The
                    <i>Y</i>
                    <sup>2</sup>
                    Stellar Evolutionary Tracks

Yi, Sukyoung K.; Kim, Yong Cheol; Demarque, P.

doi:10.1086/345101

Cited by 283 publications

(340 citation statements)

References 10 publications

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“…in Table 1 from the calibration by Alonso et al (1999). We adopt log g = 4.44 cm s −2 and T eff , = 5777 K. A cluster's turn-off mass has been estimated from the stellar evolutionary tracks by Yi et al (2003): turn-off masses are 3.3 M for NGC 2251, 2.1 M for NGC 2266, 3.8 M for NGC 2335, 3.0 M for NGC 2482, 2.8 M for NGC 2527, 3.1 M for NGC 2539 and 1.4 M for NGC 2682. Red giants are assumed to have the turn-off mass in computing the surface gravity.…”

Section: Photometrymentioning

confidence: 99%

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Reddy

Giridhar

Lambert

2015

Monthly Notices of the Royal Astronomical Society

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We have analyzed high-resolution echelle spectra of red giant members for seven open clusters in the Galactic anticentre direction to explore their chemical compositions. Cluster membership has been confirmed by radial velocity. The spread in temperatures and gravities being very small among the red giants, nearly the same stellar lines were employed for all stars thereby reducing the abundance errors: the errors of the average abundance for a cluster were generally in the 0.02 to 0.05 dex range. Our present sample covers Galactocentric distances of 8.3 to 11.3 kpc and an age range of 0.2 to 4.3 Gyr. A careful comparison of our results for the cluster NGC 2682 (M 67) to other high-resolution abundance studies in the literature shows general good agreement for almost all elements in common.

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Section: Photometrymentioning

confidence: 99%

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Reddy

Giridhar

Lambert

2015

Monthly Notices of the Royal Astronomical Society

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“…Masses and surface gravities were obtained from theoretical evolutionary tracks due to Kim et al (2002) and Yi et al (2003). We adopt this homogeneous scale of evolutionary surface gravities as our logg scale.…”

Section: Hα Samplementioning

confidence: 99%

Fine structure of the age-chromospheric activity relation in solar-type stars

Mello

Dutra-Ferreira

Ribas

2016

A&A

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Context. Strong spectral lines are useful indicators of stellar chromospheric activity. They are physically linked to the convection efficiency, differential rotation, and angular momentum evolution and are a potential indicator of age. However, for ages > 2 Gyr, the age-activity relationship remains poorly constrained thus hampering its full application. Aims. The Ca II infrared triplet (IRT lines, λλ 8498, 8542, and 8662) has been poorly studied compared to classical chromospheric indicators. We report in this paper absolute chromospheric fluxes in the three Ca II IRT lines, based on a new calibration tied to up-to-date model atmospheres. Methods. We obtain the Ca II IRT absolute fluxes for 113 FGK stars from high signal-to-noise ratio (S/N) and highresolution spectra covering an extensive domain of chromospheric activity levels. We perform an absolute continuum flux calibration for the Ca II IRT lines anchored in atmospheric models calculated as an explicit function of effective temperatures (T eff ), metallicity ([Fe/H]), and gravities (log g) avoiding the degeneracy usually present in photometric continuum calibrations based solely on color indices. Results. The internal uncertainties achieved for continuum absolute flux calculations are ≈ 2% of the solar chromospheric flux, one order of magnitude lower than for photometric calibrations. Using Monte Carlo simulations, we gauge the impact of observational errors on the final chromospheric fluxes due to the absolute continuum flux calibration and find that T eff uncertainties are properly mitigated by the photospheric correction leaving [Fe/H] as the dominating factor in the chromospheric flux uncertainty. Conclusions. Across the FGK spectral types, the Ca II IRT lines are sensitive to chromospheric activity. The reduced internal uncertainties reported here enable us to build a new chromospheric absolute flux scale and explore the ageactivity relation from the active regime down to very low activity levels and a wide range of T eff , mass, [Fe/H], and age.

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“…It should be noted that the surface gravity was allowed to vary in a small interval determined by the stellar density derived from the light curve fits only. X = 71%, helium 27% and metals Z = 2%; Yi et al 2001;Kim et al 2002;Yi et al 2003;Demarque et al 2004). The star KOI 1574 is at the end of its main sequence phase.…”

Section: Model Atmosphere Fittingmentioning

confidence: 99%

An independent planet search in theKeplerdataset

Ofir

Dreizler

Zechmeister

et al. 2014

A&A

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Context. The primary goal of the Kepler mission is the measurement of the frequency of Earth-like planets around Sun-like stars. However, the confirmation of the smallest of Kepler's candidates in long periods around FGK dwarfs is extremely difficult or even beyond the limit of current radial velocity technology. Transit timing variations (TTVs) may offer the possibility for these confirmations of near-resonant multiple systems by the mutual gravitational interaction of the planets. Aims. We previously detected the second planet candidate in the KOI 1574 system. The two candidates have relatively long periods (about 114 d and 191 d) and are in 5:3 resonance. We therefore searched for TTVs in this particularly promising system. Methods. The full Kepler data was detrended with the proven SARS pipeline. The entire data allowed one to search for TTVs of the above signals, and to search for additional transit-like signals.Results. We detected strong anti-correlated TTVs of the 114 d and 191 d signals, dynamically confirming them as members of the same system. Dynamical simulations reproducing the observed TTVs allowed us to also determine the masses of the planets. We found KOI 1574.01 (hereafter Kepler-87 b) to have a radius of 13.49 ± 0.55 R ⊕ and a mass of 324.2 ± 8.8 M ⊕ , and KOI 1574.02 (Kepler-87 c) to have a radius of 6.14 ± 0.29 R ⊕ and a mass of 6.4 ± 0.8 M ⊕ . Both planets have low densities of 0.729 and 0.152 g cm −3 , respectively, which is non-trivial for such cold and old (7−8 Gyr) planets. Specifically, Kepler-87 c is the lowest-density planet in the super-Earth mass range. Both planets are thus particularly amenable to modeling and planetary structure studies, and also present an interesting case where ground-based photometric follow-up of Kepler planets is very desirable. Finally, we also detected two more short-period super-Earth sized (<2 R ⊕ ) planetary candidates in the system, making the relatively high multiplicity of this system notable against the general paucity of multiple systems in the presence of giant planets like Kepler-87 b.

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The Y ² Stellar Evolutionary Tracks

Cited by 283 publications

References 10 publications

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Fine structure of the age-chromospheric activity relation in solar-type stars

An independent planet search in theKeplerdataset

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The Y 2 Stellar Evolutionary Tracks

Cited by 283 publications

References 10 publications

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Fine structure of the age-chromospheric activity relation in solar-type stars

An independent planet search in theKeplerdataset

Contact Info

Product

Resources

About

The Y ² Stellar Evolutionary Tracks