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J/A+A/533/A4        CoRoT photometry of three O-type stars      (Blomme+, 2011)

Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150 and HD 46966 Blomme R., Mahy L., Catala C., Cuypers J., Gosset E., Godart M., Montalban J., Ventura P., Rauw G., Morel T., Degroote P., Aerts C., Noels A., Michel E., Baudin F., Baglin A., Auvergne M., Samadi R. <Astron. Astrophys. 533, A4 (2011)> =2011A&A...533A...4B
ADC_Keywords: Stars, O ; Photometry Keywords: stars: variables: general - stars: early-type - stars: oscillations - stars: individual: HD 46223 - stars: individual: HD 46150 - stars: individual: HD 46966 Abstract: The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. We analyse the CoRoT data corresponding to three hot O-type stars, describing the properties of their light curves and we search for pulsational frequencies, which we then compare to theoretical model predictions. We determine the amplitude spectrum of the data, using the Lomb-Scargle and a multifrequency HMM-like technique. Frequencies are extracted by prewhitening, and their significance is evaluated under the assumption that the light curve is dominated by red noise. We search for harmonics, linear combinations and regular spacings among these frequencies. We use simulations with the same time sampling as the data as a powerful tool to judge the significance of our results. From the theoretical point of view, we use the MAD non-adiabatic pulsation code to determine the expected frequencies of excited modes. A substantial number of frequencies is listed, but none can be convincingly identified as being connected to pulsations. The amplitude spectrum is dominated by red noise. Theoretical modelling shows that all three O-type stars can have excited modes but the relation between the theoretical frequencies and the observed spectrum is not obvious. The dominant red noise component in the hot O-type stars studied here clearly points to a different origin than the pulsations seen in cooler O stars. The physical cause of this red noise is unclear, but we speculate on the possibility of sub-surface convection, granulation, or stellar wind inhomogeneities being responsible. Description: We use a prewhitening technique to analyse the CoRoT photometry, and list the frequencies, semi-amplitudes and phases (with their respective error bars). The phases are defined with t=0 corresponding to the first non-flagged data point. We also list the standard deviation at each stage in the prewhitening and the significance of the frequency under the assumption of red noise. Red-noise significant frequencies are noted as well as those frequencies that remain present if we split the data set in two halves. Objects: ------------------------------------------------------------ RA (2000) DE Designation(s) (file) ------------------------------------------------------------ 06 32 09.3 +04 49 25 HD 46223 = HIP 31149 (hd46223.dat) 06 31 55.5 +04 56 34 HD 46150 = HIP 31130 (hd46150.dat) 06 36 25.9 +06 04 59 HD 46966 = HIP 31567 (hd46966.dat) ------------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file hd46223.dat 74 500 Frequencies, amplitudes, phases for HD 46223 (table 2 of the paper) hd46150.dat 74 500 Frequencies, amplitudes, phases for HD 46150 (table 3 of the paper) hd46966.dat 74 300 Frequencies, amplitudes, phases for HD 46966 (table 4 of the paper)
See also: B/corot : CoRoT observation log Release 7 (CoRoT, 2010) Byte-by-byte Description of file: hd46150.dat hd46223.dat hd46966.dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID Frequency ID (running number) 6- 12 F7.4 d-1 Freq Frequency 14- 20 F7.4 d-1 e_Freq Error on the frequency 22- 29 F8.3 ct Ampl Semi-amplitude 31- 38 F8.3 ct e_Ampl Error on semi-amplitude 40- 45 F6.3 rad Phase Phase 47- 52 F6.3 rad e_Phase Error on the phase 54- 62 F9.3 ct Stdev Standard deviation at this phase prewhitening 65- 70 F6.4 --- SigRed Significance under red noise conditions 72 A1 --- Red [R] 'R' if significant under red noise, ' ' otherwise 74 A1 --- Half [*] '*' if still present when data set is split in two halves, ' ' otherwise
Acknowledgements: Ronny Blomme, Ronny.Blomme(at)oma.be
(End) Ronny Blomme [ROB, Belgium], Patricia Vannier [CDS] 02-Jul-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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