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J/ApJ/542/257 MACHO LMC first-overtone RR Lyrae (Alcock+, 2000)
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The MACHO project Large Magellanic Cloud variable-star inventory.
IX. Frequency analysis of the first-overtone RR Lyrae stars and the indication
for nonradial pulsations.
Alcock C., Allsman R., Alves D.R., Axelrod T., Becker A., Bennett D.,
Clement C., Cook K.H., Drake A., Freeman K., Geha M., Griest K., Kovacs G.,
Kurtz D.W., Lehner M., Marshall S., Minniti D., Nelson C., Peterson B.,
Popowski P., Pratt M., Quinn P., Rodgers A., Rowe J., Stubbs C.,
Sutherland W., Tomaney A., Vandehei T., Welch D.L.
<Astrophys. J. 542, 257 (2000)>
=2000ApJ...542..257A
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ADC_Keywords: Clusters, globular ; Magellanic Clouds ; Stars, variable
Keywords: globular clusters: general - Magellanic Clouds -
stars: horizontal-branch - stars: oscillations -
stars: variables: other
Abstract:
More than 1300 variables classified provisionally as first-overtone RR
Lyrae pulsators in the MACHO variable-star database of the Large
Magellanic Cloud (LMC) have been subjected to standard frequency
analysis. Based on the remnant power in the prewhitened spectra, we
found 70% of the total population to be monoperiodic. The remaining
30% (411 stars) are classified as one of nine types according to their
frequency spectra. Several types of RR Lyrae pulsational behavior are
clearly identified here for the first time. Together with the earlier
discovered double-mode (fundamental and first-overtone) variables,
this study increased the number of known double-mode stars in the LMC
to 181. During the total 6.5yr time span of the data, 10% of the
stars showed strong period changes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 63 108 Previously Unknown RR01 Variables of the
MACHO RR1 Sample (1)
table2.dat 64 24 RR1-{nu}1 Variables of the MACHO RR1 Sample (1)
table3.dat 78 28 RR1-BL Variables of the MACHO RR1 Sample (1)
table4.dat 52 141 RR1-PC Variables of the MACHO RR1 Sample (1)
table5.dat 54 37 Miscellaneous Variables of the MACHO RR1 Sample (1)
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Note (1): Variable Types in the MACHO Database for the first-Overtone
RR Lyrae Stars in the LMC (Table 7)
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Type Short Description Number % {sigma}%
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RR1 Single-mode 916 69.0 1.3
RR1-{nu}1 Two close components 24 1.8 0.4
RR1-{nu}2 Two asymmetric close components 3 0.2 0.1
RR1-{nu}M Multifrequency close components 5 0.4 0.2
RR1-BL Two symmetric close components 28 2.1 0.4
RR1-PC Period change 141 10.6 0.9
RR01 First and zeroth overtone double-mode 181 13.6 0.9
RR12 Second and first overtone double-mode 3 0.2 0.1
RR1-D1 Integer day^-1^ frequencies 20 1.5 0.3
RR1-NC Nonclassified 6 0.5 0.2
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See also:
J/AJ/114/326 : MACHO Variables V. (Alcock+ 1997)
J/A+A/363/L1 : The distance modulus of the LMC (Kovacs, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- MACHO MACHO designation (FFF.NNNNN.NNNN)
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 35 I2 arcsec DEs Declination (J2000)
37- 44 F8.6 d P1 Fundamental mode period
46- 51 F6.4 --- P1/P0 Period ratio (fundamental to first-overtone)
53- 57 F5.3 mag A1 Fundamental mode amplitude (in MACHO r magnitude
59- 63 F5.3 --- A0/A1 Amplitude ratio (fundamental to first-overtone)
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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- 13 A13 --- MACHO MACHO designation (FFF.NNNNN.NNNN)
14 A1 --- n_MACHO Individual notes (1)
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 35 I2 arcsec DEs Declination (J2000)
37- 43 F7.5 d-1 nu0 Frequency of the main component
45- 49 F5.3 mag A0 Amplitude of the main component
(in MACHO r magnitude)
51- 58 F8.5 d-1 nu1-nu0 Frequency separation
60- 64 F5.3 --- A0/A1 Ratio of the secondary and main amplitudes
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Note (1): Individual notes:
a: Also an RR01 variable, with P1/P0 = 0.7443 and A1/A0 = 0.22
b: The b data support RR1 status
c: In b there is a third component at P({nu}2)/P({nu}1)=0.757
d: Hint for RR1-BL classification in the b data
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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- 13 A13 --- MACHO MACHO designation (FFF.NNNNN.NNNN)
14 A1 --- n_MACHO [a] a: b data are used
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 35 I2 arcsec DEs Declination (J2000)
37- 43 F7.5 d-1 f0 Frequency of the highest peak in the
frequency spectrum
45- 49 F5.3 mag A0 Amplitude of the highest peak in the
frequency spectrum (in MACHO r magnitude)
51- 58 F8.5 --- Deltaf- Smaller frequency component (1)
60- 66 F7.5 --- Deltaf+ Higher frequency component (1)
main component (1)
68- 72 F5.3 --- A-/A0 Ratio of the smaller amplitude to that of the
main component
74- 78 F5.3 --- A+/A0 Ratio of the higher amplitude to that of the
main component
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Note (1): Deltaf- = {nu}_-_ - {nu}0,
Deltaf+ = {nu}_+_ - {nu}0
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- MACHO MACHO designation (FFF.NNNNN.NNNN)
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 35 I2 arcsec DEs Declination (J2000)
37- 44 F8.6 d P1 Period
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- MACHO MACHO designation (FFF.NNNNN.NNNN)
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 25 F4.1 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 35 I2 arcsec DEs Declination (J2000)
37- 44 F8.6 d P1 Period
46- 54 A9 --- Type RR type
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Table 6: RR12 and RR1-{nu}2 variables of the MACHO RR1 Sample
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MACHO {nu}0 {nu}1 {nu}2 {nu}0/{nu}1 A1/A0 A2/A0 Type
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12.10202.285 2.511844 3.118910 0.8054 0.260 RR12
12.10443.367 2.971251 3.701164 0.8028 0.294 RR12
9.4278.179 3.059812 3.801934 0.8048 0.296 RR12
2.5023.5787 3.081326 3.068358 3.073338 1.0042 1.000 0.926 RR1-{nu}2
11.8987.787 3.288101 3.238294 3.129587 1.0154 0.638 0.345 RR1-{nu}2
15.9947.338 3.469549 3.421443 3.434602 1.0141 0.559 0.419 RR1-{nu}2
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History:
From electronic version
References:
Alcock et al., Paper I 1996ApJ...461...84A
Alcock et al., Paper II 1996AJ....111.1146A
Alcock et al., Paper III 1997ApJ...482...89A
Alcock et al., Paper IV 1996ApJ...470..583A
Alcock et al., Paper V 1997AJ....114..326A
Alcock et al., Paper VI 1999ApJ...511..185A
Alcock et al., Paper VII 1998AJ....115.1921A
Alcock et al., Paper VIII 1999AJ....117..920A
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(End) James Marcout, Patricia Bauer [CDS] 05-Dec-2000