Space Telescope Imaging Spectrograph Slitless Observations of Small Magellanic Cloud Planetary Nebulae: A Study on Morphology, Emission‐Line Intensity, and Evolution

Abstract

A sample of 27 Planetary Nebulae (PNs) in the Small Magellanic Clouds (SMC) have been observed with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) to determine their morphology, size, and the spatial variation of the ratios of bright emission lines. The morphologies of SMC PNs are similar to those of LMC and Galactic PNs. However, only a third of the resolved SMC PNs are asymmetric, compared to half in the LMC. The low metallicity environment of the SMC seems to discourage the onset of bipolarity in PNs. We measured the line intensity, average surface brightness (SB), and photometric radius of each nebula in Hα , Hβ , [Oiii] λ4959 and 5007, [Nii] λ6548 and 6584, [Sii] λ6716 and 5731, He I λ6678, and [Oi] λ6300 and 6363. We show that the surface brightness to radius relationship is the same as in LMC PNs, indicating its possible use as a distance scale indicator for Galactic PNs. We determine the electron densities and the ionized masses of the nebulae where the [Sii] lines were measured accurately, and we find that the SMC PNs are denser than the LMC PNs by a factor of 1.5. The average ionized mass of the SMC PNs is 0.3 M ⊙ . We also found that the median [Oiii] /Hβ intensity ratio in the SMC is about half than the corresponding LMC median. We use Cloudy to model the dependence

Radio planetary nebulae in the Small Magellanic Cloud

“…From Stanghellini et al (2003) we used photometric radii except for SMP S11 where the measured angular dimension is at 10% of peak brightness. Radio brightness temperatures for this object at 1.4 GHz, calculated from θ = 2 and θ = 0.7 , were 350 K and 3700 K, respectively.…”

Hubble Space Telescope Images of Magellanic Cloud Planetary Nebulae

“…This portion of the processing subtracts the bias, corrects for hot pixels by scaling and subtracting dark exposures, and divides by a normalized flat-field image to correct for pixel-to-pixel variations in detector sensitivity. The pipeline also combines multiple exposures, using an anticoincidence Stanghellini et al 1999;(6) Stanghellini et al 2003; (7) Vassiliadis 1996; (8) Vassiliadis et al 1998;(9) Villaver et al 2003;(10) Herald & Bianchi 2004;(11) this paper. MIRVIS 120 2 O6CN15020 G750M 68 2 O6CN15030 G430M 132 2 2002 Apr 26 O6EL0I010 MIRVIS 120 2 O6EL0I020 G750M 30 2 O6EL0I030 G750M 150 2 O6EL0I040 G750M 600 2 O6EL0I050 G430M 48 2 O6EL0IL4Q MIRVIS 15 MIRVIS 120 2 O6EL0M020 G750M 36 2 O6EL0M030 G750M 180 2 O6EL0M040 G430M 60 2 technique to remove cosmic-ray trails and other transient artifacts.…”

Clues on Post-Asymptotic Giant Branch Evolution and Planetary Nebulae Populations from the Magellanic Clouds

“…The snapshot survey targets plotted in Figures 5 and 6 were selected from the brightest LMC and SMC PNe [4,5], thus the completeness near the high luminosity cut-off should be adequate [17]. In both Figures, but more clearly in Figure 5, one can see two different branches of PNe, running from small to large radii.…”

“…The majority of Galactic PNe are elliptical, but the actual number of B PNe could be underestimated, given that they typically lie in the Galactic plane (i.e., they may suffer from high reddening). PNe in the Magellanic Clouds, when spatially resolved, show the same admixture of morphological types than the Galactic PNe, as illustrated in Figure 1 [3,4,5]. While we do not attempt a statistical comparison of the Magellanic and Galactic PN morphological types, given the selection effects that hamper Galactic PNe, we can meaningfully compare the LMC and SMC samples.…”