Theory and Observations of Stars

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SEEK ID: https://publications.h-its.org/projects/17

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Project created: 10th Aug 2020

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Felix Ahlborn

Projects: Theory and Observations of Stars

Institutions: Heidelberg Institute for Theoretical Studies

Saskia Hekker

Projects: Theory and Observations of Stars

Institutions: Heidelberg Institute for Theoretical Studies, Heidelberg University

https://orcid.org/0000-0002-1463-726X

Nathalie Themeßl

Projects: Theory and Observations of Stars

Institutions: Heidelberg Institute for Theoretical Studies

Heidelberg Institute for Theoretical Studies

Country: Germany

City: Heidelberg

Web page: https://www.h-its.org

Heidelberg University

Country: Germany

City: Heidelberg

Web page: http://www.uni-heidelberg.de/index_e.html

Impact of central mixing scheme and nuclear reaction network on the extent of convective cores

Theory and Observations of Stars

Abstract (Expand)

Convective cores are the hydrogen reservoirs of main sequence stars that are more massive than around 1.2 solar masses. The characteristics of the cores have a strong impact on the evolution and structure …

Authors: Anthony Noll, Sébastien Deheuvels

Date Published: 1st Aug 2023

Publication Type: Journal

DOI: 10.1051/0004-6361/202245710

Citation: A&A 676:A70

Created: 19th Sep 2023 at 14:27, Last updated: 19th Sep 2023 at 14:30

Exoplanet interior retrievals: core masses and metallicities from atmospheric abundances

Theory and Observations of Stars

Abstract (Expand)

ABSTRACT The mass and distribution of metals in the interiors of exoplanets are essential for constraining their formation and evolution processes. Never the less, with only masses and radii measured, …

Authors: S Bloot, Y Miguel, M Bazot, S Howard

Date Published: 1st Aug 2023

Publication Type: Journal

DOI: 10.1093/mnras/stad1873

Citation: Monthly Notices of the Royal Astronomical Society 523(4):6282-6292

Created: 22nd Sep 2023 at 08:45, Last updated: 22nd Sep 2023 at 08:46

Testing angular momentum transport processes with asteroseismology of solar-type main-sequence stars

Theory and Observations of Stars

Abstract (Expand)

Context: Thanks to the so-called photometry revolution with the space-based missions CoRoT, Kepler, and TESS, asteroseismology has become a powerful tool to study the internal rotation of stars. The … rotation rate depends on the efficiency of the angular momentum (AM) transport inside the star, and its study allows to constrain the internal AM transport processes, as well as improve our understanding of their physical nature. Aims: We compared the ratio of the rotation rate predicted by asteroseismology and starspot measurements of solar-type stars considering different AM transport prescriptions and investigated whether some of these prescriptions can be ruled out observationally. Methods: We conducted a two-step modelling procedure of four main-sequence stars from the Kepler LEGACY sample, which consists of an asteroseismic characterisation that serves as a guide for a modelling with rotating models, including a detailed and coherent treatment of the AM transport. The rotation profiles derived with this procedure were used to estimate the ratio of the mean asteroseismic rotation rate with the surface rotation rate from starspot measurements for each AM transport prescriptions. Comparisons between the models were then conducted. Results: In the hotter part of the Hertzsprung-Russell (HR) diagram (masses typically above ∼1.2 M⊙ at solar metallicity), models with only hydrodynamic transport processes and models with additional transport by magnetic instabilities are found to be consistent with previous measurements that observed a low degree (below 30%) of radial differential rotation between the radiative and convective zones. For these stars, which constitute a significant fraction of the Kepler LEGACY sample, a combination of asteroseismic constraints from the splitting of pressure modes and of the surface rotation rate does not allow us to conclude that an efficient AM transport is required in addition to transport by meridional circulation and shear instability alone. Even a model assuming local AM conservation cannot be ruled out. In the colder part of the HR diagram, the situation is different because of the efficient braking of the stellar surface by magnetised winds. We find a clear disagreement between the rotational properties of models that only include hydrodynamic processes and asteroseismic constraints, while models with magnetic fields correctly reproduce the observations, similarly to the solar case. Conclusions: This shows the existence of a mass regime corresponding to main-sequence F-type stars for which it is difficult to constrain the AM transport processes, unlike for hotter, Gamma Dor stars or colder, less massive solar analogues. The comparison between asteroseismic measurements and surface rotation rates enables us to easily rule out models with an inefficient transport of AM in the colder part of the HR diagram.

Authors: J. Bétrisey, P. Eggenberger, G. Buldgen, O. Benomar, M. Bazot

Date Published: 1st May 2023

Publication Type: Journal

DOI: 10.1051/0004-6361/202245764

Citation: A&A 673:L11

Created: 22nd Sep 2023 at 08:51, Last updated: 22nd Sep 2023 at 08:52

Jupiter’s interior from Juno: Equation-of-state uncertainties and dilute core extent

Theory and Observations of Stars

Abstract (Expand)

Context: The Juno mission has provided measurements of Jupiter’s gravity field with an outstanding level of accuracy, leading to better constraints on the interior of the planet. Improving our knowledge …

Authors: S. Howard, T. Guillot, M. Bazot, Y. Miguel, D. J. Stevenson, E. Galanti, Y. Kaspi, W. B. Hubbard, B. Militzer, R. Helled, N. Nettelmann, B. Idini, S. Bolton

Date Published: 1st Apr 2023

Publication Type: Journal

DOI: 10.1051/0004-6361/202245625

Citation: A&A 672:A33

Created: 22nd Sep 2023 at 08:53, Last updated: 22nd Sep 2023 at 08:54

Revised Extinctions and Radii for 1.5 Million Stars Observed by APOGEE, GALAH, and RAVE

Theory and Observations of Stars

Abstract (Expand)

Abstract Asteroseismology has become widely accepted as a benchmark for accurate and precise fundamental stellar properties. It can therefore be used to validate and calibrate stellar parameters derived …

Authors: Jie Yu, Shourya Khanna, Nathalie Themessl, Saskia Hekker, Guillaume Dréau, Laurent Gizon, Shaolan Bi

Date Published: 1st Feb 2023

Publication Type: Journal

DOI: 10.3847/1538-4365/acabc8

Citation: ApJS 264(2):41

Created: 22nd Sep 2023 at 08:12, Last updated: 22nd Sep 2023 at 08:15

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