* Astronomy

Title: The age of the Solar System redefined by the oldest Pb-Pb age of a meteoritic inclusion
Authors: Audrey Bouvier & Meenakshi Wadhwa

The age of the Solar System can be defined as the time of formation of the first solid grains in the nebular disc surrounding the proto-Sun. This age is estimated by dating calcium-aluminium-rich inclusions in meteorites. These inclusions are considered as the earliest formed solids in the solar nebula. Their formation marks the beginning for several long- and short-lived radiogenic clocks that are used to precisely define the timescales of Solar System events, such as the formation and evolution of planetary bodies. Here we present the 207Pb-206Pb isotope systematics in a calcium-aluminium-rich inclusion from the Northwest Africa 2364 CV3-group chondritic meteorite, which indicate that the inclusion formed 4,568.2 million years ago. This age is between 0.3 and 1.9 million years older than previous estimates and is the oldest age obtained for any Solar System object so far. We also determined the 26Al-26Mg model age of this inclusion, and find that it is identical to its absolute Pb-Pb age, implying that the short-lived radionuclide 26Al was homogeneously distributed in the nebular disc surrounding the proto-Sun. From the consistently old ages in the studied inclusion, we conclude that the proto-Sun and the nebular disc formed earlier than previously thought.

Source