J/MNRAS/460/1970 Kepler δ Sct stars amplitude modulation (Bowman+, 2016)
Amplitude modulation in δ Sct stars: statistics from an ensemble study
of Kepler targets.
Bowman D.M., Kurtz D.W., Breger M., Murphy S.J., Holdsworth D.L.
<Mon. Not. R. Astron. Soc. 460, 1970 (2016)>
=2016MNRAS.460.1970B 2016MNRAS.460.1970B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable; Stars, A-type; Stars, F-type
Keywords: asteroseismology - stars: oscillations -
stars: variables: δ Scuti
Abstract:
We present the results of a thorough search for amplitude modulation
of pulsation modes in 983 δ Sct stars, which have effective
temperatures between 6400<Teff<10000K in the Kepler Input
Catalogue and were continuously observed by the Kepler Space Telescope
for 4yr. We demonstrate the diversity in pulsational behaviour
observed, in particular non-linearity, which is predicted for δ
Sct stars. We analyse and discuss examples of δ Sct stars with
constant amplitudes and phases; those that exhibit amplitude
modulation caused by beating of close-frequency pulsation modes; those
that exhibit pure amplitude modulation (with no associated phase
variation); those that exhibit phase modulation caused by binarity;
and those that exhibit amplitude modulation caused by non-linearity.
Using models and examples of individual stars, we demonstrate that
observations of the changes in amplitude and phase of pulsation modes
can be used to distinguish among the different scenarios. We find that
603 δ Sct stars (61.3 per cent) exhibit at least one pulsation
mode that varies significantly in amplitude over 4yr. Conversely,
many δ Sct stars have constant pulsation amplitudes so
short-length observations can be used to determine precise
frequencies, amplitudes and phases for the most coherent and periodic
δ Sct stars. It is shown that amplitude modulation is not
restricted to a small region on the HR diagram, therefore not
necessarily dependent on stellar parameters such as Teff, logg or
[Fe/H]. Our catalogue of 983 δ Sct stars will be useful for
comparisons to similar stars observed by K2 and TESS, because the
length of the 4-yr Kepler data set will not be surpassed for some
time.
Description:
We searched for amplitude modulation of pulsation modes in δ Sct
stars observed by the Kepler Space Telescope.
The number of pulsation modes out of a maximum of twelve that have
constant amplitudes and variable amplitudes are given in the columns
NoMod and AMod, respectively, along with stellar parameters from Huber
et al. (2014, Cat. J/ApJS/211/2). Table 1 is the full version for all
983 δ Sct stars the abridged version of the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 983 Stellar parameters for the δ Sct stars
discussed in this paper, as listed in
Huber et al. (2014, Cat. J/ApJS/211/2)
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See also:
J/ApJS/211/2 : Q1-16 Kepler targets revised stellar properties (Huber+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 9 I8 --- KIC KIC identification number
11- 15 I5 K Teff ?=-99 effective temperature (1)
17- 21 F5.2 [cm/s2] logg ?=-9.99 surface gravity (1)
24- 28 F5.2 [-] [Fe/H] ?=-9.99 metallicity (1)
31- 35 F5.2 mag kepmag Kepler magnitude
38- 39 I2 --- NoMod Number of constant-amplitude pulsation mode
frequencies above our amplitude cut-off of
0.10mmag
42- 43 I2 --- AMod Number of variable-amplitude pulsation mode
frequencies above our amplitude cut-off of
0.10mmag
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Note (1): value taken from Huber et al. (2014, Cat. J/ApJS/211/2).
If no value listed in Huber et al. (2014), therefore value set to -99 or -9.99.
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Acknowledgements:
Dominic M. Bowman, dmbowman(at)uclan.ac.uk
Cristina C. Popescu, cpopescu(at)uclan.ac.uk
(End) D. Bowman [Univ. of Central Lancs., UK], P. Vannier [CDS] 16-Jun-2016