Abstract
The [O iii] 5007 Å line is typically the brightest line in planetary nebula (PN) spectra. Observations show that the brightest [O iii] 5007 Å PN in a galaxy—the planetary nebula luminosity function (PNLF) bright-end cutoff—is surprisingly independent of galaxy type. To understand the origin of this puzzling uniformity, we simulate PNe with a range of cloud and star parameters using the photoionization code CLOUDY. We find that the peak [O iii] 5007 Å luminosity depends weakly on both the central stellar effective temperature at high temperature and on the total PN ejecta mass; however, the peak [O iii] 5007 Å luminosity depends strongly on the central stellar luminosity and the PN dust-to-gas mass ratio. We explain these scalings physically. They imply that a higher dust-to-gas mass ratio at higher central stellar luminosity can help explain a constant bright-end cutoff in the PNLF across galaxy types. This prediction is testable with a survey of galactic PNe. The surviving remnants of double white dwarf (WD) mergers should also produce photoionized nebulae analogous to PNe. These may be preferentially present at the high luminosity end of the [O iii] PLNF and could explain the existence of PNe in early-type galaxies that are more luminous in [O iii] than expected from single-star evolutionary models. The presence of WD mergers in both young and old stellar populations could contribute to the uniformity of the [O iii] PNLF across galaxy types; such nebulae would lack the hydrogen lines otherwise characteristic of PNe.
Original language | English (US) |
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Article number | 30 |
Journal | Astrophysical Journal |
Volume | 957 |
Issue number | 1 |
DOIs | |
State | Published - Nov 1 2023 |
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science