Classical novae (CNe) are violent thermonuclear explosions arising on the surface
of white dwarfs in binary systems and are contributors to the chemical evolu-
tion of the interstellar medium through the production and ejection of copious
amounts of metal-rich material. Observations and modeling of CNe eruptions
illuminate numerous fundamental processes of astrophysical interest, including
non-equilibrium thermonuclear runaway, radiative processes in dynamic nebular
environments, binary star interaction, as well as dust condensation and grain
growth. Here I summarize key findings from selected Galactic CNe observed as
part of a 5 year, panchromatic optical/infrared observing campaign using Spitzer,
Gemini, and other ground based optical facilities.
In particular, I present detailed analysis of nova V1065 Centauri, including
photoionization analysis of the emission lines, which enabled the derivation of
abundances in the ejecta, and radiative transport modeling of the dust emission
features, which allowed determination of the composition and characteristics of
the dust in this system. I present analysis of three novae, V1974 Cygni, V382
Velorum, and V1494 Aquilae, observed from 4.4−15.5 years after outburst, discuss
the characteristics of the nebulae at these late times, and estimate the abundances
in their ejecta. In the case of V1494 Aql, I also report the first detection of neon.
Finally, I present observations of three novae, DZ Crucis, V2361 Cygni, and V2362
Cygni, that exhibited unidentified infrared (UIR) features in their mid-infrared
spectra, which exhibited unusual characteristics. I relate these features to other
dusty novae in which features with similar characteristics were observed, and discuss possible sources for the UIR carriers.
Analysis of the data obtained in the CNe monitoring campaign presented here
highlights the need for synoptic observations obtained with broad wavelength cov-
erage. Observations of V1065 Cen, which exhibited spectra rich in metals (e.g O,
Ne, Mg, S, Ar, and Fe) produced during the thermonuclear runaway and through
dredge up from the surface layers of the underlying WD, yielded robust esti-
mates of WD composition, ejecta mass, and absolute abundances in the ejecta.
Dusty novae such as V1065 Cen, V2362 Cyg, and V2361 Cyg, produced a va-
riety of grain types as revealed by emission features characteristic of silicates,
hydrogenated amorphous carbon dust, and PAH-like molecules, often in the same
system. This data set is exceptional in that observations of many targets com-
menced immediately after eruption and followed the development for hundreds of
days post-outburst providing unique insight into the evolution of conditions within the ejecta including the complete cycle of growth, processing, and dissipation of
Univertsity of Minnesota Ph.D. dissertation. December 2010. Major:Astrophysics. Advisors:Bob Gehrz and Chick
Woodward. Bob. 1 computer file (PDF); xiv, 226 pages; appendix A.
Helton, Lorren Andrew.
Photometric and spectroscopic analysis of classical novae: an examination of their observational characteristics and greater astronomical impact..
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