scholarly journals AGB stars and galactic dynamics

1999 ◽  
Vol 191 ◽  
pp. 500-510 ◽  
Author(s):  
H. Dejonghe ◽  
K. Van Caelenberg
Keyword(s):  
Chemical Composition ◽  
Stellar Population ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Line Of Sight ◽  
Galactic Dynamics ◽  
Stellar Systems ◽  
Agb Stars ◽  
Dynamical Models ◽  
Ir Stars

AGB stars, seen as a stellar population, can be used to probe the dynamical state of galaxies. The relevant data are mostly positions and line-of-sight velocities, sometimes together with information on chemical composition and/or age. As of now, dynamical models have been made for OH/IR stars and Planetary Nebulae. Other candidates are C stars, S stars, and Miras. We review the methods used and the results obtained so far, for the Milky Way and for (relatively nearby) extragalactic stellar systems.

scholarly journals Dynamics of Agb Stars and Planetary Nebulae in the Galaxy

1993 ◽  
Vol 155 ◽  
pp. 541-548
Author(s):  
H. Dejonghe
Keyword(s):  
Planetary Nebulae ◽  
Agb Stars ◽  
Dynamical Models ◽  
Ir Stars ◽  
The Galaxy ◽  
Kinematical Data

The available kinematical data on OH/IR stars and PNs are reviewed. Dynamical models for the OH/IR stars are presented.

scholarly journals Observations of Long Period Variable Stars

1989 ◽  
Vol 106 ◽  
pp. 241-257
Author(s):  
T. Lloyd Evans
Keyword(s):  
Chemical Composition ◽  
Stellar Population ◽  
Variable Stars ◽  
Circumstellar Dust ◽  
Stellar Systems ◽  
Intrinsic Properties ◽  
Long Period ◽  
Large Samples ◽  
Period Variable ◽  
Infrared Wavelengths

The study of long period variable stars has been transformed in recent years by two observational developments. Large samples of stars have been observed at infrared wavelengths, providing knowledge of the intrinsic properties of the star as well as of circumstellar dust shells, and these observations have been extended to the variables in well defined stellar systems to allow their properties to be studied in relation to the stellar population to which they belong. Spectroscopic determinations of chemical composition have also provided several crucial insights.

scholarly journals Intracluster Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 597-604 ◽  
Author(s):  
John J. Feldmeier
Keyword(s):  
Velocity Field ◽  
Stellar Population ◽  
Planetary Nebulae ◽  
Line Of Sight ◽  
Galaxy Groups ◽  
The Past ◽  
Star Production ◽  
Intracluster Light ◽  
Lower Luminosity

We review the progress of research on intracluster planetary nebulae (IPN). In the past five years, hundreds of IPN candidates have been detected in the Virgo and Fornax galaxy clusters and searches are also underway in poorer galaxy groups. From the observations to date, and applying the known properties of extragalactic planetary nebulae, the intracluster light in Virgo and Fornax: 1) is significant, at least 20% of the total cluster stellar luminosity, 2) is elongated in Virgo along our line of sight, and 3) may derive from lower-luminosity galaxies, consistent with some models of intracluster star production. A fraction of IPN candidates are not true IPN, but emission-line sources of very large observed equivalent width (≥ 200 Å). The most likely source for these contaminating objects are Lyman-α galaxies at z ≈ 3.1. Follow-up spectroscopy of the IPN candidates will be crucial to discriminate against high red-shift galaxies and to derive the velocity field of the intracluster stellar population.

scholarly journals ISO Spectra of Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 303-304 ◽  
Author(s):  
Kevin Volk ◽  
Sun Kwok
Keyword(s):  
Chemical Composition ◽  
Dust Emission ◽  
Planetary Nebulae ◽  
Emission Feature ◽  
Significant Fraction ◽  
Energy Output ◽  
Agb Stars ◽  
Dust Component

It has been well known since the IRAS mission that dust emission represents a significant fraction of the energy output from PNe (Zhang & Kwok 1991). Although the dust component in PNe was long thought to be due to the remnants of the envelopes of AGB stars (Kwok 1982), we now know that dust in PNe has a much richer chemical composition. In addition to amorphous silicates and SiC features commonly seen in AGB stars, PNe have been found to have strong aromatic infrared features (Russell et al. 1977), crystalline silicate features (Waters et al. 1997), and an unidentified emission feature at 30 μm (Forrest et al. 1981). In this paper, we show the ISO spectra of a number of PNe illustrating the diverse dust chemistry in PNe.

scholarly journals Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 74-81
Author(s):  
N. C. Sterling
Keyword(s):  
Neutron Capture ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Experimental Investigations ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Element Abundances ◽  
Nearby Galaxies

AbstractNeutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more than 100 PNe in the Milky Way and nearby galaxies. In some objects, several different n-capture elements have been detected, providing valuable constraints to models of AGB nucleosynthesis and evolution. These detections have motivated theoretical and experimental investigations of the atomic data needed to derive accurate n-capture element abundances. In this review, I discuss the methods and results of these atomic data studies, and their application to abundance determinations in PNe.

