CO-SPATIAL LONG-SLIT UV/OPTIC AL SPECTRA OF 10 GALACTIC PLANETARY NEBULAE WITH HST/STIS. I. DESCRIPTION OF THE OBSERVATIONS, GLOBAL EMISSION-LINE MEASUREMENTS, AND CNO ABUNDANCES

Journal Article · Fri Apr 10 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/803/1/23· OSTI ID:22521989

Dufour, Reginald J. ^[1]; Kwitter, Karen B. ^[2]; Shaw, Richard A. ^[3]; Henry, Richard B. C. ^[4]; Balick, Bruce ^[5]; Corradi, Romano L. M. ^[6]

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1. Department of Space Physics and Astronomy, Rice University, Houston, TX 77251 (United States)
2. Department of Astronomy, Williams College, Williamstown, MA 01267 (United States)
3. National Optical Astronomy Observatory, Tucson, AZ 85719 (United States)
4. Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)
5. Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)
6. Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain)

We present observations and initial analysis from a Hubble Space Telescope (HST) Cycle 19 program using STIS to obtain the first co-spatial, UV–optical spectra of 10 Galactic planetary nebulae (PNs). Our primary objective was to measure the critical emission lines of carbon and nitrogen with unprecedented signal-to-noise ratio (S/N) and spatial resolution over the wavelength range 1150–10270 Å, with the ultimate goal of quantifying the production of these elements in low- and intermediate-mass stars. Our sample was selected from PNs with a near-solar metallicity, but spanning a broad range in N/O based on published ground-based and IUE spectra. This study, the first of a series, concentrates on the observations and emission-line measurements obtained by integrating along the entire spatial extent of the slit. We derived ionic and total elemental abundances for the seven PNs with the strongest UV line detections (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, and NGC 7662). We compare these new results with other recent studies of the nebulae and discuss the relative merits of deriving the total elemental abundances of C, N, and O using ionization correction factors (ICFs) versus summed abundances. For the seven PNs with the best UV line detections, we conclude that summed abundances from direct diagnostics of ions with measurable UV lines give the most accurate values for the total elemental abundances of C and N (although ICF abundances often produced good results for C). In some cases where significant discrepancies exist between our abundances and those from other studies, we show that the differences can often be attributed to their use of fluxes that are not co-spatial. Finally, we examined C/O and N/O versus O/H and He/H in well-observed Galactic, LMC, and SMC PNs and found that highly accurate abundances are essential for properly inferring elemental yields from their progenitor stars. Future papers will discuss photoionization modeling of our observations, of both the integrated spectra and spatial variations of the UV versus optical lines along the STIS slit lengths, which are unique to our observations.

• OSTI ID: 22521989
• Journal Information: Astrophysical Journal, Vol. 803, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON
CARBON MONOXIDE
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DETECTION
ELEMENT ABUNDANCE
GALAXIES
MASS
METALLICITY
NITROGEN
PHOTOIONIZATION
PLANETARY NEBULAE
SIGNAL-TO-NOISE RATIO
SPACE
SPATIAL RESOLUTION
STAR CLUSTERS
STAR EVOLUTION
STARS
TELESCOPES