P-type pulsators on the main sequence of HR Diagram

Gyöngyi KerekesCOROT-day Budapest March, 2007

HRD

δ Scuti

β Cephei

SPB

γ Doradus

Comparison

Type Period Amplitude (in magnitude)

Spectral

type

β Cephei 3-8 hours 0.01-0.8 B2-B5

δ Scuti 1-3 hours 0.03-0.9 A0-F5

δ Scuti HD 170782

• Vmag = 7.81• Spectral type: A2• Outside of the instability strip, blue

edge• Reopens the problem of variability

Whitening

1

2

3 4 5 6

123456

Fitting

Frequencies of HD 170782Frequenc

y(cycle/

day)

Amplitude(magnitude) Phase Noise

(S/N)

2.9 0.0081 0.83 18.794.1 0.0064 0.45 14.9125.5 0.0031 0.63 8.8413.2 0.0026 0.02 5.97.8 0.0020 0.33 4.2

Frequency

(cycle/day)

Amplitude(magnitude) Phase Noise

(S/N)

2.9 0.0081 0.83 18.794.1 0.0064 0.45 14.9125.5 0.0031 0.63 8.8413.2 0.0026 0.02 5.97.8 0.0020 0.33 4.2

β Cephei stars

• Known since 1902• 10-20 solar masses• Main pulsation modes radial • But non-radial pulsations also detected• Large fraction is multiperiodic• Frequency spectrum is not too dense

modelling becomes possible• Very interesting from astroseismologic

point of view

β Cephei HD 180642

• Main target of the first COROT long run• Vmag = 8.3• Spectral type: B 1.5

Whitening1

2

3

4 5 6 7

1234567

Fitting

FrequenciesFrequenc

y(cycle/

day)

Amplitude(magnitude

)Phase Noise

(S/N)

5.49 0.037 0.83 36.0150.43 0.010 0.48 10.6599.97 0.009 0.12 8.8040.35 0.005 0.98 5.351

8.81 0.005 0.54 5.524

16.88 0.004 0.91 4.59

Frequency

(cycle/day)

Amplitude(magnitude

)Phase Noise

(S/N)

5.49 0.037 0.83 36.0150.43 0.010 0.48 10.6599.97 0.009 0.12 8.8040.35 0.005 0.98 5.351

8.81 0.005 0.54 5.524

16.88 0.004 0.91 4.59

Conclusions• Main obtained frequencies:

• Trends in light curves↓

Further cleanings are required

• HD 170782 belongs to small amplitude δ Scutis → maybe more modes are excited → COROT’s task to investigate if there are more modes

δ Scuti HD

170782

25.513.2

7.8

β Cephei

HD 180642

5.59.978.81

16.88

Thank you for your attention!