Solar Chemistry a New Key to Finding Exoplanets

For many years researchers have pondered why our Sun has a negligible amount of lithium compared to other stars in our galaxy. In comparison, our Sun actually has less than 1% of the lithium present in most other stars. Researchers using the ESO’s HARPS spectrograph analyzed over 500 different stars, 70 of which are planet-bearing star systems and compared each one’s lithium content, as well as other light chemicals (in comparison to the atomic weight of iron). It was revealed that star systems which bear planets contain far less lithium than those systems which bear no planets.

Artist’s impression of a baby star still surrounded by proto-planetary material in which planets could form.

Somehow, it seems that systems which host planets provide a way to destroy the lithium over the years. Lithium is thought to have been an abundant element since the big bang and is present in most every star. The anomaly of chemical amounts that vary from star to star has bewildered researchers for over 60 years. So can planets and other planetary bodies affect the star in a way enough to destroy and realign chemical composition within that star? It seems that way. Theoreticians have their work cut out for them trying to figure out what causes the anomaly.

Researchers have undergone this project of measuring and analyzing lithium content in hopes of finding a way to detect star systems which bear planets in a way easier and faster than the current method using the HARPS device. For reference, HARPS is a device attached to the La Silla 3.6″ ESO telescope and studies the “wobble” of gravity and light from stars to detect if the star hosts a planet. If the current research is right, researchers may now use the HARPS device to detect lithium content from a star to determine the likelihood of the said star hosting planets.

The team of astronomers and researchers primarily involved in the project are: Garik Israelian, Elisa Delgado Mena, Carolina Domínguez Cerdeña, and Rafael Rebolo (Instituto de Astrofisíca de Canarias, La Laguna, Tenerife, Spain), Nuno Santos and Sergio Sousa (Centro de Astrofisica, Universidade de Porto, Portugal), Michel Mayor and Stéphane Udry (Observatoire de Genève, Switzerland), and Sofia Randich (INAF, Osservatorio di Arcetri, Firenze, Italy).

Journal Reference: G. Israelian et al. Enhanced lithium depletion in Sun-like stars with orbiting planets. Nature, November 12, 2009. Adapted from materials provided by ESO.