J/A+A/506/111 Frequency analysis of HD 180642 (V1449 Aql) (Degroote+, 2009)
Evidence for nonlinear resonant mode coupling in the beta Cep star
HD 180642 (V1449 Aql) from CoRoT space-based photometry.
Degroote P., Briquet M., Catala C., Uytterhoeven K., Lefever K., Morel T.,
Aerts C., Carrier F., Auvergne M., Baglin A., Michel E.
<Astron. Astrophys. 506, 111 (2009)>
=2009A&A...506..111D 2009A&A...506..111D
ADC_Keywords: Stars, variable ; Stars, early-type
Keywords: stars: oscillations - stars: variables: general -
stars: individual: HD 180642 (V1449 Aql)
Abstract:
We present the CoRoT light curve of the beta Cep star HD 180642,
assembled during the first long run of the space mission, as well as
archival single-band photometry. Our goal is to analyse the detailed
behaviour present in the light curve and interpret it in terms of
excited-mode frequencies. After describing the noise properties in
detail, we use various time series analyses and fitting techniques to
model the CoRoT light curve, for various physical assumptions. We
apply statistical goodness-of-fit criteria that allow us to select the
most appropriate physical model fit to the data. We conclude that the
light-curve model based on nonlinear resonant frequency and phase
locking provides the best representation of the data. Interpretation
of the residuals is dependent on the chosen physical model used to
prewhiten the data. Our observational results constitute a fruitful
starting point for detailed seismic stellar modelling of this
large-amplitude and evolved beta Cep star.
Description:
The tables represent the results of the frequency analysis of various
models: under assumption of stable, long-lasting and independent
frequencies with constant amplitudes and phases, we arrive at the list
in table1.dat. When assuming dependency in the form of combination
frequencies, we arrive at the list presented in table2.dat. When
allowing for time-dependent amplitudes and phases, we finally get
tables3-10.
Objects:
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RA (2000) DE Designation(s)
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19 17 14.8 +01 03 34 HD 180642 = V* V1449 Aql
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 200 Results of frequency analysis of the first
200 frequencies
table2.dat 84 33 Frequency table with fixed combinations between
parent and daughter modes
tables.dat 53 62 Variable amplitude/phase model for
a1, a2, a3, a4, phi1, phi2, phi3 and phi4
(tables 3-10 of the paper)
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See also:
B/corot : CoRoT observation log (CoRoT, 2009)
J/A+A/361/245 : 6 new Beta Cep stars (Aerts, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Frequency ID number
5- 13 F9.6 d-1 f1 Frequency value
15- 22 F8.6 d-1 e_f1 Error on frequency value
24- 33 F10.6 uHz f2 Frequency value (identical to f1)
35- 42 F8.6 uHz e_f2 Error on frequency value (identical to e_f1)
44- 50 F7.5 --- A Ratio amplitude/average flux
52- 58 F7.5 --- e_A Error on amplitude
60- 66 F7.4 --- P ]-0.5,0.5] Phase (rad/2π)
68- 73 F6.4 --- e_P Error on phase
75- 79 F5.1 --- SNR Signal-to-noise ratio over 6d-1 interval
81- 85 F5.2 % VR Variance reduction
87- 92 F6.2 --- AIC Value of Akaike's Information Criterion
94- 99 F6.2 --- BIC Value of Bayesian Information Criterion
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.6 --- A Ratio amplitude/average flux
10- 18 F9.6 d-1 f1 Frequency value
20- 28 F9.5 uHz f2 Frequency value (same as f1)
30- 36 F7.4 --- P ]-0.5,0.5] Phase (rad/2π)
38- 42 F5.2 --- Ar ?=0.0 Relative amplitude (logarithmic)
44- 47 F4.2 --- e_Ar ?=0.0 Error on amplitude ratio
49- 53 F5.2 --- Pr ]-0.5,0.5]?=0.0 Relative phase (rad/2π)
55- 58 F4.2 --- e_Pr ]-0.5,0.5]?=0.0 Error on relative phase
60- 64 F5.1 --- SNR Signal-to-noise ratio over 6d-1 interval
66- 70 F5.2 % VR Variance reduction
72- 77 F6.2 --- AIC Value of Akaike's Information Criterion
79- 84 F6.2 --- BIC Value of Bayesian Information Criterion
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Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Param [a1, a2, a3, a4, phi1, phi2, phi3, phi4]
6- 12 F7.5 --- A Ratio amplitude/average flux
14- 20 F7.5 --- e_A Error on amplitude
22- 27 F6.4 d-1 f1 Frequency value
29- 34 F6.4 d-1 e_f1 Error on frequency value
36- 42 F7.4 uHz f2 Frequency value (same as f1)
44- 48 F5.2 --- P ]-0.5,0.5] Phase (rad/2π)
50- 53 F4.2 --- e_P Error on phase
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Acknowledgements:
Pieter Degroote, pieterd(at)ster.kuleuven.ac.be
(End) Pieter Degroote [IvS, Belgium], Patricia Vannier [CD] 17-Aug-2009