Interferometry to Determine Stellar Shapes: Application to Achernar
Abstract
The shape of stellar photospheres can depart significantly from the spherical geometry, due e.g. to fast rotation. In this chapter, I focus on the application of long-baseline interferometry to the determination of the photospheric shape of fast rotating stars. I present the example of the VLT Interferometer observations of the nearby Be star Achernar (α Eri), using the VINCI (two telescopes) and PIONIER (four telescopes) beam combiners. I present the adjustment of a simplified model of the light distribution of Achernar to the measured interferometric visibilities and closure phases . This example application is based on the LITpro software from the JMMC.