Imaging of the Egg Nebula (CRL 2688) with WFPC2/<i>HST</i>: A History of AGB/Post‐AGB Giant Branch Mass Loss

Sahai, Raghvendra; Trauger, John T.; Watson, A. M.; Stapelfeldt, K.; Hester, J. J.; Burrows, Christopher J.; Ballister, G. E.; Clarke, J. T.; Crisp, David; Evans, R. W.; Gallagher, John S.; Griffiths, R. E.; Hoessel, John G.; Holtzman, Jon A.; Mould, Jeremy; Scowen, Paul A.; Westphal, James A.

doi:10.1086/305121

Cited by 179 publications

(130 citation statements)

References 30 publications

(1 reference statement)

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“…This structure may also be compared to the HST NICMOS data (Osterbart et al 2000) which clearly shows a bipolar nebula orientated approximately N-S with an extent of ∼2 . This smaller-scale bipolar appears to have "horn"-like features along its edges which are reminiscent of the search-light beams seen in PPNe such as AGFL 2688 (Sahai et al 1998) and the red rectangle (Murakawa et al in preparation, Roddier et al 1995 • . There can be seen bumps at 3.2 for the S and the NE fans, at 4.1 for the NNW and the WNW features and at 4.7 for the NE fan.…”

Section: Discussionmentioning

confidence: 89%

Near infrared coronagraph images of IRC +10216

Murakawa

Tamura

Shimada³

et al. 2002

A&A

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Abstract. We present J, H and K band coronagraph images of the circumstellar envelope around IRC +10216 (CW Leo) obtained with a near infrared camera, CIAO and the 8.2 m Subaru telescope. A circular occulting mask of 2 in diameter was used to block out the light from the bright central object. The images show 2 collimated radial structures to the NNW and WNW, 2 fan-like structures to the S and NE, respectively, and 3 arc-like structures at a radius of 4 to 5 arcsec from the stellar center. We compare this intermediate size-scale structure to that seen on larger and smaller scales and find evidence for a deviation from spherically symmetric outflow beginning ∼150 years ago. Previous near infrared speckle imaging has revealed a complex clumpy structure on a scale of less than 200 mas, and it is likely that at least some of the radial features seen in our images could be due to shadowing by dust clumps close to the star.

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Section: Discussionmentioning

confidence: 89%

Near infrared coronagraph images of IRC +10216

Murakawa

Tamura

Shimada³

et al. 2002

A&A

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“…1b). The bright lobes are surrounded by a fainter halo containing multiple (about Ðve) thin shell structures, reminiscent of those seen in the prototype PPN, CRL 2688 (Egg Nebula) (Sahai et al 1998a(Sahai et al , 1998b). In contrast to CRL 2688, where the shells are nearly spherical, the shells in Roberts 22 appear distorted into shapes that roughly follow the outline of the bright lobes.…”

Section: Optical Morphologymentioning

confidence: 89%

“…The presence of jetlike outÑows has been directly seen in many young PNe and/or PPNe (e.g., He 2-142, K3-66, and BD ]30¡3639 : ST98 ; He 2-104, Corradi & Schwarz 1993 ;MyCn 18, Bryce et al 1997 ;M1-92, Bujarrabal et al 1998 ;NGC 6543, Harrington & Borkowski 1994). Direct evidence of an imprint being carved out by a high-velocity outÑow within a roughly round AGB mass-loss envelope is provided by high-resolution imaging of the prototype PPN, CRL 2688 (Sahai et al 1998a(Sahai et al , 1998b.…”

Section: Discussion : the Structure Of Roberts 22mentioning

confidence: 99%

“…It is instructive to compare and contrast Roberts 22 with CRL 2688 (see, e.g., Sahai et al 1998aSahai et al , 1998b and references therein) and another well-studied PPN, the Red Rectangle (see, e.g., Osterbart, Langer, & Weigelt 1997 and references therein). Each of these three objects is bipolar, with a pair of bright lobes separated by a dark equatorial waist, which completely obscures the central star.…”

Section: Discussion : the Structure Of Roberts 22mentioning

confidence: 99%

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Unraveling the Structure of Aspherical Proto–Planetary Nebulae. I. [ITAL]Hubble Space Telescope[/ITAL] Imaging and Hydroxyl Maser Line Observations of Roberts 22

