GARSTEC—the Garching Stellar Evolution Code

Weiß, Achim; Schlattl, Helmut

doi:10.1007/s10509-007-9606-5

Cited by 284 publications

(279 citation statements)

References 35 publications

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“…These SECs are: Victoria-Regina (VandenBerg et al 2006, hereafter VIC-REG), BaSTI (Pietrinferni et al 2004), GARSTEC (Weiss & Schlattl 2008), STAREVOL (Siess 2006), and PADOVA (Bertelli et al 2008). Table 2 shows the input physics used in these codes, where it can be seen that BaSTI and GARSTEC include nearly the same physics used in PGPUC.…”

Section: Comparison With Other Codesmentioning

confidence: 99%

Effects of helium enrichment in globular clusters

Valcarce

Catelan

Sweigart

2012

A&A

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Aims. Recently, the study of globular cluster (GC) color−magnitude diagrams (CMDs) has shown that some of them harbor multiple populations with different chemical compositions and/or ages. In the first case, the most common candidate is a spread in the initial helium abundance, but this quantity is difficult to determine spectroscopically due to the fact that helium absorption lines are not present in cooler stars, whereas for hotter GC stars gravitational settling of helium becomes important. As a consequence, indirect methods to determine the initial helium abundance among populations are necessary. For that reason, in this series of papers, we investigate the effects of a helium enrichment in populations covering the range of GC metallicities. Methods. In this first paper, we present the theoretical evolutionary tracks, isochrones, and zero-age horizontal branch (ZAHB) loci calculated with the Princeton-Goddard-PUC (PGPUC) stellar evolutionary code, which has been updated with the most recent input physics and compared with other theoretical databases. The chemical composition grid covers 9 metallicities ranging from Z = 1.60 × 10 −4 to 1.57 × 10 −2 (−2.25 < ∼ [Fe/H] < ∼ −0.25), 7 helium abundances from Y = 0.230 to 0.370, and an alpha-element enhancement of [α/Fe] = 0.3. Results. The effects of different helium abundances that can be observed in isochrones are: splits in the main sequence (MS), differences in the luminosity (L) and effective temperature (T eff ) of the turn off point, splits in the sub giant branch being more prominent for lower ages or higher metallicities, splits in the lower red giant branch (RGB) being more prominent for higher ages or higher metallicities, differences in L of the RGB bump (with small changes in T eff ), and differences in L at the RGB tip. At the ZAHB, when Y is increased there is an increase of L for low T eff , which is affected in different degrees depending on the age of the GC being studied. Finally, the ZAHB morphology distribution depending on the age explains how for higher GC metallicities a population with higher helium abundance could be hidden at the red ZAHB locus.

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Section: Comparison With Other Codesmentioning

confidence: 99%

Effects of helium enrichment in globular clusters

Valcarce

Catelan

Sweigart

2012

A&A

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“…While both methods use the same input physics (including a solar-calibrated mixing length parameter, α), the ASTFIT method uses models calculated with astec, whereas the BASTA uses models calculated with the Garching Stellar Evolution Code (garstec; Weiss & Schlattl 2008). Furthermore, they differ in the asteroseismic variables that are fitted.…”

Section: Modellingmentioning

confidence: 99%

Keplerobservations of the asteroseismic binary HD 176465

White

Benomar

Aguirre

et al. 2017

A&A

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Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0 ± 0.5 Gyr old. The two components of HD 176465 are young physicallysimilar oscillating solar analogues, the first such system to be found, and provide important constraints for stellar evolution and asteroseismology.

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“…For our model calculations we used the Garching Stellar Evolution Code (GARSTEC, Weiss and Schlattl 2008). The input physics considered includes the OPAL equation of state complemented with the MHD equation of state for low temperatures (Hummer and Mihalas 1988), Ferguson's opacities for low temperature (Ferguson et al 2005), OPAL opacities for high temperatures , the Grevesse and Sauval (1998) solar mixture, and the NACRE compilation for thermonuclear reaction rates (Angulo et al 1999).…”

Section: Modelsmentioning

confidence: 99%

Semiconvective mixing in low-mass stars

Aguirre

Ballot

Serenelli

et al. 2010

Astrophys Space Sci

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Mixing processes such as convection, overshooting and rotational mixing have long been known to affect the evolutionary properties of low-mass stars. While modeling a 1.2 M star, we encountered a semiconvective region outside the fully convective core, reminiscent of the wellknown situation for massive stars. In this study we focus on low-mass stars presenting convective cores and, by applying different prescriptions for the determination of the convective boundaries and, using different mixing descriptions for the dynamical processes in the core, we look for the effects of semiconvective mixing in the interior structure of the stars and its observable quantities. With this purpose, we have constructed different sets of evolutionary models using a stellar evolution code (GARSTEC), and analyzed the models looking for imprints of these processes.

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GARSTEC—the Garching Stellar Evolution Code

Cited by 284 publications

References 35 publications

Effects of helium enrichment in globular clusters

Effects of helium enrichment in globular clusters

Keplerobservations of the asteroseismic binary HD 176465

Semiconvective mixing in low-mass stars

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