J/AJ/143/101 The classification of Kepler B-star variables (McNamara+, 2012)
The classification of Kepler B-star variables.
McNamara B.J., Jackiewicz J., McKeever J.
<Astron. J., 143, 101 (2012)>
=2012AJ....143..101M 2012AJ....143..101M
ADC_Keywords: Stars, B-type ; Photometry, SDSS ; Proper motions ;
Stars, variable ; Stars, double and multiple
Keywords: stars: early-type - stars: oscillations - stars: variables: general
Abstract:
The light curves of 252 B-star candidates in the Kepler database are
analyzed in a similar fashion to that done by
Balona et al. (2011MNRAS.413.2403B 2011MNRAS.413.2403B) to further characterize B-star
variability, increase the sample of variable B stars for future study,
and to identify stars whose power spectra include particularly
interesting features such as frequency groupings. Stars are classified
as either constant light emitters, β Cep stars, slowly pulsating
B stars (SPBs), hybrid pulsators, binaries or stars whose light curves
are dominated by rotation (Bin/Rot), hot subdwarfs, or white dwarfs.
One-hundred stars in our sample were found to be either light
constants or to be variable at a level of less than 0.02mmag. We
increase the number of candidate B-star variables found in the Kepler
database by Balona et al. (2011MNRAS.413.2403B 2011MNRAS.413.2403B) in the following
fashion: β Cep stars from 0 to 10, SPBs from eight to 54, hybrid
pulsators from seven to 21, and Bin/Rot stars from 23 to 82. For
comparison purposes, approximately 51 SPBs and six hybrids had been
known prior to 2007. The number of β Cep stars known prior to
2004 was 93. A secondary result of this study is the identification of
an additional 11 pulsating white dwarf candidates, four of which
possess frequency groupings.
Description:
The Kepler satellite was launched on 2009 March 6. It monitors the
brightness variations of about 150000 stars in a 105deg2 region in
the constellations of Cygnus and Lyra.
This study targets B stars. Program objects were identified by
requiring (1) that they have a Teff>10000K in the
KIC (Kepler Input Catalog, Cat. V/133), or (2) a position in a KIC
color-color plot that is close to that of a B star. Our final sample
contains 252 stars. An examination of their power spectra revealed
that many (100) candidates were not light variables or possessed a
very low level of variability. The KIC numbers of these stars are
listed in table 1. The properties of the remaining 152 stars in our
sample are listed in table 2. Table 3 shows the classification
assigned to each of our 152 program stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 10 100 KIC numbers of non-variable stars in the sample
table2.dat 47 152 B-type star target list with general parameters
table3.dat 88 152 Variable classifications
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/AJ/141/78 : Low-mass eclipsing binaries in KIC (Coughlin+, 2011)
J/AJ/142/160 : Kepler Mission. II. 2165 eclipsing binaries (Slawson+, 2011)
J/A+A/529/A89 : Kepler satellite variability study (Debosscher+, 2011)
J/A+A/534/A125 : Variability of A & -F-stars from Kepler (Uytterhoeven+ 2011)
J/MNRAS/414/2860 : Kepler compact pulsator candidates (Ostensen+, 2011)
J/MNRAS/413/2709 : BVRI light curves of KIC Cepheids (Szabo+, 2011)
J/A+A/517/A3 : Parameters of Kepler early-type targets (Catanzaro+, 2010)
J/MNRAS/409/1470 : Kepler compact pulsator candidates (Ostensen+, 2010)
J/AcA/59/33 : Variable stars catalog in Kepler field. (Pigulski+, 2009)
J/ApJS/158/193 : Catalog of Galactic β Cephei stars (Stankov+, 2005)
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 [1028085/12885346] Star identifier from KIC
(Kepler Input Catalog, Cat. V/133) (1)
10 A1 --- f_KIC [*d] Flag on KIC (G1)
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Note (1): An examination of their power spectra revealed that these candidates
were not light variables or possessed a very low level of variability.
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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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1- 8 I8 --- KIC [1430353/12268319] Star identifier from KIC
(Kepler Input Catalog, Cat. V/133)
10 A1 --- f_KIC [d] Star in common with Balona (G1)
12- 16 F5.2 mag Kpmag [6.6/16.67] Kepler magnitude
18- 23 F6.3 mag gmag [6.37/16.75] SDSS g band magnitude
25- 29 F5.2 mag g-i [-0.84/-0.04] SDSS (g-i) color index
31- 35 F5.1 mas/yr pmRA ? Proper motion along RA times cos(DE)
37- 41 F5.1 mas/yr pmDE ? Proper motion along DE
43- 47 F5.2 mag gMag ? Pseudo absolute magnitude (1)
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Note (1): Using a star's proper motion as a proxy for its distance, a pseudo
absolute magnitude is computed from the relation:
Mag=gmag+5log(µ), where
µ=Δµ/(1mas/yr), and Δµ is the difference between
the stars's proper motion and the center of the B-star concentration.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC [1430353/12268319] Star identifier from KIC
(Kepler Input Catalog, Cat. V/133)
10 A1 --- f_KIC [d] Star in common with Balona (G1)
12- 15 I4 --- Qobs Quarters observed (0, 1, 2, 3, 4 and/or 5)
17- 23 A7 --- Type Our variable classification (2)
24 A1 --- u_Type Uncertainty on Type
26- 30 F5.2 d-1 numax [0.08/24.47]? Frequency of the waveform with the
largest amplitude νmax in cycle/day units (3)
31 A1 --- u_numax Uncertainty on numax
33- 38 I6 ppm Amax [9/110297]? Amplitude of numax (in 10-6)
40- 42 I3 --- N20 [1/254]? Number of waveforms detected with an
amplitude >20% of the largest amplitude
43 A1 --- u_N20 Uncertainty on N20 (4)
45- 88 A44 --- Notes Associated notes (5)
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Note (2): Types are:
BCEP = β Cephei stars. Stars whose pulsation frequencies extend from
about 3.5 to 20/day;
SPB = Slowly pulsating B stars. B stars that pulsate with frequencies
between 0.5 and 3.5/day;
BIN/ROT = binaries or stars whose light curves are dominated by rotation;
H = hybrid pulsators (SPB/BCEP). To be classified as an hybrid, a B star
must possess modes of both of these classes, i.e., between 0.5 to
20day;
sdB = pulsating hot subdwarf B stars;
WD = pulsating white dwarfs.
Note (3): In cases where it was not possible to distinguish a real variation
from the low frequency noise, the frequency information is left blank.
Note (4): The uncertainty is associated with the noise
Note (5): Abbreviations are:
Fg = Precence of a frequency grouping
large µ = When a star's proper motion is large, this is also noted since it
is used to differentiate variable classes.
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Global notes:
Note (G1): Flag as follows:
* = Denotes that pulsations might be present but are below the 20 ppm level.
d = Denotes stars in common with Balona et al. (2011MNRAS.413.2403B 2011MNRAS.413.2403B).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 03-Jun-2013