Double-line eclipsing binaries (DLEBs) have been recently used to constrain the amount of central mixing as a function of stellarmass, with contrasting results. In this work, we reanalyse the DLEB sample by Claret & Torres, using a Bayesian method and new PARSEC tracks that account for both convective core overshooting and rotational mixing. Using overshooting alone, we obtain that, for masses larger than about 1.9Mo, the distribution of the overshooting parameter, eöv, has a wide dispersion between 0.3 and 0.8, with essentially no values below eöv = 0.3 and 0.4. While the lower limit supports a mild convective overshooting efficiency, the large dispersion derived is difficult to explain in the framework of current models of that process, which leave little room for large randomness.We suggest that a simple interpretation of our results can be rotational mixing: Different initial rotational velocities, in addition to a fixed amount of overshooting, could reproduce the high dispersion derived for intermediatemass stars. After a reanalysis of the data, we find good agreement with models computed with a fixed overshooting parameter, δov = 0.4, and initial rotational rates, ù, uniformly distributed in a wide range between 0 and 0.8 times the break-up value, at varying initial mass. We also find that our best-fitting models for the components of α Aurigae and TZ Fornacis agree with their observed rotational velocities, thus providing independent support to our hypothesis.We conclude that a constant efficiency of overshooting in concurrence with a star-to-star variation in the rotational mixing might be crucial in the interpretation of such data.

Mixing by overshooting and rotation in intermediate-mass stars / Costa, G.; Girardi, L.; Bressan, A.; Marigo, P.; Rodrigues, T. S.; Chen, Y.; Lanza, A.; Goudfrooij, P.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 485:4(2019), pp. 4641-4657. [10.1093/mnras/stz728]

Mixing by overshooting and rotation in intermediate-mass stars

Costa G.;Bressan A.;Lanza A.;
2019-01-01

Abstract

Double-line eclipsing binaries (DLEBs) have been recently used to constrain the amount of central mixing as a function of stellarmass, with contrasting results. In this work, we reanalyse the DLEB sample by Claret & Torres, using a Bayesian method and new PARSEC tracks that account for both convective core overshooting and rotational mixing. Using overshooting alone, we obtain that, for masses larger than about 1.9Mo, the distribution of the overshooting parameter, eöv, has a wide dispersion between 0.3 and 0.8, with essentially no values below eöv = 0.3 and 0.4. While the lower limit supports a mild convective overshooting efficiency, the large dispersion derived is difficult to explain in the framework of current models of that process, which leave little room for large randomness.We suggest that a simple interpretation of our results can be rotational mixing: Different initial rotational velocities, in addition to a fixed amount of overshooting, could reproduce the high dispersion derived for intermediatemass stars. After a reanalysis of the data, we find good agreement with models computed with a fixed overshooting parameter, δov = 0.4, and initial rotational rates, ù, uniformly distributed in a wide range between 0 and 0.8 times the break-up value, at varying initial mass. We also find that our best-fitting models for the components of α Aurigae and TZ Fornacis agree with their observed rotational velocities, thus providing independent support to our hypothesis.We conclude that a constant efficiency of overshooting in concurrence with a star-to-star variation in the rotational mixing might be crucial in the interpretation of such data.
2019
485
4
4641
4657
https://academic.oup.com/mnras/issue
Costa, G.; Girardi, L.; Bressan, A.; Marigo, P.; Rodrigues, T. S.; Chen, Y.; Lanza, A.; Goudfrooij, P.
File in questo prodotto:
File Dimensione Formato  
stz728.pdf

accesso aperto

Descrizione: This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Tipologia: Versione Editoriale (PDF)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 4.57 MB
Formato Adobe PDF
4.57 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/106043
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 40
  • ???jsp.display-item.citation.isi??? 39
social impact