Multiple Collimated Outflows in the Proto–Planetary Nebula GL 618

Trammell, Susan R.; Goodrich, Robert W.

doi:10.1086/342943

Cited by 36 publications

(49 citation statements)

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“…Roughly the same value of t t ($400 yr) is obtained independently from an expanding torus model of the dense inner regions (r t $ 0:75 00 , v t $ 5Y12 km s À1 ) observed in HC 3 N ( Pardo et al 2004). The angle j is for the single jet b in the nomenclature of Trammell & Goodrich (2002), and v j is the H 2 velocity for same jet (Cox et al 2003).…”

Section: A2 Notes On Individual Sourcessupporting

confidence: 52%

Jets and Tori in Proto–Planetary Nebulae

Huggins¹

2007

ApJ

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We investigate the time sequence for the appearance of jets and molecular tori in the transition of stars from the asymptotic giant branch to the planetary nebula phase. Jets and tori are prominent features of this evolution, but their origins are uncertain. Using optical and millimeter line kinematics, we determine the ejection history in a sample of well-observed cases. We find that jets and tori develop nearly simultaneously. We also find evidence that jets typically appear slightly later than tori, with a lag time of a few hundred years. These characteristics provide strong evidence that jets and tori are physically related, and they set new constraints on theories of jet formation. The ejection of a discrete torus followed by jets on a short timescale favors the class of models in which a companion interacts with the central star. Models with long timescales, or with jets followed by a torus, are ruled out. Subject headingg s: circumstellar matter -planetary nebulae: general -stars: AGB and post-AGBstars: mass loss

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Section: A2 Notes On Individual Sourcessupporting

confidence: 52%

Jets and Tori in Proto–Planetary Nebulae

Huggins¹

2007

ApJ

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“…CRL 618 is located at a distance of 900 pc (Goodrich 1991). It shows several narrow lobes at different orientations in Hubble Space Telescope (HST) images (Trammell & Goodrich 2002) and belongs to the "multipolar" morphological classification (Sahai et al 2007), perhaps resulting from multiple ejections at different orientations. The general structures of the different lobes are similar and we focus only on the northwestern (W1) lobe, which seems to be better separated from other lobes.…”

Section: Introductionmentioning

confidence: 99%

Collimated Fast Wind in the Preplanetary Nebula CRL 618

Lee

Hsu

Sahai

2009

ApJ

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Collimated fast winds (CFWs) have been proposed to operate during the post asymptotic giant branch (post-AGB) evolutionary phase (and even earlier during the late AGB phase), responsible for the shaping of preplanetary nebulae (PPNs) and young planetary nebulae (PNs). This paper is a follow-up to our previous study of CFW models for the well-studied PPN CRL 618. Previously, we compared our CFW models with optical observations of CRL 618 in atomic and ionic lines and found that a CFW with a small opening angle can readily reproduce the highly collimated shape of the northwestern (W1) lobe of CRL 618 and the bowlike structure seen at its tip. In this paper, we compare our CFW models with recent observations of CRL 618 in CO J = 2-1, J = 6-5, and H 2 1-0 S(1). In our models, limb-brightened shell structures are seen in CO and H 2 at low velocity (LV) arising from the shocked AGB wind in the shell, and can be identified as the LV components in the observations. However, the shell structure in CO J = 2-1 is significantly less extended than that seen in the observations. None of our models can properly reproduce the observed high-velocity (HV) molecular emission near the source along the body of the lobe. In order to reproduce the HV molecular emission in CRL 618, the CFW is required to have a different structure. One possible CFW structure is the cylindrical jet, with the fast wind material confined to a small cross section and collimated to the same direction along the outflow axis.

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“…In the bright East lobe the slit position 1 slices diffuse emission to the south of the bright compact nebulosity (see Fig. 2) and several bow-shaped, ripple-like features (Trammell & Goodrich 2002). Slit 2 crosses the East lobe, sampling several bow-shaped structures at the tips of the outflows.…”

Section: Observations and Reductionmentioning

confidence: 97%

“…SSG02 suggested that region A is the outermost parts of the HII region surrounding the star. In addition to the Hα emission detected in the inner regions and the shocked lobes, a faint halo of emission is present in the Hα HST image (Trammell & Goodrich 2002), likely to be Hα emission scattered by dust present in the outer regions of CRL 618.…”

Section: Introductionmentioning

confidence: 96%

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STIS optical spectroscopy of the lobes of CRL 618

Riera

Raga

Velázquez

et al. 2011

A&A

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Context. Many proto-planetary nebulae show collimated structures sometimes showing multiple outflows. Aims. We present the results of new optical spectroscopic observations (both medium (with a dispersion of 0.56 Å pixel −1 ) and low (2.73 and 4.92 Å pixel −1 for the G430L and G750L gratings) spectral resolution) of the lobes of the proto-planetary nebula CRL 618 obtained with the Space Telescope Imaging Spectrograph on board of the Hubble Space Telescope. Methods. We analyse the density structure and the excitation conditions of the lobes of CRL 618. The spectra obtained at medium spectral resolution (∼50 km s −1 ) allow us to quote the fraction of unscattered (intrinsic) Hα emission. We have also obtained dereddened emission line ratios of several features from the low spectral resolution spectra. Results. We find that most of the analysed line ratios are reproduced by planar shocks moving through a dense medium (with preshock densities ∼10 4 cm −3 ) with shock velocities from 30 to 40 km s −1 (except the [O III]/Hβ line ratios which require shock velocities of 80 to 90 km s −1 ). We find that the [S II]-weighted ionization fraction ranges from 0.015 to 0.06. The total densities derived from the electron density and the ionization fraction are ∼10 5 to 10 6 cm −3 . Conclusions. We conclude that the spectra of the lobes of CRL 618 can be margially reproduced by steady plane-parallel shock models for shock velocities which are significantly lower than the velocities at which the jet moves outwards (∼200 km s −1 ). These results are consistent with the predictions of a jet with a variable ejection velocity. The mirror-symmetry, the luminosity asymmetry between both lobes and the ejection velocity variability suggest that its central source may host a binary system.

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Multiple Collimated Outflows in the Proto–Planetary Nebula GL 618

Cited by 36 publications

References 46 publications

Jets and Tori in Proto–Planetary Nebulae

Jets and Tori in Proto–Planetary Nebulae

Collimated Fast Wind in the Preplanetary Nebula CRL 618

STIS optical spectroscopy of the lobes of CRL 618

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