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UBVRIJH photometry of two new luminous δ Scuti stars and the discovery of δ Scuti pulsation in the most evolved Ap star known
Handler, G.; Kurtz, D. W.; Kilkenny, D. +5 more
Time-series photometry of the Hipparcos variable stars HD 199434 and 21190 is reported. Both stars are pulsators of the δ Scuti type. Reclassifications of the MK types of the stars, based on new spectrograms, are given. HD 21190 is found to be F2III SrEuSi:, making it the most evolved Ap star known. Its Strömgren photometric indices support the pe…
A search for previously unrecognized metal-poor subdwarfs in the Hipparcos astrometric catalogue
Reid, I. Neill; Kilkenny, D.; Marang, F. +3 more
We have identified 317 stars included in the Hipparcos astrometric catalogue that have parallaxes measured to a precision of better than 15 per cent, and the location of which in the (MV,(B-V)T) diagram implies a metallicity comparable to or less than that of the intermediate-abundance globular cluster M5. We have undertaken …
Cygnus X-3 with ISO: investigating the wind
Fender, R. P.; Ogley, R. N.; Bell Burnell, S. J.
We have observed the energetic binary Cygnus X-3 in both quiescent and flaring states between 4 and 16µm using the ISO satellite. We find that the quiescent source shows the thermal free-free spectrum typical of a hot, fast stellar wind, such as from a massive helium star. The quiescent mass-loss rate arising from a spherically symmetric, no…
The distance to Supernova 1998aq in NGC 3982
Gibson, Brad K.; Stetson, Peter B.
The distance to NGC 3982, host galaxy to the Type Ia supernova SN 1998aq, is derived using 32 Cepheids discovered in archival multi-epoch Hubble Space Telescope observations. Employing recent Large Magellanic Cloud Cepheid period-luminosity relations and absolute zero-point, we find a distance to NGC 3982 of [formmu3]20.5+/-0.8 (r) +/-1.7 (s)Mpc, …
The European Large Area ISO Survey - VI. Discovery of a new hyperluminous infrared galaxy
Pérez-Fournon, I.; Pozzi, F.; Alexander, D. M. +20 more
We report the discovery of the first hyperluminous infrared galaxy (HyLIG) in the course of the European Large Area ISO Survey (ELAIS). This object has been detected by ISO at 6.7, 15 and 90µm, and is found to be a broad-line, radio-quiet quasar at a redshift [formmu4]z=1.099. From a detailed multicomponent model fit of the spectral energy d…
Far-ultraviolet spectroscopy of the hot DA white dwarf WD 2218+706 (DeHt5) with STIS
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +3 more
We report a study of the photospheric composition of the hot DAQ3 white dwarf WD 2218+706, which is also the central star of the old planetary nebula DeHt5. Helium is detected in the far-UV spectrumQ4. In addition, the star clearly contains significant quantities of elements heavier than He at abundances generally a factor of 2 to 10 higher than t…
The electron pressure in the outer atmosphere of ɛ Eri (K2 V)
McMurry, A. D.; Jordan, C.; Sim, S. A. +1 more
Observations of ɛ Eri (K2 V) have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The spectra obtained show a number of emission lines which can be used to determine, or place limits on, the electron density and pressure. Values of the electron pressure are required in order to make quantitative models of the…
First XMM-Newton observations of strongly magnetic cataclysmic variables - I. Spectral studies of DP Leo and WW Hor
Cropper, Mark; Ramsay, Gavin; Córdova, France +4 more
We present an analysis of the X-ray spectra of two strongly magnetic cataclysmic variables, DP Leo and WW Hor, made using XMM-Newton. Both systems were in intermediate levels of accretion. Hard optically thin X-ray emission from the shocked accreting gas was detected from both systems, while a soft blackbody X-ray component from the heated surface…
Detection of magnetic dipole lines of Fexii in the ultraviolet spectrum of the dwarf star ɛ Eri
McMurry, A. D.; Jordan, C.; Sim, S. A. +1 more
We report observations of the dwarf star ɛ Eri (K2V) made with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope. The high sensitivity of the STIS instrument has allowed us to detect the magnetic dipole transitions of Fexii at 1242.00 and 1349.38Å for the first time in a star other than the Sun. The width of the stronge…
Multiwavelength monitoring of QS Tel
de Martino, D.; Buckley, D. A. H.; Howell, S. B. +6 more
Multiwavelength monitoring observations of the AM Her system, QS Tel, are presented, the centrepiece being a coordinated campaign with the ASCA, EUVE and HST satellites and optical observations on 1996 September 28-29. The star was initially observed in an intermediate brightness, single pole state in 1996 April by ROSAT. However two EUVE snapshot…