The branch of astrophysics that investigates the interior structure of the Sun by studying its surface wave oscillations. The surface of the Sun vibrates much like a bell. A piano has 88 keys or musi
cal tones, whereas the Sun has millions of notes. These vibrations are the result of internal pressure waves that reflect off the photosphere and repeatedly cross the solar interior. They are detected through the Doppler shift of absorption lines formed in the photosphere. Because these vibrations make the solar surface move up and down, analysis of the surface patterns is used to study conditions far below the Sun's surface. The mean period of the vibrations is about five minutes, which corresponds to a frequency of about 3 mHz.
The region located between the termination shock and the heliopause where the turbulent and hot solar wind is compressed as it passes outward against the interstellar wind.
The region located between the termination shock and the heliopause where the turbulent and hot solar wind is compressed as it passes outward against the interstellar wind.
The region of space dominated by the Sun’s extended, outflowing atmosphere. Based on views of other stellar spheres, the heliosphere probably has a tear-drop shape due to its interaction with the inte
rstellar wind.
The vast, three-dimensional region of space around the Sun filled with the solar wind and the remnant of the solar magnetic field carried in it. It is bounded by the heliopause, which is estimated to
be 100 astronomical units or more from the Sun. The radius of the heliosphere is expected to vary with the solar cycle. The heliosphere may be very elongated owing to the presence of an interstellar wind of neutral hydrogen flowing from the direction of the Galactic center.