Reginald J. Dufour

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We have used the Wide Field Planetary Camera 2 on theHubble Space Telescope to image a star field in the wing of the Small Magellanic Cloud (SMC), near the H ii region N81. The images were taken in the F336W, F547M, F675W, and F814W filters. From photometry of stars in this field, we construct color-magnitude diagrams (CMDs) for about 4200 stars and compare(More)
We are engaged in a comprehensive program to find reliable elemental abundances in and to probe the physical structure of the Orion Nebula, the brightest and best-resolved H ii region. In the course of developing a robust extinction correction covering our optical and ultraviolet FOS and STIS observations, we examined the decrement within various series of(More)
  • R. H. Rubin, P. G. Martin, +7 authors J. A. Baldwin
  • 2017
We present Hubble Space Telescope (HST)/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (tA) across the nebula. We also measure the intrinsic line ratio [N II] 5756/6585 in order to estimate Te and tA in(More)
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(More)
The goal of the present study is twofold. First, we employ new HST/STIS spectra and photoionization modeling techniques to determine the progenitor masses of eight planetary nebulae (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, and PB 6). Second, for the first time we are able to compare each object’s observed nebular abundances of(More)
We reexamine the spectroscopic underpinnings of recent suggestions that [O I] and [Fe II] lines from the Orion H II region are produced in gas where the iron-carrying grains have been destroyed and the electron density is surprisingly high. Our new observations show that previous detections of [O I] 5577 were dominated by telluric emission. Our limits are(More)