The COROT star HD

For the "COROT star" HD 52265, which will be observed for five consecutive months, we expect very precise data, which it is hoped will lead to very good frequency determinations and mode identifications. We will use the same kind of tests as before, and we expect to be able to draw precise conclusions on the internal structure and past history of this exoplanet-host star.

Preliminary computations and modeling of HD52265 have been done using the same techniques as for |x-Arae, as a preparation for the future observations with COROT. Five groups of observers have given external parameters for HD 52265 (Table 40.2). Its luminosity is L/LQ = 1.94 ± 0.16 (Soriano et al. 2006).

Evolutionary tracks have been computed for three different metallicities, as given from spectroscopic observations (Figure 40.4). Oscillation frequencies and seismic tests have been studied for specific models. Here I show only two extreme and interesting examples, for metallicities [Fe/H] = 0.19 and 0.27.

Figure 40.4. These graphs display the error boxes for the position of the star HD 52265 in the log g-log reff diagram, as given by the five groups that observed this star (Table 40.2). The author's boxes which correspond to the chosen metallicity, in each graph, are emphasized with boldface lines. After Soriano et al. (2006)

frequency modulo 1GG |Hz

frequency modulo 1GG |Hz

frequency modulo 77 |Hz

Figure 40.5. Echelle diagrams computed for two extreme models of HD 52265, the first one with metallicity 0.27 inside the Gonzalez et al. (2001) error box (model 3) and the second with metallicity 0.19 inside the Takeda et al. (2005) error box (model 6).

frequency modulo 77 |Hz

Figure 40.5. Echelle diagrams computed for two extreme models of HD 52265, the first one with metallicity 0.27 inside the Gonzalez et al. (2001) error box (model 3) and the second with metallicity 0.19 inside the Takeda et al. (2005) error box (model 6).

The echelle diagrams for these two models are given in Figure 40.5. They present important differences. The most interesting feature is found in the Takeda et al. (2005) case. The l = 0 and l = 2 lines cross for a frequency around 3 mHz, and the l = 1 and l = 3 lines also come very close. This is related to the presence of a convective, helium-rich core, as discussed in Soriano et al. (2006).

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