Calibration of CoRoT seismological methods using

the star Boo observed by MOST

Marian Doru SuranAstronomical Institute of the Romanian Academy

e-mail: suran@aira.astro.ro

Supported by the Romanian Space Agency (ROSA) contract Nr. 124/30.09.2004

Boo

High precision stellar modeling and rigorous asteroseismic tests for p and g modes:• Observations:

– MOST space mission (g and p modes 100< i <700 Hz, l=0) (M);– Kjeldsen (p modes, 600< i <1000 Hz, l=0-2) (K);– Carrier (p modes, 600< i <1000 Hz, l=0-2) (C);40 frequencies M+K+C (see Table 1)– HIPPARCOS astrometry: Bedding 1997 (see Table 2) – Interferometry: VLTI/VINCI, Thevenin et al. 2005 (see Table 2)

• Theory:– QDG method, Guenther&Brown 2004 (M);– Guenther et al. 2005 (M, M+K, M+C) (see Table 2)– Straka et al. 2005 (M, M+K with turbulence) (see Table 2)

Boo• Our asteroseismological method:

– Minimization of:

– for dense grids of stellar evolutive tracks: [M, X,Z, t ]. – us: CESAM (Cesam2k V2)+ LNAWENR (linear, nonadiabatic, nonradial)

with an automated queue of calculations for entire tracks (pms-ms-postms): [M,X,Z,t][M,X,Z,Te][qi,qi,ad,qi,nad] [R, I] ,(qi/qi) [2

[M,X,Z,Te,obs,k], DZ] CESAM osc-ad+osc-nad LNAWENR SEISMOLOGY

where DZ>0: theoretical excited and stables modes.• Our calculations:

– 40 observed modes M+K+C (g, p, l=0-2, see Table 1); 2 minima for a grid of tracks:

• M = 1.70 M, 1.71 M, 1.72 M ;• Z = 0.02; 0.04;

– range of effective temperature: 6050 60K;• Results are presented in tables 1-2 and in Figures 1-5.Calibration COROT/MOST using CESAM+LNAWENR/YREQ+QDG.

∑=

−=N

iiCiON 1

2,,

2 )(1

ννχ

BooReferences

• Bedding, T.R. 1997, astro-ph/9709005;• Carrier, F., Eggenberger, P., Bouchy, F. 2005, A&A, 434,550 (C);• Di Mauro, M.P., Christensen-Dalsgaard, J., Kjeldsen, H.,Bedding, T.R., Paterno, L.

2003, A&A,404, 341;• Guenther, D.B. 2004, Ap.J., 612,454;• Guenther, D.B., Brown, K.I.T. 2004, Ap.J., 600, 419 (QDG);• Guenther, D.B., Kallinger, T., Reegen, P., Weiss, W. W., Matthews, J.M.,

Kusching, R., Marchenko, S., Moffat, A. F. J, Rucinski, S.M., Sasselov, D., Walker, G.A.H. 2005, astro-ph/0508449 (M);

• Kjeldsen, H., Bedding,T.R., baldry, I.K. Bruntt, H., Buthler, R.P., Fischer, D.A., Frandsen, S., Gates, E.L. 2003, A.J.,126,1483 (K);

• Straka, C., Demarque, P., Guenther, D.B., Li, L., Robinson F.J. 2005, astro-ph/0509403;

• Thevenin, F., Kervella, P., Pichon, B., Morel, P., di Folco, E., Lebreton, Y. 2005, A&A, 436, 253;

Figure 1. Evolutionary tracks in the HR diagram for a star of 1.71 M , Z = 0.04 star in diagram HR.

Also, in the diagram the position of the star Boo is indicated.

Figure 2. The minima of the 2 as function of log(Te), calculated using the observed modes for the star Boo

(40 modes M+K+C) and the evolutionary postms tracks of 1.70 M (blue) ,1.71 M (red), 1.72 M (green).

Up: Z = 0.04. Down: Z = 0.02. The deepest minima of 2 coresponds to the star of 1.71M , Z =0.04. In brown is indicated the observed zone in temperature

for the star Boo: 6050 60 K. In magenta is indicated the corresponding number of modes excited but unstable, from the

40 modes taken into account for the star Boo (zero means all modes excited and stable).

Figure 3. The minima of the 2 as function of log(Te), calculated using the observed modes for the star Boo.

Thick lines are for all 40 modes (M+K+C), thin lines are for 8 modes (M, see Guenther et al. 2005). The evolutionary postms tracks are for a star of 1.71 M , Z = 0.04, X = 0.71 (red) and X = 0.70 (blue).

In brown is indicated the observed zone in temperature for the star Boo: 6050 60 K.

Figure 4. Up: The spectra of the observed modes for the star Boo (40 modes M+K+C; in red) compared with the theoretical ones (in DZ; blue) for a star of 1.71M Z=0.04. Down: the corresponding (O-C)i

for the 40 modes M+K+C as function of frequency.

Figure 5. The comparison of the calculated i,COROT (this paper, CESAM+ LNAWENR model)

and i,MOST (Guenther et al. 2005, Straka et al 2005, YREC+QDG model without turbulence).

The comparison was made for 100< i <1100 Hz, l = 0-2 (see Table 1).

Parameter Bucharestminim I[8 modes(M); 40modes(M+K+C)]1.71M,

Z=0.04

Bucharestminim II40modes(M+K+C)1.71M,

Z=0.04

Guentherwith turbulencel = 0[(M) ; (M+K)]1.71M,

Z=0.04

Guentherwithoutturbulence l = 0(M+K)1.706M,

Z=0.04

Guentherwithout turbulencel = 0(M+C)1.71M,

Z=0.04

HIPPARCOSBedding (1997) + interferometry

Thevenin et al(2005)withoutdiffusion

2 0.967;8.94 12.01 1.4; 2.5 18. 131.

M/M 1.71 1.71 1.71 1.71 1.71 1.70

Z 0.04 0.04 0.04 0.04 0.04 0.367

Te 6105;6088 6034 6028 6078 605060 6090

L/L 8.77 8.82 9.03 8.83 9.460.65 8.978

R/R 2.78 2.84 2.68 2.810.08 +2.680.05

2.697

Paralax 85.82.3

t (Gyr) 2.35 2.40 2.40 2.40 2.40 2.35

Table 2. The physical parameters for the star Boo obtained using different methods.