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Masses and luminosities of O- and B-type stars and red supergiants
Neuhäuser, R.; Hohle, M. M.; Schutz, B. F.
Massive stars are of interest as progenitors of supernovae, i.e. neutron stars and black holes, which can be sources of gravitational waves. Recent population synthesis models can predict neutron star and gravitational wave observations but deal with a fixed supernova rate or an assumed initial mass function for the population of massive stars. He…
X-ray emission from optical novae in M 31
Pietsch, W.
The first supersoft source (SSS) identification with an optical nova in
Expanding atmosphere models for SSS spectra of novae
Ness, J. -U.; van Rossum, D. R.
Super Soft Source (SSS) spectra are powered by nuclear burning on the surface of a white dwarf. The released energy causes a radiatively-driven wind that leads to a radially extended atmosphere around the white dwarf. Significant blue shifts in photospheric absorption lines are found in the spectra of novae during their SSS phase, being an evidenc…
Observational evidence for expansion in the SSS spectra of novae
Ness, J. -U.
For several novae, a bright X-ray source with a spectrum resembling the class of Super Soft X-ray Sources (SSS) has been observed a few weeks to months after outburst. Novae are powered by explosive nuclear burning on the surface of a white dwarf, and enough energy is produced to power a radiatively driven wind. Owing to the evolution of the opaci…
Non-LTE model atmospheres for supersoft X-ray sources
Rauch, T.; Werner, K.
In the last decade, X-ray observations of hot stellar objects became available with unprecedented resolution and S/N ratio. For an adequate interpretation, fully metal-line blanketed Non-LTE model-atmospheres are necessary. The Tübingen Non-LTE Model Atmosphere Package (TMAP) can calculate such model atmospheres at a high level of sophistication. …
Dynamics of the solar magnetic field from SOHO/MDI
Benevolenskaya, E. E.
The investigation of the dynamics of magnetic fields from small scales to the large scales is very important for the understanding of the nature of solar activity. It is also the base for producing adequate models of the solar cycle with the purpose to predict the level of solar activity. Since December 1995 the Michelson Doppler Imager (MDI) on b…
X-ray observations of classical novae: Theoretical implications
Hernanz, M.; Sala, G.
Detection of X-rays from classical novae, both in outburst and post-outburst, provides unique and crucial information about the explosion mechanism. Soft X-rays reveal the hot white dwarf photosphere, whenever hydrogen (H) nuclear burning is still on and expanding envelope is transparent enough, whereas harder X-rays give information about the eje…
On the relation between supersoft X-ray sources and VY Scl stars: The cases of V504 Cen and VY Scl
Greiner, J.; Sala, G.; Mennickent, R. E. +3 more
We summarise our optical monitoring program of VY Scl stars with the SMARTS telescopes, and triggered X-ray as well as optical observations after/during state transitions of V504 Cen and VY Scl.
Based partially on CNTAC programs 04B-0086, 05A-0004, 05B-0209, 06A-0099, 06B-0250, 07A-0384, 07B-0054, 08A-0026, 08B-0056, 09A-0025, as well as ESO …X-ray energy spectra of CAL87
Rauch, T.; Ebisawa, K.; Takei, D.
V5116 Sgr: A disc-eclipsed SSS post-outburst nova?
Greiner, J.; Hernanz, M.; Sala, G. +1 more
Nova V5116 Sgr 2005 No. 2, discovered on 2005 July 4, was observed with XMM-Newton in March 2007, 20 months after the optical outburst. The X-ray spectrum showed that the nova had evolved to a pure supersoft X-ray source, indicative of residual H-burning on top of the white dwarf. The X-ray light-curve shows abrupt decreases and increases of the f…