Near infrared coronagraph images of IRC +10216

Murakawa, K.; Tamura, Motohide; Shimada, Hiroshi; Itoh, Yoichi; Hayashi, Soichi; Oasa, Yumiko; Kaifu, Norio; Yates, J. A.; Gledhill, T. M.; Richards, A. M. S.; Hough, J. H.; Kosugi, George; Usuda, Tomonori

doi:10.1051/0004-6361:20021421

Cited by 7 publications

(9 citation statements)

References 11 publications

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“…Both of our models show that the axisymmetric structure is caused by equatorial mass loss and is not a bi-polar outflow as previously described (e.g. Murakawa et al 2002).…”

Section: Previous Observationssupporting

confidence: 85%

“…IRC+10216 has been observed from very large (100s of arcseconds) to very small (milli-acrseconds) spatial scales, mostly at infrared wavelengths. Many of these studies have found evidence for axi-symmetric structure Mauron & Huggins (2000); Skinner et al (1998); Murakawa et al (2002); Leão et al (2006) and have only indirectly inferred the possible existence of an equatorial density enhancement of gas and dust in the inner regions of the wind. However, so far with direct imaging, conclusive evidence for such a density enhancement has been elusive because observations were either done at infrared wavelengths, using regular intensity imaging, or with coronographs that obscure the inner regions of the circumstellar shell.…”

Section: Previous Observationsmentioning

confidence: 99%

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Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Jeffers

Min

Waters

et al. 2014

A&A

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Aims. Understanding the formation of planetary nebulae remains elusive because in the preceding asymptotic giant branch (AGB) phase these stars are heavily enshrouded in an optically thick dusty envelope. Methods. To further understand the morphology of the circumstellar environments of AGB stars we observe the closest carbon-rich AGB star IRC+10216 in scattered light. Results. When imaged in scattered light at optical wavelengths, IRC+10216 surprisingly shows a narrow equatorial density enhancement, in contrast to the large-scale spherical rings that have been imaged much further out. We use radiative transfer models to interpret this structure in terms of two models: firstly, an equatorial density enhancement, commonly observed in the more evolved post-AGB stars, and secondly, in terms of a dust rings model, where a local enhancement of mass-loss creates a spiral ring as the star rotates. Conclusions. We conclude that both models can be used to reproduce the dark lane in the scattered light images, which is caused by an equatorially density enhancement formed by dense dust rather than a bipolar outflow as previously thought. We are unable to place constraints on the formation of the equatorial density enhancement by a binary system.

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“…Both of our models show that the axisymmetric structure is caused by equatorial mass loss and is not a bi-polar outflow as previously described (e.g. Murakawa et al 2002).…”

Section: Previous Observationssupporting

confidence: 85%

Section: Previous Observationsmentioning

confidence: 99%

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Jeffers

Min

Waters

et al. 2014

A&A

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“…2 radius from the NE to the W. These features are also seen in previous images with middle-size FOVs (e.g. Kastner & Weintraub 1994;Skinner et al 1998;Murakawa et al 2002). The NE and S lobes have polarizations of 15−20%, and the NW lobe has 15−24%.…”

Section: Polarimetric Imagesupporting

confidence: 73%

High resolutionHband imaging polarimetry of IRC +10216

Murakawa¹,

Shimada²,

Oya³

et al. 2005

A&A

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Abstract. We have carried out an H band imaging polarimetry of an evolved AGB star IRC +10216 using CIAO and AO on the Subaru telescope. Our polarimetric images show NE-S bipolar lobes, a NW lobe, a discrete NW arc with ∼4. 2 radius and two new features of a fan-like shape at the SE and of an elliptic shape at the NW with small polarizations (P < 4%) near the intensity peak. The polarization vectors in the NE-S lobes and the NW lobe have a centrosymmetric pattern centered at the position of the illumination source (the central star). The illumination source is located at (+0. 25, −0. 065) from the intensity peak between the SE fan and the NW ellipse. The polarization vectors between these two features are aligned along a line across them. We interpret that the appearance of the SE fan and the NW ellipse reflects a sudden increase of the mass loss rate that likely initiated the formation of an edge-on dust torus. This sudden mass loss increase probably began about a half century ago.

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“…The wavelengths in figures 7a and 7b are J and H , respectively, but such a difference does not change this discussion. This kind of advantage is also seen in results of the circumstellar envelope around IRC + 10 216 [Murakawa et al (2002) for coronagraphic images and Murakawa et al are in prepreparation of a paper for a non-coronagraphic image].…”

Section: Coronagraph Imaging Of a Red Supergiant Vy Cmamentioning

confidence: 70%

CIAO: Coronagraphic Imager with Adaptive Optics on the Subaru Telescope

Murakawa

Shimada

Tamura

et al. 2004

Publications of the Astronomical Society of Japan

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We present the performances of direct imaging with adaptive optics, coronagraph, and imaging-polarimetry of the coronagraphic imager with adaptive optics (CIAO) for the Subaru telescope. Combining with the 36-element adaptive optics system, CIAO produces high-resolution images with a full width at half maximum of 0. 072 and a Strehl ratio of 0.28 in the K band. CIAO has a Lyot's-type stellar coronagraph facility with 0. 1 to 4. 0 diameter masks. The limiting magnitude difference of a companion star at the K band is 11.0 mag at 5 σ , 10 minutes integration time, and 2. 0 separation from the central star. CIAO also has a polarimetry facility with a rotatable half-wave plate and a wire grid polarizer. Currently, the measurement of J H K band linear polarization is available.

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Near infrared coronagraph images of IRC +10216

Cited by 7 publications

References 11 publications

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

High resolutionHband imaging polarimetry of IRC +10216

CIAO: Coronagraphic Imager with Adaptive Optics on the Subaru Telescope

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