J/ApJ/810/61 Early-type EBs with intermediate orbital periods (Moe+, 2015)
Early-type eclipsing binaries with intermediate orbital periods.
Moe M., Stefano R.D.
<Astrophys. J., 810, 61 (2015)>
=2015ApJ...810...61M 2015ApJ...810...61M (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Photometry, UBVRI ; Stars, masses ;
Stars, ages ; Stars, diameters ; Effective temperatures
Keywords: binaries: close - binaries: eclipsing - stars: evolution -
stars: formation - stars: massive - stars: statistics
Abstract:
We analyze 221 eclipsing binaries (EBs) in the Large Magellanic Cloud
with B-type main-sequence (MS) primaries (M1∼4-14 M☉) and orbital
periods P=20-50 days that were photometrically monitored by the
Optical Gravitational Lensing Experiment. We utilize our three-stage
automated pipeline to (1) classify all 221 EBs, (2) fit physical
models to the light curves of 130 detached well-defined EBs from which
unique parameters can be determined, and (3) recover the intrinsic
binary statistics by correcting for selection effects. We uncover two
statistically significant trends with age. First, younger EBs tend to
reside in dustier environments with larger photometric extinctions, an
empirical relation that can be implemented when modeling stellar
populations. Second, younger EBs generally have large eccentricities.
This demonstrates that massive binaries at moderate orbital periods
are born with a Maxwellian "thermal" orbital velocity distribution,
which indicates they formed via dynamical interactions. In addition,
the age-eccentricity anticorrelation provides a direct constraint for
tidal evolution in highly eccentric binaries containing hot MS stars
with radiative envelopes. The intrinsic fraction of B-type MS stars
with stellar companions q=M2/M1>0.2 and orbital periods P=20-50 days
is (7±2)%. We find early-type binaries at P=20-50 days are weighted
significantly toward small mass ratios q∼0.2-0.3, which is different
than the results from previous observations of closer binaries with
P<20 days. This indicates that early-type binaries at slightly wider
orbital separations have experienced substantially less competitive
accretion and coevolution during their formation in the circumbinary disk.
Description:
In this study, we select the NB∼96000 systems in the OGLE-III LMC
catalog (Udalski et al. 2008AcA....58...89U 2008AcA....58...89U) with mean magnitudes
16.0<Imean<17.6 and observed colors -0.25<V-I<0.20. Given the distance
modulus µ=18.5 to the LMC (Pietrzynski et al. 2013Natur.495...76P 2013Natur.495...76P)
and typical dust reddenings E(V-I)∼0.1-0.3 mag toward hot young stars
in the LMC (Zaritsky et al. J/AJ/128/1606), these stars have
luminosities and surface temperatures that correspond to B-type MS
primaries. From this sample, we analyze the 221 systems that were
identified as EBs with orbital periods P=20-50 days (Graczyk et al. 2011,
J/AcA/61/103).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 221 Analytic Model Parameters that Describe the
Basic Light Curve Features for the 221 EBs with
OGLE-III LMC Catalog Properties
16.0<Imean<17.6, -0.25<V-I<0.20, and
P=20-50 days
table2.dat 114 130 Physical Model Properties and Statistics for
the 130 Detached EBs in the Well-defined Sample
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See also:
V/118 : Catalog of eclipsing binaries parameters (Perevozkina+, 1999)
J/AJ/121/254 : Eclipsing Binaries in OGLE (Rucinski+, 2001)
J/AcA/53/1 : OGLE eclipsing binaries in LMC (Wyrzykowski+, 2003)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: the LMC
(Zaritsky+, 2004)
J/A+A/439/559 : OGLE eclipsing binaries (bulge+lmc+smc) (Groenewegen+, 2005)
J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Graczyk+, 2011)
J/MNRAS/443/432 : Eclipsing binaries in LMC (Muraveva+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Cat [1/8] Sample category (1)
3- 7 I5 --- ID [91/26109] Identification number
(OGLE LMC-ECL-NNNNN in Simbad) (2)
9- 13 F5.2 mag <V-I> Mean V-I color index
15- 18 I4 --- NI [211/1049] Number of I-band measurements
20- 26 F7.4 d Per Orbital period
28- 35 F8.3 d t0 Epoch of primary eclipse minimum (JD-2450000)
36 A1 --- n_t0 [a] Note on t0 (3)
38- 42 F5.2 mag <Imag> Mean I-band magnitude
44- 47 F4.2 mag DeltaI1 Primary eclipse depth
49- 52 F4.2 mag DeltaI2 ? Secondary eclipse depth
54- 58 F5.3 --- Phi2 ? Orbital phase of secondary eclipse
60- 65 F6.4 --- Tetha1 Eclipse width (fraction of the orbital period)
67- 72 F6.4 --- Tetha2 ? Eclipse width (fraction of the orbital period)
74- 77 F4.2 --- fsigmaI Photometric correction factor in I-band
79 I1 --- Nc [0/2] Number of clipped data points
81- 84 F4.2 --- F2 Goodness-of-fit statistic
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Note (1): Based on the measured analytic model parameters, we divide the total
sample into eight categories.
