Analysis of Co-spatial UV-optical STIS Spectra of Planetary Nebula NGC 3242

TL;DR

This study used HST/STIS spectra to analyze the chemical homogeneity and stellar properties of planetary nebula NGC 3242, finding it to be chemically uniform and estimating its stellar temperature and luminosity.

Contribution

It provides new insights into the chemical uniformity of NGC 3242 and constrains stellar parameters using photoionization models with different density profiles.

Findings

Elements He, C, O, Ne are chemically homogeneous across regions.

Stellar temperature is approximately 90,000 K, and luminosity is log(L/Lsun)=3.36.

Stellar initial and final masses are estimated at about 0.95 and 0.56 solar masses.

Abstract

This project sought to consider two important aspects of the planetary nebula NGC 3242 using new long-slit HST/STIS spectra. First, we investigated whether this object is chemically homogeneous by dividing the slit into different regions spatially and calculating the abundances of each region. The major result is that the elements of He, C, O, and Ne are chemically homogeneous within uncertainties across the regions probed, implying that the stellar outflow was well-mixed. Second, we constrained the stellar properties using photoionization models computed by CLOUDY and tested the effects of three different density profiles on these parameters. The three profiles tested were a constant density profile, a Gaussian density profile, and a Gaussian with a power law density profile. The temperature and luminosity were not affected significantly by the choice of density structure. The values for the stellar temperature and luminosity from our best fit model are 89.7$^{+7.3}_{-4.7}$kK and log(L/Lsol)=3.36$^{+0.28}_{-0.22}$, respectively. Comparing to evolutionary models on an HR diagram, this corresponds to an initial and final mass of 0.95$^{+0.35}_{-0.09}$ Msol and 0.56$^{+0.01}_{-0.01}$ Msol, respectively.