Fundamental Parameters of Four Massive Eclipsing Binaries in Westerlund 1

AbstractWe present preliminary results of the first near-infrared variability study of the Arches cluster, using adaptive optics data from NIRI/Gemini and NACO/VLT. The goal is to discover eclipsing binaries in this young (2.5 ± 0.5 Myr), dense, massive cluster for which we will determine accurate fundamental parameters with subsequent spectroscopy. Given that the Arches cluster contains more than 200 Wolf-Rayet and O-type stars, it provides a rare opportunity to determine parameters for some of the most massive stars in the Galaxy.

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Variability of young massive stars in the Arches cluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311010659 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 298-299

Author(s):

Kostas Markakis ◽

Alceste Z. Bonanos ◽

Grzegorz Pietrzynski ◽

Lucas Macri ◽

Kris Z. Stanek

Keyword(s):

Adaptive Optics ◽

Near Infrared ◽

Massive Stars ◽

Eclipsing Binaries ◽

Fundamental Parameters ◽

Preliminary Results ◽

The Galaxy ◽

Variability Study ◽

Massive Cluster ◽

Rare Opportunity

AbstractWe present preliminary results of the first near-infrared variability study of the Arches cluster, using adaptive optics data from NIRI/Gemini and NACO/VLT. The goal is to discover eclipsing binaries in this young (2.5 ± 0.5 Myr), dense, massive cluster for which we will determine accurate fundamental parameters with subsequent spectroscopy. Given that the Arches cluster contains more than 200 Wolf-Rayet and O-type stars, it provides a rare opportunity to determine parameters for some of the most massive stars in the Galaxy.

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A survey for high-mass eclipsing binaries

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2953 ◽

2019 ◽

Vol 490 (4) ◽

pp. 5147-5173

Author(s):

F Pozo Nuñez ◽

R Chini ◽

A Barr Domínguez ◽

Ch Fein ◽

M Hackstein ◽

...

Keyword(s):

Eclipsing Binaries ◽

Light Curves ◽

High Mass ◽

System Component ◽

Fundamental Parameters ◽

Average Value ◽

Short Period ◽

Orbital Periods ◽

Photometric Monitoring ◽

Period System

ABSTRACT We report results from a search for Galactic high-mass eclipsing binaries. The photometric monitoring campaign was performed in Sloan r and i with the robotic twin refractor RoBoTT at the Universitätssternwarte Bochum in Chile and complemented by Johnson UBV data. Comparison with the SIMBAD data base reveals 260 variable high-mass stars. Based on well-sampled light curves, we discovered 35 new eclipsing high-mass systems and confirm the properties of six previously known systems. For all objects, we provide the first light curves and determine orbital periods through the Lafler–Kinman algorithm. Apart from GSC 08173-0018 and Pismis 24-13 ($P = 19.47\, d$ and $20.14\, d$) and the exceptional short-period system TYC 6561-1765-1 ($P = 0.71\, d$), all systems have orbital periods between 1 and 9 d. We model the light curves of 26 systems within the framework of the Roche geometry and calculate fundamental parameters for each system component. The Roche lobe analysis indicates that 14 systems have a detached geometry, while 12 systems have a semidetached geometry; seven of them are near-contact systems. The deduced mass ratios q = M2/M1 reach from 0.4 to 1.0 with an average value of 0.8. The similarity of masses suggests that these high-mass binaries were created during the star formation process rather than by tidal capture.

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A critical test to disentangle the role of overshooting and rotation in stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318006208 ◽

2018 ◽

Vol 14 (S343) ◽

pp. 375-376

Author(s):

G. Costa ◽

L. Girardi ◽

A. Bressan ◽

P. Marigo ◽

Y. Chen ◽

...

Keyword(s):

Bayesian Estimation ◽

Massive Stars ◽

Estimation Method ◽

Eclipsing Binaries ◽

Evolutionary Models ◽

Critical Test ◽

Rotation Rates ◽

Reasonable Explanation ◽

Convective Core

AbstractWe study the mixing in low-intermediate massive stars using eclipsing binaries. We compute stellar evolutionary models with a varying convective core overshooting parameter and different rotation rates. Using a Bayesian estimation method, we found that the coexistence of the two phenomena may be a reasonable explanation of the observed extra-mixing.

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Fundamental parameters of 4 massive eclipsing binaries in Westerlund 1

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311011240 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 515-516

Author(s):

Eugenia Koumpia ◽

Alceste Z. Bonanos

Keyword(s):

Binary Systems ◽

Local Group ◽

Massive Stars ◽

Eclipsing Binaries ◽

Fundamental Parameters ◽

Red Supergiants ◽

The Masses ◽

Rare Opportunity ◽

Luminous Blue Variable

AbstractWesterlund 1 is one of the most massive young clusters known in the Local Group, with an age of 3-5 Myr. It contains an assortment of rare evolved massive stars, such as blue, yellow and red supergiants, Wolf-Rayet stars, a luminous blue variable, and a magnetar, as well as 4 massive eclipsing binary systems (Wddeb, Wd13, Wd36, WR77o, see Bonanos 2007). The eclipsing binaries present a rare opportunity to constrain evolutionary models of massive stars, the distance to the cluster and furthermore, to determine a dynamical lower limit for the mass of a magnetar progenitor. Wddeb, being a detached system, is of great interest as it allows determination of the masses of 2 of the most massive unevolved stars in the cluster. We have analyzed spectra of all 4 eclipsing binaries, taken in 2007-2008 with the 6.5 meter Magellan telescope at Las Campanas Observatory, Chile, and present fundamental parameters (masses, radii) for their component stars.

