Pristine CNO abundances from Magellanic Cloud B stars

Korn, A. J.; Keller, Stefan; Kaufer, A.; Langer, N.; Przybilla, N.; Stahl, O.; Wolf, B.

doi:10.1051/0004-6361:20020116

Cited by 80 publications

(118 citation statements)

References 28 publications

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“…The chemical diffusion process is then dominated by magnetic diffusion, resulting in too strong mixing, incompatible with the observations. The data points show data of [13] (circles), [14] (triangles), [15] (upsidedown triangles) and [16] (diamonds). The grey box indicates data that will become available soon [9, in preparation].…”

Section: The Modelsmentioning

confidence: 99%

How Efficient is Rotational Mixing in Massive Stars ?

Brott¹,

Hunter²,

Anders³

et al. 2008

AIP Conference Proceedings

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Abstract. The VLT-Flames Survey for Massive Stars [1,2] provides precise measurements of rotational velocities and nitrogen surface abundances of massive stars in the Magellanic Clouds. Specifically, for the first time, such abundances have been estimated for stars with significant rotational velocities. This extraordinary data set gives us the unique possibility to calibrate rotationally and magnetically induced mixing processes. Therefore, we have computed a grid of stellar evolution models varying in mass, initial rotational velocity and chemical composition. In our models we find that although magnetic fields generated by the Spruit-Taylor dynamo are essential to understand the internal angular momentum transport (and hence the rotational behavior), the corresponding chemical mixing must be neglected to reproduce the observations. Further we show that for low metallicities detailed initial abundances are of prime importance, as solar-scaled abundances may result in significant calibration errors.

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Section: The Modelsmentioning

confidence: 99%

How Efficient is Rotational Mixing in Massive Stars ?

Brott¹,

Hunter²,

Anders³

et al. 2008

AIP Conference Proceedings

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“…These studies include those of Lennon et al (1997), Gies & Lambert (1992), Kudritzki et al (1999), McErlean et al (1999) and Repolust et al (2004) in our Galaxy, Fitzpatrick & Bohannan (1993), Puls et al (1996), Dufton et al (2000), Korn et al (2002), Trundle et al (2004Trundle et al ( , 2005 and Venn (1999) for the Magellanic System, Venn et al (2000a), Smartt et al (2001) and Trundle et al (2002) for M 31, Monteverde et al (1997Monteverde et al ( , 2000 and Urbaneja et al (2003) for M 33 and Kaufer et al (2004), Urbaneja et al (2003) and Venn et al (2001Venn et al ( , 2000b for other Local Group galaxies. Studies of the progenitor O-type stars (see Bouret et al 2003;Hillier et al 2003;Heap et al 2004) and B-type giants (see Korn et al 2002, Lennon et al 2003 have also provided relevant observations to aid our understanding of the evolution of the surface chemical composition of early-type stars.…”

Section: Introductionmentioning

confidence: 99%

“…Studies of the progenitor O-type stars (see Bouret et al 2003;Hillier et al 2003;Heap et al 2004) and B-type giants (see Korn et al 2002, Lennon et al 2003 have also provided relevant observations to aid our understanding of the evolution of the surface chemical composition of early-type stars.…”

Section: Introductionmentioning

confidence: 99%

B-type supergiants in the SMC: Chemical compositions and comparison of static and unified models

Dufton¹,

Ryans²,

Trundle

et al. 2005

A&A

134

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Abstract. High-resolution UCLES/AAT spectra are presented for nine B-type supergiants in the SMC, chosen on the basis that they may show varying amounts of nuclear-synthetically processed material mixed to their surface. These spectra have been analysed using a new grid of approximately 12 000 non-LTE line blanketed  model atmospheres to estimate atmospheric parameters and chemical composition. The abundance estimates for O, Mg and Si are in excellent agreement with those deduced from other studies, whilst the low estimate for C may reflect the use of the C  doublet at 4267 Å. The N estimates are approximately an order of magnitude greater than those found in unevolved B-type stars or H  regions but are consistent with the other estimates in AB-type supergiants. These results have been combined with results from a unified model atmosphere analysis of UVES/VLT spectra of B-type supergiants (Trundle et al. 2004, A&A, 417, 217) to discuss the evolutionary status of these objects. For two stars that are in common with those discussed by Trundle et al., we have undertaken a careful comparison in order to try to understand the relative importance of the different uncertainties present in such analyses, including observational errors and the use of static or unified models. We find that even for these relatively luminous supergiants,  models yield atmospheric parameters and chemical compositions similar to those deduced from the unified code .

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“…Composition values relative to PSC values given by de Boer (1991) for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are fO=Hg $ 0:3 2 and fN=Og $ 0:3. Recently, Korn et al (2002) reported for the LMC an even lower nitrogen abundance, i.e., fN=Og $ 0:2. Some data on the isotopic abundances of carbon, nitrogen, and oxygen in dwarf galaxies have been published.…”

Section: Infall Of External Materials Into the Galactic Diskmentioning

confidence: 99%

Chemical Evolution in Our Galaxy during the Last 5 Gyr

Geiss

Gloeckler

Charbonnel

2002

ApJ

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A significant fraction of the gas in the Galactic disk comes from quasi-continuous infall of external material that is moderately processed by stellar nucleosynthesis. Based on a comparison of the abundances in the protosolar cloud (PSC) and the Local Interstellar Cloud (LIC), we propose that the infalling matter carries the nucleosynthetic signature of dwarf galaxies. The dwarfs have low metallicity, and secondary products of stellar nucleosynthesis are scarce as compared to primary products. Using a simple model, we show that the differences found in the LIC and PSC compositions can be explained by adding material processed in dwarf galaxies to the material processed in the Galactic disk. Moreover, some previously unexplained composition observations in the Galaxy, such as the apparently anomalously high metallicity of the Sun, or the '' 18 O puzzle '' could be resolved in this way.

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Pristine CNO abundances from Magellanic Cloud B stars

Cited by 80 publications

References 28 publications

How Efficient is Rotational Mixing in Massive Stars ?

How Efficient is Rotational Mixing in Massive Stars ?

B-type supergiants in the SMC: Chemical compositions and comparison of static and unified models

Chemical Evolution in Our Galaxy during the Last 5 Gyr

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