AN INFRARED CENSUS OF DUST IN NEARBY GALAXIES WITHSPITZER(DUSTiNGS). II. DISCOVERY OF METAL-POOR DUSTY AGB STARS

This paper is based on photometry from two different observational approaches. Both are of an explorative character and act as feasibility studies. For the future we plan to use these methods to study Asymptotic Giant Branch (AGB) stars in nearby galaxies.First, we present results on broad-band photometry in Bessell V and I, as well as narrow-band measurements in the Wing 778 nm and 812 nm filters of a galactic globular cluster using the new Austrian Oe-FOSC (Oesterreich Faint Object Spectrograph and Camera), a copy of the ESO Instrument EFOSC mounted on our 1.5 m-telescope.The second part of the contribution deals with the possibilities of using Gunn I, J and KS measurements originating from the DENIS (DEep Near Infrared Survey of the Southern Sky) project on similar objects. A few southern dwarf spheroidals already observed within DENIS (covering now some 40% of the southern hemisphere) are selected.

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Carbon-rich AGB stars in our Galaxy and nearby galaxies as possible sources of PAHs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308021558 ◽

2008 ◽

Vol 4 (S251) ◽

pp. 197-200

Author(s):

M. Matsuura ◽

G. C. Sloan ◽

J. Bernard-Salas ◽

A. A. Zijlstra ◽

P. R. Wood ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Agb Stars ◽

Carbon Production ◽

Very Large Telescope ◽

Infrared Spectrometer ◽

Low Metallicity ◽

Nearby Galaxies ◽

Array Camera

AbstractWe have obtained infrared spectra of carbon-rich AGB stars in three nearby galaxies – the Large and Small Magellanic Clouds, and the Fornax dwarf spheroidal galaxy. Our primary aim is to investigate gas compositions and mass-loss rate of these stars as a function of metallicity, by comparing AGB stars in several galaxies with different metallicities. C2H2are detectable from AGB stars, and possibly PAHs are subsequently formed from C2H2. Thus, it is worth investigating chemical processes at low metallicity. These stars were observed using the Infrared Spectrometer (irs) onboard theSpitzer Space Telescopewhich covers 5–35 μm region, and the Infrared Spectrometer And Array Camera (isaac) on the Very Large Telescope which covers the 2.9–4.1 μm region. HCN, CH and C2H2molecular bands, as well as SiC and MgS dust features are identified in the spectra. The equivalent width of C2H2molecular bands is larger at lower metallicity, thus PAHs might be abundant in AGB stars at low metallicity. We find no evidence that mass-loss rates depend on metallicity. Chemistry of carbon stars is affected by carbon production during the AGB phase rather than the metallicities. We argue that lower detection rate of PAHs from the interstellar medium of lower metal galaxies is caused by destruction of PAHs in the ISM by stronger UV radiation field.

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Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

Proceedings of the International Astronomical Union ◽

10.1017/s174392131700062x ◽

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.

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TP-AGB stars in population synthesis models

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310002498 ◽

2009 ◽

Vol 5 (S262) ◽

pp. 36-43 ◽

Cited By ~ 2

Author(s):

Paola Marigo ◽

Léo Girardi ◽

Alessandro Bressan ◽

Bernhard Aringer ◽

Marco Gullieuszik ◽

...

Keyword(s):

Mass Loss ◽

Stellar Evolution ◽

Magellanic Clouds ◽

Asymptotic Giant Branch ◽

Agb Stars ◽

Population Synthesis ◽

Future Developments ◽

First Results ◽

Nearby Galaxies ◽

The Subject

AbstractIn spite of its relevance, the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase is one of the most uncertain phases of stellar evolution, and a major source of disagreement between the results of different population synthesis models of galaxies. I will briefly review the existing literature on the subject, and recall the basic prescriptions that have been used to fix the contribution of TP-AGB stars to the integrated light of stellar populations. The simplicity of these prescriptions greatly contrasts with the richness of details provided by present-day databases of AGB stars in the Magellanic Clouds, which are now being extended to other nearby galaxies. I will present the first results of an ongoing study aimed at simulating photometry, chemistry, pulsation, mass loss, dust properties of AGB star populations in resolved and un-resolved galaxies. We test our predictions against observations from various surveys of the Magellanic Clouds (DENIS, 2MASS, OGLE, MACHO, Spitzer, and AKARI). I will discuss the implications and outline the plan of future developments.

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AGB stars in nearby galaxies

10.1063/1.2348026 ◽

2006 ◽

Author(s):

P. Tsalmantza

Keyword(s):

Agb Stars ◽

Nearby Galaxies

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Global Dust Budgets of the Magellanic Clouds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313001336 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 267-270 ◽

Cited By ~ 1

Author(s):

Mikako Matsuura

Keyword(s):

Life Cycle ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Agb Stars ◽

Dust Production ◽

Space Observatory ◽

Great Opportunity ◽

Dust Sources ◽

Nearby Galaxies

AbstractWithin galaxies, gas and dust are constantly exchanged between stars and the interstellar medium (ISM). The life-cycle of gas and dust is the key to the evolution of galaxies. Despite its importance, it is has been very difficult to trace the life-cycle of gas and dust via observations. The Spitzer Space Telescope and Herschel Space Observatory have provided a great opportunity to study the life-cycle of the gas and dust in very nearby galaxies, the Magellanic Clouds. AGB stars are more important contributors to the dust budget in the Large Magellanic Cloud (LMC), while in the Small Magellanic Cloud (SMC), SNe are dominant. However, it seems that the current estimates of the total dust production from AGB stars is insufficient to account for dust present in the ISM. Other dust sources are needed, and supernovae are promising sources. Alternatively the time scale of dust lifetime itself needs some revisions, potentially because they could be unevenly distributed in the ISM or clumps.

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Spitzer observations of molecules and dust in evolved stars in nearby galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310010720 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 557-557

Author(s):

Mikako Matsuura

Keyword(s):

High Sensitivity ◽

Gas Production ◽

Asymptotic Giant Branch ◽

Agb Stars ◽

Chemical Enrichment ◽

Evolved Stars ◽

Wide Range ◽

Nearby Galaxies ◽

The Impact ◽

High Metallicity

Molecules and dust are formed in and around the asymptotic giant branch (AGB) stars and supernovae (SNe), and are ejected into the interstellar medium (ISM) through the stellar wind. The dust and gas contain elements newly synthesised in stars, thus, dying stars play an important role in the chemical enrichment of the ISM of galaxies. However, quantitative analysis of molecules and dust in these stars had been difficult beyond our Galaxy. The high sensitivity instruments on-board the Spitzer Space Telescope (SST; Werner et al. 2004) have enabled us to study dust and molecules in these stars in nearby galaxies. Nearby galaxies have a wide range in metallicity, thus the impact of the metallicity on dust and gas production can be studied. This study will be useful for chemical evolution of galaxies from low to high metallicity.

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