The solar photospheric nitrogen abundance

Caffau, E.; Maiorca, E.; Bonifacio, P.; Faraggiana, R.; Steffen, M.; Ludwig, H.‐G.; Kamp, I.; Busso, M.

doi:10.1051/0004-6361/200810859

Cited by 136 publications

(146 citation statements)

References 27 publications

(47 reference statements)

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“…Serenelli et al 2009). Furthermore, according to Caffau et al (2009), the solar metallicity using their own three-dimensional analysis is given by the values Z = 0.0156 and Z/X = 0.0213, which are closer to those of Grevesse & Noels (1993). In all cases, the solar abundances remain uncertain.…”

Section: Input Physicssupporting

confidence: 74%

Lithium in M 67: From the main sequence to the red giant branch

Pace

Castro

Meléndez

et al. 2012

A&A

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Context.Lithium abundances in open clusters are a very effective probe of mixing processes, and their study can help us to understand the large depletion of lithium that occurs in the Sun. Owing to its age and metallicity, the open cluster M 67 is especially interesting on this respect. Many studies of lithium abundances in M 67 have been performed, but a homogeneous global analysis of lithium in stars from subsolar masses and extending to the most massive members, has yet to be accomplished for a large sample based on high-quality spectra. Aims. We test our non-standard models, which were calibrated using the Sun with observational data. Methods.We collect literature data to analyze, for the first time in a homogeneous way, the non-local thermal equilibrium lithium abundances of all observed single stars in M 67 more massive than ∼0.9 M . Our grid of evolutionary models is computed assuming a non-standard mixing at metallicity [Fe/H] = 0.01, using the Toulouse-Geneva evolution code. Our analysis starts from the entrance into the zero-age main-sequence. Results. Lithium in M 67 is a tight function of mass for stars more massive than the Sun, apart from a few outliers. A plateau in lithium abundances is observed for turn-off stars. Both less massive (M ≤ 1.10 M ) and more massive (M ≥ 1.28 M ) stars are more depleted than those in the plateau. There is a significant scatter in lithium abundances for any given mass M ≤ 1.1 M . Conclusions. Our models qualitatively reproduce most of the features described above, although the predicted depletion of lithium is 0.45 dex smaller than observed for masses in the plateau region, i.e. between 1.1 and 1.28 solar masses. More work is clearly needed to accurately reproduce the observations. Despite hints that chromospheric activity and rotation play a role in lithium depletion, no firm conclusion can be drawn with the presently available data.

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Section: Input Physicssupporting

confidence: 74%

Lithium in M 67: From the main sequence to the red giant branch

Pace

Castro

Meléndez

et al. 2012

A&A

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“…Recent analysis of spectroscopic data using three dimensional hydrodynamic atmospheric models (see Asplund et al 2005Asplund et al , 2009) have reduced the derived abundances of CNO and other heavy elements with respect to the previous estimate by Grevesse & Sauval (1998, hereafter GS98), even if additional investigations are needed (see e.g. Caffau et al 2009;Socas-Navarro & Norton 2007). If one takes into account the still widely used solar mixture by Grevesse & Noels (1993), with C, N and O abundances slightly higher than those by GS98, the discrepancy with the Asplund et al (2005Asplund et al ( , 2009) composition slightly increases.…”

Section: Comparison With Recent Stellar Model Databasesmentioning

confidence: 88%

The Pisa Stellar Evolution Data Base for low-mass stars

Dell’Omodarme

Valle

Degl’Innocenti

et al. 2012

A&A

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Context. The last decade showed an impressive observational effort from the photometric and spectroscopic point of view for ancient stellar clusters in our Galaxy and beyond, leading to important and sometimes surprising results. Aims. The theoretical interpretation of these new observational results requires updated evolutionary models and isochrones spanning a wide range of chemical composition so that the possibility of multipopulations inside a stellar cluster is also taken also into account. Methods. With this aim we built the new "Pisa Stellar Evolution Database" of stellar models and isochrones by adopting a welltested evolutionary code (FRANEC) implemented with updated physical and chemical inputs. In particular, our code adopts realistic atmosphere models and an updated equation of state, nuclear reaction rates and opacities calculated with recent solar elements mixture. Results. A total of 32 646 models have been computed in the range of initial masses 0.30 ÷ 1.10 M for a grid of 216 chemical compositions with the fractional metal abundance in mass, Z, ranging from 0.0001 to 0.01, and the original helium content, Y, from 0.25 to 0.42. Models were computed for both solar-scaled and α-enhanced abundances with different external convection efficiencies. Correspondingly, 9720 isochrones were computed in the age range 8÷15 Gyr, in time steps of 0.5 Gyr. The whole database is available to the scientific community on the web. Models and isochrones were compared with recent calculations available in the literature and with the color-magnitude diagram of selected Galactic globular clusters. The dependence of relevant evolutionary quantities, namely turn-off and horizontal branch luminosities, on the chemical composition and convection efficiency were analyzed in a quantitative statistical way and analytical formulations were made available for reader's convenience. These relations can be useful in several fields of stellar evolution, e.g. evolutionary properties of binary systems, synthetic models for simple stellar populations and for star counts in galaxies, and chemical evolution models of galaxies.

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“…We used two different intensity atlases of the solar photosphere which have a good signal-to-noise (S/N) ratio and have been widely used in previous works (e.g. Caffau et al 2008Caffau et al , 2009Ayres 2008;Maiorca et al 2009). …”

Section: Observational Datamentioning

confidence: 99%

Uncertainties in the solar photospheric oxygen abundance

Armas

Ramos

Socas‐Navarro

2017

A&A

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Aims. The purpose of this work is to better understand the confidence limits of the photospheric solar oxygen abundance derived from three-dimensional models using the forbidden [OI] line at 6300 Å, including correlations with other parameters involved. Methods. We worked with a three-dimensional empirical model and two solar intensity atlases. We employed Bayesian inference as a tool to determine the most probable value for the solar oxygen abundance given the model chosen. We considered a number of error sources, such as uncertainties in the continuum derivation, in the wavelength calibration and in the abundance/strength of Ni. Results. Our results shows correlations between the effects of several parameters employed in the derivation. The Bayesian analysis provides robust confidence limits taking into account all of these factors in a rigorous manner. We obtain that, given the empirical threedimensional model and the atlas observations employed here, the most probable value for the solar oxygen abundance is log( O ) = 8.86 ± 0.04. However, we note that this uncertainty does not consider possible sources of systematic errors due to the model choice.

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The solar photospheric nitrogen abundance

Cited by 136 publications

References 27 publications

Lithium in M 67: From the main sequence to the red giant branch

Lithium in M 67: From the main sequence to the red giant branch

The Pisa Stellar Evolution Data Base for low-mass stars

Uncertainties in the solar photospheric oxygen abundance

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