Orbits, Distance, and Stellar Masses of the Massive Triple Star Σ Orionis

Schaefer, Gail H.; Hummel, C. A.; Gies, Douglas R.; Zavala, R. T.; Monnier, John D.; Walter, F. M.; Turner, N.; Baron, Fabien; Brummelaar, T. ten; Chen, Xiao; Farrington, C.; Kraus, Stefan; Sturmann, J.; Sturmann, L.

doi:10.3847/0004-6256/152/6/213

Cited by 71 publications

(67 citation statements)

References 84 publications

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“…• (Schaefer et al 2016) could be formed by a different process. Figure 12 compares the period ratios and outer eccentricities of the multiple systems studied here with the dynamical stability criterion of Mardling & Aarseth (2001).…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Without thorough re-assessment and filtering, the VB6 sample is not suitable for statistical study of relative orbit orientation. Long-baseline stellar interferatokovinin@ctio.noao.edu dlatham@cfa.harvard.edu ometers help in resolving closer and faster subsystems, but require substantial efforts, contributing so far only a handful of cases (e.g., Kervella et al 2013;Schaefer et al 2016) Motion in a triple system can be described by two Keplerian orbits only approximately because dynamical interaction between the inner and outer subsystems constantly changes their orbits. The time scale of this evolution is normally much longer than the time span of the observations, so the orbits represent the "instantaneous" osculating elements in the three-body problem.…”

Section: Introductionmentioning

confidence: 99%

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Relative Orbit Orientation in Several Resolved Multiple Systems

Tokovinin

Latham

2017

ApJ

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This work extends the still modest number of multiple stars with known relative orbit orientation. Accurate astrometry and radial velocities are used jointly to compute or update outer and inner orbits in three nearby triple systems HIP 101955 (orbital periods 38.68 and 2.51 years), HIP 103987 (19.20 and 1.035 years), HIP 111805 (30.13 and 1.50 years) and in one quadruple system HIP 2643 (periods 70.3, 4.85 and 0.276 years), all composed of solar-type stars. The masses are estimated from the absolute magnitudes and checked using the orbits. The ratios of outer to inner periods (from 14 to 20) and the eccentricities of the outer orbits are moderate. These systems are dynamically stable, but not very far from the stability limit. In three systems all orbits are approximately coplanar and have small eccentricity, while in HIP 101955 the inner orbit with e = 0.6 is highly inclined.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relative Orbit Orientation in Several Resolved Multiple Systems

Tokovinin

Latham

2017

ApJ

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“…(1) Schaefer et al (2016); (2) van Leeuwen (2007); (3) Gaia DR1: Gaia Collaboration (2016b), Lindegren et al (2016), Fabricius et al (2016), Gaia Collaboration (2016a); (4) Anthony-Twarog (1982); (5) Hummel et al (2013).…”

Section: Iram-30 M Observationsmentioning

confidence: 99%

The anatomy of the Orion B giant molecular cloud: A local template for studies of nearby galaxies

Pety

Guzmán

Orkisz

et al. 2017

A&A

196

319

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Context. Molecular lines and line ratios are commonly used to infer properties of extra-galactic star forming regions. The new generation of millimeter receivers almost turns every observation into a line survey. Full exploitation of this technical advancement in extra-galactic study requires detailed bench-marking of available line diagnostics. Aims. We aim to develop the Orion B giant molecular cloud (GMC) as a local template for interpreting extra-galactic molecular line observations. Methods. We use the wide-band receiver at the IRAM-30 m to spatially and spectrally resolve the Orion B GMC. The observations cover almost 1 square degree at 26 resolution with a bandwidth of 32 GHz from 84 to 116 GHz in only two tunings. Results. We introduce the molecular anatomy of the Orion B GMC, including relationships between line intensities and gas column density or far-UV radiation fields, and correlations between selected line and line ratios. We also obtain a dust-traced gas mass that is less than approximately one third the CO-traced mass, using the standard X CO conversion factor. The presence of over-luminous CO can be traced back to the dependence of the CO intensity on UV illumination. As a matter of fact, while most lines show some dependence on the UV radiation field, CN and C 2 H are the most sensitive. Moreover, dense cloud cores are almost exclusively traced by N 2 H + . Other traditional high-density tracers, such as HCN(1−0), are also easily detected in extended translucent regions at a typical density of ∼500 H 2 cm −3 . In general, we find no straightforward relationship between line critical density and the fraction of the line luminosity coming from dense gas regions. Conclusions. Our initial findings demonstrate that the relationships between line (ratio) intensities and environment in GMCs are more complicated than often assumed. Sensitivity (i.e., the molecular column density), excitation, and, above all, chemistry contribute to the observed line intensity distributions, and they must be considered together when developing the next generation of extra-galactic molecular line diagnostics of mass, density, temperature, and radiation field.

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“…σ Ori (Schaefer et al 2016) or ζ Aqr (Tokovinin 2016). The misaligned triple systems could have been shaped by dynamical interactions between stars in clusters or in small groups.…”

Section: Introductionmentioning

confidence: 99%

Orbit Alignment in Triple Stars

Tokovinin

2017

ApJ

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Statistics of the angle Φ between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. Correlation between apparent revolution directions proves partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ∼50 AU, where the average Φ is about 20• . In contrast, outer orbits wider than 1000 AU are not aligned with the inner orbits. It is established that the orbit alignment decreases with increasing mass of the primary component. Average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. Analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of Φ is likely bimodal, where 80% of triples have Φ < 70• and the remaining ones are randomly aligned.

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Orbits, Distance, and Stellar Masses of the Massive Triple Star Σ Orionis

Cited by 71 publications

References 84 publications

Relative Orbit Orientation in Several Resolved Multiple Systems

Relative Orbit Orientation in Several Resolved Multiple Systems

The anatomy of the Orion B giant molecular cloud: A local template for studies of nearby galaxies

Orbit Alignment in Triple Stars

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