Related papers: Neutron-Capture Element Abundances in Planetary Ne…
We present emission line strengths, abundances, and element ratios (X/O for Ne, S, Cl, and Ar) for a sample of 38 Galactic disk planetary nebulae (PNe) consisting primarily of Peimbert classification Type I. Spectrophotometry for these PNe…
We investigate the enrichment in elements produced by the slow neutron-capture process ($s$-process) in the globular clusters M4 (NGC 6121) and M22 (NGC 6656). Stars in M4 have homogeneous abundances of Fe and neutron-capture elements, but…
Utilising the optical imaging Fourier transform spectrograph SITELLE, the Star-formation, Ionized Gas and Nebular Abundances Legacy Survey (SIGNALS) is designed to study the connection between star-forming regions and their environments.…
In a short review of neutron-capture elemental abundances in Galactic halo stars, emphasis is placed on the use of these elements to estimate the age of the Galactic halo. Two prominent characteristics of neutron-capture elements in halo…
The chemical abundances of elements such as barium and the lanthanides are essential to understand the nucleosynthesis of heavy elements in the early Universe as well as the contribution of different neutron capture processes (for example…
We present spectroscopy of three planetary nebulae (PNe) in the Northern Spur of the Andromeda Galaxy (M31) obtained with the Double Spectrograph on the 5.1 m Hale Telescope at the Palomar Observatory. The samples are selected from the…
We present observations and initial analysis from an HST/STIS program to obtain the first co-spatial, UV-optical spectra of ten Galactic planetary nebulae (PNe). Our primary objective was to measure the critical emission lines of carbon and…
A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are…
We present 5 - 40 micron spectroscopy of 41 planetary nebulae (PNe) in the Magellanic Clouds, observed with the Infrared Spectrograph on board the Spitzer Space Telescope. The spectra show the presence of a combination of nebular emission…
We present four new planetary nebulae (PNe) discovered in the Small Magellanic Cloud (SMC) from deep UK Schmidt telescope (UKST) narrow band H-alpha and broad-band short-red "SR" continuum images and confirmed spectroscopically. All new PNe…
We present an extensive analysis of the gas-phase abundances and depletion behaviors of neutron-capture elements in the interstellar medium (ISM). Column densities (or upper limits to the column densities) of Ga II, Ge II, As II, Kr I, Cd…
It is already known that about 10% of central stars of PNe are very short-period binaries (hours to days), which are detected through photometric variations. These must have been formed through common-envelope interactions in initially wide…
Spectroscopic observations of 48 emission-line objects of M33 have been obtained with the multi-object, wide field, fibre spectrograph AF2/WYFFOS at the 4.2m WHT telescope (La Palma, Spain). Line intensities and logarithmic extinction,…
The failure of S and O abundances in most planetary nebulae to display the same strong direct correlation that is observed in extragalactic H II regions represents one of the most perplexing problems in the area of PN abundances today.…
A revival over the past two decades in planetary nebula (PN) morphological studies springs from a combination of factors, including the advent of wide-area, high dynamic range detectors; the growing archives of high resolution images from…
New abundances of planetary nebulae located towards the bulge of the Galaxy are derived based on observations made at LNA (Brazil). We present accurate abundances of the elements He, N, S, O, Ar, and Ne for 56 PNe located towards the…
Planetary nebulae (PNe) are an important tool for studying the dynamics and chemical evolution of galaxies in the Local Universe, given their characteristic, bright emission line spectra. The Andromeda Galaxy (M31) provides a unique…
In this contribution, I will briefly review the development of the theory of photoionized gaseous nebulae, highlighting some of the key events. I will then present some recent developments of deep spectroscopy of planetary nebulae (PNe) and…
How are the heavy elements formed? This has been a key open question in physics for decades. Recent direct detections of neutron star mergers and observations of evolved stars show signatures of chemical elements in the blue range of their…
Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also…