A multiwavelength analysis of planetary nebulae in the Large Magellanic Cloud

This paper examines, compares and plots optical, near- and mid-infrared (MIR) photometric data for 605 planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). With the aid of multi-wavelength surveys such as the Spitzer legacy programme Surveying the Agents of a Galaxy's Evolution, the Two Micron All Sky Survey and the Magellanic Cloud Photometric Survey, plots have been constructed to expose the relative contributions from molecular hydrogen, polycyclic aromatic hydrocarbons, forbidden emission lines, warm dust continuum and stellar emission at various bands. Besides identifying trends, these plots have helped to reveal PN mimics including six previously known PNe in the outer LMC which are re-classied as other object types. Together with continuing follow-up optical observations, the data have enabled a substantial reduction in the number of PNe previously tagged as `likely' and `possible'. The total number of LMC PNe is adjusted to 715 but with a greater degree of confidence in regard to classification. In each colour-colour plot, the more highly evolved LMC PNe are highlighted for comparison with younger, brighter PNe. The faintest and most evolved PNe typically cluster in areas of colour-colour space occupied by ordinary stars. Possible reasons for the wide disparity in infrared colour-colour ratios, such as evolution and dust composition, are presented for evaluation. A correlation is found between the optical luminosity of PNe, emission-line ratios and the MIR dust luminosity at various bands. Luminosity functions using the four Infrared Array Camera and Multiband Imaging Photometer of Spitzer (MIPS) [24] bands are directly compared, revealing an increasing accumulation of PNe within the brightest two magnitudes at longer wavelengths. A correlation is also found between the MIPS [24] band and the [O III] 5007 and H-beta fluxes.Comment: 25 pages, 18 figures, accepted in MNRA

A New Population of Planetary Nebulae Discovered in the Large Magellanic Cloud (I): Preliminary Sample

We report our initial discovery of 73 new planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) following confirmatory 2dF spectroscopy on the Anglo-Australian Telescope (AAT). Preliminary candidate sources come from a 10 per cent sub-area of our new deep, high resolution H-alpha map of the central 25 deg. square of the LMC obtained with the UK Schmidt Telescope (UKST). The depth of the high resolution map was extended to Requiv~22 for H-alpha (4.5 x 10-17 ergs cm-2 s-1 Ang-1) by a process of multi-exposure median co-addition of a dozen 2-hour H-alpha exposures. The resulting map is at least 1-magnitude deeper than the best wide-field narrow-band LMC images currently available. This depth, combined with our selection technique, has also led to the discovery of extended AGB halos around many new and previously known LMC PNe for the first time. Once complete, our new survey is expected to triple the LMC PN population and have significant implications for the LMC PN luminosity function, kinematics, abundance gradients chemical evolution and, via study of the AGB halos, the initial to final mass relation for low to intermediate mass stars.Comment: 14 pages, 21 figures (zipped). Accepted for publication in Mmonthly Notices of the Royal Astronomical Societ

The object the metaphor the power and evergreen or the eighth way to make a hypermedia project fail

A patented software technique is described that is necessary and sufficient to keep hypermedia data bases current with the manufacturing technology. The technique proved its validity in four years of use in petrochemical plants. This technique is based on the following principles: (1) the data base must be object structured, i.e., all components must retain visible individuality; (2) the author must be seeing and experiencing the multimedia data objects as he creates; and (3) the hypermedia tools must possess power in the form of unlimited capacity

Homotopy theoretic models of identity types

This paper presents a novel connection between homotopical algebra and mathematical logic. It is shown that a form of intensional type theory is valid in any Quillen model category, generalizing the Hofmann-Streicher groupoid model of Martin-Loef type theory.Comment: 11 page

H-alpha Stacked Images Reveal Large Numbers of PNe in the LMC

Our new, deep, high resolution H-alpha and matching R-band UKST multi-exposure stack of the central 25 sq. degrees of the LMC promises to provide an unprecedented homogeneous sample of >1,000 new PNe. Our preliminary 2dF spectroscopy on the AAT has vindicated our selection process and confirmed 136 new PNe and 57 emission-line stars out of a sample of 263 candidate sources within an initial 2.5 sq. deg. area. To date approximately one third of the entire LMC has been scanned for candidates (~7.5 sq.deg.). More than 750 new emission sources have been catalogued so far along with independent re-identification of all known and possible PNe found from other surveys. Once our image analysis is complete, we plan comprehensive spectroscopic follow-up of the whole sample, not only to confirm our PN candidates but also to derive nebula temperatures and densities which, with the aid of photoionization modeling, will yield stellar parameters which are vital for constructing H-R diagrams for these objects. A prime objective of the survey is to produce a Luminosity Function which will be the most accurate and comprehensive ever derived in terms of numbers, magnitude range and evolutionary state; offering significant new insights into the LMC's evolutionary history. The observation and measurement of our newly discovered AGB halos around 60% of these PN will also assist in determining the initial- to final-mass ratios for this phase of stellar evolution.Comment: 6 pages, 3 figures, LaTeX, to be published in Proceedings of the ESO workshop on Planetary Nebulae beyond the Milky Way held at ESO, Garching, May 19-21, 200

Optical analogs of NMR phase coherent multiple pulse spectroscopy

A new technique is presented for producing optical pulse sequences using acousto-optical modulation. The method is applied to gaseous I2 at −15 °C