J/ApJ/660/1486 Variability of LMC semiregular variables (Soszynski+, 2007)
Long secondary periods and binarity in red giant stars.
Soszynski I.
<Astrophys. J., 660, 1486-1491 (2007)>
=2007ApJ...660.1486S 2007ApJ...660.1486S
ADC_Keywords: Magellanic Clouds ; Stars, variable ; Stars, giant
Keywords: binaries: close - planetary systems - stars: AGB and post-AGB
Abstract:
Observational arguments supporting the binary explanation of the
long secondary period (LSP) phenomenon in red giants are presented.
Photometry of about 1200 semiregular variables with LSPs in the Large
Magellanic Cloud is analyzed using the MACHO and OGLE photometry. For
about 5% of these objects, additional ellipsoidal-like or
eclipsing-like modulation with the same periods as the LSP is
detectable. These double-humped variations are usually shifted in
phase compared to LSP light curves. I discuss the model of a binary
system with a red giant as the primary component and a low-mass object
as the secondary. The mass lost by the red giant through the wind
follows a spiral pattern in the orbit around the primary star and
obscures it, causing LSP variations.
Description:
Merged light curves from both projects covered 15yr of observations,
from 1992 to 2006. The sequence D stars selected by Soszynski et al.
(2004, Cat. J/AcA/54/347) in the OGLE database were cross identified
with objects collected in the MACHO archive.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 67 61 Additional information for the sources
table1.dat 39 63549 The residual data for 61 LSP stars with
double-humped variations
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See also:
II/247 : Variable Stars in the Large Magellanic Clouds (MACHO, 2001)
J/AcA/54/347 : IVB mag of LMC ellipsoidal variables (Soszinski+, 2004)
http://wwwmacho.mcmaster.ca/Data/MachoData.html : MACHO Home Page
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- MACHO MACHO identification
14- 28 A15 --- OGLE OGLE identification (lmcscNNNNNNNNN)
31- 32 I2 h RAh Right ascension (J2000)
34- 35 I2 min RAm Right ascension (J2000)
37- 41 F5.2 s RAs Right ascension (J2000)
43 A1 --- DE- Declination sign (J2000)
44- 45 I2 deg DEd Declination (J2000)
47- 48 I2 arcmin DEm Declination (J2000)
50- 53 F4.1 arcsec DEs Declination (J2000)
55- 60 F6.1 d Per Period
64- 67 F4.2 --- A(B)/A(R) Amplitude ratio A(B)/A(R)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- MACHO The MACHO identification
14- 26 F13.5 d HJD Heliocentric Julian Date
28- 33 F6.3 mag Dmag Differential magnitude (1)
35- 39 F5.3 mag e_Dmag Error in Dmag
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Note (1): A difference between MACHO R-band data scaled by the amplitude
ratio A(B)/A(R) and MACHO B-band data.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 18-Mar-2009