J/A+A/614/A40 Spectral significance for 15 delta Scuti (Pascual-Granado+, 2018)
Impact of gaps in the asteroseismic characterization of pulsating stars.
I. The efficiency of pre-whitening.
Pascual-Granado J., Suarez J.C., Garrido R., Moya A., Garcia Hernandez A.,
Rodon J.R., Lares-Martiz M.
<Astron. Astrophys. 614, A40 (2018)>
=2018A&A...614A..40P 2018A&A...614A..40P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Asteroseismology
Keywords: asteroseismology - methods: data analysis - stars: oscillations -
stars: variable: delta Scuit
Abstract:
It is known that the observed distribution of frequencies in CoRoT and
Kepler δ Scuti stars has no parallelism with any theoretical
model. Pre-whitening is a widespread technique in the analysis of time
series with gaps from pulsating stars located in the classical
instability strip such as δ Scuti stars. However, some studies
have pointed out that this technique might introduce biases in the
results of the frequency analysis.
This work aims at studying the biases that can result from
pre-whitening in asteroseismology. The results will depend on the
intrinsic range and distribution of frequencies of the stars. The
periodic nature of the gaps in CoRoT observations, just in the range
of the pulsational frequency content of the δ Scuti stars, is
shown to be crucial to determine their oscillation frequencies, the
first step to perform asteroseismology of these objects. Hence, here
we focus on the impact of pre-whitening on the asteroseismic
characterization of δ Scuti stars.
We select a sample of 15 δ Scuti stars observed by the CoRoT
satellite, for which ultra-high quality photometric data have been
obtained by its seismic channel. In order to study the impact on the
asteroseismic characterization of δ Scuti stars we perform the
pre-whitening procedure on three datasets: gapped data, linearly
interpolated data, and data with gaps interpolated using
Autoregressive and Moving Average models (ARMA).
The different results obtained show that at least in some cases
pre-whitening is not an efficient procedure for the deconvolution of
the spectral window. Therefore, in order to reduce the effect of the
spectral window to the minimum it is necessary to interpolate with an
algorithm that is aimed to preserve the original frequency content,
and not only to perform a pre-whitening of the data.
Description:
We have used the program package SigSpec (Reegen 2007A&A...467.1353R 2007A&A...467.1353R).
We performed iterations until the limit of signi=5.0 for spectral
significance is found. We later clean the list of frequencies using
Combine and an heuristic algorithm that identifies spurious
frequencies and nonlinear interactions.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 80 15 List of studied stars
table5.dat 43 1188 Frequencies of HD50844 in ARMA interpolated data
table6.dat 43 519 Frequencies of HD174936 in ARMA interpolated data
table7.dat 43 364 Frequencies of HD174966 in ARMA interpolated data
table8.dat 43 1782 Frequencies of HD181555 in ARMA interpolated data
table9.dat 43 1232 Frequencies of HD49434 in ARMA interpolated data
table10.dat 43 1360 Frequencies of HD172189 in ARMA interpolated data
table11.dat 43 516 Frequencies of HD174532 in ARMA interpolated data
table12.dat 43 237 Frequencies of HD174589 in ARMA interpolated data
table13.dat 43 1460 Frequencies of HD51722 in ARMA interpolated data
table14.dat 43 1692 Frequencies of HD51359 in ARMA interpolated data
table15.dat 43 2041 Frequencies of HD50870 in ARMA interpolated data
table16.dat 43 2878 Frequencies of HD170699 in ARMA interpolated data
table17.dat 43 2971 Frequencies of GSC00144-03031 in ARMA
interpolated data
table18.dat 43 2017 Frequencies of HD41641 in ARMA interpolated data
table19.dat 43 183 Frequencies of HD48784 in ARMA interpolated data
table20.dat 43 1124 Frequencies of HD50844 in linearly interpolated
data
table21.dat 43 550 Frequencies of HD174936 in linearly interpolated
data
table22.dat 43 583 Frequencies of HD174966 in linearly interpolated
data
table23.dat 43 1836 Frequencies of HD181555 in linearly interpolated
data
table24.dat 43 1161 Frequencies of HD49434 in linearly interpolated
data
table25.dat 43 1427 Frequencies of HD172189 in linearly interpolated
data
table26.dat 43 584 Frequencies of HD174532 in linearly interpolated
data
table27.dat 43 273 Frequencies of HD174589 in linearly interpolated
data
table28.dat 43 2722 Frequencies of HD51722 in linearly interpolated
data
table29.dat 43 1782 Frequencies of HD51359 in linearly interpolated
data
table30.dat 43 3269 Frequencies of HD50870 in linearly interpolated
data
table31.dat 43 2924 Frequencies of HD170699 in linearly interpolated
data
table32.dat 43 2328 Frequencies of GSC00144-03031 in linearly
interpolated data
table33.dat 43 2833 Frequencies of HD41641 in linearly interpolated
data
table34.dat 43 170 Frequencies of HD48784 in linearly interpolated
data
table35.dat 43 1001 Frequencies of HD50844 in gapped data
table36.dat 43 348 Frequencies of HD174936 in gapped data
table37.dat 43 152 Frequencies of HD174966 in gapped data
table38.dat 43 2654 Frequencies of HD181555 in gapped data
table39.dat 43 2243 Frequencies of HD49434 in gapped data
table40.dat 43 1790 Frequencies of HD172189 in gapped data
table41.dat 43 405 Frequencies of HD174532 in gapped data
table42.dat 43 116 Frequencies of HD174589 in gapped data
table43.dat 43 1378 Frequencies of HD51722 in gapped data
table44.dat 43 2674 Frequencies of HD51359 in gapped data
table45.dat 43 2150 Frequencies of HD50870 in gapped data
table46.dat 43 2042 Frequencies of HD170699 in gapped data
table47.dat 43 1735 Frequencies of GSC00144-03031 in gapped data
table48.dat 43 2301 Frequencies of HD41641 in gapped data
table49.dat 43 141 Frequencies of HD48784 in gapped data
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See also:
B/corot : CoRoT observation log (CoRoT, 2009)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 ---- Star Star name
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 29 F8.5 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 44 F7.4 arcsec DEs Declination (J2000)
46- 56 A11 --- ARMA Name of the table with frequencies in ARMA
interpolated data
58- 68 A11 --- lin Name of the table with frequencies in linear
interpolated data
70- 80 A11 --- gapped Name of the table with frequencies in gapped
interpolated data
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.8 d-1 Freq Frequency
13- 22 F10.4 --- Signi Significance of frequency (1)
24- 35 F12.6 --- Amp Amplitude
39- 43 F5.3 rad Phase Phase
--------------------------------------------------------------------------------
Note (1): As defined by Reegen, 2007A&A...467.1353R 2007A&A...467.1353R.
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Acknowledgements:
Javier Pascual-Granado, javier(at)iaa.es
(End) Patricia Vannier [CDS] 19-Feb-2018