the Turkish National Observatory (TUG). These observations, together with IUE spectra and times of eclipse minima collected from the literature, were used to study the system parameters. Simultaneous solution of the light curves by the Wilson-Devinney code allows a sem…
The Secret Inner Life of the Orion Nebula
Schultz, A. S. B.
Beneath the familiar surface of the Orion Nebula is a spectacular molecular hydrogen outflow from a young stellar object, of very unusual morphology. In this paper I briefly discuss this outflow, its possible origins, and its interaction with the Nebula.
Gravitational Microlensing of Giant Luminous Arcs: a Test for Compact Dark Matter in Clusters of Galaxies
Lewis, Geraint F.
The true nature of dark matter in the universe still eludes us. This paper discusses a new test for the detection of stellar mass compact dark matter in galaxy clusters by observing its gravitational lensing influence on the surface brightness of giant luminous arcs. If dark matter is in the form of stellar mass compact objects, then the extremes …
The Hubble Constant
Mould, Jeremy
With the completion of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, it is interesting to form the dimensionless quantity H 0 t 0 by multiplying the Hubble Constant by the age of the Universe. In a matter dominated decelerating Universe with a density exceeding 0.26 of the critical value, H…
The Low-redshift Intergalactic Medium
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
The low-redshift Lyα forest of absorption lines provides a probe of large-scale baryonic structures in the intergalactic medium, some of which may be remnants of physical conditions set up during the epoch of galaxy formation. We discuss our recent Hubble Space Telescope (HST) observations and interpretation of low-z Lyα clouds toward nearby Seyfe…
Hipparcos Observations of Hydrogen-deficient Carbon Stars *
Cottrell, P. L.; Lawson, W. A.
Parallax measurements for 21 hydrogen-deficient carbon stars have been made by the Hipparcos satellite. These stars include most of the brighter R Coronae Borealis (RCB) variables, other cool hydrogen-deficient carbon (HdC) stars, and several higher-T eff extreme helium (eHe) stars. Most of these stars have either negative or statistica…
Winds in central stars of planetary nebulae.
Patriarchi, P.; Perinotto, M.
IUE spectral analysis of the Be star HD 184279.
Hirata, R.; Dawanas, D. N.
A catalogue of QSOs and link stars for the HST link of the HIPPARCOS reference frame.
White, G. L.; Hemenway, P. D.; Argue, A. N. +6 more
A list of bright (less than 17 mag) southern QSOs and bright (less than 11 mag) stars that may be suitable for the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the VLBI extragalactic frame is presented. The QSOs have been selected from various lists of radio objects and identifications. The stars have been sele…