Infrared photometry and evolution of mass-losing AGB stars

Guandalini, R.

doi:10.1051/0004-6361/200911764

Cited by 9 publications

(10 citation statements)

References 25 publications

(20 reference statements)

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“…It has been shown (Knapp 1985) that oxygen-rich stars have a wider range of mass-loss rates than C-rich stars for which theṀ is globally more homogeneous. On average, mass loss rates of C stars are higher than those of MS and S stars (Guandalini 2010). Apart from the fact that the mass-loss rate standard deviation of O-rich stars is indeed found to be somewhat larger than that of C-rich stars, no clear dichotomy emerges between the mass loss rates of O-rich stars and C-rich stars in the present sample.…”

Section: Oxygen-rich Versus Carbon-rich Chemistrycontrasting

confidence: 55%

A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants

Cox

Kerschbaum

Marle

et al. 2011

A&A

192

263

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Aims. Our goal is to study the different morphologies associated to the interaction of the stellar winds of AGB stars and red supergiants with the interstellar medium (ISM) to follow the fate of the circumstellar matter injected into the interstellar medium. Methods. Far-infrared Herschel/PACS images at 70 and 160 μm of a sample of 78 Galactic evolved stars are used to study the (dust) emission structures developing out of stellar wind-ISM interaction. In addition, two-fluid hydrodynamical simulations of the coupled gas and dust in wind-ISM interactions are used for comparison with the observations. Results. Four distinct classes of wind-ISM interaction (i.e. "fermata", "eyes", "irregular", and "rings") are identified, and basic parameters affecting the morphology are discussed. We detect bow shocks for ∼40% of the sample and detached rings for ∼20%. The total dust and gas mass inferred from the observed infrared emission is similar to the stellar mass loss over a period of a few thousand years, while in most cases it is less than the total ISM mass potentially swept-up by the wind-ISM interaction. De-projected stand-off distances (R 0 ) -defined as the distance between the central star and the nearest point of the interaction region -of the detected bow shocks ("fermata" and "eyes") are derived from the PACS images and compared to previous results, model predictions, and the simulations. All observed bow shocks have stand-off distances smaller than 1 pc. Observed and theoretical stand-off distances are used together to independently derive the local ISM density. Conclusions. Both theoretical (analytical) models and hydrodynamical simulations give stand-off distances for adopted stellar properties that are in good agreement with the measured de-projected stand-off distance of wind-ISM bow shocks. The possible detection of a bow shock -for the distance-limited sample -appears to be governed by its physical size as set roughly by the stand-off distance. In particular the star's peculiar space velocity and the density of the ISM appear decisive in detecting emission from bow shocks or detached rings. In most cases the derived ISM densities concur with those typical of the warm neutral and ionised gas in the Galaxy, though some cases point towards the presence of cold diffuse clouds. Tentatively, the "eyes" class objects are associated to (visual) binaries, while the "rings" generally do not appear to occur for M-type stars, only for C or S-type objects that have experienced a thermal pulse.

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Section: Oxygen-rich Versus Carbon-rich Chemistrycontrasting

confidence: 55%

A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants

Cox

Kerschbaum

Marle

et al. 2011

A&A

192

263

View full text Add to dashboard Cite

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“…2 in that paper), the present model is in agreement with the bolometric magnitude (M bol ) observed for TP−AGB stars (e.g. [12]). PPN is described in Herwig et al (this vol.…”

Section: Post−processing Calculationssupporting

confidence: 92%

Complete nucleosynthesis calculations for low-mass stars from NuGrid

Pignatari¹,

Herwig²,

Bennett³

et al. 2009

Proceedings of 10th Symposium on Nuclei in the Cosmos — PoS(NIC X)

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Many nucleosynthesis and mixing processes of low−mass stars as they evolve from the Main Sequence to the thermal-pulse Asymptotic Giant Branch phase (TP−AGB) are well understood (although of course important physics components, e.g. rotation, magnetic fields, gravity wave mixing, remain poorly known). Nevertheless, in the last years presolar grain measurements with high resolution have presented new puzzling problems and strong constraints on nucleosynthesis processes in stars. The goal of the NuGrid collaboration is to present uniform yields for a large range of masses and metallicities, including low−mass stars and massive stars and their explosions. Here we present the first calculations of stellar evolution and high−resolution, post−processing simulations of an AGB star with an initial mass of 2 M ⊙ and solar−like metallicity (Z=0.01), based on the post−processing code PPN. In particular, we analyze the formation and evolution of the radiative 13 C−pocket between the 17th TP and the 18th TP. The s-process nucleosynthesis profile of a sample of heavy isotopes is also discussed, before the next convective TP occurrence. 10th Symposium on Nuclei in the Cosmos

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“…All our models include the mass‐loss rate from Vassiliadis and Wood (1993), which mimics the entire evolution of the mass‐loss rate in AGB stars. This includes an initial long phase where the star remains a semi‐regular variable, with rather short variability periods and moderate mass‐loss rates (of the order of 10 −7 M ⊙ /yr, e.g., Guandalini et al. 2006) and a final “superwind” phase, which sets off when the radial pulsation period exceeds 500 days, with the mass‐loss rate increasing to a few 10 −5 M ⊙ /yr.…”

Section: Super‐agb Stellar Modelsmentioning

confidence: 99%

Short‐lived radioactivity in the early solar system: The Super‐AGB star hypothesis

Lugaro

Doherty

Karakas

et al. 2012

Meteorit & Planetary Scien

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Abstract-The composition of the most primitive solar system condensates, such as calciumaluminum-rich inclusions (CAIs) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., 26 Al, were present in the early solar system. Their abundances require a local or stellar origin, which, however, is far from being understood. We present for the first time the abundances of several SLR up to 60 Fe predicted from stars with initial mass in the range approximately 7-11 M x . These stars evolve through core H, He, and C burning. After core C burning they go through a ''Super''-asymptotic giant branch (Super-AGB) phase, with the H and He shells activated alternately, episodic thermal pulses in the He shell, a very hot temperature at the base of the convective envelope (approximately 10 8 K), and strong stellar winds driving the H-rich envelope into the surrounding interstellar medium. The final remnants of the evolution of Super-AGB stars are mostly O-Ne white dwarfs. Our Super-AGB models produce 26 Al ⁄ 27 Al yield ratios approximately 0.02-0.26. These models can account for the canonical value of the 26 Al ⁄ 27Al ratio using dilutions with the solar nebula of the order of 1 part of Super-AGB mass per several 10 2 to several 10 3 of solar nebula mass, resulting in associated changes in the O-isotope composition in the range D 17 O from 3 to 20&. This is in agreement with observations of the O isotopic ratios in primitive solar system condensates, which do not carry the signature of a stellar polluter. The radionuclides 41 Ca and 60 Fe are produced by neutron captures in Super-AGB stars and their meteoritic abundances are also matched by some of our models, depending on the nuclear and stellar physics uncertainties as well as the meteoritic experimental data. We also expect and are currently investigating Super-AGB production of SLR heavier than iron, such as 107 Pd.

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Infrared photometry and evolution of mass-losing AGB stars

Cited by 9 publications

References 25 publications

A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants

A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants

Complete nucleosynthesis calculations for low-mass stars from NuGrid

Short‐lived radioactivity in the early solar system: The Super‐AGB star hypothesis

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