J/ApJ/748/96 Massive binaries in the LMC (Massey+, 2012)
Photometric and spectroscopic studies of massive binaries in the Large
Magellanic Cloud.
I. Introduction and orbits for two detached systems: evidence for a mass
discrepancy?
Massey P., Morrell N.I., Neugent K.F., Penny L.R., DeGioia-Eastwood K.,
Gies D.R.
<Astrophys. J., 748, 96 (2012)>
=2012ApJ...748...96M 2012ApJ...748...96M
ADC_Keywords: Stars, variable ; Binaries, eclipsing ; Stars, O ;
Radial velocities ; Photometry ; Spectral types
Keywords: binaries: eclipsing - binaries: spectroscopic - stars: early-type -
stars: fundamental parameters
Abstract:
The stellar mass-luminosity relation is poorly constrained by
observations for high-mass stars. We describe our program to find
eclipsing massive binaries in the Magellanic Clouds using photometry
of regions rich in massive stars, and our spectroscopic follow-up to
obtain radial velocities and orbits. Our photometric campaign
identified 48 early-type periodic variables, of which only 15 (31%)
were found as part of the microlensing surveys. Spectroscopy is now
complete for 17 of these systems, and in this paper we present
analysis of the first two, LMC 172231 and ST2-28, simple detached
systems of late-type O dwarfs of relatively modest masses. Our orbit
analysis yields very precise masses (∼2%), and we use tomography to
separate the components and determine effective temperatures by model
fitting, necessary for determining accurate (0.05-0.07 dex) bolometric
luminosities in combination with the light-curve analysis. Our
approach allows more precise comparisons with evolutionary theory than
previously possible. To our considerable surprise, we find a small,
but significant, systematic discrepancy: all of the stars are slightly
undermassive, by typically 11% (or overluminous by 0.2 dex) compared
with that predicted by the evolutionary models. We examine our
approach for systematic problems, but find no satisfactory
explanation. The discrepancy is in the same sense as the
long-discussed and elusive discrepancy between the masses measured
from stellar atmosphere analysis with the stellar evolutionary models,
and might suggest that either increased rotation or convective
overshooting is needed in the models.
Description:
Our photometric monitoring of stars in selected OB associations in the
Magellanic Clouds began in 2003 July, and continued through 2011
February. Three telescopes were used: Swope 1m, SMARTS Yale 1m and
SMARTS 1.3m.
All spectroscopy intended for radial velocities was carried out on the
Magellan Clay and Baade 6.5m telescopes, although a few classification
spectra were also obtained on the DuPont 2.5m telescope. All in all,
we collected data at the Magellan telescopes on 21 nights between 2008
December 8 and 2010 November 27.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 166 48 Identified periodic variables in SMC and LMC
table5.dat 32 285 LMC 172231 photometry
table6.dat 42 11 Radial velocities of LMC 172231
table9.dat 32 279 ST2-28 photometry
table10.dat 42 14 Radial velocities of ST2-28 (He II lines only)
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See also:
J/AcA/62/247 : OGLE-III shallow survey LMC photometric maps (Ulaczyk+, 2012)
J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Szymanski+, 2011)
J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009)
J/AJ/134/1963 : MACHO light curves of MC eclipsing binaries (Faccioli+, 2007)
J/ApJ/663/249 : LMC eclipsing binaries in the MACHO database (Derekas+, 2007)
J/AJ/130/2701 : Stars in the Sagittarius Rift (Fresneau+, 2005)
J/AcA/54/1 : OGLE II SMC eclipsing binaries (Wyrzykowski+, 2004)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: the LMC (Zaritsky+, 2004)
J/AJ/119/2214 : Photometry of Magellanic OB associations (Massey+, 2000)
