High-mass binaries in the very young open cluster NGC 6231

García, Beatriz; Mermilliod, J. C.

doi:10.1051/0004-6361:20000528

Cited by 111 publications

(136 citation statements)

References 31 publications

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“…For comparison, Mason et al (1998) derives a binary fraction of 59-75% for O stars in clusters and associations. García & Mermilliod (2001) find fractions between 14-80%, whereas Kobulnicky & Fryer (2007) infer a fraction higher than 70%. On the other hand, Pols et al (1991) adopted a fraction of 27.5% of binaries with B-type primaries, P < 10 yr and Assuming that all systems with orbital periods between 1000 and 2000 days produce IIb's 1,3 -2.3-3.5% -Notes.…”

Section: Predicted Ratesmentioning

confidence: 98%

Binary progenitor models of type IIb supernovae

Claeys

Mink

Pols

et al. 2011

A&A

120

147

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Massive stars that lose their hydrogen-rich envelope down to a few tenths of a solar mass explode as extended type IIb supernovae, an intriguing subtype that links the hydrogen-rich type II supernovae with the hydrogen-poor type Ib and Ic. The progenitors may be very massive single stars that lose their envelope due to their stellar wind, but mass stripping due to interaction with a companion star in a binary system is currently considered to be the dominant formation channel. Anticipating the upcoming automated transient surveys, we computed an extensive grid of binary models with the Eggleton binary evolution code. We identify the limited range of initial orbital periods and mass ratios required to produce type IIb binary progenitors. The rate we predict from our standard models, which assume conservative mass transfer, is about six times smaller than the current rate indicated by observations. It is larger but still comparable to the rate expected from massive single stars. We evaluate extensively the effect of various assumptions such as the adopted accretion efficiency, the binary fraction and distributions for the initial binary parameters. To recover the observed rate we must generously allow for uncertainties and consider low accretion efficiencies in combination with limited angular momentum loss from the system. Motivated by the claims of detection and non-detection of companions for a few IIb supernovae, we investigate the properties of the secondary star at the moment of explosion. We identify three cases: (1) the companion is predicted to appear as a hot O star in about 90% of the cases, as a result of mass accretion during its main sequence evolution, (2) the companion becomes an over-luminous B star in about 3% of the cases, if mass accretion occurred while crossing the Hertzsprung gap or (3) in systems with very similar initial masses the companion will appear as a K supergiant. The second case, which applies to the well-studied case of SN 1993J and possibly to SN 2001ig, is the least common case and requires that the companion very efficiently accretes the transferred material -in contrast to what is required to recover the overall IIb rate. We note that relative rates quoted above depend on the assumed efficiency of semi-convective mixing: for inefficient semi-convection the presence of blue supergiant companions is expected to be more common, occurring in up to about 40% of the cases. Our study demonstrates that type IIb supernovae have the potential to teach us about the physics of binary interaction and about stellar processes such as internal mixing and possibly stellar-wind mass loss. The fast increasing number of type IIb detections from automated surveys may lead to more solid constraints on these model uncertainties in the near future.

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Section: Predicted Ratesmentioning

confidence: 98%

Binary progenitor models of type IIb supernovae

Claeys

Mink

Pols

et al. 2011

A&A

120

147

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“…These detailed observations led to a serious correction of the results proposed by García & Mermilliod (2001) for O-type star rich clusters, by greatly improving our knowledge of the precise physical parameters of the binaries in these clusters. To extend these studies, we undertook a similar spectroscopic monitoring of the O-type star population in another young open cluster, NGC 2244.…”

Section: Introductionmentioning

confidence: 93%

Early-type stars in the young open cluster NGC 2244 and in the Monoceros OB2 association

Mahy¹,

Nazé²,

Rauw³

et al. 2009

A&A

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Aims. We present the results obtained from a long-term spectroscopic campaign to study the multiplicity of O-type stars in both the young open cluster NGC 2244 and the Mon OB2 association. Methods. Our spectroscopic monitoring was performed over several years, allowing us to investigate different timescales. For each star, several spectral diagnostic tools were applied to search for line shifts and profile variations. We also measured the projected rotational velocity and revisited the spectral classification. Results. Several stars in our sample have been previously considered to be spectroscopic binaries, although only a few scattered observations were available. Our results now have identified a more complex situation for two new spectroscopic binaries (HD 46 149 in NGC 2244 and HD 46 573 in Mon OB2). The first object is a long-period double-lined spectroscopic binary, although the exact value of its period remains uncertain and the second object is classified as an SB1 system with a period of about 10.67 days but the time series of our observations do not enable us to derive a unique orbital solution for this system. We also find another star to be variable in radial velocity (HD 46 150) and detect line profile variations in two rapid rotators (HD 46 056 and HD 46 485). Conclusions. This spectroscopic investigation places a firm lower limit (17%) on the binary fraction of O-stars in NGC 2244 and reveals the lack of short-period O+OB systems in this cluster. In addition, a comparison of these new results with two other wellstudied clusters (NGC 6231 and IC 1805) puts forward possible hints of a relation between stellar density and binarity, which could provide constraints on the theories of the formation and early evolution of hot stars.

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“…Morrell & Levato (1991) have determined the rate of binaries among B stars in the Orion OB1 association, and obtained an overall frequency of binaries with P orb < 10 days of 26 ± 6%. Garcia & Mermilliod (2001) found a rate of binaries as high as 82% among stars hotter than B1.5 in the very young open cluster NGC 6231, though in a sample of 34 stars only. Most orbits have periods shorter than 10 days.…”

Section: The Binary Fractionmentioning

confidence: 88%

Analysis of the Eclipsing Binaries in the LMC Discovered by OGLE: Period Distribution and Frequency of the Short–Period Binaries

Mazeh¹,

Tamuz²,

North

2006

Proc. IAU

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Abstract.We review the results of our analysis of the OGLE LMC eclipsing binaries (Mazeh, Tamuz & North 2006), using EBAS -Eclipsing Binary Automated Solver, an automated algorithm to fit lightcurves of eclipsing binaries .After being corrected for observational selection effects, the set of detected eclipsing binaries yielded the period distribution and the frequency of all LMC short-period binaries, and not just the eclipsing systems.Somewhat surprisingly, the period distribution is consistent with a flat distribution in log P between 2 and 10 days. The total number of binaries with periods shorter than 10 days in the LMC was estimated to be about 5000. This figure led us to suggest that (0.7 ± 0.4)% of the main-sequence A-and B-type stars are found in binaries with periods shorter than 10 days. This frequency is substantially smaller than the fraction of binaries found by small Galactic radial-velocity surveys of B stars.

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High-mass binaries in the very young open cluster NGC 6231

Cited by 111 publications

References 31 publications

Binary progenitor models of type IIb supernovae

Binary progenitor models of type IIb supernovae

Early-type stars in the young open cluster NGC 2244 and in the Monoceros OB2 association

Analysis of the Eclipsing Binaries in the LMC Discovered by OGLE: Period Distribution and Frequency of the Short–Period Binaries

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