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  The Aarhus red giants challenge - I. Stellar structures in the red giant branch phase

Aguirre, V. S., Christensen-Dalsgaard, J., Cassisi, S., Miller Bertolami, M., Serenelli, A., Stello, D., et al. (2020). The Aarhus red giants challenge - I. Stellar structures in the red giant branch phase. Astronomy and Astrophysics, 635: A164. doi:10.1051/0004-6361/201935843.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0006-8FF5-5 Version Permalink: http://hdl.handle.net/21.11116/0000-0006-8FF6-4
Genre: Journal Article


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Aguirre, V. Silva, Author
Christensen-Dalsgaard, J., Author
Cassisi, S., Author
Miller Bertolami, M.1, Author              
Serenelli, A., Author
Stello, D., Author
Weiss, A.1, Author              
Angelou, G.1, Author              
Jiang, C., Author
Lebreton, Y., Author
Spada, F., Author
Bellinger, E. P., Author
Deheuvels, S., Author
Ouazzani, R. M., Author
Pietrinferni, A., Author
Mosumgaard, J. R., Author
Townsend, R. H. D., Author
Battich, T., Author
Bossini, D., Author
Constantino, T., Author
Eggenberger, P., AuthorHekker, S., AuthorMazumdar, A., AuthorMiglio, A., AuthorNielsen, K. B., AuthorSalaris, M., Author more..
1Stellar Astrophysics, MPI for Astrophysics, Max Planck Society, ou_159882              


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 Abstract: Context. With the advent of space-based asteroseismology, determining accurate properties of red-giant stars using their observed oscillations has become the focus of many investigations due to their implications in a variety of fields in astrophysics. Stellar models are fundamental in predicting quantities such as stellar age, and their reliability critically depends on the numerical implementation of the physics at play in this evolutionary phase. Aims. We introduce the Aarhus red giants challenge, a series of detailed comparisons between widely used stellar evolution and oscillation codes that aim to establish the minimum level of uncertainties in properties of red giants arising solely from numerical implementations. We present the first set of results focusing on stellar evolution tracks and structures in the red-giant-branch (RGB) phase. Methods. Using nine state-of-the-art stellar evolution codes, we defined a set of input physics and physical constants for our calculations and calibrated the convective efficiency to a specific point on the main sequence. We produced evolutionary tracks and stellar structure models at a fixed radius along the red-giant branch for masses of 1.0 M, 1.5 M, 2.0 M, and 2.5 M, and compared the predicted stellar properties. Results. Once models have been calibrated on the main sequence, we find a residual spread in the predicted effective temperatures across all codes of ∼20 K at solar radius and ∼30–40 K in the RGB regardless of the considered stellar mass. The predicted ages show variations of 2–5% (increasing with stellar mass), which we attribute to differences in the numerical implementation of energy generation. The luminosity of the RGB-bump shows a spread of about 10% for the considered codes, which translates into magnitude differences of ∼0.1 mag in the optical V-band. We also compare the predicted [C/N] abundance ratio and find a spread of 0.1 dex or more for all considered masses. Conclusions. Our comparisons show that differences at the level of a few percent still remain in evolutionary calculations of red giants branch stars despite the use of the same input physics. These are mostly due to differences in the energy generation routines and interpolation across opacities, and they call for further investigation on these matters in the context of using properties of red giants as benchmarks for astrophysical studies.


Language(s): eng - English
 Dates: 2020-03-27
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: -
 Identifiers: DOI: 10.1051/0004-6361/201935843
Other: LOCALID: 3238174
 Degree: -



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Source 1

Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
Publ. Info: France : EDP Sciences S A
Pages: - Volume / Issue: 635 Sequence Number: A164 Start / End Page: - Identifier: ISSN: 1432-0746
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1