Stellar granulation and interferometry

TL;DR

This paper discusses how stellar surface granulation, caused by convection, affects various astrophysical measurements and how interferometry can be used to study and correct for these effects across different star types.

Contribution

It reviews the role of interferometric observations in characterizing stellar surface granulation and its impact on astrophysical parameter determinations.

Findings

Interferometry helps characterize stellar surface dynamics.

Granulation patterns vary with stellar type.

Surface activity can bias stellar measurements.

Abstract

Stars are not smooth. Their photosphere is covered by a granulation pattern associated with the heat transport by convection. The convection-related surface structures have different size, depth, and temporal variations with respect to the stellar type. The related activity (in addition to other phenomena such as magnetic spots, rotation, dust, etc.) potentially causes bias in stellar parameters determination, radial velocity, chemical abundances determinations, and exoplanet transit detections. The role of long-baseline interferometric observations in this astrophysical context is crucial to characterize the stellar surface dynamics and correct the potential biases. In this Chapter, we present how the granulation pattern is expected for different kind of stellar types ranging from main sequence to extremely evolved stars of different masses and how interferometric techniques help to study their photospheric dynamics.