High resolution<i>H</i>band imaging polarimetry of IRC +10216

Murakawa, K.; Shimada, Hiroshi; Oya, Shin; Yates, J. A.; Ueta, Toshiya; Meixner, M.

doi:10.1051/0004-6361:20042477

Cited by 29 publications

(52 citation statements)

References 28 publications

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“…Since there is no bright single star near Frosty Leo which would be appropriate for AO wavefront sensing (m R brighter than 16 mag and a separation less than 20 ) and the target is sufficiently bright at λ ∼ 0.8 μm for wavefront sensing (m R = 9.7), on-source AO wavefront sensing was applied. We followed the observation sequence described in a previous paper (Murakawa et al 2005). In order to measure the linear polarization, we obtained four sets of images with half-wave plate (HWP) orientations of 0…”

Section: Hk-band Ao Imaging Polarimetrymentioning

confidence: 99%

“…We reduced the recorded data as described in our previous papers (Murakawa et al 2004(Murakawa et al , 2005. After preprocessing (subtraction of the dark frame and flat fielding), we obtained images of the Stokes IQU parameters, the degree of polarization (P), the polarization position angle (θ), as well as their error images.…”

Section: Hk-band Ao Imaging Polarimetrymentioning

confidence: 99%

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Near-IR bispectrum speckle interferometry, AO imaging polarimetry, and radiative transfer modeling of the proto-planetary nebula Frosty Leonis

Murakawa¹,

Ohnaka²,

Driebe³

et al. 2008

A&A

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Aims. We combined bispectrum speckle interferometry, adaptive optics (AO) imaging polarimetry, and radiative transfer modeling of polarized light to derive various physical properties of the proto-planetary nebula Frosty Leo. Methods. We performed bispectrum K -band speckle interferometry and H-and K-band imaging polarimetry of Frosty Leo using the ESO 3.6 m telescope and the AO-equipped CIAO instrument of the 8 m Subaru telescope, respectively. Two-dimensional radiative transfer modeling was carried out in order to obtain a quantitative interpretation of our observations. Results. Our diffraction-limited speckle image shows distinct hourglass-shaped, point-symmetric bipolar lobes, an equatorial dust lane, and complex clumpy structures in the lobes. Our polarimetric data display a centro-symmetric polarization vector pattern with P ∼ 30-50% in the bipolar lobes and a polarization disk between them. The polarization images also reveal an elongated region with low polarization along a position angle of −45• . The observations suggest that this region has a low dust density and was carved out by a jet-like outflow. Our radiative transfer modeling can simultaneously explain the observed spectral energy distribution, the intensity distribution of the hourglass-shaped lobes, and our polarization images if we use two grain species with sizes of 0.005 ≤ a ≤ 2.0 μm at latitudes between −2• and +2• , and 0.005 ≤ a ≤ 0.7 μm in the bipolar lobes. Assuming a distance of 3 kpc, an expansion velocity of 25 km s −1 , and a gas-to-dust mass ratio of 160, we derive a dust mass of the disk of 2.85 × 10 −3 M , a gas mass-loss rate of 8.97 × 10 −3 M yr −1 , and a total envelope mass of 4.23 M .

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Section: Hk-band Ao Imaging Polarimetrymentioning

confidence: 99%

Section: Hk-band Ao Imaging Polarimetrymentioning

confidence: 99%

Near-IR bispectrum speckle interferometry, AO imaging polarimetry, and radiative transfer modeling of the proto-planetary nebula Frosty Leonis

Murakawa¹,

Ohnaka²,

Driebe³

et al. 2008

A&A

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“…Although it is inconclusive whether these flows are parts of a general equatorial rotation (e.g., Kastner et al 2001), it is not inconceivable that there are multiple outflows on the equatorial plane. For example, Murakawa et al (2005) have suggested that some of the multiple lobes seen in the shell of an AGB star, IRC +10 216 (considered less evolved than the Egg on a similar evolutionary path), are actually due to scattered starlight that has leaked out of the central dust torus through fissures in the torus.…”

Section: Outflow Structure In the Nebulamentioning

confidence: 99%

Proper‐Motion Measurements of the Cygnus Egg Nebula

Ueta

Murakawa

Meixner

2006

ApJ

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We present the results of proper-motion measurements of the dust shell structure in the Egg Nebula (AFGL 2688, CRL 2688, V1610 Cyg), based on the archived two-epoch data at 2 m taken with the Hubble Space Telescope. We measured the amount of motion of local structures in the nebula by determining their relative shifts over an interval of 5.5 yr. The dynamical age of the nebula is found to be roughly 350 yr based on the overall Hubble-law-esque motion of the nebula. By adopting the deprojected velocity of 45 km s À1 at the tips of the bipolar lobes, our propermotion measurements indicate that the distance to the Egg Nebula is about 420 pc and that the lobes are inclined at 7N7 with respect to the plane of the sky. The refined distance estimate yields a luminosity of the central star of 3:3 ; 10 3 L , a total shell mass of 1.2 M , and a mass-loss rate (the upper limit) of 3:6 ; 10 À3 M yr À1 . Assuming a 0.6 M central post-AGB stellar mass, the initial mass of the Egg is 1.8 M . Upon analysis, we also discovered that (1) the central star of the Egg Nebula has a proper motion of its own at a rate of 17 mas yr À1 , (2) the tips of the lobes increased their velocity due to shock acceleration, and (3) the apparent bipolar lobes consist of multiple outflows at distinct inclination angles projected onto each other.

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“…The availability of polarimeters on the HST telescope and at large aperture ground based telescopes equipped with Adaptive Optics (AO) have recently allowed probing the asymmetry of dusty shells at sub-arcsec angular scale for sources at different evolutionary stage (see e.g. Gledhill & Takami 2001;Gledhill 2005;Ueta, Murakawa & Meixner 2007;Murakawa et al 2005Murakawa et al , 2008.…”

Section: Fossil Dust Shells In Scattered Lightmentioning

confidence: 99%