Français English
Send to a friend Print

Constantly stretching the limits of the Universe

Inside the core of stars

Studies of the physics of stars and their atmospheres began in the 1930s. Though scientists have obtained considerable data on solar structure and development, many questions remain.

The Sun, our nearest star, has only begun to reveal some of its secrets in the past 20 years. In the 1970s, astronomers discovered that our Sun experiences many rapid and complex vibrations. They later observed that many celestial bodies exhibit similar movement, with waves spreading through a star like ocean swells.

The CoRoT satellite records the subtle changes in brightness caused by these sound waves as they resonate through the star. Studies of these vibrations (solar seismology) will enable researchers to determine the main characteristics of the stars observed, giving us valuable insights into their internal rotation profile, convective region boundaries, the size of their core and chemical composition.

The existence of extrasolar planets

Artist’s impression of a planetary system that might resemble our own. The Jupiter-like planet was discovered orbiting the star 55 Cancri. Vue d’artiste de Lynette Cook, crédits ESA

Since 1955, some planets circling other stars have been detected. Most of them are gas giants like Jupiter, with diameters 10 times greater than that of the Earth, some of them gravitating very close to their parent star (such planets are known as hot Jupiters).

Corot is the first spacecraft capable of discovering rocky planets smaller than these gas giants.

To do so, the satellite uses the transit method. This technique detects planets when they pass in front of their mother star, thus blocking part of the light received by the telescope. Although this configuration is relatively rare, planets detected in this way are of great scientific value because analysing the dip in the light curve during a transit gives us a more detailed picture of a planet’s characteristics.

Transit method: this method could detect a 1% drop in brightness when Jupiter passes in front of the Sun.
Transit method: this method could detect a 1% drop in brightness when Jupiter passes in front of the Sun.

More about...

Related links