Narrow-band 500.7 nm HST Images of Planetary Nebulae in the Magellanic Clouds

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Session 47 -- Planetary Nebulae
Display presentation, Tuesday, 10, 1995, 9:20am - 6:30pm

[47.03] Narrow-band 500.7 nm HST Images of Planetary Nebulae in the Magellanic Clouds

E.Vassiliadis (STScI), M.A.Dopita (MSSSO), R.C.Bohlin, H.C. Ford (STScI), S.J.Meatheringham (MSSSO), J.P.Harrington (U.Maryland), P.R.Wood (MSSSO), T.P.Stecher, S.P.Maran (GSFC)

The planetary camera onboard HST is used to image six planetary nebulae in the Magellanic Clouds: LMC-SMP7, 37, 61, 67, 101, and SMC-SMP22\@. The narrow-band F502N filter isolates the strong nebular [O~III] emission line at 500.7 nm. The images are obtained from August to October 1993, prior to the first HST servicing mission. Each image is restored with 100 iterations of the standard Richardson-Lucy method, which gives a reliable representation of the nebular morphology. For the major and minor axes of each object, a Gaussian function is convolved with the HST PSF and compared with the unrestored nebular profile. For 5 of the 6 objects, the results are consistent to within 30\% of the outer nebular radii determined from photoionisation modelling of ground-based optical spectrophotometry. The exception, LMC-SMP101, is optically thin and has a radius of $\sim 0.3$ pc; $\sim 5$ times the radius determined from the photoionisation model. The time elapsed since the onset of the AGB superwind is calculated by dividing the nebular radius by the published [O~III] expansion velocity for each object. The values range from 585 years for LMC-SMP37 to 5620 years for LMC-SMP101. Central star ages inferred using published stellar parameters from photoionisation models and published theoretical stellar evolutionary tracks, are at least a factor of two greater than the dynamical ages. For LMC-SMP7, ${\rm t}_{\rm evol}/{\rm t}_{\rm dyn} = 14000/585 \sim 20$. The HST [O~III] fluxes, measured with a 3.3$^{\prime\prime}$-radius circular aperture, are consistent with ground-based [O~III] aperture photometry to within 0.15 mag.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for this work was provided by NASA through grant number GO-2266 from the STScI\@.

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