J/MNRAS/436/953 OGLE-LMC-CEP-0227 RV and VI[3.6] curves (Pilecki+, 2013)
Physical parameters and the projection factor of the classical Cepheid in the
binary system OGLE-LMC-CEP-0227.
Pilecki B., Graczyk D., Pietrzynski G., Gieren W., Thompson I.B.,
Freedman W.L., Scowcroft V., Madore B.F., Udalski A., Soszynski I.,
Konorski P., Smolec R., Nardetto N., Bono G., Prada Moroni P.G., Storm J.,
Gallenne A.
<Mon. Not. R. Astron. Soc., 436, 953-967 (2013)>
=2013MNRAS.436..953P 2013MNRAS.436..953P
ADC_Keywords: Binaries, eclipsing ; Photometry, VRI ;
Photometry, millimetric/submm
Keywords: binaries: eclipsing - stars: distances - stars: oscillations -
stars: variables: Cepheids
Abstract:
A novel method of analysis of double-lined eclipsing binaries
containing a radially pulsating star is presented. The combined
pulsating-eclipsing light curve is built up from a purely eclipsing
light-curve grid created using an existing modelling tool. For every
pulsation phase, the instantaneous radius and surface brightness are
taken into account, being calculated from the disentangled radial
velocity curve of the pulsating star and from its out-of-eclipse
pulsational light curve and the light ratio of the components,
respectively. The best model is found using the Markov chain Monte
Carlo method. The method is applied to the eclipsing binary Cepheid
OGLE-LMC-CEP-0227 (Ppuls=3.80d, Porb=309d). We analyse a set of
new spectroscopic and photometric observations for this binary,
simultaneously fitting OGLE V-band, I-band and Spitzer 3.6µm
photometry. We derive a set of fundamental parameters of the system
significantly improving the precision comparing to the previous
results obtained by our group. The Cepheid mass and radius are
M1=4.165±0.032M☉ and R1=34.92±0.34R☉, respectively.
For the first time a direct, geometrical and distance-independent
determination of the Cepheid projection factor is presented. The value
p=1.21±0.03(stat.)±0.04(syst.) is consistent with theoretical
expectations for a short-period Cepheid and interferometric
measurements for δ Cep. We also find a very high value of the
optical limb darkening coefficients for the Cepheid component, in
strong disagreement with theoretical predictions for static
atmospheres at a given surface temperature and gravity.
Description:
In total, we acquired 1045 measurements in the I band and 317 in the V
band collected with the Warsaw telescope by the OGLE project (Udalski
2003AcA....53..291U 2003AcA....53..291U; Soszynski et al. 2012AcA....62..219S 2012AcA....62..219S, Cat.
J/AcA/62/219) and during the time granted to the Araucaria project by
CNTAC organization. The auxiliary K-band data (only outside eclipses)
were acquired by the Araucaria group using the SOFI instrument
attached to the New Technology Telescope at La Silla Observatory,
which allowed us to use the V-K colour variation to calculate the
effective temperature as a function of the pulsation phase. We have
also acquired 3.6 and 4.5um photometry from the Spitzer Space
Telescope (114 points) - the observations and data reduction
provided by the CHP team.
Objects:
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RA (2000) DE Designation(s)
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04 52 15.70 -70 14 31.3 OGLE LMC-CEP-227 = OGLE LMC137.4 20
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 24 1045 OGLE LMC-CEP-227 OGLE I-band photometry
table2.dat 24 317 OGLE LMC-CEP-227 OGLE V-band photometry
table3.dat 24 114 OGLE LMC-CEP-227 Spitzer 3.6um photometry
table4.dat 32 123 RV measurements of OGLE LMC-CEP-227
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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- 10 F10.5 d HJD Heliocentric Julian date (HJD-2450000)
12- 17 F6.3 mag Imag OGLE I magnitude
19- 24 F6.4 mag e_Imag rms uncertainty on Imag (G1)
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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- 10 F10.5 d HJD Heliocentric Julian date (HJD-2450000)
12- 17 F6.3 mag Vmag OGLE V magnitude
19- 24 F6.4 mag e_Vmag rms uncertainty on Vmag (G1)
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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- 10 F10.5 d HJD Heliocentric Julian date (HJD-2450000)
12- 17 F6.3 mag [3.6] Spitzer/IRAC 3.6um magnitude
19- 24 F6.4 mag e_[3.6] rms uncertainty on [3.6] (G1)
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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- 10 F10.5 d HJD Heliocentric Julian date (HJD-2450000)
11 A1 --- Inst [ab] Instrument: a=HARPS, b=UVES
13- 18 F6.2 km/s RV1 Orbital radial velocity of the primary
20- 25 F6.2 km/s RV2 Orbital radial velocity of the secondary
27- 32 F6.2 km/s RVp Pulsation radial velocity
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Global notes:
Note (G1): The errors are rescaled to match the condition that the
reduced χ2 is equal to 1.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Jan-2015