scholarly journals Absolute Dimensions and Distance Modulus for HV 2226 in the SMC

1992 ◽  
Vol 151 ◽  
pp. 501-504
Author(s):  
S.A. Bell ◽  
G. Hill ◽  
R.W. Hilditch ◽  
J.V. Clausen ◽  
A.P. Reynolds ◽  
...  
Keyword(s):  
Mass Transfer Process ◽  
Yield Component ◽  
Radial Velocities ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Distance Modulus ◽  
Early Type ◽  
Effective Temperatures ◽  
Distance Indicators ◽  
Absolute Dimensions

Absolute dimensions and the distance modulus have been established for the early-type eclipsing binary HV 2226 in the SMC. Analyses of the new radial velocities reported here, and CCD light curves published by Jensen et al. (1988) yield component masses of 9.3 ± 0.7 and 5.6 ± 0.5 M⊙, respectively. The radii are 5.6 ± 0.2 and 5.3 ± 0.2 R⊙ with the secondary component filling its Roche lobe which implies that HV 2226 must have evolved through a case A mass-transfer process. A distance modulus of (mv – Mv)0 = 18m.6 ± 0m.3 is derived, marginally lower than the adopted mean of 18m.9 for the SMC. The position of HV 2226, however, indicates that it is in fact situated in the near side of the SMC. In the present case, the accuracy of this estimate is limited mainly by the uncertainties of ≈ 2000 K in the effective temperatures. We point out that distance moduli with uncertainties of ± 0m.15 can be achieved from accurate radial velocities, light curves and colour indices of eclipsing binaries; such systems in the SMC and LMC are therefore promising distance indicators and work on further selected candidates is in progress.

scholarly journals New distance and depth estimates from observations of eclipsing binaries in the SMC

2008 ◽  
Vol 4 (S256) ◽  
pp. 57-62
Author(s):  
Pierre L. North ◽  
Romain Gauderon ◽  
Frédéric Royer
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Average Error ◽  
Distance Modulus ◽  
Orbital Parameters ◽  
Individual System ◽  
The Mean

AbstractA sample of 33 eclipsing binaries observed in a field of the SMC with FLAMES@VLT is presented. The radial velocity curves obtained, together with existing OGLE light curves, allowed the determination of all stellar and orbital parameters of these binary systems. The mean distance modulus of the observed part of the SMC is 19.05 mag, based on the 26 most reliable systems. Assuming an average error of 0.1 mag on the distance modulus to an individual system, and a gaussian distribution of the distance moduli, we obtain a 2-σ depth of 0.36 mag or 10.6 kpc. Some results on the kinematics of the binary stars and of the H ii gas are also given.

scholarly journals CM Draconis: Masses and Radii of Very Low Mass Stars

2006 ◽  
Vol 2 (S240) ◽  
pp. 628-630
Author(s):  
J.C. Morales ◽  
I. Ribas ◽  
C. Jordi ◽  
G. Torres ◽  
E.F. Guinan ◽  
...  
Keyword(s):  
Magnetic Activity ◽  
Time Span ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Low Mass Stars ◽  
Fundamental Properties ◽  
Low Mass ◽  
Effective Temperatures ◽  
Better Than

AbstractIn this work we have studied CM Draconis, one of the least massive eclipsing binaries known. Its components are very similar, with masses and radii of about 0.23 M⊙ and 0.25 R⊙. We have analysed light curves in the R and I bands to calculate the fundamental properties of this system with accuracies better than 1%. With these results we plan to carry out a thorough test of the models, which have been found to predict smaller radii and larger effective temperatures than observed for these low-mass stars. This will also be especially interesting in the case of CM Dra since the mechanism driving magnetic activity is thought to be different from that of more massive stars. In addition, the extended time-span of the observations has led to the detection of apsidal motion. This provides a further check on models through the determination of the internal structure of the stars.

scholarly journals Rotational Properties and Synchronization in Early-Type Close Binaries

1985 ◽  
Vol 111 ◽  
pp. 401-402
Author(s):  
G. Giuricin ◽  
F. Mardirossian ◽  
M. Mezzetti
Keyword(s):  
Angular Velocity ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Spectroscopic Binaries ◽  
Close Binaries ◽  
Early Type ◽  
Orbital Inclination ◽  
Eccentric Orbits ◽  
The Mean ◽  
The Absolute

