Speaker: Pavan Tanna (Cambridge)

Date: Tuesday 5 September 2023

Time: 13:30

Location: Physics 3.27

Detecting giant impacts in other star systems

Giant impacts play an important role in planetary system formation and are the current leading explanation for the formation of the Moon. A synestia, a large rotating planet sized object formed in high angular momentum giant impacts, is a promising mechanism for the formation of the Moon, given it successfully explains the compositional similarity between the Earth and the Moon through mixing. Synestias are common outcomes of giant impacts. This paper assesses whether a synestia formed after a moon forming impact can be detected in another star system. Synestia producing giant impacts were simulated and an extrapolation model is applied to calculate the outer properties of the synestia. A silicate photon absorption model from Kraus et al. (2012) was used to find the radiating surface of the synestia so its luminosity can be calculated. Synestia luminosities were found to range from 10⁻⁴ to 10⁻³ L⊙. This luminosity was compared with Gaia's photometric sensitivity. With some estimations on giant impact frequencies and the number of terrestrial planet, it was estimated that, over the full 10+ year lifetime of Gaia, 1-20 giant impacts should be observable and these should be found in the final Gaia Data Release 5. It is thus possible with our current technology to detect a moon forming impact. Detecting a giant impact would improve our understanding of planetary system and moon formation.