X-ray Impact on Planet Formation: an experimental view

I this talk, I will introduce how planets are formed in the disk of gas and dust surrounding young stars. Stars like classical T Tauri emit copious amounts of X-rays, in addition to ultraviolet photons, confirmed by Chandra/XMM observations of targets in the Taurus molecular cloud. Soft (<1 keV) and hard (>1 keV) stellar X-rays impinge and are absorbed by the protoplanetary disk during its million year lifetime. Yet, the effects of stellar X-rays on protoplanetary matter remain elusive due to a lack of fundamental X-ray photochemical data. Because X-rays are known to penetrate deeper in matter than UV photons or electrons this could have far-reaching consequences on protoplanetary dust.

 

To unveil the microphysical effects of X-rays on cosmic dust we tackle this problem using experimental astrophysics. We simulate cosmic dust in protoplanetary disks by using solid-state analogs, and simulate high doses of X-ray radiation using synchrotron radiation at large facilities. Dust nanoparticles are irradiated with X-rays until reaching astrophysically-relevant doses. The samples are examined via X-ray diffraction, infrared and isotopic microprobes.  Our experiments show that large doses of X-rays significantly impact the structural, optical and isotopic properties of the smallest dust grains. I will provide an overview of what this means in the context of primordial planet formation and of our future work.

Speaker: Lisseth Gavilan-Marin, NASA Ames