We have rediscussed the synchronism between rotation and revolution in close binaries by an inspection of the published projected rotational velocities V sin i of about 250 early-type (from 0 to F5) eclipsing and double-lined spectroscopic binaries. Corrections of the V sin i - values (which are mainly taken from the catalog of Uesugi and Fukuda, 1982) for the aspect effect is straightforward for the eclipsing binaries with analyzed light-curves; in the other cases we have estimated the value of the orbital inclination angle i from the primary's minimum mass M1 sin3 i on the assumption that its mass follows Straižys and Kuriliené's (1981) mass-spectrum relations for different luminosity classes. For the components of non-eclipsing binaries, for which the absolute radii are not directly known, we have adopted values of the absolute radii in accordance with Straižys and Kuriliené's (1981) radius-spectrum relations for different luminosity classes. By using our estimates of the radii, for each component we have evaluated the synchronized velocity Vk (corresponding to the mean orbital angular velocity) and the pseudosynchronized velocity Ve, which corresponds to a synchronization with the instantaneous orbital angular velocity at periastron of an eccentric orbit; in close binaries with appreciably eccentric orbits synchronization is attained with V/Vk>1 and it is probably quickly reached at periastron (Hut 1981).

scholarly journals An OB-type eclipsing binary system ALS 1135

2010 ◽  
Vol 6 (S272) ◽  
pp. 529-530
Author(s):  
Gabriela Michalska ◽  
Ewa Niemczura ◽  
Marek Steslicki ◽  
Andrew Williams
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Light Curves ◽  
Early Type ◽  
Eclipsing Binary ◽  
Orbital Parameters ◽  
Effective Temperatures

AbstractWe present new physical and orbital parameters of an early-type double-lined eclipsing binary system ALS 1135. The UBVIC light curves and radial velocity curves were modeled simultaneously by means of the Wilson-Devinney code. As a result, we obtained inclination and size of the orbit, as well as masses, radii and effective temperatures of the components.

Magellanic Cloud Eclipsing Binaries: Primary Distance Indicators

1999 ◽  
Vol 190 ◽  
pp. 563-566
Author(s):  
J. D. Pritchard ◽  
W. Tobin ◽  
J. V. Clausen ◽  
E. F. Guinan ◽  
E. L. Fitzpatrick ◽  
...  
Keyword(s):  
New Zealand ◽  
Magellanic Cloud ◽  
Eclipsing Binaries ◽  
Fundamental Parameters ◽  
Distance Indicators

Our collaboration involves groups in Denmark, the U.S.A. Spain and of course New Zealand. Combining ground-based and satellite (IUEandHST) observations we aim to determine accurate and precise stellar fundamental parameters for the components of Magellanic Cloud Eclipsing Binaries as well as the distances to these systems and hence the parent galaxies themselves. This poster presents our latest progress.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

scholarly journals SuperWASP variable stars: classifying light curves using citizen science

2021 ◽  
Vol 502 (1) ◽  
pp. 1299-1311
Author(s):  
Heidi B Thiemann ◽  
Andrew J Norton ◽  
Hugh J Dickinson ◽  
Adam McMaster ◽  
Ulrich C Kolb
Keyword(s):  
Variable Stars ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Data Set ◽  
Resultant Data ◽  
Sky Survey ◽  
Short Period ◽  
Contact Binaries ◽  
Analysis Of Results

ABSTRACT We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 million classifications corresponding to >500 000 object–period combinations, provided by citizen–scientist volunteers. Volunteer-classified light curves have ∼89 per cent accuracy for detached and semidetached eclipsing binaries, but only ∼9 per cent accuracy for rotationally modulated variables, based on known objects. We demonstrate that this Zooniverse project will be valuable for both population studies of individual variable types and the identification of stellar variables for follow-up. We present preliminary findings on various unique and extreme variables in this analysis, including long-period contact binaries and binaries near the short-period cut-off, and we identify 301 previously unknown binaries and pulsators. We are now in the process of developing a web portal to enable other researchers to access the outputs of the SuperWASP variable stars project.

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