Related papers: Advances in Atomic Data for Neutron-Capture Elemen…
[Abridged] Investigations of neutron(n)-capture element nucleosynthesis and chemical evolution have largely been based on stellar spectroscopy. However, the recent detection of these elements in several planetary nebulae (PNe) indicates…
The detection of neutron(n)-capture elements in several planetary nebulae (PNe) has provided a new means of investigating s-process nucleosynthesis in low-mass stars. However, a lack of atomic data has inhibited accurate trans-iron element…
Spectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in asymptotic giant branch (AGB) stars. However, accurate abundance determinations of…
Neutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more…
We present results from the first large-scale survey of neutron(n)-capture element abundances in planetary nebulae (PNe). This survey was motivated by the fact that a PN may be enriched in n-capture elements if its progenitor star…
Nebular spectroscopy is a valuable tool for assessing the production of heavy elements by slow neutron(n)-capture nucleosynthesis (the s-process). Several transitions of n-capture elements have been identified in planetary nebulae (PNe) in…
We have conducted a large-scale survey of 120 planetary nebulae (PNe) to search for the near-infrared emission lines [Kr III] 2.199 and [Se IV] 2.287 microns. The neutron(n)-capture elements Se and Kr may be enriched in a PN if its…
We present preliminary results from a large-scale survey of the neutron(n)-capture elements Se and Kr in Galactic planetary nebulae (PNe). These elements may be produced in PN progenitors by s-process nucleosynthesis, and brought to the…
We present results from an ongoing survey of the infrared emission lines [Kr III] 2.199 and [Se IV] 2.287 micron in Galactic planetary nebulae (PNe). Krypton and selenium may be produced by slow neutron-capture nucleosynthesis (the…
We present results from an ongoing survey of infrared emission lines from the neutron-capture elements Se and Kr in Galactic planetary nebulae (PNe). Se and Kr may be produced in the initial steps of the s-process during the asymptotic…
We have done a spectroscopical analysis of the type I planetary nebula (PN) NGC 5315, through high-resolution (R$\sim$40000) optical spectroscopy with UVES at the 8.2m Very Large Telescope, and medium-resolution (R$\sim$4800) near-IR…
We present the results of a large-scale survey of neutron(n)-capture elements in Galactic planetary nebulae (PNe), undertaken to study enrichments from s-process nucleosynthesis in their progenitor stars. From new K band observations of…
We analyze the chemical composition of the planetary nebula (PN) NGC 5315, through high-resolution (R = 40000) optical spectroscopy with UVES at the Very Large Telescope, and medium-resolution (R = 4800) near-infrared spectroscopy with FIRE…
We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of distorted-wave photoionization (PI) cross sections, and total and partial final-state resolved radiative recombination (RR) and dielectronic recombination (DR) rate…
We present near-infrared spectra of ten planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5-m Baade and 8.1-m Gemini South Telescopes, respectively. We…
New abundances for neutron-capture (n-capture) elements in a large sample of metal-poor giants from the Bond survey are presented. The spectra were acquired with the KPNO 4-m echelle and coude feed spectrographs, and have been analyzed…
We have identified two new near-infrared emission lines in the spectra of planetary nebulae (PNe) arising from heavy elements produced by neutron capture reactions: [Te III] 2.1019 $\mu$m and [Br V] 1.6429 $\mu$m. [Te III] was detected in…
The s-process should occur in all but the lower mass progenitor stars of planetary nebulae, and this should be reflected in the chemical composition of the gas which is expelled to create the current planetary nebula shell. Weak forbidden…
Neutron-capture elements, those with Z > 35, are the least well-understood in terms of nucleosynthesis and formation environments. The rapid neutron-capture, or r-process, elements are formed in the environments and/or remnants of massive…
Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have…