scholarly journals Some aspects of the chemical evolution of 4He in the Galaxy: the He/H radial gradient and the ΔY/ΔZ enrichment ratio

2000 ◽  
Vol 198 ◽  
pp. 204-213
Author(s):  
W. J. Maciel
Keyword(s):  
Chemical Evolution ◽  
Heavy Element ◽  
Planetary Nebulae ◽  
Enrichment Ratio ◽  
Radial Gradient ◽  
The Galaxy ◽  
Element Enrichment ◽  
Progenitor Stars

Two aspects of the chemical evolution of 4He in the Galaxy are considered on the basis of a sample of disk planetary nebulae by the application of corrections due to the contamination of 4He from the progenitor stars. First, the He/H radial gradient is analyzed, and then, the helium to heavy element enrichment ratio is determined for metallicities up to the solar value.

scholarly journals Planetary Nebulae: A Probe of the Galaxies Evolution up to the Hubble Time

2006 ◽  
Vol 2 (S235) ◽  
pp. 324-324
Author(s):  
A. F. Kholtygin ◽  
Yu. V. Milanova
Keyword(s):  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Early Age ◽  
The Galaxy ◽  
Galactic Abundance ◽  
Progenitor Stars ◽  
Hubble Time

Chemical evolution of the galactic and extragalactic planetary nebulae (PNe) system beginning from the early age of the Galaxy is investigated. We determine the radial and vertical abundance gradients for C, N, O, Ne, Ar, Cl and S in a dependence on mass and age of the progenitor stars of the nebula. In the Table 1 we compare the galactic abundance gradients for O and Ne for our and neigbour galaxies.

scholarly journals Abundance gradients: tracing the chemical properties of the disk

2009 ◽  
Vol 5 (H15) ◽  
pp. 790-790
Author(s):  
Roberto D.D. Costa ◽  
Walter J. Maciel
Keyword(s):  
Time Evolution ◽  
Chemical Evolution ◽  
Galactic Disk ◽  
Chemical Properties ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
B Stars ◽  
Radial Gradient ◽  
The Galaxy ◽  
Vertical Gradients

AbstractAbundance gradients are key parameters to constrain the chemical evolution of the galactic disk. In this review recent determinations for the radial gradient are described, including its slope as derived from different objects such as planetary nebulae, HII regions, cepheids, or B stars, and for different elements. Inner and outer limits for the radial gradient, as well as its time evolution, both related to the chemical evolution of the Galaxy, are also described. The possible existence of azimuthal and vertical gradients is also discussed.

scholarly journals Helium abundances in planetary nebulae: Nucleosynthesis and chemical evolution

2009 ◽  
Vol 5 (S268) ◽  
pp. 181-182
Author(s):  
W. J. Maciel ◽  
R. D. D. Costa ◽  
T. E. P. Idiart
Keyword(s):  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Heavy Elements ◽  
Solar Neighbourhood ◽  
Host Galaxies ◽  
Intermediate Mass ◽  
Large Sample ◽  
Intermediate Mass Stars ◽  
Progenitor Stars

AbstractWe have obtained a large sample of PN with accurately determined helium abundances, as well as abundances of several heavy elements. The nebulae are located in the solar neighbourhood, in the galactic bulge, disk and anticentre, and in the Magellanic Clouds. The abundances are analyzed both in terms of the nucleosynthesis of intermediate mass stars and the chemical evolution of the host galaxies. In particular, correlations between the He/H ratio and the abundances of N and O are used as constraints of the nucleosynthetic processes occurring in the progenitor stars.

scholarly journals Chemical Abundances of Planetary Nebulae in the LMC

1993 ◽  
Vol 155 ◽  
pp. 586-586
Author(s):  
J.A. De Freitas Pacheco ◽  
R.D.D. Costa
Keyword(s):  
Electron Temperature ◽  
Chemical Evolution ◽  
Spectroscopic Data ◽  
National Laboratory ◽  
Planetary Nebulae ◽  
Chemical Abundances ◽  
Ccd Detector ◽  
Progenitor Stars

We report new spectroscopic data on a sample constituted of 21 well observed planetary nebulae in the LMC. The observations were performed at the National Laboratory for Astrophysics (Brazópolis — Brasil) using the 1.6m telescope and a CCD detector. Extinction, electron temperature and densities were derived for all the planetaries and a comparison is made with results obtained by other surveys, including common objects. Chemical abundances of helium, nitrogen, oxygen, sulphur and argon were also derived for all sample objects. Enrichment of the progenitor stars in He and N due to mixing episodes as well as the relation with the chemical evolution of the LMC are discussed in terms of our data and other observations.

scholarly journals The Origins of Planetary Nebulae in the Inner and Outer Disks of M 31

2016 ◽  
Vol 12 (S323) ◽  
pp. 264-268
Author(s):  
Bruce Balick ◽  
Karen Kwitter ◽  
Romano Corradi ◽  
Rebeca Galera Rosillo ◽  
Richard Henry
Keyword(s):  
Chemical Evolution ◽  
Stellar Population ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Radial Gradient ◽  
M 31 ◽  
Stark Contrast ◽  
Entire Ensemble

