Thursday 6 September 2012

Exoplanets give insight into Planet Formation

A team of astrophysicists led by EXOEarths researcher Dr Vardan Adibekyan of the Centro de Astrofísica da Universidade do Porto, Portugal have found that metals like magnesium might play a significant role in the formation of low mass planets.
The team used the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph to observe and analyse the high-resolution spectra of 1111 Sun-like stars. Of these, 109 are known to have high mass Jupiter-like planets, while 2 have Neptune-like planets.

Refractory Alpha Elements like magnesium, silicon or titanium make up the bulk of the mass of the terrestrial planets (Mercury, Venus, Earth and Mars) and a fraction of the giant planets and their moons. Researchers therefore focused especially on studying the abundance of these elements. The results show that the ratio of these elements, compared with the amount of iron, is consistently higher in stars with planets; magnesium shows the greatest discrepancy. The results may provide constraints for the models of planet formation, particularly planets with low mass.

Previously, the theories around planet formation suggested that planets were created through the clumping together of smaller particles of heavy elements, into larger bodies. These new results show that planets need a minimum amount of ‘metals’ to be formed; the formation of planets is dependent on the dust content of the cloud where the star and planetary system formed.

Photo: THE CHEMISTRY OF STARS THAT HOST EXOPLANETS GIVES INSIGHTS INTO PLANET FORMATION

A team of astrophysicists led by EXOEarths researcher Dr Vardan Adibekyan of the Centro de Astrofísica da Universidade do Porto, Portugal have found that metals like magnesium might play a significant role in the formation of low mass planets.
The team used the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph to observe and analyse the high-resolution spectra of 1111 Sun-like stars. Of these, 109 are known to have high mass Jupiter-like planets, while 2 have Neptune-like planets. 

Refractory Alpha Elements like magnesium, silicon or titanium make up the bulk of the mass of the terrestrial planets (Mercury, Venus, Earth and Mars) and a fraction of the giant planets and their moons. Researchers therefore focused especially on studying the abundance of these elements. The results show that the ratio of these elements, compared with the amount of iron, is consistently higher in stars with planets; magnesium shows the greatest discrepancy. The results may provide constraints for the models of planet formation, particularly planets with low mass.

Previously, the theories around planet formation suggested that planets were created through the clumping together of smaller particles of heavy elements, into larger bodies. These new results show that planets need a minimum amount of ‘metals’ to be formed; the formation of planets is dependent on the dust content of the cloud where the star and planetary system formed.

-TEL

Read more about HARPS here: http://www.eso.org/sci/facilities/lasilla/instruments/harps/overview.html
More on EXOEarths: http://www.astro.up.pt/exoearths/

Photo is an artist’s concept of a star surrounded by a swirling disk of planet-building dust (NASA/JPL-Caltech/T. Pyle/SSC)

http://www.sci-news.com/astronomy/article00543.html; http://www.sciencedaily.com/releases/2012/08/120816121856.htm; Adibekyan et al. 2012. Overabundance of alpha-elements in exoplanet-hosting stars. Astronomy & Astrophysics, vol. 543, article no. A89; doi: 10.1051/0004-6361/201219564

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