6 papers
Probing S-Process Yields of Field Carbon Stars by the Analysis of 21micron Post-AGB Stars
M. Reyniers, H. Van Winckel
The observational data guiding the theoretical chemical evolutionary models of AGB stars come mainly from the analysis of intrinsic and extrinsic s-process enriched objects. The fi…
The composition and nature of the dust shell surrounding the binary AFGL 4106
F. J. Molster, L. B. F. M. Waters, N. R. Trams +8
We present infrared spectroscopy and imaging of AFGL~4106. The 2.4-5 micron ISO-SWS spectrum reveals the presence of a cool, luminous star (T_eff ~ 3750 K) in addition to an almost…
The circumstellar envelope of AFGL 4106
Jacco Th. van Loon, F. J. Molster, Hans van Winckel +1
We present new imaging and spectroscopy of the post-red supergiant binary AFGL 4106. Coronographic imaging in H-alpha reveals the shape and extent of the ionized region in the circ…
Spectral variability of the binary HR 4049
Eric J. Bakker, David L. Lambert, Hans van Winckel +3
The H profile varies with the orbital period. The two strong shell type emission peaks are identified as from one single broad emission feature with an absorption centered aroun…
Photospheric composition of the carbon-rich 21 micron post-AGB stars IRAS 22223+4327 and IRAS 04296+3429
Leen Decin, Hans Van Winckel, Christoffel Waelkens +1
We present a detailed chemical analysis on the basis of high-resolution, high signal-to-noise optical spectra of two post-AGB objects IRAS 22223+4327 and IRAS 04296+3429. Both disp…
Variability and nature of the binary in the Red Rectangle Nebula
C. Waelkens, H. Van Winckel, L. B. F. M. Waters +1
We present new observations of the central binary inside the Red Rectangle nebula. The detection of zinc in the optical spectrum confirms that the peculiar photospheric abundances…