  Oscillations of the Sun have been used to understand its interior structure.
The extension of similar studies to more distant stars has raised many
difficulties despite the strong efforts of the international community over the
past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite,
launched in December 2006, has now measured oscillations and the stellar
granulation signature in three main sequence stars that are noticeably hotter
than the sun. The oscillation amplitudes are about 1.5 times as large as those
in the Sun; the stellar granulation is up to three times as high. The stellar
amplitudes are about 25% below the theoretic values, providing a measurement of
the nonadiabaticity of the process ruling the oscillations in the outer layers
of the stars.
