J/MNRAS/479/183 Kepler field pulsating A-F stars (Balona, 2018)
Gaia luminosities of pulsating A-F stars in the Kepler field.
Balona L.A.
<Mon. Not. R. Astron. Soc., 479, 183-191 (2018)>
=2018MNRAS.479..183B 2018MNRAS.479..183B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Parallaxes, trigonometric ;
Effective temperatures
Keywords: parallaxes - stars: oscillations - stars: variables: delta Scuti
Abstract:
All stars in the Kepler field brighter than 12.5 mag have been
classified according to variability type. A catalogue of δ Scuti
and γ Doradus stars is presented. The problem of low frequencies
in δ Sct stars, which occurs in over 98 percent of these stars,
is discussed. Gaia DR2 parallaxes were used to obtain precise
luminosities, enabling the instability strips of the two classes of
variable to be precisely defined. Surprisingly, it turns out that the
instability region of the γ Dor stars is entirely within the
δ Sct instability strip. Thus, γDor stars should not be
considered a separate class of variable. The observed red and blue
edges of the instability strip do not agree with recent model
calculations. Stellar pulsation occurs in less than half of the stars
in the instability region and arguments are presented to show that
this cannot be explained by assuming pulsation at a level too low to
be detected. Precise Gaia DR2 luminosities of high-amplitude δ
Sct stars (HADS) show that most of these are normal δ Sct stars
and not transition objects. It is argued that current ideas on A star
envelopes need to be revised.
Description:
The light curves and periodograms of over 20000 stars in the Kepler
field were visually examined in order to detect the various classes of
variables. Among these are 2570 stars of the delta Scuti and gamma
Doradus types. Parallaxes from Gaia DR2 were obtained for 2476 of
these variables, from which precise stellar luminosities were derived.
The effective temperatures of stars with effective temperatures less
than 6500K were obtained from the Huber et al. (2014ApJS..211....2H 2014ApJS..211....2H).
For hotter stars, 144K was added to the KIC values in accordance with
Balona et al. (2015MNRAS.452.3073B 2015MNRAS.452.3073B). Interstellar absorption in the V
band was obtained by linear interpolation of the 3D table by
Gontcharov (2017AstL...43..472G 2017AstL...43..472G). For stars more distant than 1200pc,
the absorption was assumed to follow the simple model described in
Brown et al. (2011AJ....142..112B 2011AJ....142..112B) adjusted to give the same value at
1200 pc. The de-reddening procedure to the KIC griz values followed
the procedure outlined in Pinsonneault et al. (2012ApJS..199...30P 2012ApJS..199...30P),
from which the unreddened r magnitude was obtained. The absolute r
magnitude was then obtained from the Gaia DR2 parallax (Gaia
Collaboration, 2018, Cat. I/345) and using the bolometric correction
in the r band from Castelli and Kurucz, 2004astro.ph..5087C 2004astro.ph..5087C) the
absolute bolometric magnitude was derived. The 2476 stars for which
luminosities could be calculated are listed in Table 1.
Luminosities could not be obtained for some of the delta Scuti and gamma
Doradus stars identified in the Kepler field, either because the
parallax was not measured or because the effective temperature could not
be estimated. These stars are listed in Table 2.
Tables 1 and 2: KIC numbers, variability type and stellar parameters
for delta Scuti and gamma Doradus stars in the Kepler field.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 73 2476 Stars with precise Gaia luminosities
table2.dat 51 94 Stars with photometric luminosities
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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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2- 9 I8 --- KIC KIC identification number
11- 26 A16 --- VType Variability classification (G1)
28- 34 F7.4 mas Plx Parallax
37- 42 F6.4 mas e_Plx Error in the parallax
44- 48 I5 K Teff Effective temperature (G2)
52- 54 I3 K e_Teff Error in the effective temperature
56- 59 F4.2 mag AV Interstellar absorbtion in V
60- 66 F7.4 [Lsun] logL Logarithm of the luminosity
69- 73 F5.3 [Lsun] e_logL Error in LogL
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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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2- 9 I8 --- KIC KIC identification number
11- 26 A16 --- VType Variability classification (G1)
29- 34 F6.3 mag Kpmag Kepler magnitude
36- 40 I5 K Teff ? Effective temperature (G2)
43- 45 I3 K e_Teff ? Error in effective temperature
47- 51 F5.2 [Lsun] logL ? Logarithm of the luminosity (2)
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Note (2): The luminosity is calculated from Teff and the KIC stellar radius.
The standard deviation in logL is about 0.4dex.
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Global notes:
Note (G1): Code names were developed to describe the variability class of each
star as follows:
DSCT = delta Scuti star
GDOR = gamma Doradus star
GDORA = gamma Doradus star with asymmetric light curve
GDORS = gamma Doradus star with symmetric light curve
GDORM = gamma Doradus star with multiple frequencies
In addition to these basic types, evidence was found for other types of
variation in the same star as follows:
ROT = Rotational variable
EB = Eclipsing binary
HRTB = Heartbeat binary
MAIA = High frequencies in a star between the red edge of the beta Cep
variables and the blue edge of the delta Scuti variables.
SOLR = Solar-like frequency comb seen in periodogram.
SPB = Low frequencies in a star cooler than the red edge of the SPB
variables and hotter than the blue edge of the gamma Dor variables.
Note (G2): The effective temperature and its standard deviation is from the
Huber et al. (2014ApJS..211....2H 2014ApJS..211....2H) for Teff<6500.
For hotter stars Teff is from the KIC, but increased by 144K in accordance
with Balona et al. (2015MNRAS.452.3073B 2015MNRAS.452.3073B).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Feb-2022