Image: An artist conception of a newly formed star surrounded by a swirling protoplanetary disk of dust and gas, where debris coalesces to create rocky ‘planetesimals’ that collide and grow to eventually form planets. A new study suggests small rocky planet may actually be widespread in our Milky Way galaxy. Credit: University of Copenhagen, Lars A. Buchhave
Planets may not be able to form without a heaping helping of heavy elements such as silicon, titanium and magnesium, a new study suggests.
Stars that host planets have higher concentrations of such “metals” — astronomer-speak for elements heavier than hydrogen and helium — compared to iron than do planetless stars, the study found.
“To form planets, one needs heavy elements,” said lead author Vardan Adibekyan, of the Centre for Astrophysics of the University of Porto in Portugal.
Connected at birth
Planets coalesce from the disk of dust and gas left over after the birth of their parent star. According to the leading theory of planet formation, the core accretion model, small particles clump together, growing larger and larger until they produce protoplanets.
Scientists have long suspected that stars with higher metallicities are more likely to have planets orbiting them. Iron has long been a primary indicator.
“Usually, in stellar physics, people use the iron content as a proxy of overall metallicity,”