scholarly journals PAH anions as carriers of the mid-IR emission bands in planetary nebulae

2008 ◽  
Vol 4 (S251) ◽  
pp. 207-212
Author(s):  
Ryszard Szczerba ◽  
Christine Joblin ◽  
Olivier Berné ◽  
Cezary Szyszka
Keyword(s):  
Ir Spectra ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Electron Densities ◽  
Ir Emission

AbstractWe present results of the mid-IR spectra decomposition for planetary nebulae and compact H ii regions in our Galaxy and Magellanic Clouds. The striking correlation between the required PAH component with “7.7” μm band shifted to about 7.8 μm and electron densities of the modeled sources allows us to argue that this PAH component may be in fact PAH anions (PAH−).

scholarly journals Unidentified Species in Envelopes around Carbon Stars

2013 ◽  
Vol 9 (S297) ◽  
pp. 219-222
Author(s):  
B. W. Jiang ◽  
A. Li ◽  
K. Zhang ◽  
J. M. Liu ◽  
J. Gao ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Emission Spectrum ◽  
Single Photon ◽  
Dust Emission ◽  
Planetary Nebulae ◽  
Agb Stars ◽  
Carbon Stars ◽  
Unidentified Species ◽  
Ir Emission

AbstractThe infrared (IR) spectra of many evolved carbon-rich stars exhibit two prominent dust emission features peaking around 21μm and 30μm, with the former exclusively seen in proto-planetary nebulae (PPNe), while the latter seen in a much wider range of objects, including AGB stars, PPNe and planetary nebulae (PNe). The 30μm feature is seen in all the 21μm sources, but no correlation is found between these two features. Over a dozen carrier candidates have been proposed for the 21μm feature, but none of them has been widely accepted and the nature of the 21μm feature remains a mystery. The carrier of the 30μm feature also remains unidentified. MgS dust, once widely accepted as a valid carrier, was ruled out because of the sulfur budget problem. In this work we examine nano-sized FeO dust as a carrier for the 21μm feature. We calculate the IR emission spectrum of FeO nanodust which undergoes single-photon heating in PPNe. It is found that the 21μm feature emitted by FeO nanodust is too broad to explain the observed feature. For the 30μm feature, we argue that graphite could be a viable carrier. Graphite, provided its d.c. conductivity σd.c. exceeds ~100ohm−1cm−1, exhibits a pronounced band at 30μm.

Physical Properties of the Central Stars of Planetary Nebulae in the Magellanic Clouds

1983 ◽  
pp. 373-373
Author(s):  
T. P. Stecher ◽  
S. P. Maran ◽  
T. R. Gull ◽  
L. H. Aller ◽  
M. P. Savedoff
Keyword(s):  
Physical Properties ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Central Stars

Stellar Evolution in the Magellanic Clouds from Studies of Planetary Nebulae

1992 ◽  
pp. 502-502
Author(s):  
N. A. Walton ◽  
M. J. Barlow ◽  
D. J. Monk ◽  
R. E. S. Clegg
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Magellanic Clouds

Spectrophotometry of Selected Planetary Nebulae of Type I in the Magellanic Clouds

1993 ◽  
pp. 584-584
Author(s):  
S. Torres-Peimbert ◽  
M. Peimbert ◽  
M. T. Ruitz ◽  
M. Peña
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Type I

scholarly journals Large-scale structure of the Magellanic Clouds using planetary nebulae

1991 ◽  
Vol 148 ◽  
pp. 89-95
Author(s):  
S. J. Meatheringham
Keyword(s):  
Large Scale ◽  
Planetary Nebulae ◽  
Large Scale Structure ◽  
Magellanic Clouds ◽  
Scale Structure ◽  
The Galaxy ◽  
Young Clusters

The Small and Large Magellanic Clouds (SMC, LMC) are of considerable interest from a kinematical viewpoint. The tidal interation of the Clouds with each other and with the Galaxy appears to have been quite significant in recent times (Murai & Fujimoto 1980). The SMC in particular appears to have been considerably disrupted by a recent close passage to the LMC (Mathewson & Ford 1984, Mathewson 1984, Mathewson et al. 1986). For the LMC Freeman et al. (1983) found that the young and old populations have significantly different rotation solutions.Planetary Nebulae (PN) form a population with age intermediate between the HI and young clusters and the old Population II clusters. A large number of PN are known in the MCs. Sanduleak et al. (1978) compiled a list of 102 in the LMC and 28 in the SMC. Since then other authors have increased the total number known to approximately 140 in the LMC and 50 in the SMC.

scholarly journals Planetary Nebulae in the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 332-338 ◽  
Author(s):  
Michael A. Dopita
Keyword(s):  
Hubble Space Telescope ◽  
Morphological Structure ◽  
Planetary Nebulae ◽  
Spectroscopic Studies ◽  
Magellanic Clouds ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
Central Stars ◽  
The Ideal

The proximity, accurately known distance and low line-of-sight reddening give the ideal circumstances to pursue studies of individual stellar populations in the Magellanic Clouds. Here we show how our understanding of the evolution and chemical composition of the planetary nebulae in the Magellanic Clouds has been impacted by imaging and UV spectroscopic studies using the Hubble Space Telescope. Images provide sizes, internal morphological structure, absolute fluxes, and dynamical ages, while spectra allow us to place the central stars accurately on the H-R Diagram, and we can also examine the details of the evolution, of mass- and age- dependent chemical dredge-up processes, and infer the star-formation history of the Magellanic Clouds.

scholarly journals Spectroscopic Observations of Planetary Nebulae in the Magellanic Clouds

1968 ◽  
Vol 34 ◽  
pp. 34-35 ◽  
Author(s):  
M. W. Feast
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Preliminary Results ◽  
Spectroscopic Observations

A programme of spectroscopic observations of planetary nebulae in both Magellanic Clouds has been underway in Pretoria for some years, and some preliminary results for the LMC have been published (Feast, 1964b). More extensive observations are now available (altogether in both clouds 112 spectra of 39 objects), and these are being prepared for publication elsewhere. Below are summarized the main conclusions so far deduced.

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