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J/ApJ/789/139       Three O-type binaries photometry in LMC     (Morrell+, 2014)

Photometric and spectroscopic studies of massive binaries in the Large Magellanic Cloud. II. Three O-type systems in the 30 Dor region. Morrell N.I., Massey P., Neugent K.F., Penny L.R., Gies D.R. <Astrophys. J., 789, 139 (2014)> =2014ApJ...789..139M (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, O ; Photometry ; Binaries, spectroscopic Keywords: binaries: eclipsing - binaries: spectroscopic - stars: early-type - stars: fundamental parameters - stars: individual: [M2002] LMC 169782, [M2002] LMC 171520, [P93] 921 Abstract: This is the second paper in a series devoted to the study of massive binary systems in the Large Magellanic Cloud (LMC). We mainly aim to provide accurate data that constrains the mass-luminosity relation for the most massive stars but also to address the long lasting problem known as the "mass discrepancy." We present here our results for three binaries (LMC 169782, LMC 171520, and [P93] 921) harboring the earliest O-type components-ranging from O4 V to O6.5 V-among our sample of 17 systems. Our photometry provided accurate periods for the studied systems, allowing the spectroscopic observations to be performed at selected phases where the radial velocity separation between binary components is larger. Following the procedure outlined in our first paper of this series, after solving the radial velocity curves for orbital parameters, we used tomographic reconstruction to obtain the individual spectra of each star, from which we determined effective temperatures via a model atmosphere fitting with FASTWIND. This information, combined with the light-curve analysis that was performed with GENSYN, enabled the determination of absolute masses, radii, and bolometric luminosities that are compared with those predicted by modern stellar evolutionary models finding that they agree within the uncertainties. Nevertheless, the comparison seems to confirm the small differences found in the first paper of this series in the sense that the evolutionary masses are slightly larger than the Keplerian ones, with differences averaging ∼10%, or alternatively, the stellar evolutionary models predict luminosities that are somewhat lower than observed. Still, the overall agreement between the current evolutionary models and the empirically determined stellar parameters is remarkable. Description: We will concentrate on the presentation and discussion of our photometric and spectroscopic observations of 3 binary systems containing the earliest type components among the observed sample of 17 binaries in the LMC, namely, LMC 169782, LMC 171520, and [P93] 921. All three systems belong to the 30 Dor region, which harbors some of the most massive stars known to date (Crowther et al. 2010MNRAS.408..731C; Schnurr et al. 2009MNRAS.395..823S).Time-resolved photometry was carried out for all three systems in order to provide the light curves needed to establish periods and calculate orbital inclinations. As described in Paper I (Massey et al. 2012ApJ...748...96M), this was carried out using simple aperture photometry as opposed to point-spread-function fitting; tests showed that we obtained equally accurate results with aperture photometry, which was expected given that our targets are not overly crowded. In order to compute the observed absolute magnitudes for our targets, we have assumed a distance modulus of 18.50 (50 kpc) for the LMC following van den Bergh (2000, The Galaxies of the Local Group (Cambridge: Cambridge Univ. Press)), and we have used the intrinsic colors given by FitzGerald (1970A&A.....4..234F) and a normal reddening law with Rv = 3.1. Objects: ---------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------- 05 37 59.44 -69 09 01.0 [M2002] LMC 169782 = VFTS 217 05 38 41.23 -69 02 58.3 [M2002] LMC 171520 = VFTS 500 05 38 42.10 -69 05 45.4 [P93] 921 = VFTS 522 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 34 342 LMC 169782 Photometry table6.dat 34 269 LMC 171520 Photometry table9.dat 34 444 [P93] 921 Photometry
See also: J/MNRAS/349/833 : uVI photometry of 3 LMC eclipsing binaries (Bayne+, 2004) J/AJ/131/407 : BV photometry of stars in the LMC (Kaluzny+, 2006) J/ApJ/748/96 : Massive binaries in the LMC (Massey+, 2012) Byte-by-byte Description of file: table2.dat table6.dat table9.dat
Bytes Format Units Label Explanations
1- 12 F12.4 d HJD Heliocentric Julian Date 14- 19 F6.3 mag Vmag Observed V band magnitude 21- 25 F5.3 mag e_Vmag The 1σ error in Vmag 27 I1 --- Tel [1/3] Telescope code (1) 29- 34 F6.3 --- Phase Orbital phase (2)
Note (1): Flag as follows : 1 = SITe#3 on Swope 1.0-m; 2 = Y4KCam on SMARTS Yale 1.0-m; 3 = ANDICAM on SMARTS 1.3-m. Note (2): Orbital phase : Table 2 : Based upon P = 1.855280 days and T = 2453285.909. Table 6 : Based upon P = 2.875275 days and T = 2453287.010. Table 9 : Based upon P = 2.389321 days and T = 2453285.541.
History: From electronic version of the journal References: Massey et al., Paper I, 2012ApJ...748...96M, Cat. J/ApJ/748/96
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 10-Mar-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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