Search Publications
Intrinsic parameters of galactic luminous OB stars.
Butler, K.; Kudritzki, R. P.; Herrero, A. +3 more
We present the results of a spectroscopic analysis of 25 galactic luminous OB stars. The gravities are in general lower than previously assumed, especially for giants. The helium abundances are also higher than normal in many cases. Using data from the spectroscopic analysis, radii, luminosities and masses are derived. The observed wind terminal v…
Reconstruction of the accretion disk in six cataclysmic variable stars.
Rutten, R. G. M.; van Paradijs, J.; Tinbergen, J.
The maximum-entropy eclipse-mapping algorithm is used to reconstruct images of the accretion disks of the novalike variable stars RW Tri, UX UMa, SW Sex, LX Ser, V 1315 Aql, and V363 Aur. The 2D disk intensity maps deduced from the light curves reveal the size of the disk and its radial intensity dependence. Black-body temperature maps deduced fro…
Near-infrared spectroscopy of galactic Wolf-Rayet stars.
Schmutz, Werner; Howarth, Ian D.
We present high-quality near-IR spectra of 24 Galactic WR stars, of a broad range of subtypes, selected as having known distances. The data cover the region 0.97-1.12 micron and include the 10830-A He I triplet. Measurements of He I and He II lines, together with the absolute magnitudes, yield temperatures, luminosities, mass-loss rates, and termi…
Orbital elements of S stars : revisiting the evolutionary status of S stars.
Jorissen, A.; Mayor, M.
The hypothesis of an evolutionary link between barium stars and the non-Mira S stars is discussed. The hypothesis of an evolutionary link between the barium stars and the non-Mira S stars is confirmed. The mass function distribution of S stars, indicating that the companions are likely white dwarfs, as is the case for barium stars, supports this h…
The SN 1986G in Centaurus A.
Schmutz, W.; Danziger, J.; Heydari-Malayeri, M. +10 more
We present photometric and spectroscopic observations of SN 1986 G, spanning up to one year after the explosion. The overall photometric behavior of this SN Ia results rather normal. The maximum at B = 1245+/-0.05 was reached on May 11,1986, then the decline to the inflection point was relatively fast (β_B_ = 12.0 mag/100 d), but similar to other …
A spectacular mass-loss event of the central star of Longmore 4.
Rauch, T.; Werner, K.; Heber, U. +3 more
We report on a dramatic change in spectral type of the central star of the planetary nebula Longmore 4. Its 'low state' spectrum is that of a PG 1159 star, i.e., of an extremely hot hydrogen-deficient (pre-) white dwarf, whereas its 'high state' spectrum has to be classified as of early Wolf-Rayet type (WC2-3). The observed spectral change reveals…
The extreme helium star BD -9 4395.
Heber, U.; Jeffery, C. S.
Simultaneous optical and UV spectroscopy is used to investigate both the photospheric variations and emission-line behavior of the extreme helium star BD-9 deg 4395. The photospheric parameters of the star are rederived from the optical spectra by the method of fine analysis, on the basis of up-to-date atomic data and new line-blanketed model atmo…
Variability pattern from X-ray to IR wavelengths in the active nucleus ofNGC 1566.
Alloin, D.; Pelat, D.; Baribaud, T. +1 more
This study presents the results of a multiwavelength monitoring of the active galactic nucleus in NGC 1566. Data collected in the X-rays, ultraviolet, visible and near-infrared domains have been combined together, in order to disentangle the various components and to better understand the patterns of variability in this active nucleus. At all wave…
Nearly simultaneous observations of chromospheric and coronal radiative losses of cool stars.
Schrijver, C. J.; Dobson, A. K.; Radick, R. R.
The flux-flux relationships of cool stars are studied on the basis of nearly simultaneous measurements of Ca II H+K, Mg II h+k, and soft X-ray fluxes. A linear relationship is derived between IUE Mg II h+k fluxes and Mount Wilson Ca II H+K fluxes which were obtained within 36 hr of each other for a sample of 26 F5-K3 main-sequence stars. Nearly si…
PU Vulpeculae : the outburst of a symbiotic nova.
Vogel, M.; Nussbaumer, H.
We report the full history of PU Vulpeculae from outburst to 1991 as seen in its ultraviolet emission. We show that PU Vul is a symbiotic nova, which went into outburst in 1977 after a nova-like thermonuclear event. The outbursting object went first into an F supergiant phase. The spectrum evolved between 1979 and 1989 from F-type into that of Ao.…