5,109 research outputs found
Abundances of Disk Planetary Nebulae in M31 and the Radial Oxygen Gradient
We have obtained spectra of 16 planetary nebulae in the disk of M31 and
determined the abundances of He, N, O, Ne, S and Ar. Here we present the median
abundances and compare them with previous M31 PN disk measurements and with PNe
in the Milky Way. We also derive the radial oxygen gradient in M31, which is
shallower than that in the Milky Way, even accounting for M31's larger disk
scale length.Comment: 2 pages, 1 figure, 1 table, to appear in the proceedings of IAU
Symposium No. 283, Planetary Nebulae: An Eye to the Futur
Abundances of PNe in the Outer Disk of M31
We present spectroscopic observations and chemical abundances of 16 planetary
nebulae (PNe) in the outer disk of M31. The [O III] 4363 line is detected in
all objects, allowing a direct measurement of the nebular temperature essential
for accurate abundance determinations. Our results show that the abundances in
these M31 PNe display the same correlations and general behaviors as Type II
PNe in the Milky Way Galaxy. We also calculate photoionization models to derive
estimates of central star properties. From these we infer that our sample PNe,
all near the peak of the Planetary Nebula Luminosity Function, originated from
stars near 2 M_sun. Finally, under the assumption that these PNe are located in
M31's disk, we plot the oxygen abundance gradient, which appears shallower than
the gradient in the Milky Way.Comment: 48 pages, including 12 figures and 8 tables, accepted by
Astrophysical Journa
Separator development for a heat sterilizable battery Final summary progress report, 1 May 1966 - 15 Mar. 1967
Development and testing of vivyl polymer separator materials for sterilized silver-zinc secondary batter
A STOL airworthiness investigation using a simulation of an augmentor wing transport. Volume 2: Simulation data and analysis
A simulator study of STOL airworthiness was conducted using a model of an augmentor wing transport. The approach, flare and landing, go-around, and takeoff phases of flight were investigated. The simulation and the data obtained are described. These data include performance measures, pilot commentary, and pilot ratings. A pilot/vehicle analysis of glide slope tracking and of the flare maneuver is included
Development of improved semi-organic structural adhesives for elevated temperature applications Technical summary report, 1 ~JUL. 1964 - 29 ~FEB. 1968
Titanium chelate polymer adhesive formulation for aluminum joint curing in high temperature application
Empirical Studies of Evolving Systems
This paper describes the results of the working group investigating the issues of empirical studies for
evolving systems. The groups found that there were many issues that were central to successful evolution and this
concluded that this is a very important area within software engineering. Finally nine main areas were selected for consideration. For each of these areas the central issues were identified as well as success factors. In some cases success stories were also described and the critical factors accounting for the success analysed. In some cases it was later found that a number of areas were so tightly coupled that it was important to discuss them together
The Wild Turkey in South Dakota
This bulletin provides an extensive look at the wild turkey in South Dakota
An annotated list of the Lepidoptera of Honduras
A biodiversity inventory of the Lepidoptera of Pico Bonito National Park and vicinity, in the Department of Atlantida of northern Honduras, was initiated in 2009 to obtain baseline data. We present a revised checklist of Honduran butterfly species (updated from the initial 1967 lists), as well as the first comprehensive list of Honduran moths. Our updated list includes 550 species of Papilionoidea, 311 Hesperioidea, and 1,441 moth species
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