The Radio and Infrared Spectrum of Early-type Stars Undergoing Mass Loss

Wright, A. E.; Barlow, M. J.

doi:10.1093/mnras/170.1.41

Cited by 628 publications

(587 citation statements)

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“…These power laws can be interpreted as free-free emission: optically thin for the positive slopes between 2 and 4.5 µm in April 17 and 23, and the negative slope (λ −0.6 ) corresponding to the intermediate regime between optically thin and optically thick free-free emission. This −0.6 slope is the exact theoretical spectral index for the free-free emission from an ionized homogeneous wind flowing out from a star with a spherical expansion and at a constant velocity (Panagia & Felli 1975;Wright & Barlow 1975). This is characteristic of hot stars with strong winds, such as O and WR stars (Cohen et al 1975).…”

Section: Data Fittingmentioning

confidence: 93%

SS 433: a phenomenon imitating a Wolf-Rayet star

Fuchs

Miramond

Ábrahám

2006

A&A

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We present mid-infrared (2-12 µm) spectra of the microquasar SS 433 obtained with the Infrared Space Observatory (spectroscopic mode of ISOPHOT and ISOCAM). We compare them to the spectra of four Wolf-Rayet stars: WR 78, WR 134, WR 136, and WR 147 in the same wavelength range. The mid-infrared spectrum of SS 433 mainly shows H i and He i emission lines and is very similar to the spectrum of WR 147, a WN8(h)+B0.5V binary. The 2-12 µm continuum emission of SS 433 corresponds to optically thin and partially optically thick free-free emission, from which we calculate a mass loss rate of 2−3 × 10 −4 M yr −1 if the wind is homogeneous and a third of these values if it is clumped. This is consistent with a strong stellar wind from a WN star. However, following recent studies concluding that the mass donor star of SS 433 is not a Wolf-Rayet star, we propose that this strong wind out flows from a geometrically thick envelope of material that surrounds the compact object like a stellar atmosphere, imitating the Wolf-Rayet phenomenon. This wind could also wrap the mass donor star, and at larger distances (∼40 AU), it might form a dust envelope from which the thermal emission, detected with ISOPHOT at 25 µm and 60 µm, would originate. This wind also probably feeds the material that is ejected in the orbital plane of the binary system and that forms the equatorial outflow detected in radio at distances > 100 AU.

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Section: Data Fittingmentioning

confidence: 93%

SS 433: a phenomenon imitating a Wolf-Rayet star

Fuchs

Miramond

Ábrahám

2006

A&A

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“…Although such spectral indices may also arise from ionized jets, the flux density in IRAS 16333−4807 is too high to be explained in this way with reasonable mass-loss rates. As in the case of IRAS 17347−3139 (de Gregorio-Monsalvo et al 2004), a mass loss rate ofṀ ≃ 10 −4 (D/kpc) 3/2 M⊙ yr −1 , where D is the distance to the source, would be required for a spherical ionized wind to explain the observed radio continuum emission (Wright & Barlow 1975;Panagia & Felli 1975). Even assuming a collimated wind, and following the formulation by Reynolds (1986), the required mass loss rate is as high as ≃ 3 × 10 −6 (D/kpc) 3/2 M⊙ yr −1 , and this is a lower limit, assuming that the wind is fully ionized.…”

Section: The Nature Of Iras 16333−4807 As a Planetary Nebulamentioning

confidence: 98%

H2O maser emission associated with the planetary nebula IRAS 16333−4807

Uscanga

Gómez

Miranda

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present simultaneous observations of H 2 O maser emission and radio continuum at 1.3 cm carried out with the Australia Telescope Compact Array towards two sources, IRAS 16333−4807 and IRAS 12405−6219, catalogued as planetary nebula (PN) candidates, and where single-dish detections of H 2 O masers have been previously reported. Our goal was to unambiguously confirm the spatial association of the H 2 O masers with these two PN candidates. We detected and mapped H 2 O maser emission in both fields, but only in IRAS 16333−4807 the maser emission is spatially associated with the radio continuum emission. The properties of IRAS 16333−4807 provide strong support for the PN nature of the object, hereby confirming it as the fifth known case of a H 2 O maser-emitting PN. This source is bipolar, like the other four known H 2 O maser-emitting PNe, indicating that these sources might pertain to a usual, but short phase in the evolution of bipolar PNe. In IRAS 12405−6219, the H 2 O maser and radio continuum emission are not associated with each other and, in addition, the available data indicate that this source is an H ii region rather than a PN.

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“…For emission from a spherically symmetric wind with an arbitrary µ a -n r density profile the expected spectral dependence of free-free emission is (Wright & Barlow 1975). n turn is the frequency where the wind becomes partially optically thick, and is determined by the radius of the inner boundary of the ionized envelope.…”

Section: Estimating the Free-free Emission Spectrummentioning

confidence: 99%

A Vla Survey for Faint Compact Radio Sources in the Orion Nebula Cluster

Sheehan

Eisner

Mann

et al. 2016

ApJ

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We present Karl G. Jansky Very Large Array 1.3, 3.6, and 6 cm continuum maps of compact radio sources in the Orion Nebular Cluster (ONC). We mosaicked 34 arcmin 2 at 1.3 cm, 70 arcmin 2 at 3.6 cm and 109 arcmin 2 at 6 cm, containing 778 near-infrared detected young stellar objects and 190 Hubble Space Telescope-identified proplyds (with significant overlap between those characterizations). We detected radio emission from 175 compact radio sources in the ONC, including 26 sources that were detected for the first time at these wavelengths. For each detected source, we fitted a simple free-free and dust emission model to characterize the radio emission. We extrapolate the free-free emission spectrum model for each source to ALMA bands to illustrate how these measurements could be used to correctly measure protoplanetary disk dust masses from submillimeter flux measurements. Finally, we compare the fluxes measured in this survey with previously measured fluxes for our targets, as well as four separate epochs of 1.3 cm data, to search for and quantify the variability of our sources.

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The Radio and Infrared Spectrum of Early-type Stars Undergoing Mass Loss

Cited by 628 publications

References 0 publications

SS 433: a phenomenon imitating a Wolf-Rayet star

SS 433: a phenomenon imitating a Wolf-Rayet star

H2O maser emission associated with the planetary nebula IRAS 16333−4807

A Vla Survey for Faint Compact Radio Sources in the Orion Nebula Cluster

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