Radio observations of compact planetary nebulae

Kwok, S.; Purton, C. R.; Keenan, D. W.

doi:10.1086/159367

Cited by 28 publications

(19 citation statements)

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“…The deconvolved images of SwSt 1 (Fig. 10) reveal a broken ring of diameter , elongated in the east–west direction, in agreement with the radio images of Kwok, Purton & Keenan (1981) and Aaquist & Kwok (1990), but smaller than the 5 arcsec quoted by Perek & Kohoutek (1967). Although the images are of poor quality, this structure could be a ring whose plane is at about 30° from the line of sight.…”

Section: Hst Imagessupporting

confidence: 85%

SwSt 1: an O-rich planetary nebula around a C-rich central star

Marco

Crowther

Barlow

et al. 2001

Monthly Notices of the Royal Astronomical Society

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The hydrogen-deficient carbon-rich [WCL] type central star HD167362 and its oxygen-rich planetary nebula (PN) SwSt~1 are investigated. The nebular chemistry might indicate a recent origin for the carbon-rich stellar spectrum. Its stellar and nebular properties might therefore provide further understanding of the origin of the [WCL] central star class. The UV-IR stellar spectra are modelled with state of the codes and show ~40kK central star with a wind and a C/O~3, indicative of efficient third dredge-up. The synthetic stellar flux distribution is used to model the high density, compact PN, which has a solar C/O ratio, is still enshrouded by 1200K and 230K dust shells and, reported here for the first time, in molecular hydrogen. Although it appears that the change in C/O ratio has been recent, the published spectroscopy since 1895 has been re-examined and no clear spectral change is seen. If an event occurred that has turned it into a hydrogen-deficient central star, it did not happen in the last 100 years.Comment: 31 pages, 19 figures (some are gif files), MNRAS in pres

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Section: Hst Imagessupporting

confidence: 85%

SwSt 1: an O-rich planetary nebula around a C-rich central star

Marco

Crowther

Barlow

et al. 2001

Monthly Notices of the Royal Astronomical Society

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“…The mean emission measure is in cm −6 pc. Young PNe should have emission measures of the order of 10 6 −10 8 cm −6 pc (Terzian & Dickey 1973;Kwok et al 1981) and, as reported in Table 2, our sample, in general, appears to have a more diluted nebula.…”

Section: Emission Measuresupporting

confidence: 60%

A search for very young Planetary Nebulae

Umana

Cerrigone

Trigilio

et al. 2004

A&A

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Abstract. Despite numerous efforts, the transition from Asymptotic Giant Branch (AGB) stars to Planetary Nebulae (PN) is a poorly understood phase of stellar evolution. We have therefore carried out interferometric (VLA) radio observations of a sample of hot post-AGB stars, selected on the basis of their optical and infrared properties. Ten sources out of the 16 observed were detected. This indicates that most of our targets are surrounded by a nebula where the ionization has already started. This definitively determines the evolutionary status of the selected sources and provides us with a unique sample of very young Planetary Nebulae (yPNe). A comparison with another sample of yPNe confirms our working hypothesis that our targets are indeed very young, probably just in the transition toward PN. Finding transition objects is extremely important as they can provide unique clues for a better understanding of this important phase of stellar evolution.

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“…Analysis of the radio spectrum of a PN can reveal model‐dependent information regarding its physical properties (e.g. Wright & Barlow 1975; Terzian 1978; Kwok, Purton & Keenan 1981; Taylor, Pottasch & Zhang 1987; Calabretta 1991; Aaquist & Kwok 1991). In the case of MyCn 18, the obvious density variations between the core and the lobes suggest that the spectral behaviour of these two regions should be studied separately.…”

Section: Discussionmentioning

confidence: 99%

A radio continuum study of the ‘Engraved Hourglass’ nebula, MyCn 18

Bains¹,

Bryce²,

Calabretta³

et al. 2002

Monthly Notices of the Royal Astronomical Society

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We present the first radio continuum images of the 'Engraved Hourglass' planetary nebula (PN) MyCn 18 from multifrequency observations with the Australia Telescope. The radio emission is strongly core-dominated at all frequencies investigated. At the three higher observing frequencies, the radio emission is seen to trace the optically-visible hourglass lobes. In the highest resolution image, the position of peak radio brightness is found in a region which we show to be geometrically off-centre in the same sense as the offset of the 'central' star seen in the WFPC2 HST images of Sahai et al. The brightness temperatures measured are surprisingly low and this is interpreted as an effect of beam dilution and nebular clumpiness. We have attempted to separate the contributions to the integrated flux density from the lobes and the core and we present individual plots of the radio spectrum for these regions and also for the total nebular emission. These plots are used to obtain (lower, upper) limits to the turnover frequency of the core and the lobes, which in turn are used to derive (lower, upper) limits to the emission measure, density and ionized mass of the respective regions. Assuming the PN is at a distance of 2.4 kpc, we derive (lower, upper) limits to the total ionized mass of the PN of (0.2, 0.8) M .

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Radio observations of compact planetary nebulae

Cited by 28 publications

References 0 publications

SwSt 1: an O-rich planetary nebula around a C-rich central star

SwSt 1: an O-rich planetary nebula around a C-rich central star

A search for very young Planetary Nebulae

A radio continuum study of the ‘Engraved Hourglass’ nebula, MyCn 18

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