J/MNRAS/485/2380 Gaia-derived luminosities of Kepler A/F stars (Murphy+, 2019)
Gaia-derived luminosities of Kepler A/F stars and the pulsator fraction across
the δ Scuti instability strip.
Murphy S.J., Hey D., Van Reeth T., Bedding T.R.
<Mon. Not. R. Astron. Soc., 485, 2380-2400 (2019)>
=2019MNRAS.485.2380M 2019MNRAS.485.2380M (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Parallaxes, trigonometric ; Stars, variable ;
Optical
Keywords: asteroseismology - parallaxes -
Hertzsprung-Russell and colour-magnitude diagrams -
stars: oscillations - stars: variables: δ Scuti
Abstract:
We study the fraction of stars in and around the δ Scuti
instability strip that are pulsating, using Gaia DR2 parallaxes to
derive precise luminosities. We classify a sample of over 15000 Kepler
A and F stars into δ Sct and non-δ Sct stars, paying close
attention to variability that could have other origins. We find that
18 per cent of the δ Sct stars have their dominant frequency
above the Kepler long-cadence Nyquist frequency (periods<1h), and 30
per cent have some super-Nyquist variability. We analyse the pulsator
fraction as a function of effective temperature and luminosity,
finding that many stars in the δ Sct instability strip do not
pulsate. The pulsator fraction peaks at just over 70 per cent in the
middle of the instability strip. The results are insensitive to the
amplitude threshold used to identify the pulsators. We define a new
empirical instability strip based on the observed pulsator fraction
that is systematically hotter than theoretical strips currently in
use. The stellar temperatures, luminosities, and pulsation
classifications are provided in an online catalogue.
Description:
We selected Kepler targets with temperatures between 6500 and 10000K,
according to the 'input' temperatures in Mathur et al.
(2017ApJS..229...30M 2017ApJS..229...30M, Cat. J/ApJS/229/30). This range covers the
δ Sct instability strip and the region around it where δ Sct
pulsators are observed.
We made no selection based on logg or [Fe/H] values, which we also
gathered from the input values of Mathur et al. (2017ApJS..229...30M 2017ApJS..229...30M,
Cat. J/ApJS/229/30). We made no cut on Kepler magnitude, but we did
cut stars with a luminosity 0.4dex (i.e. 1mag) fainter than the
zero-age main-sequence (ZAMS) because we focus here on stars on the
main-sequence and immediate post-main-sequence. We did not include
stars for which there are no Kepler light curves available. The total
sample size in our Teff range and after filtering by luminosity is
15229.
In DR2, stars with Gaia temperatures above 8000K had no available
extinction values in the Gaia G band, AG, and thus no luminosities.
It also appears that extinctions were not used in calculating the
luminosities of stars where AG was available (Andrae et al.
2018A&A...616A...8A 2018A&A...616A...8A), hence the Gaia luminosities as provided in the
DR2 catalogue are unreliable for our targets. We therefore calculated
luminosities for all targets, taking from Gaia DR2 only stellar
parallaxes, π, and their uncertainties (Gaia Collaboration
2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345). Most of our targets have precise
parallaxes, with only 249 having fractional uncertainties above 0.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 132 14330 Stellar data
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC KIC name (NNNNNNNN)
10- 28 I19 --- GaiaDR2 Gaia DR2 source name
30- 35 F6.3 mag gmag g-band SDSS magnitude
37- 42 F6.3 mas plx Parallax
44- 48 F5.3 mas e_plx Error on plx
50- 53 F4.2 mag Ag Computed extinction in the g-band
55- 58 F4.2 mag e_Ag Error on Ag
60- 63 I4 K Teff Effective temperature
65- 67 I3 K e_Teff Error on Teff
69- 73 F5.2 --- [Fe/H] Iron to hydrogen abundance ratio
75- 78 F4.2 --- e_[Fe/H] Error on [Fe/H]
80- 83 F4.2 [cm/s2] logg ? Surface gravity
85- 88 F4.2 [cm/s2] e_logg ? Error on logg
90- 94 F5.2 Rsun Rad Star radius
96- 99 F4.2 Rsun e_Rad Error on Rad
101-104 F4.2 Msun Mstar Star mass
106-109 F4.2 Msun e_Mstar Error on Mstar
111 I1 --- q_Mstar [0/6] Quality flag on Mstar (1)
113-118 F6.3 [Lsun] logLbol Star luminosity (2)
120-124 F5.3 [Lsun] E_logLbol Upper error on logLbol
126-130 F5.3 [Lsun] e_logLbol Lower error on logLbol
132 I1 --- dSct [0/2] Indicates if the star is a
δ Sct (3)
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Note (1): Quality flag as follows:
0 = The mass estimate is reliable
1 = The star lies within 2-sigma of the zero-age main-sequence (ZAMS)
2 = The star lies within 1-sigma of the zero-age main-sequence (ZAMS)
3 = The luminosity uncertainty is larger than 0.2. Many of these stars are
close to the 3M☉ boundary
4 = The observed Teff value of the star lies outside of the grid range
5 = The observed position of the star lies below the ZAMS
6 = The mode of the derived mass distribution lies at the edge of the grid
mass range. In this case, it is almost certain that the best mass for
the star lies outside of the grid range.
Note (2): Logarithmic bolometric luminosities were calculated via absolute
magnitudes using the standard formulae: Mg=gmag-5(logd-1)-Ag,
and logLbol/L☉=-(Mg+BC-Mbolsun)/2.5, where BC is the bolometric
correction and Mbolsun is the bolometric magnitude of the Sun (=4.74;
Mamajek et al. 2015arXiv151006262M 2015arXiv151006262M)
Note (3): Flag as follows:
0 = non-δ Sct star
1 = δ Sct star
2 = star with other variability
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 20-Sep-2022