A VLBI study of the wind-wind collision region in the massive multiple HD 167971

Sánchez-Bermúdez, J.; Alberdi, A.; Schödel, R.; Brandner, W.; Galván-Madrid, Roberto; Guirado, J. C.; Herrero-Illana, R.; Hummel, C. A.; Marcaide, J. M.; Pérez-Torres, M. Á.

doi:10.1051/0004-6361/201834659

Cited by 13 publications

(12 citation statements)

References 29 publications

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“…CWBs emit radio waves but are dim and scarce. Only the closer systems can be detected with current facilities, and intensity distribution maps could be obtained for a handful of them only (Benaglia et al 2015;Sanchez-Bermudez et al 2019, and references therein). As the NT emission arises from the CWR, a significant variability on the orbital time scale is expected and confirmed by adequate radio monitoring, such as in the case of the emblematic system WR 140 (White & Becker 1995).…”

Section: Introductionmentioning

confidence: 99%

Megahertz emission of massive early-type stars in the Cygnus region

Benaglia

Becker

Ishwara‐Chandra

et al. 2020

Publ. Astron. Soc. Aust.

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Massive, early-type stars have been detected as radio sources for many decades. Their thermal winds radiate free–free continuum and in binary systems hosting a colliding-wind region, non-thermal emission has also been detected. To date, the most abundant data have been collected from frequencies higher than 1 GHz. We present here the results obtained from observations at 325 and 610 MHz, carried out with the Giant Metrewave Radio Telescope, of all known Wolf-Rayet and O-type stars encompassed in area of $\sim$ 15 sq degrees centred on the Cygnus region. We report on the detection of 11 massive stars, including both Wolf-Rayet and O-type systems. The measured flux densities at decimeter wavelengths allowed us to study the radio spectrum of the binary systems and to propose a consistent interpretation in terms of physical processes affecting the wide-band radio emission from these objects. WR 140 was detected at 610 MHz, but not at 325 MHz, very likely because of the strong impact of free–free absorption (FFA). We also report—for the first time—on the detection of a colliding-wind binary system down to 150 MHz, pertaining to the system of WR 146, making use of complementary information extracted from the Tata Institute of Fundamental Research GMRT Sky Survey. Its spectral energy distribution clearly shows the turnover at a frequency of about 600 MHz, that we interpret to be due to FFA. Finally, we report on the identification of two additional particle-accelerating colliding-wind binaries, namely Cyg OB2 12 and ALS 15108 AB.

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Section: Introductionmentioning

confidence: 99%

Megahertz emission of massive early-type stars in the Cygnus region

Benaglia

Becker

Ishwara‐Chandra

et al. 2020

Publ. Astron. Soc. Aust.

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“…Continued radio observations and future work on the correlation between the mid-IR dust morphology and radio light curve would therefore provide valuable insight on the wind collision region and the properties of the stellar winds. Additionally, future observations utilizing very long baseline interferometry may be able to reveal the morphology of nonthermal emission (e.g., Dougherty et al 2005;Sanchez-Bermudez et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Resolving Decades of Periodic Spirals from the Wolf–Rayet Dust Factory WR 112

Lau¹,

Hankins

Han

et al. 2020

ApJ

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WR112 is a dust-forming carbon-rich Wolf-Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR112 therefore provides an opportunity to understand the dust formation process in colliding-wind WC binaries. In this work, we present a multi-epoch analysis of the circumstellar dust around WR112 using seven high spatial resolution (FWHM ∼0 3-0 4) N-band (λ∼12 μm) imaging observations spanning almost 20 yr and that includes images obtained from Subaru/COMICS in 2019 October. In contrast to previous interpretations of a face-on spiral morphology, we observe clear evidence of proper motion of the circumstellar dust around WR112 consistent with a nearly edge-on spiral with a θ s =55°half-opening angle and a ∼20 yr period. The revised near edge-on geometry of WR112 reconciles previous observations of highly variable nonthermal radio emission that was inconsistent with a face-on geometry. We estimate a revised distance to WR112 of =-+ d 3.39 0.84 0.89 kpc based on the observed dust expansion rate and a spectroscopically derived WC terminal wind velocity of =  ¥ v 1230 260 km s −1. With the newly derived WR112 parameters, we fit optically thin dust spectral energy distribution models and determine a dust production rate of  =-+-M 2.7 10 d 1.3 1.0 6 M e yr −1 , which demonstrates that WR112 is one of the most prolific dust-making WC systems known.

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“…Additionally, future observations utilizing very long baseline interferometry may be able to reveal the morphology of non-thermal emission (e.g. Dougherty et al 2005;Sanchez-Bermudez et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Resolving Decades of Periodic Spirals from the Wolf-Rayet Dust Factory WR 112

Lau¹,

Hankins²,

Han³

et al. 2020

Preprint

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WR 112 is a dust-forming carbon-rich Wolf-Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR 112 therefore provides an opportunity to understand the dust formation process in colliding-wind WC binaries. In this work, we present a multi-epoch analysis of the circumstellar dust around WR 112 using seven high spatial resolution (FWHM ∼ 0.3 − 0.4 ) N-band (λ ∼ 12 µm) imaging observations spanning almost 20 years and includes newly obtained images from Subaru/COMICS in Oct 2019. In contrast to previous interpretations of a face-on spiral morphology, we observe clear evidence of proper motion of the circumstellar dust around WR 112 consistent with a nearly edge-on spiral with a θ s = 55 • half-opening angle and a ∼ 20-yr period. The revised near edge-on geometry of WR 112 reconciles previous observations of highly variable non-thermal radio emission that was inconsistent with a faceon geometry. We estimate a revised distance to WR 112 of d = 3.39 +0.89 −0.84 kpc based on the observed dust expansion rate and a spectroscopically derived WC terminal wind velocity of v ∞ = 1230 ± 260 km s −1 With the newly derived WR 112 parameters we fit optically-thin dust spectral energy distribution models and determine a dust production rate of Ṁd = 2.7 +1.0 −1.3 × 10 −6 M yr −1 , which demonstrates that WR 112 is one of the most prolific dust-making WC systems known.

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A VLBI study of the wind-wind collision region in the massive multiple HD 167971

Cited by 13 publications

References 29 publications

Megahertz emission of massive early-type stars in the Cygnus region

Megahertz emission of massive early-type stars in the Cygnus region

Resolving Decades of Periodic Spirals from the Wolf–Rayet Dust Factory WR 112

Resolving Decades of Periodic Spirals from the Wolf-Rayet Dust Factory WR 112

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