Corot 2009 - HD180642 - A.Thoul Modeling of HD180642 = V1449 Aql (THE only Cephei star main target of CoRoT). Anne Thoul + Maryline Briquet, Pieter Degroote,

Corot 2009 - HD180642 - A.Thoul

Modeling of HD180642 = V1449 Aql (THE only Cephei star main target of CoRoT).

Anne Thoul

+ Maryline Briquet, Pieter Degroote, Andrea Miglio, Josefina Montalban, Conny Aerts, Thierry Morel, Ewa

Niemczura, Kévin Belkacem, ...

+ the Corot B star Team


HD180642

photometry

spectroscopy

Zobs=0.0099+-0.0016

Data from T. Morel, E.Niemczura et al.


dominant radial (l=0) mode

l=3

ground photometry

groundspectroscopy

HD180642

11 independent frequencies from Corot

Courtesy Pieter DegrooteP62


HD180642

df/dt=[7.6;14.4]10-11Hz/y

df/dt ~ 10-10 Hz/y

Hipparcos0.7m Swiss telescope

1.2m Mercator telescope

ASAS photometry

COROT

Degroote, Aerts et al


HD180642

11 independent frequencies determined from Corot light curve

Only one high frequency mode identified : the high amplitude radial mode

One low frequency mode identified

No clear multiplet

Main radial mode shows a frequency decrease

Photometric and spectroscopic error boxes do not overlap


HD180642

Modelling:

using CLES and OSC

with AGS05 and OP opacities

Fit the radial mode

“Free parameters”: X, Z, ov

, M


HD180642

Range of parameters explored:

X = 0.72 – 0.74Z = 0.010 – 0.015

ov

and M: all possible values which give

solutions close to the error box in HR diagram


HD180642A. Fit the main frequency with the fundamental

radial mode on the main sequence

n=1

n=2 n=3

X=0.72, Z=0.015, ov=0, M=12


HD180642

modelling radial mode with fundamental on MSeffect of M and

ov (X=0.72, Z=0.010)

M=10M=12

=0.4=0.2=0.0


HD180642

modelling radial mode with fundamental on MSeffect of Z (X=0.72,

ov=0)

Z=0.010Z=0.015


HD180642

modelling radial mode with fundamental on MSeffect of X

(Z=0.010,

ov=0)

X=0.72X=0.74

M=10M=12


HD180642radial = fundamental on MS

log g fixed by radial mode

M~9

M~13


HD180642

B. Fit the main frequency with the first overtone of the radial mode on the main sequence

n=1

n=2 n=3

X=0.72, Z=0.015, ov=0, M=12


HD180642

radial mode = fundamental

radial mode = first overtone

M~13M~10


HD180642C. Fit the main frequency with the second overtone

of the radial mode on the main sequence

n=1

n=2 n=3

X=0.72, Z=0.015, ov=0.4, M=10


HD180642

n=3n=2

n=1


HD180642

D. Fit the main frequency with a radial mode after the TAMS

n=1

n=2

n=3

log

X=0.72, Z=0.010, ov=0.2, M=10

n=1

n=2n=3

n=2n=3


HD180642

TAMS

MS

X=0.72,Z=0.010,ov=0.2,M=10

n=1

n=2n=3


HD180642

n=1

n=2n=3


HD180642TAMS

MS

df/dt on MS much too small


HD180642TAMS

MS


HD180642TAMS

MS


HD180642


HD180642

photometry

spectroscopy


HD180642

X=0.72, Z=0.010, ov=0, M=10 X=0.72, Z=0.010, ov=0.5, M=10

X=0.72, Z=0.015, ov=0, M=10 X=0.72, Z=0.015, ov=0, M=12


HD180642

radial mode is n=1, MS

radial mode is n=1, after TAMS

X=0.72, Z=0.015, ov

=0, M=9




MAD


HD180642

X=0.72, Z=0.015, ov

=0.4, M=12




MAD


HD180642

CONCLUSIONS We’ve got a problem!

Modelling of the star using main high amplitude radial mode:

l=0, n=1 out of 2 error box in HR diagram (log g too high) range of excited frequencies more or less OK

l=0, n=2 in 2 error box but range of excited frequencies too low

l=0, n=3 in 1 error box but range of excited frequencies much too low

df/dt cannot be explained by evolution


HD180642

We’ve got a problem!

Is log g correct?

If yes, how can we have such high amplitude oscillations with high order radial modes?

What about the excitation of the modes?

What is the explanation for df/dt? Evolution? Resonant coupling?

Is the star on MS or after TAMS? (1%)


HD180642

A “CHIMERA” STAR

Hybrid Cephei / SPB star + solar-like oscillations(Kévin Belkacem et al.)

next step: try modelling the star using all stable and unstable modes

NOTE: PROBLEM ==> We will learn something!

Documents

Corot 2009 - HD180642 - A.Thoul Modeling of HD180642 = V1449 Aql (THE only Cephei star main target of CoRoT). Anne Thoul + Maryline Briquet, Pieter Degroote,