J/AJ/146/101 LINEAR. III. Catalog of periodic variables (Palaversa+, 2013)
Exploring the variable sky with LINEAR.
III. Classification of periodic light curves.
Palaversa L., Ivezic Z., Eyer L., Ruzdjak D., Sudar D., Galin M.,
Kroflin A., Mesaric M., Munk P., Vrbanec D., Bozic H., Loebman S.,
Sesar B., Rimoldini L., Hunt-Walker N., Vanderplas J., Westman D.,
Stuart J.S., Becker A.C., Srdoc G., Wozniak P., Oluseyi H.
<Astron. J., 146, 101 (2013)>
=2013AJ....146..101P 2013AJ....146..101P
ADC_Keywords: Surveys ; Stars, variable ; Photometry, SDSS ;
Photometry, infrared
Keywords: binaries: eclipsing - blue stragglers; catalogs - Galaxy: halo -
stars: statistics - stars: variables: general
Abstract:
We describe the construction of a highly reliable sample of ∼7000
optically faint periodic variable stars with light curves obtained by
the asteroid survey LINEAR across 10000deg2 of the northern sky. The
majority of these variables have not been cataloged yet. The sample
flux limit is several magnitudes fainter than most other wide-angle
surveys; the photometric errors range from ∼0.03mag at r=15 to
∼0.20mag at r=18. Light curves include on average 250 data points,
collected over about a decade. Using Sloan Digital Sky Survey (SDSS)
based photometric recalibration of the LINEAR data for about 25
million objects, we selected ∼200000 most probable candidate variables
with r<17 and visually confirmed and classified ∼7000 periodic
variables using phased light curves. The reliability and uniformity of
visual classification across eight human classifiers was calibrated
and tested using a catalog of variable stars from the SDSS Stripe 82
region and verified using an unsupervised machine learning approach.
The resulting sample of periodic LINEAR variables is dominated by 3900
RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and
includes small fractions of relatively rare populations such as
asymptotic giant branch stars and SX Phoenicis stars. We discuss the
distribution of these mostly uncataloged variables in various diagrams
constructed with optical-to-infrared SDSS, Two Micron All Sky Survey,
and Wide-field Infrared Survey Explorer photometry, and with LINEAR
light-curve features. We find that the combination of light-curve
features and colors enables classification schemes much more powerful
than when colors or light curves are each used separately. An
interesting side result is a robust and precise quantitative
description of a strong correlation between the light-curve period and
color/spectral type for close and contact eclipsing binary stars
(β Lyrae and W UMa): as the color-based spectral type varies from
K4 to F5, the median period increases from 5.9hr to 8.8hr. These large
samples of robustly classified variable stars will enable detailed
statistical studies of the Galactic structure and physics of binary
and other stars and we make these samples publicly available.
Description:
This paper is the third in a series based on light-curve data
collected by the LINEAR (Lincoln Near-Earth Asteroid Research)
asteroid survey over a period roughly from 1998 to 2009.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 84 7194 Periodic LINEAR Variables (PLV) catalog: light
curve data
table6.dat 101 7194 PLV catalog: SDSS data
table7.dat 92 7194 PLV catalog: 2MASS and WISE data
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2013)
II/328 : AllWISE Data Release (Cutri+ 2013)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/146/21 : LINEAR. II. Catalog of RR Lyrae stars (Sesar+, 2013)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
https://astroweb.lanl.gov/lineardb/ : SkyDOT Web site
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- LINEAR [2522/24268361] Internal LINEAR source number
10- 11 I2 --- T1 [0/11] Light curve type (1)
13- 23 F11.6 d Period [0.04/1964]?=-9.9 Best-fit period (2)
25- 29 F5.2 mag Amp [0.01/9.4]?=-9.9 Light curve amplitude (3)
31- 35 F5.2 mag mag [14/17] Median LINEAR magnitude
37- 40 F4.2 mag e_mag Standard deviation of LINEAR magnitudes; all
points
42- 45 F4.2 mag rms Robust estimate of the standard deviation (4)
47- 51 F5.3 [-] chi2 [0.477/] log(χ2) for non-variable (5)
53- 56 I4 --- No [30/1150] Number of LINEAR observations
58- 62 F5.2 --- skew Skewness in LINEAR light curve
64- 69 F6.2 --- kurt Kurtosis in LINEAR light curve
71- 76 F6.3 [-] chi95 log(χ2) on 95% points (6)
78 I1 --- q_T1 [0/5] Classification grade, 0=best (7)
80- 81 I2 --- T2 [0/11] Alternative classification type (1)
83- 84 I2 --- T3 [0/12] Alternative classification type
(type 12 is not defined) (1)
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Note (1): From visual classification (the numbers in parenthesis give counts
for main type), defined as follows:
1 = RRab, fundamental mode RR Lyr-type (2923);
2 = RRc, overtone RR Lyr-type (990);
3 = "SM", flat light curve with single minimum (20);
4 = EA, Algol-like eclipsing binary with 2 minima (357);
5 = EB/EW, contact binary (2385);
6 = SXP/DSCT, δ Sct/SX Phe (112);
7 = LPV, long-period variable, including semi-regular variables (77);
8 = hearbeat candidates (1);
9 = BL Her, Type II Cepheids (6);
11 = anomalous Cepheids (5);
0 = other (318, including some quasars).
