Search Publications
A HgMn companion to the Cepheid SU Cyg.
Wahlgren, G. M.; Evans, N. R.
We report here the discovery of a chemically peculiar star of the HgMn type as a companion to the classical Cepheid variable SU Cyg. This is the first investigation of a HgMn star in a binary system in which a star of a more advanced evolutionary stage is the primary. The age of the Cepheid provides an estimate to the age of the chemical peculiari…
ISO-SWS Observations of the Time Variability of Oxygen-righ Mira Variables
Izumiura, H.; Onaka, T.; Tanabé, T. +3 more
We present the first observation of variation of the infrared spectrum of circumstellar dust emission around an oxygen-rich Mira variable star, Z Cyg, over an entire light variation cycle, based on the periodic SWS01 observations. The 10 µm and 20 µm ‘silicate features’ become stronger relative to the photospheric emission at maximum that at minim…
The Pleiades and alpha Persei Clusters
Eggen, Olin J.
The upper-main-sequence members of the Pleiades and alpha Persei clusters, considered as members of the Local Association, yield mean parallaxes that are only 4% larger than the mean values from Hipparcos observations. The (log T_eff, M_V) diagram reveals that in the temperature range from 6000 to 8000 K, the Hyades and alpha Persei main-sequence …
Search for cool circumstellar matter in the Ursae Majoris group with ISO
Henning, Thomas; Abraham, Peter; Lemke, Dietrich +2 more
We observed the mid- and far-infrared spectral energy distributions of 9 A-type stars from the 300 Myrs old Ursae Majoris group using the ISO satellite and the UKIRT telescope. We found that only 1 out of the 9 stars shows clear signature of circumstellar dust, and we derived an upper limit of 0.05 Mmoon for the dust mass around the oth…
PZ Mon - An Active Evolved Star
Saar, Steven H.
An Hipparcos parallax and new high-resolution spectra show that PZ Mon, long considered a spotted UV Ceti flare star, is actually a distant active giant (K1III+?), probably an RS CVn, with km s
Broad band X-ray spectrum of Cygnus X-1
Rao, A. R.; Chitnis, V. R.; Agrawal, P. C.
We present the hard X-ray (20 - 100 keV) observations of Cygnus X-1 obtained using a large area balloon-borne Xenon filled Multi-anode Proportional Counter (XMPC) telescope. The observations were carried out during the gamma_2 state of the source and we obtain a power law photon index of 1.62+/-0.07. To constrain the spectral shape of the source, …
Structure of the Solar Wind and Compositional Variations
Bochsler, P.
The composition of the solar wind is largely determined by the composition of the source material, i.e. the present-day composition of the outer convective zone. It is then modified by the processes which operate in the transition region and in the inner corona. In situ measurements of the solar wind composition give a unique opportunity to obtain…
The IUE Spectra of Three Optically Narrow-Line O VI Planetary Nebulae: NGC 1501, IC 1747, and IC 1297
Feibelman, Walter A.
The IUE spectra of NGC 1501, IC 1747, and IC 1297 have been analyzed with the Final Archive NEWSIPS processing and contain a large amount of new information. The UV spectra of the first two objects have received very little attention up to now, although they belong to the astrophysically rare but important group of planetary nebulae that exhibit O…
The pulsating yellow supergiant V810 Centauri
Meynet, G.; Burki, G.; Burnet, M. +1 more
The F8 Ia supergiant
MG II h&k line diagnostics of IM Pegasi
Houdebine, E. R.; Dempsey, R. C.; Olah, K. +2 more
We have analysed the Mgii h&k resonance lines of IM Peg (KII-III) on 14 high resolution IUE LWR spectra and compared the results coming from visual spectroscopic and UBV(RI)_C photometric data. The `clean' spectra (free from interstellar absorption) were modelled using a convolution of the rotational profile with a Gaussian profile, that repre…