Visual disk map5/8/2023 ![]() ![]() ![]() Gentile Fusillo 9, Sandra Greiss 9, Antonio Hales, Simon Hodgkin 2, L. Drake 10, Jochen Eislöffel, Juan Fabregat 11, Boris T. Groot 4, Antonio Mampaso 5, Antonio Mampaso 6, Stuart E. Drew 1, Eduardo Gonzalez-Solares 2, Robert Greimel 3, Mike Irwin 2, Brent Miszalski, C. These features are also common in nebulae around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN.read more read less A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggesting they have a binary origin. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. Nearly 30% of nebulae have canonical bipolar morphologies, however this could be as high as 60% once inclination effects are incorporated with the aid of geometric models. High quality Gemini South narrow-band images are presented for most of the OGLE sample, while some previously known post-CE PNe are reanalysed with images from the literature. The discovery of several new binary central stars (CSPN) from the OGLE-III photometric variability survey has significantly increased the number of post-CE PNe available for morphological analysis to 30 PNe. At least 10–20% of PNe have central stars (CSPN) with a close binary companion thought responsible for heavily shaping the ejected PN during common-envelope (CE) evolution, however morphological studies of the few available examples found no clear distinction between PNe and post-CE PNe. Interestingly, stellar ejecta around massive stars plot on a tight locus in SHα–r space with the potential to act as a separate distance indicator for these objects.read more read lessĪbstract: Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). ![]() Finally, in an appendix, we investigate both a set of transitional PNe and a range of PN mimics in the SHα–r plane, to demonstrate its use as a diagnostic tool. We use this technique to create a catalogue of statistical distances for over 1100 Galactic PNe, the largest such compilation in the literature to date. This is significantly better than any previous statistical indicator. This enables sub-trends to be developed which offer even better precision in the determination of distances, as good as 18 per cent in the case of optically thin, high-excitation PNe. Furthermore, we have found that optically thick PNe tend to populate the upper bound of the trend, while optically thin PNe fall along the lower boundary in the SHα–r plane. From these quantities, an intrinsic radius is calculated, which when combined with the angular size, yields the distance directly. The SHα–r technique is simple in its application, requiring only an angular size, an integrated Hα flux, and the reddening to the PN. We developed thisrelationfromacriticallyevaluatedsampleofprimarycalibratingPNe.Therobustnatureof the method results from our revised calibrating distances with significantly reduced systematic uncertainties, and the recent availability of high-quality data, including updated nebular diameters and integrated Hα fluxes. We have now established a robust optical statistical distance indicator, the Hα surface brightness–radius or SHα–r relation, which addresses this problem. The library spectra and associated tables are available as text files by remote electronic access.read more read lessĪbstract: Measuring the distances to Galactic planetary nebulae (PNe) has been an intractable problem for many decades. A program to combine the library spectra in the ratios appropriate to a selected isochrone is described and an example of a spectral component signature of a composite population of solar age and metallicity is illustrated. The library spectra are each given as Fl versus l, from 1150 to 25000 Ain steps of 5 A ˚. The library is designed to permit inclusion of additional digital spectra, particularly of non-solar abundance stars in the infrared, as they become available. Missing spectral coverage in the infrared currently consists of a smooth energy distribution formed from standard colors for the relevant types. The library has complete spectral coverage from 1150 to 10620 Afor all components and to 25000 Afor about half of them, mainly later types of solar abundance. The SIMBAD database, measured colors, and line strengths were used to check that each input component has closely similar stellar type. Each library spectrum was formed by combining data from several sources overlapping in wavelength coverage. The new library consists of 131 flux-calibrated spectra, encompassing all normal spectral types and luminosity classes at solar abundance, and metal-weak and metal-rich F-K dwarf and G-K giant components. Abstract: A stellar spectral flux library of wide spectral coverage and an example of its application are presented. ![]()
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