AbstractThe planetary nebulae (PNe) of M 31 are receiving considerable attention as probes of its structure and chemical evolution in a galactic environment that is putatively similar to the Milky Way. We have obtained deep spectra for about 30 luminous PNe in M 31’s inner disk and beyond (Rgal < 105 kpc). The entire ensemble of PNe exhibit O/H ~ 2/3 solar with no discernible radial gradient, in stark contrast to the H ii regions of M 31. This suggests that the outer PNe in M 31 formed from a common O-rich ISM at least 5 GY ago. We infer that the outer PNe and the underlying stellar population have little common history in M 31, and that the formation of the O-rich PNe preceded any putative encounter with M 33 ~2–3 Gy ago.

scholarly journals Heavy Element Nucleosynthesis

2018 ◽  
Vol 184 ◽  
pp. 01007
Author(s):  
Mounib F. El Eid
Keyword(s):  
Chemical Evolution ◽  
Neutron Capture ◽  
Heavy Element ◽  
Slow Neutron ◽  
Heavy Elements ◽  
Galactic Chemical Evolution ◽  
Physical Processes ◽  
The Galaxy ◽  
R Process

This contribution deals with the important subject of the nucleosynthesis of heavy elements in the Galaxy. After an overview of several observational features, the physical processes responsible mainly for the formation of heavy elements will be described and linked to possible stellar sites and to galactic chemical evolution. In particular, we focus on the neutron-capture processes, namely the s-process (slow neutron capture) and the r-process (rapid neutron capture) and discuss some problems in connection with their sites and their outcome. The aim is to give a brief overview on the exciting subject of the heavy element nucleosynthesis in the Galaxy, emphasizing its importance to trace the galactic chemical evolution and illustrating the challenge of this subject.

scholarly journals Planetary Nebulae and the Chemical Evolution of Galaxies

1983 ◽  
Vol 103 ◽  
pp. 463-472 ◽  
Author(s):  
Alfonso Serrano
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Low Mass Stars ◽  
Chemical Enrichment ◽  
The Past ◽  
The Galaxy ◽  
History Of ◽  
Low Mass

Tinsley (1978) has done an excellent review that illustrates the methods and concepts that can be developed to assess the effects of planetary nebulae (PN) on the long-term history of the galaxy. Tinsley concluded that research in PN could put constraints on the past rate of star formation and provide information on chemical enrichment by low mass stars.

scholarly journals Planetary nebulae and determination of the bulge–disk boundary

2012 ◽  
Vol 8 (S289) ◽  
pp. 375-378
Author(s):  
Roberto D. D. Costa ◽  
Oscar Cavichia ◽  
Walter J. Maciel
Keyword(s):  
Galactic Center ◽  
Chemical Properties ◽  
Planetary Nebulae ◽  
Galactocentric Distance ◽  
Disk Interface ◽  
Radial Gradient ◽  
Element Abundances ◽  
Outer Component ◽  
The Galaxy ◽  
Kolmogorov Smirnov

AbstractIn this paper, a sample of planetary nebulae in the Galaxy's inner-disk and bulge is used to find the galactocentric distance that optimally separates these two populations in terms of their abundances. Statistical distance scales were used to investigate the distribution of abundances across the disk–bulge interface, while a Kolmogorov–Smirnov test was used to find the distance at which the chemical properties of these regions separate optimally. The statistical analysis indicates that, on average, the inner population is characterized by lower abundances than the outer component. Additionally, for the α-element abundances, the inner population does not follow the disk's radial gradient toward the Galactic Center. Based on our results, we suggest a bulge–disk interface at 1.5 kpc, marking the transition between the bulge and the inner disk of the Galaxy as defined by the intermediate-mass population.

scholarly journals Planetary nebulae and the chemical evolution of the galactic bulge: New abundances of older objects

2011 ◽  
Vol 7 (S283) ◽  
pp. 326-327 ◽  
Author(s):  
Oscar Cavichia ◽  
Roberto D. D. Costa ◽  
Mercedes Mollá ◽  
Walter J. Maciel
Keyword(s):  
Chemical Evolution ◽  
Planetary Nebula ◽  
Luminosity Function ◽  
Planetary Nebulae ◽  
Physical Parameters ◽  
Galactic Bulge ◽  
Chemical Abundances ◽  
The Galaxy ◽  
Low Dispersion ◽  
Chemical Evolution Model

AbstractIn view of their nature, planetary nebulae have very short lifetimes, and the chemical abundances derived so far have a natural bias favoring younger objects. In this work, we report physical parameters and abundances for a sample of old PNe located in the galactic bulge, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman Spectrograph. The new data allow us to extend our database including older, weaker objects that are at the faint end of the planetary nebula luminosity function (PNLF). The results show that the abundances of our sample are lower than those from our previous work. Additionally, the average abundances of the galactic bulge do not follow the observed trend of the radial abundance gradient in the disk. These results are in agreement with a chemical evolution model for the Galaxy recently developed by our group.

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