Optical spectroscopy and photoionization modeling of four selected planetary nebulae

We present the results of chemical abundance measurements for four compact planetary nebulae (PNe) located in the Northern Hemisphere, selected from the HASH (Hong Kong/Australian Astronomical Observatory/Strasbourg H-alpha Planetary Nebula) database. Spectral data were collected using the medium-resolution TUG Faint Object Spectrograph and Camera mounted on the 1.5 m RTT telescope at the TÜBİTAK National Observatory. For each object, we determined key physical parameters, including the extinction coefficient, electron density, electron temperature, and ionization correction factors. Additionally, we constructed the spectral energy distribution across multiple wavelengths for each PN using advanced photoionization modeling with the cloudy code. The elemental abundance analysis, focusing on He, N, O, Ne, S, Cl, and Ar, indicates that the chemical composition of these PNe is consistent with both solar and Galactic values. The central stars exhibit effective temperatures ranging from approximately 53,000 to 180,000 K and luminosities between 2,500 and 9,000 L${}_{\odot }$. Based on their positions on the H-R diagram and post-AGB evolutionary tracks, their initial masses are estimated to range from 1 to 3 M${}_{\odot }$, with nebular masses between 0.69 and 2.34 M${}_{\odot }$. The ages of the nebulae, calculated to be between $\sim$300 and 5,000 years, align with previous findings, emphasizing their evolutionary importance.