Search Publications
The age, life expectancy, and space density of Post Common Envelope Binaries
Gänsicke, B. T.; Schreiber, M. R.
We present a sample of 30 well observed Post Common Envelope Binaries (PCEBs). Deriving the cooling age of the white dwarfs, we show that the PCEB population is dominated by young systems. Having calculated the orbital evolution of the systems under the assumption of two different prescriptions for the angular momentum loss, we find that most of t…
Star formation rate in galaxies from UV, IR, and Hα estimators
Buat, V.; Inoue, A. K.; Hirashita, H.
Infrared (IR) luminosity of galaxies originating from dust thermal emission can be used as an indicator of the star formation rate (SFR). Inoue et al. (\cite{inoue00}, IHK) have derived a formula for the conversion from dust IR luminosity to SFR by using the following three quantities: the fraction of Lyman continuum luminosity absorbed by gas (f)…
Discovery of a magnetic field in the Slowly Pulsating B star zeta Cassiopeiae
Frémat, Y.; Neiner, C.; Wiersema, K. +5 more
Rotation and magnetic field in the Be star omega Orionis
Frémat, Y.; Zorec, J.; Neiner, C. +5 more
Rotation, pulsations and magnetic field in V 2052 Ophiuchi : A new He-strong star
Frémat, Y.; Neiner, C.; Jankov, S. +7 more
Discovery of a helium-core white dwarf progenitor
Heber, U.; Napiwotzki, R.; Lisker, T. +1 more
We discovered that HD 188112, a bright (V = \magpt{10}{2}), nearby (80 pc) B-type star, is a unique subluminous B (sdB) star. SdB stars are usually identified with models of core helium burning Extreme Horizontal-Branch (EHB) stars of half a solar mass. A spectral analysis of the hydrogen and helium lines resulted in T_eff = 21 500 +/- 500 K, log …
The circumstellar envelope of the C-rich post-AGB star HD 56126
Waters, L. B. F. M.; Hony, S.; de Koter, A. +1 more
We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch ``21 mu m object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use amorphous carbon…
The dust disk of HR 4049. Another brick in the wall
Dominik, C.; van Winckel, H.; Dullemond, C. P. +1 more
We present the Spectral Energy Distribution of HR 4049 based on literature data and new continuum measurements at 850 µm . The SED shows variable absorption in the UV, and a large IR excess, both caused by circumstellar dust. The shape of the IR excess from 1 µm all the way down to 850 µm can be nearly perfectly fitted with a sin…
More nitrogen rich B-type stars in the SMC cluster, NGC 330
Dufton, P. L.; Lennon, D. J.; Crowley, C.
High resolution spectra of seven early B-type giant/supergiant stars in the SMC cluster NGC 330 are analysed to obtain their chemical compositions relative to SMC field and Galactic B-type stars. It is found that all seven stars are nitrogen rich with an abundance approximately 1.3 dex higher than an SMC main-sequence field B-type star, AV304. The…
Abundances of Planetary Nebulae BD+30 3639 and NGC 6543
Pottasch, S. R.; Feibelman, W. A.; Bernard-Salas, J. +1 more
Infrared spectra taken with the Short Wavelength Spectrometer on board ISO and UV observations with IUE of planetary nebulae