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Interferometric Surface Mapping of Rapidly Rotating Stars: Application to the Be star Achernar

  • Armando Domiciano de SouzaEmail author
Chapter
Part of the Lecture Notes in Physics book series (LNP, volume 914)

Abstract

Rotation is one of the fundamental parameters that governs the physical structure and evolution of stars. Massive stars are those presenting the highest rotation velocities and thus those for which the consequences of rotation are the strongest. On the stellar photosphere fast-rotation induces (1) a geometrical flattening and (2) a non-uniform distribution of flux/effective temperature (gravity darkening effect). A detailed mapping of these effects on the stellar photosphere, including large scale surface velocity fields, is nowadays possible thanks to modern techniques of optical/infrared long-baseline interferometry (OLBI). In this paper we focus on the measurement of gravity darkening from OLBI, while the determination of flattening is detailed by Kervella (this volume). In addition, we also show that, for fast-rotators, the combination of OLBI and spectroscopy (spectro-interferometry) allows to go beyond the spatial resolution limit of interferometers in order to measure angular sizes of stars, otherwise not measurable by classical OLBI techniques. The results presented here are based on ESO-VLTI interferometric observations of the Be star Achernar.

Notes

Acknowledgements

I am grateful to the organizers of the Besançon school for their invitation to write this paper. PIONIER is funded by the Université Joseph Fourier (UJF), the Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), the Agence Nationale pour la Recherche (ANR-06-BLAN-0421 and ANR-10-BLAN-0505), and the Institut National des Science de l’Univers (INSU PNP and PNPS). The integrated optics beam combiner is the result of a collaboration between IPAG and CEA-LETI based on CNES R&T funding. This research has made use of the SIMBAD database, operated at the CDS, Strasbourg, France, of NASA Astrophysics Data System Abstract Service.2 We also have used the Jean-Marie Mariotti Center (JMMC) services OIFits Explorer,3 and SearchCal.4

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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Laboratoire LagrangeUniversité Côte d’Azur, Observatoire de la Côte d’Azur, CNRSNice cedex 4France

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