Stellar parameters of Be targets for CorotStellar parameters of Be targets for CorotC. Neiner1,2, Y.Frémat3, A.-M. Hubert2, M. Floquet2,

E. Janot-Pacheco4, J. Fabregat5 , J. Zorec6

1RSSD, ESTEC / ESA, Netherlands2GEPI, Observatoire de Paris-Meudon, France

3Observatoire Royal de Bruxelles, Belgium4University of Sao Paulo, Brazil5University of Valencia, Spain

6IAP, France

Contact: cneiner@rssd.esa.int

AbstractWe determine the stellar parameters of the Be stars in the cones of Corot, to allow a selection of the most interesting targets to be observed with Corot. The spectra were collected from GAUDI for the brightest stars. For the faintest objects, data have been obtained in Brazil or will be obtained in France in January. The stellar parameters are determined by fitting observed hydrogen and helium spectral lines with theoretical NLTE line profiles. The model has already been applied to all the spectra extracted from GAUDI. The FASTROT code is then used to study the effects of fast rotation: stellar flattening and gravitational darkening.

Stellar parametersThe temperature (Teff in K), gravity (log g in dex) and projected velocity (vsini in km/s) of the Be stars observed for GAUDI are summarized in Tables 1 and 2, for the galactic anticentre and centre respectively. Among those are new Be stars, discovered in GAUDI and presented in the bottom part of the Tables. Depending on the quality of the spectrum, the error bars are between 800 and 3000 K for Teff, around 0.1 dex for log g and between 5 and 30 km/s for vsini. Be stars which are close to a primary target of Corot are indicated in boldface in the Tables. The other Be stars can be chosen as targets for the short runs.

ConclusionsWe determined the stellar parameters of Be stars in the cones of Corot and showed that the effects of fast rotation have to be taken into account. This study will allow us to select the most interesting targets for the Corot observations.

Figure 1

FiguresFigure 1 shows two examples of line fits (red line) computed with FASTROT on GAUDI data (black dots) to determine the stellar parameters. The fitting procedure only takes into account the regions without emission (horizontal black lines).

Figure 2 is a HR diagram with evolutionary tracks from Schaller et al. (1992). Be stars from Tables 1 and 2 are reported on the diagram with blue circles. This corresponds to their position if no correction for fast rotation is applied. The red lines show the effect of fast rotation on the parameters and the importance of taking it into account. Note that some of the targets appear in the supergiants region (right from the green line), while Be stars are by definition a class of main sequence stars. Their apparent position in the HR diagram is due to the large error bars on the stellar parameters, to the presence of a companion or to the underestimation of the veiling effect.

Figure 2

Work in progressThe work presented in this poster corresponds to 30 Be stars. However, the total number of Be stars in the cones of COROT is around 70, including 13 Be stars which are close to primary targets of Corot. The data collected in Brazil are currently being analysed. The data that will be collected in France in January will be analysed early 2004. The correction for fast rotation will be applied to all the targets.

HD V Type vsini Teff log g P (d)

173371 6.89 B9IIIe 291 12300 3.60175869 5.56 B9IIIpe 170 11800 3.43171219 7.65 B8e 220 11200 2.75173219 7.82 B1Vnpe 61 27000 3.78 var170714 7.38 B1Vne 268 18800 4.07 var168797 6.14 B3Ve 264 18550 3.40 0.48174886 7.77 B8e 69 15100 3.45

166917 6.69 B9e 190 12200 3.09176630 7.70 B4IVe 187 16200 3.39 0.63184767 7.18 A2e 22 10500 3.38194244 6.14 B9Ve 255 10250 3.22

Table 2 : Be stars towards the galactic centre

HD V Type vsini Teff log g P (d)

50209 8.33 B9Ve 292 12640 3.14 0.59

49330 8.92 B0nnpe 197 27200 3.81 1.2850696 8.87 B1Vnne 345 21660 3.54 var50891 8.88 A0pe 215 10250 3.4953085 7.21 B8e 200 15200 3.66 var49787 7.55 B1Vpe 145 24000 3.95 var50138 6.58 B9e 77 12200 3.10 var55606 9.04 B1Vnnpe 336 28600 4.0746380 8.00 B2Vne 289 22100 3.53 var53667 7.76 B0.5IIIe 112 24800 3.3543285 6.07 B6Ve 225 14700 3.91 0.4553367 6.97 B0IVe 112 24800 3.35 var

43264 7.51 B9e 303 10800 2.6444783 6.23 B8Vne 250 10200 2.7046484 7.65 B1Ve 96 30300 3.9047160 7.10 B9e 173 12000 3.8749567 6.15 B3II-IIIe 77 17100 2.97 2.5550581 7.54 A0e 215 10250 3.4951506 7.68 B9Ve 181 16100 3.43

Table 1 : Be stars towards the galactic anticentre