Publication Abstracts

Wilson and Biermann 1976

Wilson, R.E., and P. Biermann, 1976: TX Cancri — Which component is hotter? Astron. Astrophys., 48, 349-357.

We raise the question of whether the W-type light curves (occultation primary eclipse) of TX Cnc are due to the low mass component being slightly the hotter component, as presumed until now, or whether it might be due to TX Cnc having the relatively strong classical gravity darkening law. To decide this question, we have analysed TXCnc light curves from four "epochs" showing dissimilar behavior. Two of these epochs appear (almost) reasonably normal, while the other two are very abnormal. The analysis was done in two different modes — one with the second temperature a free parameter, as in Whelan et al. (1973), and one with the second temperature determined by the first temperature and the surface gravity as in Wilson and Devinney (1973). We prefer the latter approach for two reasons, which are discussed in the paper. We find that the polar effective temperature of the low mass star is then about 30°K cooler than that of the high mass star, compared to values of 125 to 175°K hotter under the "T 2 free parameter" approach. Thus we find no evidence for a significant difference in the adiabatic constants of the two convection zones. TX Cnc is the second contact binary, after RZ Corn, for which a gravity darkening explanation adequately accounts for a W-type light curve. In regard to the mass ratio and inclination, our results are in good agreement with those of Whelan et al., but we find a significantly smaller geometrical overcontact. Epoch to epoch changes in the gravity darkening and albedo parameters suggest differences in the degree of thermal contact over the time scale of a few years. Some accuracy-related improvements in the Wilson-Devinney light curve and differential corrections procedures are described. Also, a scheme is given for ensuring convergence in differential corrections solutions in the presence of high correlations involving many parameters.

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BibTeX Citation

  author={Wilson, R. E. and Biermann, P.},
  title={TX Cancri — Which component is hotter?},
  journal={Astron. Astrophys.},

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RIS Citation

ID  - wi04100j
AU  - Wilson, R. E.
AU  - Biermann, P.
PY  - 1976
TI  - TX Cancri — Which component is hotter?
JA  - Astron. Astrophys.
VL  - 48
SP  - 349
EP  - 357
ER  -

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