J/AJ/114/326 : MACHO Variables V. (Alcock+ 1997)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Reg Region
11- 25 A15 --- Name Star name
27- 31 A5 --- Ref Reference(s) (1)
33- 34 I2 h RAh [0/5] Hour of right ascension (J2000)
36- 37 I2 min RAm [18/59] Minute of right ascension (J2000)
39- 43 F5.2 s RAs Second of right ascension (J2000)
45 A1 --- DE- [-] Sign of declination (J2000)
46- 47 I2 deg DEd [69/72] Degree of declination (J2000)
49- 50 I2 arcmin DEm [2/30] Arcminute of declination (J2000)
52- 55 F4.1 arcsec DEs Arcsecond of declination (J2000)
57- 73 A17 --- SpT MK spectral type
75 A1 --- r_SpT [ce] Reference flag for SpT (2)
77- 84 F8.6 d Per [1.062/8.105] Period
86-128 A43 --- Status Study status
130-153 A24 --- OName Other name
155-162 F8.6 d Per2 [1.360,8.099]? Period from litterature
164-166 A3 --- r_Per2 [,bdf-l] Flag(s) for Per2 or Name (2)
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Note (1): Reference as follows:
1 = Massey et al. 1989, Cat. J/AJ/98/1305;
2 = Massey 2002ApJ...565..982M 2002ApJ...565..982M;
3 = Lucke 1972PhDT........10L 1972PhDT........10L; Massey et al. 2000, Cat. J/AJ/119/2214;
4 = Breysacher et al. 1999A&AS..137..117B 1999A&AS..137..117B;
5 = Sanduleak 1970, Cat. III/113;
6 = Schild & Testor 1992A&AS...92..729S 1992A&AS...92..729S; Massey et al. 2000,
Cat. J/AJ/119/2214;
7 = Westerlund 1961UppAn...5....1W 1961UppAn...5....1W;
8 = Breysacher 1981A&AS...43..203B 1981A&AS...43..203B;
9 = Massey & Hunter 1998ApJ...493..180M 1998ApJ...493..180M;
10 = Massey et al. 2002ApJ...565..982M 2002ApJ...565..982M;
11 = Melnick 1985A&A...153..235M 1985A&A...153..235M;
12 = Parker 1993, Cat. II/187.
Note (2): Flag as follows:
b = Wyrzykowski et al. (2004, Cat. J/AcA/54/1).
c = Spectral type from Evans et al. (2006, Cat. J/A+A/456/623).
d = Also MACHO 207.16490.12 P=1.41713, from Faccioli et al. (2007,
Cat. J/AJ/134/1963).
e = Spectral type from Hunter et al. (2008, Cat. J/A+A/479/541).
f = Derekas et al. (2007, Cat. J/ApJ/663/249).
g = Alcock et al. (1996ApJ...470..583A 1996ApJ...470..583A) quoted in VizieR Cat. II/247.
h = Faccioli et al. (2007, Cat. J/AJ/134/1963).
i = Also LMC 163763.
j = Position of MACHO source differs by 1.7" with ours.
k = Massey et al. (2002ApJ...565..982M 2002ApJ...565..982M).
l = Melnick (1985A&A...153..235M 1985A&A...153..235M).
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Byte-by-byte Description of file: table[59].dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d HJD Heliocentric Julian Day
13- 18 F6.3 mag Vmag [13.993/14.613] The V band magnitude
20- 24 F5.3 mag e_Vmag [0.003/0.032] Error in Vmag
26 I1 -- Index [1/3] Telescope/Instrument Combination (1)
28- 32 F5.3 -- Phase Orbital phase (2)
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Note (1): Telescope and instrument combination index as follows:
1 = Swope 1.0-m/SITe#3;
2 = SMARTS Yale 1.0-m/Y4KCam;
3 = SMARTS 1.3-m/ANDICAM.
Note (2): Based upon P=3.225414 and T=2453591.469 for LMC 172231 (table 5)
and upon P=2.762456 and T=2453590.217 for ST2-28 (table 9).
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Byte-by-byte Description of file: table6.dat table10.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d HJD Heliocentric Julian Date
13- 17 F5.3 --- Phase Phase (1)
19- 23 F5.1 km/s V1 [15.6/523.7] Primary radial velocity
25- 28 F4.1 km/s e_V1 [0.2/10]? V1 standard deviation of the mean
30- 34 F5.1 km/s V2 [-23.2/571.7] Secondary radial velocity
36- 39 F4.1 km/s e_V2 [1.9/13.6]? V2 standard deviation of the mean
41- 42 I2 --- N [1/17] Number of spectral lines used
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Note (1): Based upon P=3.225414 and T=2453591.469 for LMC 172231 (table 6)
and upon P=2.762456 and T=2453590.217 for ST2-28 (table 10).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Oct-2013