Spectroscopy of six Wolf-Rayet stars - The latest and faintest

Massey, Philip; Conti, Peter S.

doi:10.1086/131190

Cited by 29 publications

(35 citation statements)

References 12 publications

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“…The latter includes the data of Massey & Conti (1983) (V band), Cohen & Vogel (1978) (V band), Allen et al (1977) (JHKL bands), Williams et al (1987) Figures 3 and 4 also show the 2.13 µm visibility and SED of those 5 models, which proved to be best suited for the dust shell of WR 118 in the framework of spherical symmetry. Their parameters are given in Tables 1 and 2.…”

Section: Results Of Calculations and Discussionmentioning

confidence: 94%

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Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118

Yudin¹,

Balega²,

Blöcker³

et al. 2001

A&A

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Abstract. WR 118 is a highly evolved Wolf-Rayet star of the WC10 subtype surrounded by a permanent dust shell absorbing and re-emitting in the infrared a considerable fraction of the stellar luminosity. We present the first diffraction-limited 2.13 µm speckle interferometric observations of WR 118 with 73 mas resolution. The speckle interferograms were obtained with the 6 m telescope at the Special Astrophysical Observatory. The twodimensional visibility function of the object does not show any significant deviation from circular symmetry. The visibility curve declines towards the diffraction cut-off frequency to ∼0.66 and can be approximated by a linear function. Radiative transfer calculations have been carried out to model the spectral energy distribution, given in the range of 0.5-25 µm, and our 2.13 µm visibility function, assuming spherical symmetry of the dust shell. Both can be fitted with a model containing double-sized grains ("small" and "large") with the radii of a = 0.05 µm and 0.38 µm, and a mass fraction of the large grains greater than 65%. Alternatively, a good match can be obtained with the grain size distribution function n(a) ∼ a −3 , with a ranging between 0.005 µm and 0.6 µm. At the inner boundary of the modelled dust shell (angular diameter Θin = (17±1) mas), the temperature of the smallest grains and the dust shell density are 1750 K ± 100 K and (1 ± 0.2) × 10 −19 g/cm 3 , respectively. The dust formation rate is found to be (1.3 ± 0.5) × 10 −7 M /yr, assuming V wind = 1200 km s −1 .

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Section: Results Of Calculations and Discussionmentioning

confidence: 94%

“…It is classified as WC9-10 ( Allen et al 1977;Massey & Conti 1983). Its very prominent IR excess is attributed to the thermal emission of a warm carbon dust shell.…”

Section: Introductionmentioning

confidence: 99%

Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118

Yudin¹,

Balega²,

Blöcker³

et al. 2001

A&A

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show abstract

“…It is important to note that previous studies have spectroscopically verified the presence of a WC9 star at the center of WR112 (Massey & Conti 1983;Figer et al 1997). Additionally, a binary companion is inferred from .…”

Section: On the Nature Of The Wr112 Nebula: Mass Loss From A Previoumentioning

confidence: 94%

“…Near-IR observations, however, are not sensitive to cooler dust that has propagated further from the central system. The late-type WC+OB binary WR112 (Massey & Conti 1983;van der Hucht 2001) is one of the few dusty WC systems whose nebula has been detected and resolved in the mid-infrared (8-18μm; Marchenko et al 2002. Others known are WR48a (Marchenko & Moffat 2007) and WR140 Williams et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Stagnant Shells in the Vicinity of the Dusty Wolf–Rayet–OB Binary WR 112

Lau

Hankins

Schödel

et al. 2017

ApJL

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We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf-Rayet (WC)-OB binary system WR112 taken by the recently upgraded VLT spectrometer and imager for the midinfrared (VISIR) with the PAH1, Ne II_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments and broken shells. Dust temperatures and masses are derived for each of the identified filamentary structures, which exhibit temperatures ranging from -+ 179 6 8 K at the exterior W2 filament to -+ 355 25 37 K in the central 3″. The total dust mass summed over the features is 2.6±0.4×10−5 M e . A multi-epoch analysis of mid-IR photometry of WR112 over the past ∼20 years reveals no significant variability in the observed dust temperature and mass. The morphology of the mid-IR dust emission from WR112 also exhibits no significant expansion from imaging data taken in 2001, 2007, and 2016, which disputes the current interpretation of the nebula as a high expansion velocity (∼1200 km s −1 ) "pinwheel"-shaped outflow driven by the central WC-OB collidingwind binary. An upper limit of 120 km s −1 is derived for the expansion velocity assuming a distance of 4.15kpc. The upper limit on the average total mass-loss rate from the central 3″ of WR112 is estimated to be. We leave its true nature as an open question, but propose that the WR112 nebula may have formed in the outflow during a previous red or yellow supergiant phase of the central Wolf-Rayet star.

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“…It was discovered by Nassau & Stephenson (1963), who proposed a WR classification based on the strong emission-line spectrum. It was later reclassified as a late nitrogen-type WR (WN type) based on nitrogen emission-line ratios in the optical spectrum (Massey & Conti 1983), then later proposed to be a B [e], O[e], or Ofpe/WN9 star based on its optical-IR spectral properties (van der Hucht 1997). Subsequently, more detailed multi-wavelength investigation by Crowther & Smith (1999;hereafter CS99) showed that although NaSt1 is indeed a hot luminous object with L ∼ 10 5.1 -10 6.1 L⊙, its emission-line spectrum is mostly of nebular origin, not stellar.…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength observations of NaSt1 (WR 122): equatorial mass loss and X-rays from an interacting Wolf–Rayet binary

Mauerhan

Smith

Dyk

et al. 2015

Monthly Notices of the Royal Astronomical Society

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NaSt1 (aka Wolf-Rayet 122) is a peculiar emission-line star embedded in an extended nebula of [N ii] emission with a compact dusty core. This object was characterized by Crowther & Smith (1999) as a Wolf-Rayet (WR) star cloaked in an opaque nebula of CNO-processed material, perhaps analogous to η Car and its Homunculus nebula, albeit with a hotter central source. To discern the morphology of the [N ii] nebula we performed narrowband imaging using the Hubble Space Telescope and Wide-field Camera 3. The images reveal that the nebula has a disk-like geometry tilted ≈12 • from edge-on, composed of a bright central ellipsoid surrounded by a larger clumpy ring. Ground-based spectroscopy reveals radial velocity structure (±10 km s −1 ) near the outer portions of the nebula's major axis, which is likely to be the imprint of outflowing gas. Near-infrared adaptive-optics imaging with Magellan AO has resolved a compact ellipsoid of K s -band emission aligned with the larger [N ii] nebula, which we suspect is the result of scattered He i line emission (λ2.06 µm). Observations with the Chandra X-ray Observatory have revealed an X-ray point source at the core of the nebula that is heavily absorbed at energies < 1 keV and has properties consistent with WR stars and colliding-wind binaries. We suggest that NaSt1 is a WR binary embedded in an equatorial outflow that formed as the result of non-conservative mass transfer. NaSt1 thus appears to be a rare and important example of a stripped-envelope WR forming through binary interaction, caught in the brief Roche-lobe overflow phase.

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Spectroscopy of six Wolf-Rayet stars - The latest and faintest

Cited by 29 publications

References 12 publications

Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118

Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118

Stagnant Shells in the Vicinity of the Dusty Wolf–Rayet–OB Binary WR 112

Multiwavelength observations of NaSt1 (WR 122): equatorial mass loss and X-rays from an interacting Wolf–Rayet binary

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