Publication Abstracts

Wilson and Caldwell 1978

Wilson, R.E., and C.N. Caldwell, 1978: A model of V356 Sagittarii. Astrophys. J., 221, 917-925, doi:10.1086/156095.

A model is advanced to explain the peculiar features of the unusual eclipsing binary V356 Sgr, for which previous analysis has not been very successful. The most obvious peculiarities were pointed out by Popper and consist of the absence of a significant reflection effect and anomalous depths for the eclipses. However, additional strange features are also present. The light curves cannot be satisfied with a conventional model, even if one allows for the fast rotation of the primary. In our model, a thick, opaque ring or disk of recently transferred matter surrounds the present primary star. The ring is rather substantial and is not similar to the emission-line rings in systems such as RW Tau and U Cep. We have produced a first-order, but quantitative, computer model of the disk (along with the rest of the system) and have obtained its approximate parameters by the method of differential corrections. We account for the presence of the disk as a consequence ofthe known fast rotation of its central star, and we propose that the same condition accounts for the disk in the β Lyr system, where the central star is not directly visible. Numerous observational arguments indicate that V356 Sgr corresponds to a later evolutionary stage of a system like β Lyr, as was earlier suggested by Woolf. The system fills a gap in the observational sequence of examples of binary star evolution, and must be between the β Lyrae stage and a later detached stage, with no disk, no mass transfer, and a helium-star secondary. Probably mass transfer has been terminated by helium ignition in the present secondary, but there is a small chance that a slow mass transfer still goes on. Part of the (possible) underluminosity of the primary indicated earlier is removed by our model. The rest (about 1 mag) could be accounted for, if the primary is of spectral type Bl rather than B3, which may be within the range of uncertainty of classification.

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BibTeX Citation

  author={Wilson, R. E. and Caldwell, C. N.},
  title={A model of V356 Sagittarii},
  journal={Astrophys. J.},

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RIS Citation

ID  - wi05200y
AU  - Wilson, R. E.
AU  - Caldwell, C. N.
PY  - 1978
TI  - A model of V356 Sagittarii
JA  - Astrophys. J.
VL  - 221
SP  - 917
EP  - 925
DO  - 10.1086/156095
ER  -

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