Planetary nebula IC 5148 and its ionized halo

Abstract

Context. Many round or nearly roundish Planetary Nebulae (PNe) show multiple shells and halo structures during their evolutionary stage near the maximum temperature of their central star. Controversial debate is currently ongoing if these structures are recombination halos, as suggested by hydrodynamic modelling efforts, or ionized material. Recently we discovered a halo with even somewhat unusual structures around the sparsely studied PN IC 5148 and present for the first time spectroscopy going out to the halo of such a PN. Aims. We investigate the spatial distribution of material and its ionization state from the center of the nebula up to the very outskirts of the halo. Methods. We obtained long-slit low resolution spectroscopy (FORS2@VLT) of the nebula in two position angles, which we used to investigate the nebular structure and its halo in the optical range from 450 to 880 nm. In addition we used medium resolution spectra taken with X-SHOOTER@VLT ranging from 320 nm to 2.4 µm to derive atmospheric parameters for the central star. We obtained the distance and position in the Galaxy from various methods combined with GAIA DR2 data. We also applied Cloudy models to the nebula in order to derive physical parameters of the various regions. Results. We obtained spatially resolved structures and detailed descriptions of the outrunning shock front and a set of unusual halo structures denoted to further shock. The halo structures appears clearly as hot ionized material. Furthermore we derived a reliable photometric value for the central star at a GAIA distance of D = 1.3 kpc. Considering the large distance z = 1.0 kpc from the galactic plane together to its non-circular motion in the galaxy and, a metallicity only slightly below that of typical disk PNe, most likely IC 5148 originates from a thick disk population star.

Recombination of Hot Ionized Nebulae: The Old Planetary Nebula around V4334 Sgr (Sakurai’s Star)*

“…Diagnostic diagrams of observed spectral line ratios yield T e 11,000 K and 140 n e 180 cm −3 (Pollacco 1999;Kerber et al 1999;Juffinger 2021). These values are typical for old PNe generally (see, e.g., Öttl et al 2014;Barría et al 2018). This density is much lower than the one used in the test for dynamical evolution with CLOUDY by van Hoof et al (2020).…”

Exploring the differences of integrated and spatially resolved analysis using integral field unit data: the case of Abell 14

“…BPT diagrams for PNe, SNRs, and H ii regions based on observations are presented by Frew & Parker (2010); Sabin et al (2013). Very recently, the so-called "2D extended diagnostic diagram " was used by Barría & Kimeswenger (2018a,b); Barría et al (2018) to search for shocked regions or identify low-ionization structures in PNe. Abell 14 lies in the left-bottom corner and it is characterized by 0.4<log(H α/[S ii])<0.6.…”

YY Hya and its interstellar environment

“…This filter is know to suppress contamination from possible [N ii] to a level below 5% of the intensity of those lines. As the [N ii]:[S ii] ratio is about 10:1 in shocked nebulae like supernovae remnants and even lower for H ii regions (Magrini et al 2003;Barría et al 2018), and as [S ii] was not detected in even the brightest regions, we are able to conclude, that we do not suffer from contamination by the nitrogen line.…”