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A survey of the most massive stars in the Magellanic Clouds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308028688 ◽

2008 ◽

Vol 4 (S256) ◽

pp. 343-348

Author(s):

Alceste Z. Bonanos

Keyword(s):

Star Formation ◽

Massive Star ◽

Massive Stars ◽

Magellanic Clouds ◽

Eclipsing Binaries ◽

Large Impact ◽

Massive Star Formation ◽

Fundamental Parameters ◽

Precise Data ◽

Formation And Evolution

AbstractDespite the large impact very massive stars (>30 M⊙) have in astrophysics, their fundamental parameters remain uncertain. I present results of a survey aiming to characterize the most massive stars in the Magellanic Clouds. The survey targets the brightest, blue, eclipsing binaries discovered by the OGLE microlensing survey, for which masses and radii are measured to 5%. Such precise data are rare and provide constraints for theories of massive star formation and evolution at low metallicities.

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Magellanic Cloud Eclipsing Binaries: Primary Distance Indicators

Symposium - International Astronomical Union ◽

10.1017/s007418090011900x ◽

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.

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The Formation of Massive Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311000184 ◽

2010 ◽

Vol 6 (S270) ◽

pp. 57-64

Author(s):

Ian A. Bonnell ◽

Rowan J Smith

Keyword(s):

Star Formation ◽

Magnetic Fields ◽

Massive Star ◽

Massive Stars ◽

Cluster Formation ◽

High Mass ◽

Prestellar Cores ◽

Stellar Mergers ◽

Massive Clusters ◽

Viable Mechanism

AbstractThere has been considerable progress in our understanding of how massive stars form but still much confusion as to why they form. Recent work from several sources has shown that the formation of massive stars through disc accretion, possibly aided by gravitational and Rayleigh-Taylor instabilities is a viable mechanism. Stellar mergers, on the other hand, are unlikely to occur in any but the most massive clusters and hence should not be a primary avenue for massive star formation. In contrast to this success, we are still uncertain as to how the mass that forms a massive star is accumulated. there are two possible mechanisms including the collapse of massive prestellar cores and competitive accretion in clusters. At present, there are theoretical and observational question marks as to the existence of high-mass prestellar cores. theoretically, such objects should fragment before they can attain a relaxed, centrally condensed and high-mass state necessary to form massive stars. Numerical simulations including cluster formation, feedback and magnetic fields have not found such objects but instead point to the continued accretion in a cluster potential as the primary mechanism to form high-mass stars. Feedback and magnetic fields act to slow the star formation process and will reduce the efficiencies from a purely dynamical collapse but otherwise appear to not significantly alter the process.

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Tests of Evolution Models Using Eclipsing Binaries

Highlights of Astronomy ◽

10.1017/s1539299600011588 ◽

1995 ◽

Vol 10 ◽

pp. 419-422

Author(s):

J. Andersen

Keyword(s):

Chemical Composition ◽

Star Clusters ◽

Stellar Model ◽

Eclipsing Binaries ◽

Fundamental Parameter ◽

Fundamental Parameters ◽

Stellar Models ◽

Absolute Age ◽

Cluster Sequence ◽

Hr Diagram

Stellar models are the means by which we describe and understand the distribution of stars in the HR diagram. A stellar model is, in principle, completely specified by the three fundamental parameters mass, chemical composition, and age. Comparing the properties of models and real stars with the same parameters will tell us if our recipe for constructing stellar models is realistic. Unfortunately, the only star for which all three are known independently of stellar models is the Sun. For stars of other masses and ages we must devise observational tests in which at least one fundamental parameter is unknown. Two such popular test objects are double-lined eclipsing binaries and star clusters.In suitable eclipsing binaries we can determine both masses and chemical composition; the absolute age is unknown, but the same for both stars. Since evolution depends most sensitively on the mass, eclipsing binaries provide a very direct test of the models, but only for two points on a single isochrone. In star clusters, neither ages nor individual masses are known, but the detailed shape and population of a well-observed cluster sequence in the HR diagram provide a number of additional probes into the models.

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ISOCAM and DENIS Survey of 0.5 square degrees in the Bar of the LMC. Detection of the whole TP-AGB Star Population

Symposium - International Astronomical Union ◽

10.1017/s0074180900203550 ◽

1999 ◽

Vol 191 ◽

pp. 561-566

Author(s):

C. Loup ◽

E. Josselin ◽

M.-R. Cioni ◽

H.J. Habing ◽

J.A.D.L. Blommaert ◽

...

Keyword(s):

Mass Loss ◽

High Mass ◽

Evolutionary Models ◽

Agb Stars ◽

Complete Sample ◽

High Mass Loss ◽

Low Mass ◽

The One ◽

Good Agreement ◽

Loss Rates

We surveyed 0.5 square degrees in the Bar of the LMC with ISOCAM at 4.5 and 12 μm, and with DENIS in the I, J, and Ks bands. Our goal was to build a complete sample of Thermally-Pulsing AGB stars. Here we present the first analysis of 0.14 square degrees. In total we find about 300 TP-AGB stars. Among these TP-AGB stars, 9% are obscured AGB stars (high mass-loss rates); 9 of them were detected by IRAS, and only 1 was previously identified. Their luminosities range from 2 500 to 14 000 L⊙, with a distribution very similar to the one of optical TP-AGB stars (i.e. those with low mass-loss rates). Such a luminosity distribution, as well as the percentage of obscured stars among TP-AGB stars, is in very good agreement with the evolutionary models of Vassiliadis & Wood (1993) if most of the TP-AGB stars that we find have initial masses smaller than 1.5 to 2 M⊙.

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