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 Theoretical abundances in Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 257-257
Author(s):  
Paola Marigo
Keyword(s):  
Chemical Composition ◽  
Mass Loss ◽  
Analytical Model ◽  
Planetary Nebulae ◽  
Stellar Winds ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Thermal Pulse ◽  
Intermediate Mass Stars

A semi-analytical model has been constructed to calculate the TP-AGB evolution of low-and intermediate-mass stars (Marigo et al. 1996), starting from the first thermal pulse until the complete ejection of the envelope by stellar winds. We estimate the changes in the chemical composition of the envelope due to different processes: (i) the intershell nucleosynthesis and convective dredge-up; (ii) envelope burning in the most massive AGB stars (M ≥ 3–4M⊙); (iii) mass loss by stellar winds.

scholarly journals The survey of planetary nebulae in Andromeda (M 31)

2019 ◽  
Vol 624 ◽  
pp. A132 ◽  
Author(s):  
Souradeep Bhattacharya ◽  
Magda Arnaboldi ◽  
Johanna Hartke ◽  
Ortwin Gerhard ◽  
Valentin Comte ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Stellar Population ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Significant Rise ◽  
Minor Axis ◽  
Wide Field ◽  
Detection Techniques ◽  
Current Survey ◽  
M 31

Context.The Andromeda (M 31) galaxy subtends nearly 100 square degrees on the sky. Any study of its halo must therefore account for the severe contamination from the Milky Way halo stars whose surface density displays a steep gradient across the entire M 31 field of view.Aims.Our goal is to identify a population of stars firmly associated with the M 31 galaxy. Planetary nebulae (PNe) are one such population that are excellent tracers of light, chemistry, and motion in galaxies. We present a 16 square degree survey of the disc and inner halo of M 31 with the MegaCam wide-field imager at the CFHT to identify PNe, and characterise the luminosity-specific PN number and PN luminosity function (PNLF) in M 31.Methods.PNe were identified via automated detection techniques based on their bright [O III] 5007 Å emission and absence of a continuum. Subsamples of the faint PNe were independently confirmed by matching with resolvedHubbleSpace Telescope sources from the PanchromaticHubbleAndromeda Treasury and spectroscopic follow-up observations with HectoSpec at the MMT.Results.The current survey reaches two magnitudes fainter than the previous most sensitive survey. We thus identify 4289 PNe, of which only 1099 were previously known. By comparing the PN number density with the surface brightness profile of M 31 out to ∼30 kpc along the minor axis, we find that the stellar population in the inner halo has a luminosity-specific PN number value that is seven times higher than that of the disc. We measure the luminosity function of the PN population and find a bright cut-off and a slope consistent with previous determinations. Interestingly, it shows a significant rise at the faint end, present in all radial bins covered by the survey. This rise in the M 31 PNLF is much steeper than that observed for the Magellanic clouds and Milky Way bulge.Conclusions.The significant radial variation of the PN specific frequency value indicates that the stellar population at deprojected minor-axis radii larger than ∼10 kpc is different from that in the disc of M 31. The rise at the faint end of the PNLF is a property of the late phases of the stellar population. M 31 shows two major episodes of star formation and the rise at the faint end of the PNLF is possibly associated with the older stellar population. It may also be a result of varying opacity of the PNe.

scholarly journals Quantitative Spectral Analysis of hot Post-AGB Stars

2009 ◽  
Vol 5 (S265) ◽  
pp. 356-357
Author(s):  
Daniel R. Costa-Mello ◽  
Simone Daflon ◽  
Claudio B. Pereira
Keyword(s):  
Spectral Analysis ◽  
Chemical Composition ◽  
High Resolution ◽  
Planetary Nebulae ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Quantitative Spectral Analysis ◽  
Luminous Objects

AbstractPost-AGB (PAGB) stars are luminous objects of low and intermediate mass in a final and short stage of evolution in the transition between AGB stars and planetary nebulae (PNe). In this work we present a quantitative spectral analysis of some hot PAGBs based on high resolution spectra. The stellar parameters and chemical composition were obtained from the synthesis of non-LTE spectra.

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