scholarly journals Luminosity functions for asymptotic giant branch stars

1984 ◽  
Vol 105 ◽  
pp. 175-178 ◽  
Author(s):  
Jay A. Frogel ◽  
V.M. Blanco
Keyword(s):  
Main Sequence ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Ideal Situation ◽  
Luminosity Functions ◽  
Ranking Scheme ◽  
Giant Branch Stars

To understand the evolution of carbon and oxygen rich asymptotic giant branch (AGB) stars it is important to observationally establish the relations between parameters such as luminosity, age, and metallicity. The existence of luminous (brighter than the top of the first giant branch) AGB stars in clusters in the Magellanic Clouds (Mould and Aaronson 1979; Frogel, et al. 1980) provides a nearly ideal situation in which these relations can be determined. Although metallicities and main sequence turn-off ages are known for only a fraction of the clusters, the ranking scheme devised by Searle, et al. (1980; SWB) indicates that age and metallicity are closely related to one another.

scholarly journals Asymptotic Giant Branch Stars in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 363-364
Author(s):  
Neill Reid ◽  
J. R. Mould
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Red Giants ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Satellite Systems ◽  
Luminosity Functions ◽  
Theoretical Predictions

Since the pioneering objective prism surveys by Westerlund (1960) and Blanco et al. (1980), the Magellanic Clouds have proved a fruitful site for exploring the evolution of AGB stars. We have used photometric techniques to extend the prism C-star surveys to M- and S-type AGB stars, constructing luminosity functions and obtaining spectra of individual stars for comparison with theoretical predictions. We have concentrated on the Large Magellanic Cloud (LMC), but we have recently obtained observations of luminous red giants in a region of the Small Magellanic Cloud (SMC). In this paper we compare the results from these studies of the two satellite systems.

scholarly journals Obscured Asymptotic Giant Branch stars in the Magellanic Clouds

1999 ◽  
Vol 191 ◽  
pp. 567-572 ◽  
Author(s):  
Jacco Th. van Loon
Keyword(s):  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Recent Advances ◽  
Giant Branch Stars

We report on some recent advances in the study and understanding of heavily obscured AGB stars in the Magellanic Clouds.

scholarly journals Mass-Losing AGB Stars in the Magellanic Clouds

1993 ◽  
Vol 155 ◽  
pp. 319-319
Author(s):  
Neill Reid
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Planetary Nebula ◽  
Luminosity Function ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
The Future ◽  
Giant Branch Stars

Asymptotic giant branch stars are the immediate precursors to the planetary nebula stage of stellar evolution. It is clear that the latter stages of a stars life on the AGB are accompanied by either continuous or episodic mass-loss, with the final convulsion being the ejection of the envelope (the future planetary shell), the gradual exposure of the bare CO core and the rapid horizontal evolution to the blue in the H-R diagram. Thus, the structure of the planetary nebula luminosity function, particularly at the higher luminosities (although this phase is extremely rapid), is intimately tied to the luminosity function of the AGB.

scholarly journals Thermally-pulsing asymptotic giant branch stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 385-390
Author(s):  
Paola Marigo ◽  
Léo Girardi ◽  
Alessandro Bressan ◽  
Martin A. T. Groenewegen ◽  
Bernhard Aringer ◽  
...  
Keyword(s):  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Circumstellar Dust ◽  
Stellar Winds ◽  
Asymptotic Giant Branch Stars ◽  
Stellar Clusters ◽  
Agb Stars ◽  
Wide Range ◽  
Giant Branch Stars ◽  
Theoretical Project

AbstractWe present the latest results of a theoretical project aimed at investigating the properties of thermally-pulsing asymptotic giant branch (TP-AGB) stars in different host systems. For this purpose, we have recently calculated calibrated synthetic TP-AGB tracks — covering a wide range of metallicities (0.0001 ≤ Z ≤ 0.03) up to the complete ejection of the envelope by stellar winds (Marigo & Girardi 2007) — and used them to generate new sets of stellar isochrones (Marigo et al. 2008). The latter are converted to about 25 different photometric systems, including the mid-infrared filters of Spitzer and AKARI as the effect of circumstellar dust from AGB stars is taken into account. First comparisons with AGB data in the MC field and stellar clusters are discussed.

scholarly journals Lithium production by thermohaline mixing in low-mass, low-metallicity asymptotic giant branch stars

2009 ◽  
Vol 5 (S268) ◽  
pp. 405-410
Author(s):  
Richard J. Stancliffe ◽  
George C. Angelou ◽  
John C. Lattanzio
Keyword(s):  
Main Sequence ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Low Metallicity ◽  
Low Mass ◽  
Thermal Pulses ◽  
Giant Branch Stars

AbstractWe examine the effects of thermohaline mixing on the composition of the envelopes of low-metallicity asymptotic giant branch (AGB) stars. We have evolved models of 1, 1.5 and 2M⊙ and of metallicity Z = 10−4 from the pre-main sequence to the end of the thermal pulsing asymptotic giant branch with thermohaline mixing applied throughout the simulations. We find that the small amount of 3He that remains after the first giant branch is enough to drive thermohaline mixing on the AGB and that the mixing is most efficient in the early thermal pulses, with the efficiency dropping from pulse to pulse. We note a surprising increase in the 7Li abundance, with log10ϵ(7Li) reaching values of over 2.5 in the 1.5M⊙ model. It is thus possible to get stars which are both C- and Li-rich at the same time. We compare our models to measurements of carbon and lithium in carbon-enhanced metal-poor stars which have not yet reached the giant branch. These models can simultaneously reproduced the observed C and Li abundances of carbon-enhanced metal-poor turn-off stars that are Li-rich.