Sahai

Zijlstra

Bujarrabal

et al. 1999

The Astronomical Journal

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We have obtained high-resolution wide-band, narrowband, and polarimetric images of the bipolar protoÈplanetary nebula Roberts 22 with the Wide Field Planetary Camera 2 on the Hubble Space T elescope. OH maser-line emission has also been observed using the Australia Telescope Compact Array. The wide-band images at 0.6 km show bright bipolar lobes shaped like a butterÑyÏs "" wings,ÏÏ separated by a dark equatorial "" body ÏÏ of dense dust that completely obscures the central star. The material within each lobe appears to be organized into an amazingly complex pattern of a very large number of intersecting loops and Ðlaments. The bright lobes are surrounded by a fainter halo whose inner region contains multiple thin shell structures, reminiscent of those seen in the prototype protoÈplanetary nebula, CRL 2688 (Egg Nebula). The halo can be traced to a distance of about 25A from the nebular center. The radial surface brightness of the halo is inconsistent with that expected for time-invariant mass loss at a constant expansion velocity. A simple model of the radial scattered light distribution supports the hypothesis that the bright lobes are cavities with thin dense walls that are optically thick in scattered (\0A .5), light. The amount of mass in the cavity walls is quite large (0.3 and the dynamical timescale for M _ ) their formation is short yr). The bright lobes show high fractional polarization (40%È50%) and a ([440 centrosymmetric polarization pattern, typical of a singly scattering reÑection nebula. In contrast, the polarization in the dark equatorial region is small, and the polarization vectors do not show a simple orientation pattern. The polarization data have been compared with published models to set rough constraints on the dust albedo and scattering phase function and the nebular optical depths. The OH maserline emission at 1665 and 1667 MHz is found to be concentrated in the dark equatorial region ; the kinematics of the OH features indicates that they arise in low-latitude outÑows. The nebular morphology in Roberts 22 is characterized by a high degree of point symmetry, which may result from the interaction of collimated bipolar outÑows with the progenitor AGB envelope.

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“…The many delicate details of the pre-planetary nebula ("pPN") CRL2688 were revealed in HST images by Sahai et al (1998) and Weintraub et al (2000), including two bright N-S lobes and a surrounding system of arc-like rings. We obtained additional HST images in four broadband filters at 0.6, 0.8, 1.1, and 1.6 µm in order to study the color distribution of scattered stellar light throughout the nebula (Fig.…”

mentioning

confidence: 99%

Radiative transfer model of the dust structures of CRL 2688

Vinković¹,

Balick²

2011

Proc. IAU

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Abstract. New Hubble images of the reflection nebula CRL 2688 from 0.6 to 1.6µm reveal significant variations of color and opacity in the distribution of scattered starlight. We have constructed a detailed radiation-transfer model consisting principally of an optically thick equatorial disk-like structure; bipolar lobes with density enhancements along the polar axis and at the base of lobes; an optically thin extended envelope containing spherical density-enhanced shells to mimic the outer rings of CRL 2688; and a pair of near-stellar caps that collimate and redden the dispersing starlight near its source. Our model nicely reproduces all of the basic features detected in the HST images, including the famous searchlights and arcs, as well as the measured spectral energy distribution ("SED") of CRL 2688. Assuming a distance of 420 pc we estimate the light originates in a giant star with a temperature T ∼ 7000 K and a luminosity L = 5500 ± 1100 L . Keywords. planetary nebulae: general, planetary nebulae: individual (CRL 2688), circumstellar matter, reflection nebulae, radiative transferThe many delicate details of the pre-planetary nebula ("pPN") CRL2688 were revealed in HST images by Sahai et al. (1998) and Weintraub et al. (2000), including two bright N-S lobes and a surrounding system of arc-like rings. We obtained additional HST images in four broadband filters at 0.6, 0.8, 1.1, and 1.6 µm in order to study the color distribution of scattered stellar light throughout the nebula (Fig. 1). In this paper we present a model of radiation transfer that accounts very nicely for the observed distribution of reflected light, its color distribution, and the overall spectral energy distribution of CRL 2688.CRL 2688 is illuminated solely by direct and multiply-scattered light from a carbon and nitrogen-rich supergiant of apparent spectral type F5 Ia with T eff = 6500 K (Klochkova et al. 2000;Cohen & Kuhi 1977;Crampton et al. 1975). Ueta et al. (2006) found that the lobes are inclined out of the sky by 7.7• , a distance of 420 pc, a stellar luminosity of 3160 L from proper-motion measurements. We built an initial geometric model using these data and the geometric distribution of scattering and absorbing dust shown on the left side of Fig. 2.We used the code LELUYA (www.leluya.org) that solves the integral equation of the formal solution of radiative transfer including dust scattering, absorption and thermal emission in two spatial dimensions. It uses a highly unstructured triangular self-adaptive grid. The geometry of the dust distribution, the attributes of the dust particles (size, scattering parameters, etc.), and the radiation temperature and luminosity were varied until the model results provided a good fit to the observed images and the spectral energy distribution ("SED") of CRL2688. We find a bolometric flux = 1.0 ± 0.2 × 10 −9 W/m 2 (luminosity = 5500 ± 1100 L ), an inclination angle = 15• , a dust condensation radius = 46.4 R * , and a stellar radius R * = 51 ± 5 R . The predicted color distribution and fits 520 a...

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Imaging of the Egg Nebula (CRL 2688) with WFPC2/HST: A History of AGB/Post‐AGB Giant Branch Mass Loss

Cited by 179 publications

References 30 publications

Near infrared coronagraph images of IRC +10216

Near infrared coronagraph images of IRC +10216

Unraveling the Structure of Aspherical Proto–Planetary Nebulae. I. [ITAL]Hubble Space Telescope[/ITAL] Imaging and Hydroxyl Maser Line Observations of Roberts 22

Radiative transfer model of the dust structures of CRL 2688

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