PMAS Observing Run "Planetary Nebulae"

• Applicant: Professor Dr. Martin Matthias Roth
• Subject Area: Astrophysics and Astronomy
• Term: from 2023 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536514072

The Planetary nebula luminosity function (PNLF) is a reliable distance indicator for our local universe with an accuracy of ∼ 10%. The method assumes a constant PNLF cut-off of M5007 = −4.53 +/- 0.06 that applies to different Hubble type galaxies, where M5007 is the V-band equivalent absolute magnitude of the [OIII]λ5007 emission line of the brightest planetary nebula (PN) in the galaxy. Our recent work using integral field spectroscopy at the VLT has extended the reach of this standard candle out to a distance of ∼ 40 Mpc which would enable the method to work as an independent check of Cepheids in the 2nd rung of the distance ladder, thus a contribution to the determination of the Hubble constant Ho, and current efforts to understand the Hubble Tension. However, the PNLF method is mostly still empirical. In particular, the disturbing fact remains that because of selection effects and uncertain individual distances, the PNLF in the Milky Way has as yet not been determined reliably. This project aims at making significant progress on this front by observing luminous PNe that are known to have good GAIA distances, using integral field spectroscopy, to compare with three-dimensional photoionization models to infer the luminosities of the central stars and the absolute [OIII] magnitude of the PN proper. It is expected that the morphology, also spatially variable dust extinction (possibly enhanced in a torus for bipolar objects) renders classical slit or fiber spectroscopy useless. Spatially resolved integral field spectroscopy with PMAS at the Calar Alto 3.5m Telescope, however, will allow to reveal systematic effects that may (or may not) favour PNe that are bright in [OIII]. The long-term goal is to establish a reliable PNLF for the Milky Way.

• DFG Programme: Research Grants
• International Connection: Spain
• Cooperation Partner: Jesus Aceituno, Ph.D.