The Inner Abundance Gradient of M33 from Bright Planetary Nebulae

Author(s):  
Grażyna Stasińska ◽  
José M. Vílchez ◽  
Enrique Pérez ◽  
Rosa M. Gonzalez Delgado ◽  
Romano L.M. Corradi ◽  
...  
1983 ◽  
Vol 103 ◽  
pp. 443-460
Author(s):  
Holland C. Ford

Recent surveys for planetary nebulae have given the first identifications in Fornax, NGC 6822, M33, IC 10, Leo A, Sextans A, Pegasus, WLM, NGC 404, and M81, and extended the identifications in the SMC, the LMC, and M31. Observations of planetaries have established chemical compositions in old or intermediate age populations in 8 Local Group galaxies. The chemical compositions show that i) the helium abundance is higher in planetary nebulae than in H II regions in the same galaxy, and ii) nitrogen is overabundant relative to H II regions by factors of 4 to 100. Planetary nebulae are not a major source of helium in star-forming galaxies, and are a major source of nitrogen. The planetary in Fornax has a relatively high O abundance, and, together with Fornax's carbon stars, establishes the presence of at least 2 stellar populations. The abundance gradient derived from 3 planetaries in M31 is very shallow, and gives high abundances at ~ 20 kpc. By using planetary nebulae as standard candles, upper and lower distance limits have been set for 10 Local Group candidates, and a new distance estimated for M81.


1985 ◽  
Vol 87 ◽  
pp. 359-365 ◽  
Author(s):  
S.R. Pottasch ◽  
A. Mampaso ◽  
A. Manchado ◽  
J. Menzies

AbstractNew spectra of A78 and A58 at different positions in the nebulae are presented. An abundance gradient is found in A78, extending quite close to the center. Similarly the nebulous knot near the center of A58 has considerably higher heavy element abundances than the outer regions of this nebula. The ionization state is considerably lower in A58 than A78. In A78 most of the neon is in the form of Ne+3 and Ne+4, indicating that the standard ionization correction factor as used by Jacoby and Ford, is substantially in error. Finally, the very high infrared excesses found in this nebulae are discussed.


1989 ◽  
Vol 157 (1-2) ◽  
pp. 23-29 ◽  
Author(s):  
A. Manchado ◽  
S. R. Pottasch ◽  
A. Mampaso

2006 ◽  
Vol 453 (2) ◽  
pp. 587-593 ◽  
Author(s):  
W. J. Maciel ◽  
L. G. Lago ◽  
R. D. D. Costa

2016 ◽  
Vol 12 (S323) ◽  
pp. 341-342
Author(s):  
George J. S. Pagomenos ◽  
Jeronimo Bernard-Salas ◽  
G. C. Sloan

AbstractMuch of the new dust in the local ISM is produced in the last phases of stellar evolution of low- and intermediate-mass stars on the Asymptotic Giant Branch (AGB). Despite its importance, our knowledge of how dust properties depend on metallicity is limited. Studies of planetary nebulae in irregular galaxies in the Local Group (mostly focused on the LMC and SMC) have revealed a diverse spectral zoo and shown that low metallicity favours carbon-rich dust production by AGB stars. However, at ~1/3 and ~1/5 times the solar metallicity respectively, they provide two snapshots of dust composition at low metallicity, emphasising the need to investigate a region with a range of metallicity values. With its abundance gradient, the Milky Way fits this criterion and provides a good opportunity to observe the dust composition over a large metallicity range. In particular the Galactic anti-center, which is largely unexplored beyond galactocentric distances of 10 kpc, allows us to study the AGB dust a priori assumed to be metal-poor as well as exploring the extent of the Galactic abundance gradient. We analyse a Spitzer spectroscopic sample of 23 planetary nebulae towards the anti-center in order to understand how the metallicity gradient extends beyond 10 kpc from the Galactic center and to observe the dust composition in this region of our Galaxy. We find that the abundance gradients of Ne, S and Ar continue to distances of around 20 kpc (albeit with a large scatter) and the dust emission shows a carbon-rich chemistry similar to that in the Magellanic Clouds.


2011 ◽  
Vol 7 (S283) ◽  
pp. 438-439
Author(s):  
Jackie B. Milingo ◽  
Richard B. C. Henry ◽  
Karen B. Kwitter ◽  
Bruce Balick

AbstractWe examine the abundance gradient in the Milky Way disk via homogeneously determined data for 124 Galactic planetary nebulae (PNe). We present recent results from a detailed regression analysis of the O gradient. With O, Ne, S, Cl, and Ar available and a range of galactocentric distance (Rg) from 0.9 to 21 kpc, we present additional exploration of the disk radial gradient by statistically analyzing a series of short segments of increasing average Rg.


2010 ◽  
Vol 724 (1) ◽  
pp. 748-761 ◽  
Author(s):  
R. B. C. Henry ◽  
Karen B. Kwitter ◽  
Anne E. Jaskot ◽  
Bruce Balick ◽  
Michael A. Morrison ◽  
...  

2005 ◽  
Vol 433 (1) ◽  
pp. 127-135 ◽  
Author(s):  
W. J. Maciel ◽  
L. G. Lago ◽  
R. D. D. Costa

2015 ◽  
Vol 71-72 ◽  
pp. 299-300
Author(s):  
D. Ladjal ◽  
HerPlaNS Consortium
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