SOUTHERN MASSIVE STARS AT HIGH ANGULAR RESOLUTION: OBSERVATIONAL CAMPAIGN AND COMPANION DETECTION

By H. Sana, J. L. Bouquin, S. Lacour, J. Berger, G. Duvert, L. Gauchet, B. Norris, J. Olofsson, D. Pickel, G. Zins and 5 more. 2014

457 citations recorded by the source corpus.

Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 milliarcsec (mas) remain mostly unknown due to intrinsic observational limitations. At a typical distance of 2 kpc, this corresponds to projected physical separations of 2–200 AU. The Southern MAssive Stars at High angular resolution survey (smash+) was designed to fill this gap by providing the first systematic interferometric survey of Galactic massive stars. We observed 117 O-type stars with VLTI/PIONIER and 162 O-type stars with NACO/Sparse Aperture Masking (SAM), probing the separation ranges 1–45 and 30–250 mas and brightness contrasts of ΔH < 4 and ΔH < 5, respectively. Taking advantage of NACO's field of view, we further uniformly searched for visual companions in an 8″ radius down to ΔH = 8. This paper describes observations and data analysis, reports the discovery of almost 200 new companions in the separation range from 1 mas to 8″ and presents a catalog of detections, including the first resolved measurements of over a dozen known long-period spectroscopic binaries. Excluding known runaway stars for which no companions are detected, 96 objects in our main sample (δ < 0°; H < 7.5) were observed both with PIONIER and NACO/SAM. The fraction of these stars with at least one resolved companion within 200 mas is 0.53. Accounting for known but unresolved spectroscopic or eclipsing companions, the multiplicity fraction at separation ρ < 8″ increases to fm = 0.91 ± 0.03. The fraction of luminosity class V stars that have a bound companion reaches 100% at 30 mas while their average number of physically connected companions within 8″ is fc = 2.2 ± 0.3. This demonstrates that massive stars form nearly exclusively in multiple systems. The nine non-thermal radio emitters observed by smash+ are all resolved, including the newly discovered pairs HD 168112 and CPD−47°2963. This lends strong support to the universality of the wind-wind collision scenario to explain the non-thermal emission from O-type stars.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/788f7cb04808b1ab8214e9e94aea58582f150d0a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. F. Antonini
2. Ilya Mandel
3. Michela Mapelli
4. D. Holz
5. Selma de Mink
6. N. Giacobbo
7. B. Kocsis
8. C. Rodriguez

In Education

1. F. Antonini
2. S. Tremaine
3. R. Di Stefano
4. Ilya Mandel
5. J. Eldridge
6. M. Moe
7. Selma de Mink
8. K. Kratter

In Instrumentation

1. Selma de Mink
2. J. Eldridge
3. E. Stanway
4. Robert G. Izzard
5. H. Sana
6. B. Kocsis
7. Ilya Mandel
8. C. Rodriguez

Citations in the corpus

• Gravitational Instabilities in Circumstellar Disks (2016, result): “The susceptibility of these disks to fragmentation is consistent with the observation that nearly all massive stars are found in binaries (Sana & Evans 2010; Sana et al. 2014).”
• The evolution of hierarchical triple star-systems (2016, background): “, 2010; Tokovinin, 2008, 2014b) a fraction that gradually increases (Duchêne and Kraus, 2013) to ∼ 50% for spectral type B stars (Moe and Di Stefano, 2016; Remage Evans, 2011; Sana et al., 2014).”
• Merging binary black holes formed through chemically homogeneous evolution in short-period stellar binaries (2015, background): “The extension of the upper limit allows for wide binary stars (e.g., Sana et al. 2014) and single stars (see discussion in de Mink & Belczynski 2015).”
• The Close Binary Fraction of Solar-type Stars Is Strongly Anticorrelated with Metallicity (2018, background): “At solar metallicity, the observed binary fraction of massive stars is already large, i.e., ≈70% below a<10 au and nearly 100% within a<100 au (Sana et al. 2012, 2014; Moe & Di Stefano 2017; Section 6).”
• BPASS predictions for binary black hole mergers (2016, background): “…that most massive stars are in binary or multiple systems, with 70 per cent of massive stars having their evolution affected by binary interactions as shown by direct and indirect observations (e.g. Vanbeveren, De Loore & Van Rensbergen 1998; Eldridge, Izzard & Tout 2008; Sana et al. 2012, 2014).”
• Lidov–Kozai Cycles with Gravitational Radiation: Merging Black Holes in Isolated Triple Systems (2016, background): “In this section, we ignore systematic effects associated with the Sana et al. (2014) survey (the sample was magnitude-limited, and therefore biased toward high masses and systems with multiple unresolved O-stars), and assume the following.”
• Eccentric Black Hole Gravitational-wave Capture Sources in Galactic Nuclei: Distribution of Binary Parameters (2017, background): “Indeed, high-mass stars, the progenitors of BHs, are commonly found in triples in the galactic field (i.e., more than 25% of massive stars are in triples; see Sana et al. (2014)).”
• Binary Population and Spectral Synthesis Version 2.1: Construction, Observational Verification, and New Results (2017, background): “…from both the Milky Way (Duchêne & Kraus 2013; Yuan et al. 2015; Sheikhi et al. 2016) and the Magellanic Clouds (e.g. Li, de Grijs, & Deng 2013; Sana et al. 2014) suggest that field F, G, K stars may have an observed binary fraction of 20–40%, while that for O and B type stars may reach 100%.”
• Binary Black Hole Mergers from Field Triples: Properties, Rates, and the Impact of Stellar Evolution (2017, background): “%) of massive stars are observed to be in triple systems (Sana et al. 2014).”
• The MiMeS survey of Magnetism in Massive Stars : magnetic analysis of the O-type stars (2016, background): “• HD47129 (Plaskett’s star) is a well-known multiple star system consisting of a spectroscopic binary in addition to 3 visual companions at distances of 36 mas, 0.78 arcsec and 1.12 arcsec (Turner et al. 2008; Sana et al. 2014).”
• Massive runaway and walkaway stars (2018, background): “…for the large spatial velocity of runaways is that they originate from disrupted binary systems (Zwicky 1957; Blaauw 1961; Boersma 1961), which naturally explains the lower number of companions they have, compared to typical massive stars (e.g., Blaauw 1961; Gies & Bolton 1986; Sana et al. 2014).”
• One Channel to Rule Them All? Constraining the Origins of Binary Black Holes Using Multiple Formation Pathways (2020, background): “A significant number of massive stars form in high-order multiples such as triples and quadruples (Sana et al. 2014; Moe & Di Stefano 2017).”
• Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars (2016, methodology): “In our current analysis, we consider only the 56 O-type primaries in the Sana et al. (2014) main sample that were observed by both LBI and SAM methods and have luminosity classes II.5 -”