Planetary Nebulae: Observational Properties, Mimics and Diagnostics

Abstract

Abstract:The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is nearly 3000, double the number known a decade ago. The new discoveries are a legacy of the recent availability of wide field, narrowband imaging surveys, primarily in the light of H-alpha. In this paper, we summarise the various PN discovery techniques, and give an overview of the many types of objects which mimic PN and which appear as contaminants in both Galactic and extragalactic samples. Much improved discrimination of classical PN from their mimics is now possible based on the wide variety of high-quality multiwavelength data sets that are now available. We offer improved taxonomic and observational definitions for the PN phenomenon based on evaluation of these better diagnostic capabilities. However, we note that evidence is increasing that the PN phenomenon is heterogeneous, and PN are likely to be formed from multiple evolutionary scenarios. In particular, the relationships between some collimated symbiotic outflows and bipolar PN remain uncertain.

On the production of He, C, and N by low- and intermediate-mass stars: a comparison of observed and model-predicted planetary nebula abundances

“…, where D and b are the object's heliocentric distance and galactic longitude, respectively, and are taken from Frew (2008). Table 2 provides the details concerning the observations of each of our 35 sample objects.…”

“…We decided to base our analysis on the log(L/L ⊙ ) and log T ef f values for each of our objects found in Frew (2008) because of the thoroughness of the procedures which he used to obtain these values. In his compilation of log(L/L ⊙ ) values, Frew vetted all published V magnitude estimates for quality and then averaged the best values for each central star.…”

“…The values of log(L/L ⊙ ) and log T ef f were taken from Frew (2008) for 32 of our 35 sample objects. For the three sample objects not included in Frew (2008) (IC2165, IC3568 and NGC5315) we assumed the L and T values derived from models in Henry et al (2015).…”

“…In his compilation of log(L/L ⊙ ) values, Frew vetted all published V magnitude estimates for quality and then averaged the best values for each central star. Absolute visual magnitudes were then determined via a distance modulus, where distances were inferred from a new relation developed in Frew (2008) between the Hα surface brightness and nebular radius of a PN. Following the application of a bolometric correction, bolometric magnitudes were converted to solar luminosities.…”

A wealth of new planetary nebulae from the IPHAS survey

“…Spectra will not only allow us to confirm the nature of the nebulae, but also to compute their distance via the IPHAS extinction method (Giammanco et al 2011) and surface brightness radius (SB-r) technique (Frew & Parker 2010). Once this is done, we will have a complete sample of PNe, limited in surface brightness, in a specific area of the sky and with known distances.…”