General Catalog of Galactic Carbon Stars by C. B. Stephenson. Third Edition (Errata)

Alksnis, A.; Balklavs, A.; Dzervitis, U.; Eglitis, I.; Paupers, O.; Pundure, I.

doi:10.1515/astro-2001-0310

Cited by 30 publications

(27 citation statements)

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“…The derived pulsation masses (0.5-4 M ) are in good agreement with those initial masses. On a small sample, Alksnis et al (1998) found a reasonable agreement with tracks of (0.7-4 M ), making use of some observed parallaxes. For S stars, Van Eck et al (1998) selected 1.5 to 5 M model tracks.…”

Section: Summary and Discussionsupporting

confidence: 59%

The pulsation modes and masses of carbon-rich long period variables

Bergeat

Knapik

Rutily

2002

A&A

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Abstract. Following our study of the carbon-rich giants in the HR diagram and of their luminosity function (Paper III), we investigate the pulsation data of the long period variables (LPVs) included in our sample. Pulsation modes (fundamental, overtone(s)) for carbon LPVs are identified in the period-radius diagram, making use of observed bi-periodicity in a small subsample of those stars, and of comparison to models. Mean pulsation masses are then deduced from theoretical PMR-relations, with due attention paid to a possible bias while averaging. Mean (present) pulsation masses (0.6−4.0 M ) are found to increase along the group sequence HC5 to CV6, with still larger masses possibly associated with cool extreme CV7-objects with strong mass loss and thick circumstellar shells. This is consistent with the 0.8-4 M range of initial masses found in Paper III for the majority of carbon-rich giants affected by mass loss during their evolution. The pulsation masses found for a few HC-stars (M ≤ 0.8 M ) are consistent with their low initial masses (M i < ∼ 1.1 M ) , as inferred from their thick disk membership (age 11 Gyr?) and locus in the HR diagram. A mean pulsation mass of 0.6 M is found for the three population II Cepheids in the sample. A mass-luminosity diagram is proposed for the Galactic carbon giants. The data from observations is found consistent with theoretical predictions from AGB modeling, specially the third dredge-up (TDU) through thermal pulses (TP) with a carbon star formation line (CSFL) for TP-AGB stars. It appears that the CV-giants are close to the tip and end of their evolutionary tracks in the TP-AGB of the HR diagram. It is confirmed that this end shifts toward lower effective temperatures and higher luminosities, with increasing masses. It is shown that the C/O abundance ratios do correlate with effective temperatures, according to three distinct distributions (halo CH stars, thick disk HC-stars, and thin disk CV-stars). The mean stellar density decreases along the HC5-CV7 sequence, while the surface gravity remains nearly constant at about 0.5 CGS unit log g −0.3; 5 × 10 −3 SI . The nature of (thin disk) CV-stars as TP-AGB objects being confirmed, the discussion is focused on (thick disk) HC-stars since the origin of these old low-mass giants remains unclear. Unpredicted extra mixing on RGB and/or E-AGB is favored. Evolution from (old, low O/H) dwarf carbon stars is also considered since observations of metal-poor stars and recent calculations point to large supersolar [C/Fe] ratios in Population III objects and contamination through rapid cycling in the interstellar medium.

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Section: Summary and Discussionsupporting

confidence: 59%

The pulsation modes and masses of carbon-rich long period variables

Bergeat

Knapik

Rutily

2002

A&A

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“…Thus, Totten & Irwin (1998) assumed a single value of MR = −3.5 mag. But even N-types have a wide range of absolute visual magnitudes as determined from Hipparcos distances (Alksnis et al 1998). Mauron et al (2004) use a standard MK s calibrated against LMC carbon stars, but with the additional refinement of including (J −Ks) colour.…”

Section: Carbon Starsmentioning

confidence: 99%

Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Huxor

Grebel

2015

Mon. Not. R. Astron. Soc.

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We assemble 121 spectroscopically-confirmed halo carbon stars, drawn from the literature, exhibiting measurable variability in the Catalina Surveys. We present their periods and amplitudes, which are used to estimate distances from period-luminosity relationships. The location of the carbon stars -and their velocities when availableallow us to trace the streams of the Sagittarius (Sgr) dwarf spheroidal galaxy. These are compared to a canonical numerical simulation of the accretion of Sgr. We find that the data match this model well for heliocentric distances of 15-50 kpc, except for a virtual lack of carbon stars in the trailing arm just north of the Galactic Plane, and there is only tentative evidence of the leading arm south of the Plane. The majority of the sample can be attributed to the Sgr accretion. We also find groups of carbon stars which are not part of Sgr; most of which are associated with known halo substructures. A few have no obvious attribution and may indicate new substructure. We find evidence that there may be a structure behind the Sgr leading stream apocentre, at ∼100 kpc, and a more distant extension to the Pisces Overdensity also at ∼100 kpc. We study a further 75 carbon stars for which no good period data could be obtained, and for which NIR magnitudes and colours are used to estimate distances. These data add support for the features found at distances beyond 100 kpc.

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“…We give the stellar name, the effective temperature, the mean metallicity [M/H], the carbon over oxygen abundances ratio (C/O), the corresponding difference between carbon and oxygen abundances ( (C) − (O)), the carbon isotopic ratio and the range of estimated bolometric absolute magnitudes. Alknis et al (1998). The second one was derived after the bolometric correction by Wood et al (1983).…”

Section: Analysis: the Extragalactic Carbon Stars And Their Chemical mentioning

confidence: 99%

Chemical analysis of carbon stars in the Local Group

Laverny¹,

Abia

Domínguez

et al. 2006

A&A

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We present the first results of our ongoing chemical study of carbon stars in the Local Group of galaxies. We used spectra obtained with UVES at the 8.2 m Kueyen-VLT telescope and a new grid of spherical model atmospheres for cool carbon-rich stars which include polyatomic opacities, to perform a full chemical analysis of one carbon star, BMB-B 30, in the Small Magellanic Cloud (SMC) and two, IGI95-C1 and IGI95-C3, in the Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy. Our main goal is to test the dependence on the stellar metallicity of the s-process nucleosynthesis and mixing mechanism occurring in AGB stars. For these three stars, we find important s-element enhancements with respect to the mean metallicity ([M/H]), namely [s/M] ≈ +1.0, similar to the figure found in galactic AGB stars of similar metallicity. The abundance ratios derived between elements belonging to the first and second s-process abundance peaks, corresponding to nuclei with a magic number of neutrons N = 50 (88Sr, 89Y, 90Zr) and N = 82 (138Ba, 139La, 140Ce, 141Pr), agree remarkably well with the theoretical predictions of low mass (M < 3 M ) metal-poor AGB nucleosynthesis models where the main source of neutrons is the 13 C(α, n) 16 O reaction activated during the long interpulse phase, in a small pocket located within the He-rich intershell. The derived C/O and 12 C/ 13 C ratios are, however, more difficult to reconcile with theoretical expectations. Possible explanations, like the extrinsic origin of the composition of these carbon stars or the operation of a non-standard mixing process during the AGB phase (such as the cool bottom process), are discussed on the basis of the collected observational constraints.

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General Catalog of Galactic Carbon Stars by C. B. Stephenson. Third Edition (Errata)

Cited by 30 publications

References 0 publications

The pulsation modes and masses of carbon-rich long period variables

The pulsation modes and masses of carbon-rich long period variables

Tracing the tidal streams of the Sagittarius dSph, and halo Milky Way features, with carbon-rich long-period variables

Chemical analysis of carbon stars in the Local Group

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