scholarly journals Radiation-Pressure Ejection of Planetary Nebulae in Asymptotic-Giant-Branch Stars

1999 ◽  
Vol 190 ◽  
pp. 370-371
Author(s):  
A. V. Sweigart
Keyword(s):  
Radiation Pressure ◽  
Critical Value ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Core Mass ◽  
The Core ◽  
Giant Branch Stars ◽  
Eddington Limit

We have investigated the possibility that radiation pressure might trigger planetary nebula (PN) ejection during helium-shell flashes in asymptotic-giant-branch (AGB) stars. We find that the outward flux at the base of the hydrogen envelope during a flash will reach the Eddington limit when the envelope mass Menv falls below a critical value that depends on the core mass MH and composition. These results may help to explain the helium-burning PN nuclei found in the Magellanic Clouds.

Infrared Studies of the Variability and Mass Loss of Some of the Dustiest Asymptotic Giant Branch Stars in the Magellanic Clouds

2018 ◽  
Vol 14 (S343) ◽  
pp. 498-499
Author(s):  
B. Sargent ◽  
S. Srinivasan ◽  
M. Boyer ◽  
M. Feast ◽  
P. Whitelock ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Infrared Studies ◽  
Infrared Wavelengths ◽  
Optical Wavelengths ◽  
Giant Branch Stars

AbstractThe asymptotic giant branch (AGB) stars with the reddest colors have the largest amounts of circumstellar dust. AGB stars vary in their brightness, and studies show that the reddest AGB stars tend to have longer periods than other AGB stars and are more likely to be fundamental mode pulsators than other AGB stars. Such stars are difficult to study, as they are often not detected at optical wavelengths. Therefore, they must be observed at infrared wavelengths. Using the Spitzer Space Telescope, we have observed a sample of very dusty AGB stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) over Cycles 9 through 12 during the Warm Spitzer mission. For each cycle’s program, we typically observed a set of AGB stars at both 3.6 and 4.5 μm wavelength approximately monthly for most of a year. We present results from our analysis of the data from these programs.

scholarly journals Obscured Asymptotic Giant Branch Stars in the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 387-388
Author(s):  
Jacco Th. van Loon
Keyword(s):  
Mass Loss ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Ongoing Study ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Giant Branch Stars

I present results from an ongoing study of the evolution and mass loss of AGB stars with optically thick circumstellar envelopes in the Magellanic Clouds.

scholarly journals Stellar Models and Yields of Asymptotic Giant Branch Stars

2007 ◽  
Vol 24 (3) ◽  
pp. 103-117 ◽  
Author(s):  
Amanda Karakas ◽  
John C. Lattanzio
Keyword(s):  
Main Sequence ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Population Synthesis ◽  
Intermediate Phases ◽  
Structural Details ◽  
Solar Metallicity ◽  
Stellar Models ◽  
Giant Branch Stars

AbstractWe present stellar yields calculated from detailed models of low and intermediate-mass asymptotic giant branch (AGB) stars. We evolve models with a range of mass from 1 to 6 M⊙, and initial metallicities from solar to 1/200th of the solar metallicity. Each model was evolved from the zero age main sequence to near the end of the thermally pulsing (TP) AGB phase, and through all intermediate phases including the core He-flash for stars initially less massive than 2.5 M⊙. For each mass and metallicity, we provide tables containing structural details of the stellar models during the TP-AGB phase, and tables of the stellar yields for 74 species from hydrogen through to sulfur, and for a small number of iron-group nuclei. All tables are available for download. Our results have many applications including use in population synthesis studies and the chemical evolution of galaxies and stellar systems, and for comparison to the composition of AGB and post-AGB stars and planetary nebulae.

scholarly journals Carbon stars as standard candles – II. The median J magnitude as a distance indicator

2020 ◽  
Vol 501 (1) ◽  
pp. 933-947
Author(s):  
Javiera Parada ◽  
Jeremy Heyl ◽  
Harvey Richer ◽  
Paul Ripoche ◽  
Laurie Rousseau-Nepton
Keyword(s):  
Luminosity Function ◽  
Asymptotic Giant Branch ◽  
Distance Modulus ◽  
Asymptotic Giant Branch Stars ◽  
Luminosity Functions ◽  
Best Fitting ◽  
Distance Indicator ◽  
Ngc 6822 ◽  
The Given ◽  
Giant Branch Stars

ABSTRACT We introduce a new distance determination method using carbon-rich asymptotic giant branch stars (CS) as standard candles and the Large and Small Magellanic Clouds (LMC and SMC) as the fundamental calibrators. We select the samples of CS from the ((J − Ks)0, J0) colour–magnitude diagrams, as, in this combination of filters, CS are bright and easy to identify. We fit the CS J-band luminosity functions using a Lorentzian distribution modified to allow the distribution to be asymmetric. We use the parameters of the best-fitting distribution to determine if the CS luminosity function of a given galaxy resembles that of the LMC or SMC. Based on this resemblance, we use either the LMC or SMC as the calibrator and estimate the distance to the given galaxy using the median J magnitude ($\overline{J}$) of the CS samples. We apply this new method to the two Local Group galaxies NGC 6822 and IC 1613. We find that NGC 6822 has an ‘LMC-like’ CS luminosity function, while IC 1613 is more ‘SMC-like’. Using the values for the median absolute J magnitude for the LMC and SMC found in Paper I we find a distance modulus of μ0 = 23.54 ± 0.03 (stat) for NGC 6822 and μ0 = 24.34 ± 0.05 (stat) for IC 1613.

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