A New Catalog of Silicate Carbon Stars

Kwon, Young-Joo; Suh, Kwang Wook

doi:10.5303/jkas.2014.47.4.123

Cited by 11 publications

(17 citation statements)

References 49 publications

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“…However, this scenario could be unlikely for many objects because the timescale for such a transitional object to be observed as a silicate carbon star is predicted to be short (shorter than about 400 years; Kwon & Suh 2014). So far, about 29 silicate carbon stars have been identified in our Galaxy (Kwon & Suh 2014). Morris (1987) and Lloyd Evans (1990) suggested that a silicate carbon star is a binary system that has a primary carbon star and a low-luminosity companion.…”

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A Model for the Dust Envelope of the Silicate Carbon Star Iras 09425-6040

Suh

2016

ApJ

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IRAS 09425-6040 (I09425) is a silicate carbon star with conspicuous crystalline silicate and water-ice features and emission excesses in the far-infrared and millimeter (mm) wavelength ranges. To understand properties of the dust envelope of I09425, we propose a physical model based on the observations and known properties of asymptotic giant branch stars and dust. We perform radiative transfer model calculations using multiple dust shells and disks with various dust species. We compare the model results with the observed spectral energy distribution (SED) acquired with different telescopes. We find that the physical model for I09425 using multiple shells of carbon and silicate dust and multiple disks of amorphous and crystalline silicates reproduces the observed SED fairly well. This object looks to have detached cold O-rich (silicate and water-ice) dust shells, which could be remnants of the recent chemical transition from O to C and an inner C-rich dust shell. A long-lived thin disk of very large silicate grains can reproduce the emission excess in the mm wavelength band and a recently formed thick disk of crystalline silicates can reproduce the prominent emission features in the spectral range 8-45 μm. The highly crystallized silicates could be recently formed by high temperature annealing due to the last O-rich superwind just before the chemical transition of the central star. I09425 could be a rare object that has the remnants of past O-rich stellar winds in the outer shells as well as in the circumbinary disks.Key words: circumstellar matter -dust, extinction -infrared: stars -radiative transfer -stars: AGB and post-AGB INTODUCTIONBased on the chemistry of the photosphere and/or the circumstellar envelope, asymptotic giant branch (AGB) stars are generally classified as O-rich (M-type) or C-rich (C-type). Carbon stars are generally believed to be the evolutionary successors of O-rich AGB stars because an O-rich AGB star may become a carbon star when the star goes through C dredge-up processes due to thermal pulses (Iben 1981;Chan & Kwok 1990).As an AGB star evolves, a thermal pulse due to an internal helium shell flash has been hypothesized as a major cause of an episode of greatly enhanced mass-loss, commonly referred to as a superwind phase (Wood 1990). One thermal pulse every 10 4 -10 5 years that endures for a few hundred years is expected (Iben & Renzini 1983;Vassiliadis & Wood 1993). The chemical transition from O to C and superwind, which is induced by a thermal pulse, is known to make major effects on the dust envelopes around AGB stars (e.g., Groenewegen et al. 1995;Suh 2014).Silicate carbon stars show the characteristics of a carbon star and circumstellar silicate dust features. They were discovered by IRAS observations (Little-Marenin 1986; Willems & de Jong 1986). Willems & de Jong (1986) and Chan & Kwok (1991) suggested that silicate carbon stars are objects in transition from O-rich AGB stars to carbon stars. Many of the silicate carbon stars are fairly well fitted with a simple deta...

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A Model for the Dust Envelope of the Silicate Carbon Star Iras 09425-6040

Suh

2016

ApJ

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“…We expect that most of them are likely to be binary systems rather than single stars (e.g., Kwon & Suh 2014). Silicate carbon stars could have a low-luminosity companion and a relatively long-lived disk of silicate dust that is supposed to be formed when the primary was still an O-rich AGB star.…”

Section: Binary Stars and Dusty Disksmentioning

confidence: 99%

“…Kwon & Suh (2012) presented a revised sample of 3373 O-rich AGB stars. Kwon & Suh (2014) presented a revised sample of silicate carbon stars (29 confirmed objects and 27 unconfirmed objects). Therefore, the updated catalog lists 3373 O-rich, 1168 C-rich, 362 Stype and 29 (+27) silicate carbon stars.…”

Section: A Catalog Of Agb Starsmentioning

confidence: 99%

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Astrophysics of Dusty Stellar Winds From Agb Stars

Suh¹

2014

Journal of The Korean Astronomical Society

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Abstract:The main site of dust formation is believed to be the cool envelopes around AGB stars. Nearly all AGB stars can be identified as long-period variables (LPVs) with large amplitude pulsation. Shock waves produce by the strong pulsation and radiation pressure on newly formed dust grains drive dusty stellar winds with high mass-loss rates. IR observations of AGB stars identify various dust species in different physical conditions. Radio observations of gas phase materials are helpful to understand the overall properties of the stellar winds. In this paper, we review (i) classification of AGB stars; (ii) IR two-color diagrams of AGB stars; (iii) pulsation of AGB stars; (iv) dust around AGB stars including dusty stellar winds; (v) dust envelopes around AGB stars; (vi) mass-loss and evolution of AGB stars; and (vii) contribution of AGB dust to galactic environments. We discuss various observational evidences and their theoretical interpretations.

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“…Kwon & Suh (2012) presented a revised list of 3373 O-rich AGB stars. Kwon & Suh (2014) presented a revised catalog of 29 silicate carbon stars, from which two of them are post-AGB stars.…”

Section: Previous Catalogs Of Agb Stars and Verificationmentioning

confidence: 99%

A New Catalog of Agb Stars Based on Infrared Two-Color Diagrams

Suh¹,

Hong²

2017

Journal of The Korean Astronomical Society

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We present a new catalog of AGB stars based on infrared two-color diagrams (2CDs) and known properties of the pulsations and spectra. We exclude some misclassified objects from previous catalogs. We identify color areas in two IR 2CDs where most O-rich and C-rich objects listed in previous catalogs of AGB stars are found. By collecting new objects in these color selection areas in the two IR 2CDs, we find candidate objects for AGB stars. By using the color selection method, we identify 3996 new objects in the O-rich areas, 1487 new objects in the C-rich areas, and 295 new objects in the overlap areas of the two 2CDs simultaneously. We have found that 470 O-rich and 9 C-rich objects are Mira variables with positive spectral identification and they are newly identified AGB stars. We present a new catalog of 3828 O-rich AGB stars and 1168 C-rich AGB stars excluding misclassified objects and adding newly identified objects.

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A New Catalog of Silicate Carbon Stars

Cited by 11 publications

References 49 publications

A Model for the Dust Envelope of the Silicate Carbon Star Iras 09425-6040

A Model for the Dust Envelope of the Silicate Carbon Star Iras 09425-6040

Astrophysics of Dusty Stellar Winds From Agb Stars

A New Catalog of Agb Stars Based on Infrared Two-Color Diagrams

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