T2 and T3 are set to 0 for good classification (q_T1≤1)
Note (2): Visually confirmed. 6958 sources, from 7194, have reliably
determined period, with Pmin=0.042d and Pmax=1964d.
Note (3): Estimated non-parametrically from the cumulative magnitude
distribution as the range between the 5% and 95% points.
Note (4): Based on interquartile range.
Note (5): Computed assuming no variation (around unweighted mean
magnitudes) and using LINEAR magnitude uncertainty estimates
(candidates were selected using χ2pdf>3i (100.477)).
Note (6): Analogous to chi2, except that 5% of the most outlying points
are excluded from the computation.
Note (7): In the range 0-5. If q_T1>1, then T2 (more probable) and T3
(less probable) are offered as alternative types.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- LINEAR [2522/24268361] Internal LINEAR source number
10- 19 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
21- 30 F10.6 deg DEdeg Declination in decimal degrees (J2000)
32- 33 I2 --- To [0/6]?=-1 SDSS object type (0, 3, 6) (8)
35 I1 --- S [0/1] 1=object saturated in at least one SDSS
band, 0 otherwise
37- 41 F5.3 mag Ar SDSS r band extinction (9)
43- 47 F5.2 mag umag ?=-9.9 SDSS u band model magnitude (10)
49- 53 F5.2 mag gmag ?=-9.9 SDSS g band model magnitude (10)
55- 59 F5.2 mag rmag ?=-9.9 SDSS r band model magnitude (10)
61- 65 F5.2 mag imag ?=-9.9 SDSS i band model magnitude (10)
67- 71 F5.2 mag zmag ?=-9.9 SDSS z band model magnitude (10)
73- 77 F5.2 mag e_umag ?=-9.9 Uncertainty in umag
79- 83 F5.2 mag e_gmag ?=-9.9 Uncertainty in gmag
85- 89 F5.2 mag e_rmag ?=-9.9 Uncertainty in rmag
91- 95 F5.2 mag e_imag ?=-9.9 Uncertainty in imag
97-101 F5.2 mag e_zmag ?=-9.9 Uncertainty in zmag
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Note (8): SDSS object type is:
6 = unresolved (stellar);
3 = resolved (extended); (18 entries);
0 = unknown
-1 = Object without SDSS photometry.
Note (9): From the Schlegel, Finkbeiner and Davis (1998ApJ...500..525S 1998ApJ...500..525S)
extinction maps.
Note (10): Corrected for extinction using Ar and the extinction curve shape from
Berry et al. (2012ApJ...757..166B 2012ApJ...757..166B). WARNING: there are 116 entries without
SDSS photometry; they are mostly found close to the footprint edges, where
LINEAR fields were recalibrated with nearby objects from within the
footprint. Their RAdeg and DEdeg come from LINEAR instead of SDSS.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- LINEAR [2522/24268361] Internal LINEAR source number
10- 14 F5.2 mag Jmag ?=-9.9 2MASS J band magnitude (11)
16- 20 F5.2 mag Hmag ?=-9.9 2MASS H band magnitude (11)
22- 26 F5.2 mag Kmag ?=-9.9 2MASS Ks band magnitude (11)
28- 32 F5.2 mag e_Jmag ?=-9.9 Uncertainty in Jmag
34- 38 F5.2 mag e_Hmag ?=-9.9 Uncertainty in Hmag
40- 44 F5.2 mag e_Kmag ?=-9.9 Uncertainty in Kmag
46- 50 F5.2 mag W1mag ?=-9.9 WISE/W1 3.4µ band magnitude (11)
52- 56 F5.2 mag W2mag ?=-9.9 WISE/W2 4.6µ band magnitude (11)
58- 62 F5.2 mag W3mag ?=-9.9 WISE/W3 12µ band magnitude (11)
64- 68 F5.2 mag W4mag ?=-9.9 WISE/W4 22µ band magnitude (11)
70- 74 F5.2 mag e_W1mag ?=-9.9 Uncertainty in W1mag
76- 80 F5.2 mag e_W2mag ?=-9.9 Uncertainty in W2mag
82- 86 F5.2 mag e_W3mag ?=-9.9 Uncertainty in W3mag
88- 92 F5.2 mag e_W4mag ?=-9.9 Uncertainty in W4mag
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Note (11): 2MASS is corrected for ISM extinction using Ar, the SDSS r-band
extinction from the Schlegel, Finkbeiner and Davis (1998ApJ...500..525S 1998ApJ...500..525S)
extinction maps (see Table 6) but WISE photometry is NOT corrected for ISM.
Not all entries have corresponding 2MASS and WISE detections. Out of 7194
entries, 6657 have 2MASS detections, and of those 6620 also have at least
W1 WISE detection.
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Nomenclature Notes:
In Tables 5, 6, and 7, the variable stars are in Simbad.
History:
From electronic version of the journal
References:
Sesar et al., Paper I, 2011AJ....142..190S 2011AJ....142..190S
Sesar et al., Paper II, 2013AJ....146...21S 2013AJ....146...21S Cat. J/AJ/146/21
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 15-Jul-2014