Adaptive Optics Photometry and Astrometry of Binary Stars. Iii. A Faint Companion Search of O-Star Systems

Turner, N.; Brummelaar, Theo A. ten; Roberts, Lewis C.; Mason, Brian D.; Hartkopf, William I.; Gies, Douglas R.

doi:10.1088/0004-6256/136/2/554

Cited by 63 publications

(99 citation statements)

References 51 publications

(64 reference statements)

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“…Enhanced imaging techniques: At larger separations, AO-corrected and lucky imaging surveys (respectively, Turner et al (2008) -138 O stars -and Maíz Apellániz (2010 found that 37% of the O stars are part of wide multiple systems. These two studies are mostly limited to the northern hemisphere and are thus missing some of the richer massive star clusters and associations in the southern sky.…”

Section: Spectroscopic Binary Fraction In Various Separation Regimesmentioning

confidence: 99%

The multiplicity of massive stars

Sana

Evans

2010

Proc. IAU

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Abstract. Binaries are excellent astrophysical laboratories that provide us with direct measurements of fundamental stellar parameters. Compared to single isolated stars, multiplicity induces new processes, offering the opportunity to confront our understanding of a broad range of physics under the extreme conditions found in, and close to, astrophysical objects.In this contribution, we will discuss the parameter space occupied by massive binaries, and the observational means to investigate it. We will review the multiplicity fraction of OB stars within each regime, and in different astrophysical environments. In particular we will compare the O star spectroscopic binary fraction in nearby open clusters and we will show that the current data are adequately described by an homogeneous fraction of f ≈ 0.44.We will also summarize our current understanding of the observed parameter distributions of O + OB spectroscopic binaries. We will show that the period distribution is overabundant in short period binaries and that it can be described by a bi-modalÖpik law with a break point around P ≈ 10 d. The distribution of the mass-ratios shows no indication for a twin population of equal mass binaries and seems rather uniform in the range 0.2 q = M 2 /M1 1.0.

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Section: Spectroscopic Binary Fraction In Various Separation Regimesmentioning

confidence: 99%

The multiplicity of massive stars

Sana

Evans

2010

Proc. IAU

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“…They found a RV dispersion of about 10.2 km s −1 and, therefore, considered the star to be a potential binary. Turner et al (2008) reported some velocity variabilities of HD 46 149 because of the presence of a close spectroscopic companion.…”

Section: The O-type Star Population In Ngc 2244 and Mon Ob2mentioning

confidence: 99%

“…However, we emphasize that no evidence exists so far to confirm with any certainty the physical association of these companions, especially with such high angular separations. Turner et al (2008) published results of an adaptive optics survey to search for faint companions around Galactic Ostar systems (with V < ∼ 8). They observed in the I-band to detect companions in the projected separation between 0.5 and 5.0 .…”

Section: Photometry and Close "Visual" Companionsmentioning

confidence: 99%

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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“…Note that many groups have undertaken studies of the close environment of massive stars, among them Preibisch et al (1999), who concluded on a formation mechanism different from low-mass stars owing to an increased average number of companion stars per massive star, Duchêne et al (2001), who in contrast argue that standard accretion together with cloud fragmentation can explain their results; Turner et al (2008), who provide count statistics; Mason et al (2009), who concentrate on comparing the multiplicities of O-stars in associations to runaway and field O-stars; Sana & Evans (2011), who focus on determining the parameter distributions of massive binaries, and Maíz Apellániz (2010), who used the same instrument as we did to derive the multiplicity fraction of 138 massive stars with δ > −25 deg. This paper is organized as follows: the next section will outline the selection process for our target areas and introduce the individual regions.…”

Section: Introductionmentioning

confidence: 99%

Massive binaries in the Cepheus OB2/3 region

Peter

Feldt

Henning

et al. 2012

A&A

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Context. Two different formation scenarios for stars of masses larger than 10 M exist. Although simulations within both scenarios are capable of producing stars up to the highest observed masses, the relevance of the two formation scenarios for massive star-formation is not yet clear. Aims. We aim to detect companions to massive stars to constrain the binary parameters of the multiple systems. These findings will help to constrain the formation of massive stars. Methods. We performed z -band observations of massive and intermediate-mass stars in the Cep OB2/3 associations with the Lucky imaging camera AstraLux on the 2.2 m telescope of the Calar Alto observatory. The analysis aimed at detecting binary systems with separations out to 2. 2 (∼1700 AU), the inner limit depending on the contrast. The maximum contrast of 7 mag in z (corresponding to a mass contrast of 17:1 versus an O9V primary) requires a minimum separation of 0. 7 (∼550 AU). Results. We found 28 new companions for our sample of 148 intermediate-mass and massive stars in Cep OB2/3. The companion star fraction of the massive stars is 0.7; about 50% of the systems are triples. The mass function of the companions to the massive stars is strongly top-heavy. We found that the sample parameters closely agreed with those found in the Orion Trapezium cluster. Conclusions. The multiplicity of massive stars seems to be significantly higher than that of intermediate-mass stars, independently of the environment. The comparison of our findings with the theories of massive star-formation favor the formation of massive stars by the fragmentation of proto-stellar cores combined with competitive accretion.

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Adaptive Optics Photometry and Astrometry of Binary Stars. Iii. A Faint Companion Search of O-Star Systems

Cited by 63 publications

References 51 publications

The multiplicity of massive stars

The multiplicity of massive stars

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

Massive binaries in the Cepheus OB2/3 region

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