Planets and Planetary Nebulae: Different Evolutionary Pathways in the Stellar Life Cycle
Vejar, George
0000-0002-0356-3613
:
2022-03-29
Abstract
The stellar life cycle plays an important role in polluting the universe with heavy elements essential for life. This dissertation focuses on two different stages of a star’s life cycle – one of which allowed for multicellular life to develop and the other is the future of our own Sun. The final stage of evolution for sun-like stars, unlike high mass stars, includes the formation of a planetary nebula (PN), an object that returns processed elements back to the interstellar medium (ISM). Planetary Nebulae (PNe) can be used to study stellar evolution, galaxy dynamics, and as calibrators of the cosmological distance ladder. This work shows that color-color diagrams will be useful in identifying PNe candidates as data from the Vera Rubin Observatory (VRO) becomes available. Given the resolution and saturation limit of the telescope, VRO will be sensitive to virtually all PNe in the Magellanic Clouds with extinction up to ~5 mags; out to the distance of Andromeda, VRO would be sensitive to the youngest PNe for extinction values up to 1 mag. Metal-rich material returned to the ISM by PNe will birth new stars where the condensation of refractory elements in protoplanetary disks can form rocky planets, a process that may imprint a measurable abundance trend on the host star. This work takes advantage of the chemical homogeny of stellar clusters to test for differences in stellar abundances due to this planet formation process. Absorption spectra of cluster stars were analyzed using the custom-built Python code XSpect-EW, which has received upgrades and is now publicly available. Pr0201, known to host a short-period giant planet in the cluster,
shows no significant enrichment in refractory elements that would be consistent with a planetary accretion scenario. The sample of six stars studied in the Praesepe Open Cluster is shown to be chemically homogenous and provide a mean metallicity of [Fe/H] = +0.21 ±0.02 dex, in agreement with the current literature.