A Cosmic Abundance Standard: Chemical Homogeneity of the Solar Neighborhood and the ISM Dust-Phase Composition

Przybilla, N.; Nieva, M. F.; Butler, K.

doi:10.1086/595618

Cited by 216 publications

(272 citation statements)

References 41 publications

(52 reference statements)

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“…Indeed, the sample shows only a small scatter around the mean combined abundance, log CNO + 12 = 8.98±0.05. This is further (indirect) evidence that chemical inhomogeneities among the massive star population in the solar neighbourhood are small PNB08), even at extended distances out to 1-2 kpc from the Sun. Predictions of a high efficiency of hydrodynamic mixing in the interstellar medium and consequently of a locally well-mixed Milky Way (Edmunds 1975;Roy & Kunth 1995) are thus supported as well.…”

Section: Observational Constraintsmentioning

confidence: 64%

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Mixing of CNO-cycled matter in massive stars

Przybilla¹,

Firnstein²,

Nieva

et al. 2010

A&A

133

150

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Aims. We test predictions of evolution models on mixing of CNO-cycled products in massive stars from a fundamental perspective. Relative changes within the theoretical C:N:O abundance ratios and the buildup of helium are compared with observational results. Methods. A sample of well-studied Galactic massive stars is presented. High-quality optical spectra are carefully analysed using improved NLTE line-formation and comprehensive analysis strategies. The results are put in the context of the existing literature data. Results. A tight trend in the observed N/C vs. N/O ratios and the buildup of helium is found from the self-consistent analysis of main-sequence to supergiant stars for the first time. The catalytic nature of the CNO-cycles is confirmed quantitatively, though further investigations are required to derive a fully consistent picture. Our observational results support the case of strong mixing, as predicted e.g. by evolution models that consider magnetic fields or by models that have gone through the first dredge-up in the case of many supergiants.

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Section: Observational Constraintsmentioning

confidence: 64%

“…Carefully analysed data are available on 6 slowly-rotating early B-type stars near the MS (Nieva & Przybilla 2006, 2007Przybilla et al 2008, PNB08) and on 14 BA-type supergiants Firnstein 2006;Schiller & Przybilla 2008).…”

Section: Observational Constraintsmentioning

confidence: 99%

Mixing of CNO-cycled matter in massive stars

Przybilla¹,

Firnstein²,

Nieva

et al. 2010

A&A

133

150

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“…The question actually concerns absolute abundances rather than relative ones. We recall in this context the results by Przybilla et al (2008), who obtain much tighter results than previous works for B-type stars abundances in the solar neighbourhood. These results suggest that previous metallicity measurements are systematically too low, but the precise value of this offset and its application to stars located far outside the Solar radius is not clearly established.…”

Section: Colour Excess Distance and Post-ms Agementioning

confidence: 76%

Analysis of the stellar population in the central area of the HII region Sh 2-284 ,

Delgado

Djupvik

Alfaro

2009

A&A

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Context. There is a lack of state-of-the-art information on very young open clusters with implications for determining the structure of the Galaxy. Aims. Our main objective is to study the timing and location of the star formation processes which yielded the generation of the giant HII region Sh 2-284. This includes the determination of different physical variables of the stars, such as distance, reddening, age and evolutionary stage, including pre-main-sequence (PMS) stars. Methods. The analysis is based on UBVR C I C CCD measurements of a field of 6.5 × 6.5 containing the cluster, and JHK s photometry in the 3.5 × 3.5 subfield, centered in the apparent higher condensation. The determination of cluster distance, reddening and age is carried out through a comparison with ZAMS, post-MS and PMS isochrones. The reference lines used are obtained from theoretical post-MS and PMS isochrones from the Geneva and Yale groups for a metallicity of Z = 0.004, which agrees with the spectroscopic metallicity determination published for several cluster members. Results. The results amount to E(B − V) = 0.78 ± 0.02, DM = 12.8 ± 0.2 (3.6 kpc), Log Age(yr) = 6.51 ± 0.07 (3.2 Myr). The distance result critically depends on the use of low metallicity ZAMS and isochrones. A PMS member sequence is proposed, with an age of Log Age(yr) = 6.7 ± 0.2 (4.7 Myr) which is therefore coeval within the errors with the post-MS cluster age. The mass function for this population in the mass range above 1.3−3.5 M is well fitted by a Salpeter mass function. The presence of a different star generation in the cluster with a distinctly older age of around 40 Myr is suggested. On the other hand, the NIR photometry results indicate a large number of sources with (H − K s ) excess, practically distinct from the optical PMS candidate members. Conclusions. The analysis of our deep UBVRIJHK photometry of Dolidze 25 therefore reveals a young cluster with coeval MS and PMS populations of age 3.2−5 Myr. In addition, a distinctly older cluster member population of the age of 40 Myr is suggested. The distance determined for the cluster from quantitative fits to ZAMS and isochrones is distinctly lower than previously published values. This result originates in the consistent use of low metallicity models for ZAMS fitting, applying published metallicity values for the cluster.

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“…The abundances summarized in Table 1 are those derived for the solar photosphere by Asplund et al 82 . These abundances are thought to apply to the interstellar medium as well, although small variations are possible 83 . …”

Section: The Ingredients: Elemental Abundancesmentioning

confidence: 99%

Astrochemistry of dust, ice and gas: introduction and overview

Dishoeck

Ewine²

2014

Faraday Discuss.

136

102

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A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented, aimed at non-specialists. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other. Much of the chemistry in star- and planet-forming regions is now thought to be driven by gas-grain chemistry rather than pure gas-phase chemistry, and a critical discussion of the state of such models is given. Recent developments in studies of diffuse clouds and PDRs, cold dense clouds, hot cores, protoplanetary disks and exoplanetary atmospheres are summarized, both for simple and more complex molecules, with links to papers presented in this volume. In spite of many lingering uncertainties, the future of astrochemistry is bright: new observational facilities promise major advances in our understanding of the journey of gas, ice and dust from clouds to planets.Comment: Introductory paper for Faraday Discussions 168 conference, April 201

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A Cosmic Abundance Standard: Chemical Homogeneity of the Solar Neighborhood and the ISM Dust-Phase Composition

Cited by 216 publications

References 41 publications

Mixing of CNO-cycled matter in massive stars

Mixing of CNO-cycled matter in massive stars

Analysis of the stellar population in the central area of the HII region Sh 2-284 ,

Astrochemistry of dust, ice and gas: introduction and overview

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