J/AJ/121/254 Eclipsing Binaries in OGLE (Rucinski+, 2001)
Eclipsing binaries in the OGLE variable star catalogs. V. Long-period EB-type
light curve systems in the Small Magellanic Cloud and the PLC-β relation.
Rucinski S.M., Maceroni C.
<Astron. J., 121, 254-266 (2001)>
=2001AJ....121..254R 2001AJ....121..254R (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Magellanic Clouds
Keywords: Stars: Binaries: Eclipsing, Stars: Binaries: General,
Galaxies: Magellanic Clouds, Stars: Statistics
Abstract:
Thirty-eight long-period (P>10 days) apparently contact binary stars
discovered by the OGLE-II project in the SMC show EB-type light curves
and an ``inverted'' period-color relation with longer orbital periods
for redder systems. The strong light variations between eclipses can
be explained within a semidetached model in which ellipsoidal
variations of a large, evolved, Roche lobe-filling component dominates
over eclipse effects in the systemic light changes. The model requires
further spectroscopic and color-curve support before it can be fully
accepted. It is noted that the dominant role of the Roche lobe-filling
component in the total systemic luminosity can explain the new
period-luminosity-color (PLC) relation, which has been established for
the long-period EB (LP-EB) systems. We call it the PLC-β
relation, to distinguish it from the Cepheid relation. Two versions of
the PLC-β relation-based on the (B-V)0 or (V-I)0 color
indices-have been calibrated for 33 systems with (V-I)0>0.25
spanning the orbital period range of 11 to 181 days (it was found that
blue systems with (V-I)0≤0.25 do not follow the same calibration).
The relations can provide maximum-light, absolute-magnitude estimates
accurate to εMV~=0.35mag within the approximate range
-3<MV<+1. In terms of their number in the SMC, the LP-EB binaries are
about 50 times less common than the Cepheids. Nevertheless, their
large luminosities coupled with continuous light variations make these
binaries very easy to spot in nearby galaxies, so that the PLC-β
relation can offer an auxiliary and entirely independent method of
distance determination to nearby stellar systems rich in massive
stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 41 LP-EB Systems in the Small Magellanic Cloud
table2.dat 82 4 OGLE-II Data for LP-EB systems in Baade's
Window
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See also:
J/AcA/48/563 : OGLE SMC eclipsing binaries BVI photometry (Udalski+, 1998)
J/AcA/53/1 : OGLE eclipsing binaries in LMC (Wyrzykowski+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Consecutive identification number
4 A1 --- f_ID Indicates systems have half weight in the
calibrations of the PLC-β relation
6- 14 F9.6 --- PrimID ? Primary OGLE-II identification number (1)
16- 23 F8.6 --- SecID ? Secondary OGLE-II identification number (2)
25- 32 F8.4 d Period Orbital period
34- 39 F6.3 mag Imag Maximum I-band magnitude
41- 46 F6.3 mag B-V ? The B-V color
48- 52 F5.3 mag V-I The V-I color
54- 58 F5.3 --- a0 Light-curve Fourier coefficient a0 (3)
60- 65 F6.3 --- a1 Light-curve Fourier coefficient a1 (3)
67- 72 F6.3 --- a2 Light-curve Fourier coefficient a2 (3)
74- 79 F6.3 --- a3 Light-curve Fourier coefficient a3 (3)
81- 86 F6.3 --- a4 Light-curve Fourier coefficient a4 (3)
88- 93 F6.3 --- b1 Light-curve Fourier coefficient b1 (3)
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Note (1): The SMC OGLE-II identification is given as the field number (integer
part) and star number (fractional part).
Note (2): Case where identification in the neighboring fields is available.
The identification is the same as in Note (1).
Note (3): ai = coefficients in cos; b1 = only sin term representing
the lightcurve asymetries.
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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- 5 F5.3 --- OGLEI OGLE-I identification (1)
7- 15 F9.6 --- OGLEII ? OGLE-II identification (1)
17- 22 F6.3 d Period Orbital period
24- 27 F4.2 mag E(V-I) V-I reddening estimates for d > 2 kpc
29- 33 F5.2 mag AveI2mag ? Average I-band magnitude (2)
35- 38 F4.2 mag Ave(V-I)2 ? Average V-I color
40- 43 F4.2 mag DelImag ? Mean and maximum difference in I band (3)
45- 49 F5.2 mag I1mag Maximum I-band magnitude from Paper III
51- 54 F4.2 mag (V-I)1 The maximum V-I color from Paper III
56- 60 F5.2 mag I2mag ? Maximum I-band magnitude (4)
62- 66 F5.2 mag V2mag Maximum V-band magnitude
68- 71 F4.2 mag VMag Absolute V-band magnitude (5)
73- 76 F4.1 kpc Dist Distance estimate (6)
78- 80 F3.1 kpc e_Dist Uncertainty in Dist
82 A1 --- f_Dist Indicates OGLE-II data not available and
distance estimate is based on OGLE-I data
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Note (1): Star identifications consist of the respective OGLE field numbers
(integer part) and of the number in the field (fractional part).
Note (2): It has been assumed that the color indices (V-I)2 are the same for
the average, Ave(V-I)2, and maximum light levels.
Note (3): Calculated on the basis of the OGLE-I light curves.
Note (4): DelImag used to convert the average OGLE-II data to the maximum light
level values, I2mag.
Note (5): Calculated using eq. (3).
Note (6): Distance estimate from: V-VMag = 5 log(Dist) - 5 + 2.5 * E(V-I).
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History:
From electronic version of the journal
References:
1997AJ....113..407R 1997AJ....113..407R : I.W Uma-Type Systems as Distance and Population
Tracers in Baade's Window
1997AJ....113.1112R 1997AJ....113.1112R : II.Light Curves of the W UMA-Type Systems in
Baade's Window
1998AJ....115.1135R 1998AJ....115.1135R : III. Long-Period Contact Systems
1999AJ....118.1819M 1999AJ....118.1819M : IV. The Precontact, Equal-Mass Systems
(End) Greg Schwarz [AAS], Laurent Cambresy [CDS] 28-Jul-2004