[en] Context. Long soft gamma-ray bursts (LGRBs) are usually associated with the death of the most massive stars. A large amount of core angular momentum in the phases preceding the explosion is required to form LGRBs. A very high initial rotational velocity can provide this angular momentum. This velocity strongly influences the way the star evolves: it is mixed in a chemically homogeneous way and evolves directly towards the blue part of the Hertzsprung-Russell (HR) diagram from the main sequence. <BR /> Aims: We have shown that chemically homogeneous evolution takes place in the Small Magellanic Cloud (SMC) at low metallicity. We want to see whether there is a metallicity threshold above which such an evolution is not possible. <BR /> Methods: We performed a spectroscopic analysis of H-rich early-type WN stars in the Large Magellanic Cloud (LMC) and the Galaxy. We used the code CMFGEN to determine the fundamental properties (T[SUB]eff[/SUB], L) and the surface composition of the target stars. We then placed the stars in the HR diagram and determined their evolution. <BR /> Results: We show that both the LMC and Galactic WNh stars we selected cannot be explained by standard stellar evolution. They are located on the left of the main sequence but show surface abundances typical of CN equilibrium. In addition, they still contain a large amount of hydrogen. They are thus core-H burning objects. Their properties are consistent with chemically homogeneous evolution. We determine the metallicity of the Galactic stars from their position and Galactic metallicity gradients and conclude that they have 0.6 < Z < 1.0. A moderate coupling between the core and the envelope is required to explain that stellar winds do not extract too much angular momentum to prevent a blueward evolution. <BR /> Conclusions: We have shown that chemically homogeneous evolution takes place in environments with metallicity up to solar. Since some long gamma-ray bursts appear in (super-)solar environments, such an evolution may be a viable way to form them over a wide range of metallicities. Figures 1-6 are available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Martins, F.; LUPM-UMR 5299, CNRS & Université Montpellier II, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
Depagne, E.; Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482, Potsdam, Germany
Russeil, D.; Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388, Marseille, France
Mahy, Laurent ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Language :
English
Title :
Evidence of quasi-chemically homogeneous evolution of massive stars up to solar metallicity
scite shows how a scientific paper has been cited by providing the context of the citation, a classification describing whether it supports, mentions, or contrasts the cited claim, and a label indicating in which section the citation was made.
Bibliography
Balser, D. S., Rood, R. T., Bania, T. M., & Anderson, L. D. 2011, ApJ, 738, 27
Bestenlehner, J. M., Vink, J. S., Gräfener, G. et al., 2011, A&A, 530, L14
Bouret, J.-C., Lanz, T., Hillier, D. J. et al., 2003, ApJ, 595, 1182
Bouret, J.-C., Hillier, D. J., Lanz, T., & Fullerton, A. W. 2012, A&A, 544, A67
Breysacher, J., Azzopardi, M., & Testor, G. 1999, A&AS, 137, 117
Brott, I., de Mink, S. E., Cantiello, M. et al., 2011, A&A, 530, A115
Castor, J. I., Abbott, D. C., & Klein, R. I. 1975, ApJ, 195, 157
de Mink, S. E., Langer, N., Izzard, R. G., Sana, H., & de Koter, A. 2013, ApJ, 764, 166
Ekström, S., Georgy, C., Eggenberger, P. et al., 2012, A&A, 537, A146
Foellmi, C., Moffat, A. F. J., & Guerrero, M. A. 2003, MNRAS, 338, 1025
Galama, T. J., Vreeswijk, P. M., van Paradijs, J. et al., 1998, Nature, 395, 670
Georgy, C., Ekström, S., Meynet, G. et al., 2012, A&A, 542, A29
Gräfener, G., Vink, J. S., de Koter, A., & Langer, N. 2011, A&A, 535, A56
Gräfener, G., Vink, J. S., Harries, T. J., & Langer, N. 2012, A&A, 547, A83
Graham, J. F., Fruchter, A. S., Kewley, L. J., et al. 2009, in AIP Conf. Ser. 1133, eds. C. Meegan, C. Kouveliotou, & N. Gehrels, 269
Grevesse, N., Asplund, M., & Sauval, A. J. 2007, Space Sci. Rev., 130, 105
This website uses cookies to improve user experience. Read more
Save & Close
Accept all
Decline all
Show detailsHide details
Cookie declaration
About cookies
Strictly necessary
Performance
Strictly necessary cookies allow core website functionality such as user login and account management. The website cannot be used properly without strictly necessary cookies.
This cookie is used by Cookie-Script.com service to remember visitor cookie consent preferences. It is necessary for Cookie-Script.com cookie banner to work properly.
Performance cookies are used to see how visitors use the website, eg. analytics cookies. Those cookies cannot be used to directly identify a certain visitor.
Used to store the attribution information, the referrer initially used to visit the website
Cookies are small text files that are placed on your computer by websites that you visit. Websites use cookies to help users navigate efficiently and perform certain functions. Cookies that are required for the website to operate properly are allowed to be set without your permission. All other cookies need to be approved before they can be set in the browser.
You can change your consent to cookie usage at any time on our Privacy Policy page.