ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

Simón‐Díaz, S.; Caballero, J. A.; Lorenzo, Javier; Apellániz, J. Maíz; Schneider, F. R. N.; Negueruela, I.; Barbá, R. H.; Dorda, R.; Marco, A.; Montes, D.; Pellerin, Anne; Sánchez-Bermúdez, J.; Sódor, Á.; Sota, A.

doi:10.1088/0004-637x/799/2/169

Cited by 48 publications

(48 citation statements)

References 86 publications

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“…We scaled the contours to result in a reduced χ 2 of unity at the minimum. The positions of σ Ori A,B are in good agreement with measurements made at similar times by Simón-Díaz et al (2015) and Aldoretta et al (2015).…”

Section: Npoi Astrometric Resultssupporting

confidence: 88%

“…On average, the components contribute a mean of 47.7% ± 5.9% (Aa), 27.4% ± 5.2% (Ab), and 24.9% ± 8.0% (B) of the total light recorded on the detector in the H-band. These fractional flux contributions are very similar to those in the V -band as estimated by Simón-Díaz et al (2015), 48%, 28% and 24%, respectively.…”

Section: Chara Astrometric Resultssupporting

confidence: 84%

“…We fit a simultaneous orbit to the higher precision interferometric positions of σ Orionis Aa,Ab measured with CHARA in Table 3, the published radial velocities reported by Simón-Díaz et al (2015), and the CTIO radial velocities in Table 8. We compare the fit to the NPOI positions of the close pair in Section 4.2.…”

Section: Visual and Spectroscopic Orbit Of The Close Pair σ Orionis Amentioning

confidence: 99%

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

Schaefer¹,

Hummel²,

Gies³

et al. 2016

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We present interferometric observations of the σ Orionis triple system using the CHARA Array, NPOI, and VLTI. Using these measurements, we spatially resolve the orbit of the close spectroscopic binary (Aa,Ab) for the first time and present a revised orbit for the wide pair (A,B). Combining the visual orbits with previously published radial velocity measurements and new radial velocities measured at CTIO, we derive dynamical masses for the three massive stars in the system of M Aa = 16.99 ± 0.20 M ⊙ , M Ab = 12.81 ± 0.18 M ⊙ , and M B = 11.5 ± 1.2 M ⊙ . The inner and outer orbits in the triple are not coplanar, with a relative inclination of 120• -127• . The orbital parallax provides a precise distance of 387.5 ± 1.3 pc to the system. This is a significant improvement over previous estimates of the distance to the young σ Orionis cluster.

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Section: Npoi Astrometric Resultssupporting

confidence: 88%

Section: Chara Astrometric Resultssupporting

confidence: 84%

Section: Visual and Spectroscopic Orbit Of The Close Pair σ Orionis Amentioning

confidence: 99%

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

Schaefer¹,

Hummel²,

Gies³

et al. 2016

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“…The survey itself was presented in Maíz Apellániz (2010); we refer to that paper for details on the data and processing. Later AstraLux results for individual stars are discussed in Sota et al (2014) and Simón-Díaz et al (2015a). Maíz Apellániz (2010) used a Sloan-z-band image of LS III +46 11.…”

Section: High-resolution Imagingmentioning

confidence: 99%

The little-studied cluster Berkeley 90

Apellániz

Negueruela

Barbá

et al. 2015

A&A

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Context. It appears that most (if not all) massive stars are born in multiple systems. At the same time, the most massive binaries are hard to find owing to their low numbers throughout the Galaxy and the implied large distances and extinctions. Aims. We want to study LS III +46 11, identified in this paper as a very massive binary; another nearby massive system, LS III +46 12; and the surrounding stellar cluster, Berkeley 90. Methods. Most of the data used in this paper are multi-epoch high S/N optical spectra, although we also use Lucky Imaging and archival photometry. The spectra are reduced with dedicated pipelines and processed with our own software, such as a spectroscopicorbit code, CHORIZOS, and MGB. Results. LS III +46 11 is identified as a new very early O-type spectroscopic binary [O3.5 If* + O3.5 If*] and LS III +46 12 as another early O-type system [O4.5 V((f))]. We measure a 97.2-day period for LS III +46 11 and derive minimum masses of 38.80 ± 0.83 M and 35.60 ± 0.77 M for its two stars. We measure the extinction to both stars, estimate the distance, search for optical companions, and study the surrounding cluster. In doing so, a variable extinction is found as well as discrepant results for the distance. We discuss possible explanations and suggest that LS III +46 12 may be a hidden binary system where the companion is currently undetected.

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“…Our goals are twofold: first, we address the cluster membership of our candidates and describe their photometric and spectroscopic properties at optical and near-infrared wavelengths for the age of the cluster; second, we address the mass function in the planetary-mass domain. The σ Orionis cluster has an age of ∼3 Myr (Zapatero Osorio et al 2012a;Sherry et al 2008), solar metallicity (González Hernández et al 2008), low internal extinction (E(B − V ) = 0.05 mag, Lee 1968), and is located at a distance of 385±19 pc (determined by Hummel et al 2013 from interferometric data and adopted by Simón-Díaz et al 2015; the latter authors assigned a conservative error of 5%). More recently, Schaefer et al (2016) have measured a precise distance of 387.5 ± 1.3 pc to the massive triple star σ Ori.…”

Section: Introductionmentioning

confidence: 99%

Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-mass Objects

Osorio

Béjar

Ramírez

2017

ApJ

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We have obtained low-resolution optical (0.7-0.98 µm) and near-infrared (1.11-1.34 µm and 0.8-2.5 µm) spectra of twelve isolated planetary-mass candidates (J = 18.2-19.9 mag) of the 3-Myr σ Orionis star cluster with a view to determining the spectroscopic properties of very young, substellar dwarfs and assembling a complete cluster mass function. We have classified our targets by visual comparison with high-and low-gravity standards and by measuring newly defined spectroscopic indices. We derived L0-L4.5 and M9-L2.5 using high-and low-gravity standards, respectively. Our targets reveal clear signposts of youth, thus corroborating their cluster membership and planetary masses (6-13 M Jup ). These observations complete the σ Orionis mass function by spectroscopically confirming the planetary-mass domain to a confidence level of ∼75 percent. The comparison of our spectra with BT-Settl solar metallicity model atmospheres yields a temperature scale of 2350-1800 K and a low surface gravity of log g ≈ 4.0 [cm s−2 ], as would be expected for young planetary-mass objects. We discuss the properties of the cluster least-massive population as a function of spectral type. We have also obtained the first optical spectrum of S Ori 70, a T dwarf in the direction of σ Orionis. Our data provide reference optical and near-infrared spectra of very young L dwarfs and a mass function that may be used as templates for future studies of low-mass substellar objects and exoplanets. The extrapolation of the σ Orionis mass function to the solar neighborhood may indicate that isolated planetarymass objects with temperatures of ∼200-300 K and masses in the interval 6-13-M Jup may be as numerous as very low-mass stars.

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ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

Cited by 48 publications

References 86 publications

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

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

The little-studied cluster Berkeley 90

Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-mass Objects

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