A critical test of empirical mass loss formulas  
 applied to individual giants and supergiants

Schröder, K.-P.; Cuntz, M.

doi:10.1051/0004-6361:20066633

Cited by 66 publications

(63 citation statements)

References 29 publications

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“…This new formula has been tested using well-studied nearby stars with measured mass loss rates, reproducing them within the error bars (Schröder & Cuntz 2007). For these reasons, we used the SC05 mass loss rate formulation, instead of the R75 one.…”

Section: Mass Lossmentioning

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: Mass Lossmentioning

confidence: 99%

Effects of helium enrichment in globular clusters

Valcarce

Catelan

Sweigart

2012

A&A

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“…The numerical factor 8 × 10 −14 was adjusted by Schröder & Cuntz [69] to provide an optimum fit to HB stars in two GCs, namely M5 (NGC 5904) and NGC 5927. Then, assuming SC = 1, Schröder & Cuntz [70] have shown that, unlike with the Reimers formula, one is able to obtain good agreement, within the error bars, with the empirical data for well-studied red giants and supergiants. Very recently, a predictive theoretical model for the mass-loss rates of cool stars has been proposed by Cranmer & Saar [28] which seems to provide an even better fit to the empirical data [see also 1].…”

Section: -P6mentioning

confidence: 88%

Selected topics in the evolution of low-mass stars

Catelan

2013

EPJ Web of Conferences

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Abstract. Low-mass stars play a key role in many different areas of astrophysics. In this article, I provide a brief overview of the evolution of low-mass stars, and discuss some of the uncertainties and problems currently affecting low-mass stellar models. Emphasis is placed on the following topics: the solar abundance problem, mass loss on the red giant branch, and the level of helium enrichment associated to the multiple populations that are present in globular clusters.

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“…The treatment of the stellar mass loss rate as function of the governing stellar parameters has successfully been tested on globular clusters as well as for a set of well studied stars (Schröder & Cuntz 2007). Thus, the attained models of stellar evolution are expected to provide an accurate description of the time-dependent behavior of stellar luminosity (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Habitability of super-Earth planets around main-sequence stars including red giant branch evolution: models based on the integrated system approach

Cuntz

Bloh

Schröder

et al. 2011

International Journal of Astrobiology

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In a previous study published in Astrobiology, we focused on the evolution of habitability of a 10 M ⊕ super-Earth planet orbiting a star akin to the Sun. This study was based on a concept of planetary habitability in accordance to the integrated system approach that describes the photosynthetic biomass production taking into account a variety of climatological, biogeochemical, and geodynamical processes. In the present study, we pursue a significant augmentation of our previous work by considering stars with zero-age main sequence masses between 0.5 and 2.0 M ⊙ with special emphasis on models of 0.8, 0.9, 1.2 and 1.5 M ⊙ . Our models of habitability consider again geodynamical processes during the mainsequence stage of these stars as well as during their red giant branch evolution. Pertaining to the different types of stars, we identify so-called photosynthesissustaining habitable zones (pHZ) determined by the limits of biological productivity on the planetary surface. We obtain various sets of solutions consistent with the principal possibility of life. Considering that stars of relatively high masses depart from the main-sequence much earlier than low-mass stars, it is found that the biospheric life-span of super-Earth planets of stars with masses above approximately 1.5 M ⊙ is always limited by the increase in stellar luminosity. However, for stars with masses below 0.9 M ⊙ , the life-span of super-Earths is solely determined by the geodynamic time-scale. For central star masses between 0.9 and 1.5 M ⊙ , the possibility of life in the framework of our models depends on the relative continental area of the super-Earth planet.-2 -

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A critical test of empirical mass loss formulas applied to individual giants and supergiants

Cited by 66 publications

References 29 publications

Effects of helium enrichment in globular clusters

Effects of helium enrichment in globular clusters

Selected topics in the evolution of low-mass stars

Habitability of super-Earth planets around main-sequence stars including red giant branch evolution: models based on the integrated system approach

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