Category as follows:
1 = EBs without secondary eclipses. These EBs most likely have a certain
combination of e, ω, and i so there is only one eclipse per orbit;
2 = EBs with uncertain eclipse parameters. These EBs generally have eclipses
that are too narrow (Θ~<0.003) and/or too shallow
(ΔI~<0.15 mag) to be accurately measured;
3 = Roche-lobe filling EBs, as demonstrated by their wide eclipses
Θ>0.06;
4 = EBs with ambiguous orbital periods. These systems have
ΔI1~ΔI2, Φ2∼0.5, and Θ1~Θ2 given
the listed orbital periods. The majority of these EBs most likely have
half the listed orbital periods, and therefore exhibit only one eclipse
per orbit such as the systems listed in category 1;
5 = Intrinsic variables, as indicated by their large rms scatter
fsigma,I≳1.6;
6 = EBs with variable eclipses. These EBs either have more than Nc>2 bad
data points near the eclipses or, more likely, exhibit variations in the
eclipse parameters due to orbital motion with a tertiary companion;
7 = Peculiar EBs that exhibit variations between eclipses;
8 = Detached EBs with well-defined eclipse parameters.
Note (2): For each category, we list the OGLE-III LMC catalog properties
(Graczyk et al. 2011, J/AcA/61/103).
Note (3): Note as follows:
a = Epoch of primary eclipse minimum t0 appropriately adjusted to ensure
ΔI1>ΔI2.
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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 I5 --- ID [91/26109] Identification number
(OGLE LMC-ECL-NNNNN in Simbad)
7- 13 F7.4 d Per Orbital period
15- 22 F8.3 d t0 Epoch of primary eclipse minimum (JD-2450000)
24- 27 F4.1 Msun Mp Primary component mass
29- 32 F4.1 Msun Ms Secondary component mass
34- 38 F5.1 Myr Age Age
40- 43 F4.1 deg Inc Inclination
45- 48 F4.2 --- ecc Eccentricity
50- 52 I3 deg omega [0/359] Argument of periastron ω
54- 57 F4.2 mag AI I-band dust extinction
59- 62 F4.2 --- q Mass ratio (1)
64- 66 I3 Rsun Sep [60/145] Orbital separation
68- 70 F3.1 Rsun Rp Primary stellar radius
72- 74 F3.1 Rsun Rs Secondary stellar radius
76- 80 I5 K Tp Primary effective temperature
82- 86 I5 K Ts Secondary effective temperature
88- 91 F4.2 --- fsigmaI Photometric correction factor in the I-band
93- 96 F4.2 --- fsigmaV Photometric correction factor in the V-band
98-101 I4 --- NI [325/1049] Number of I-band measurements
103-105 I3 --- NV [31/136] Number of V-band measurements
107 I1 --- NcI [0/3] Number of clipped data points in the I-band
109 I1 --- NcV [0/3] Number of clipped data points in the V-band
111-114 F4.2 --- F2 Goodness-of-fit statistic
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Note (1): q=M2/M1=min{Mp,Ms}/max{Mp,Ms}.
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History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 29-Sep-2017