The Internal Constitution of the Stars

Eddinǵton, A. S.

doi:10.1017/cbo9780511600005

Cited by 307 publications

(407 citation statements)

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“…Assuming that the bolometric luminosity of each source is that of a single ZAMS star, mass estimates for all CMZ sample sources have been derived, using the relation (e.g. Eddington 1926;Griffiths et al 1988;Bhattacharya et al 2008)…”

Section: Massesmentioning

confidence: 99%

Recent star formation in the inner Galactic bulge seen by ISOGAL

Immer

Schüller

Omont

et al. 2012

A&A

122

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We present 5-38 μm spectroscopic observations of a sample of 68 ISOGAL sources with unknown natures, taken with the Spitzer Infrared Spectrograph. Based on the characteristics and the slope of their spectra, we classified the sources as young or late-type evolved objects. These sources were selected to test selection criteria based on the ISOGAL [7]-[15] color and the spatial extent parameter σ 15 . We revised these criteria until they reliably distinguished between young and late-type evolved objects and then applied them to all ISOGAL sources in the central molecular zone (CMZ), resulting in the selection of 485 sources believed to be young. Furthermore, we added 656 Midcourse Space Experiment (MSX) sources to the CMZ sample that fulfilled F E /F D > 2 with F D and F E being the flux densities in the D (15 μm) and E (21 μm) bands. After obtaining L bol F 15 conversion factors, we calculated the bolometric luminosity, L bol , values for the CMZ sample and subsequently the masses of the sources. Applying a Kroupa initial mass function, we derived the total mass in young objects that have been formed over the last 1 Myr, resulting in an average star formation rate of 0.08 solar masses per year for the CMZ.

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Section: Massesmentioning

confidence: 99%

Recent star formation in the inner Galactic bulge seen by ISOGAL

Immer

Schüller

Omont

et al. 2012

A&A

122

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“…In a simplified treatment, this relation can be obtained analytically, as Eddington (1926) did, where T 4 (τ) = 3 4 T 4 eff τ + 2 3 , which defines the effective temperature (T eff ) as the temperature where a photon emitted from the depth with τ = 2/3 has a probability of e −2/3 ∼ 0.5 of emerging from the surface. However, this relation uses the gray atmosphere approximation, that is not a bad approximation when: i) the opacity is dominated by H − ; ii) local thermodynamical equilibrium is achieved (which is not appropriate for low-surface-gravity stellar atmospheres, where densities are too low); iii) hydrostatic equilibrium is valid (the pressure gradient exactly balances gravity, which is not valid for hot stars); and iv) there is radiative equilibrium (radiation is the main form of energy transport).…”

Section: Boundary Conditionsmentioning

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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“…we moved from the detection of a few pulsation modes to astrophysical interpretation of stellar interiors. But astrophysical inference from stellar pulsation is much older than this: see, for example, the classic text The Internal Constitution of the Stars (Eddington 1926). Others might argue that the new name catches attention and sounds impressive, hence gives the field and its researchers prestige and authority.…”

Section: Discussionmentioning

confidence: 99%