My research focuses mainly on the early stages of planet formation, during which microscopic dust particles come together to form kilometer-size planetesimals – the building blocks of planets (see below). I am particularly interested in understanding how the chemical and elemental abundances in different regions of the protoplanetary disk are imprinted on the planets that are forming. For an up-to-date list of my publications, visit SAO/NASA ADS or Google Scholar.
DUST COAGULATION AS THE START OF PLANET FORMATION
I simulate the growth of dust grains in protoplanetary disks all the way from (sub)micrometer to kilometer sizes, paying special attention to the aggregates’ internal structure and mass-loss due to high-velocity erosive collisions (Krijt et al. 2015; Schräpler, Blum, Krijt & Raabe 2018). I am also interested in the interplay between dust coagulation and dynamics and its effects on the vertical redistribution and inward migration of particles (Krijt & Ciesla 2016; Krijt et al. 2016; and Misener, Krijt & Ciesla 2019).
EVOLUTION OF VOLATILES IN GAS-RICH PROTOPLANETARY DISKS
I have been working on modeling dust and volatile (mainly water and carbon-monoxide) evolution together to establish a more direct link between the onset of planet formation and the different volatile reservoirs present in protoplanetary disks (Krijt, Ciesla & Bergin 2016; Krijt et al. 2018). Recently, we compared predictions from such models to observations of gas-phase CO in the outer regions of nearby disks (Zhang, Bergin, Schwarz, Krijt & Ciesla 2019). Closer to the star, just outside the water snowline, the build-up of water ice on dust aggregate surfaces can potentially trigger the formation of planetesimals (Schoonenberg, Ormel & Krijt 2018).
PRISTINE BODIES IN THE SOLAR SYSTEM
Pristine bodies in the outer solar system can teach us a lot about the physical and chemical conditions in the solar nebula some 4.56 Gyr ago. Cold Classical Kuiper Belt Objects (CCKBOs) like Arrokoth, which was visited by NASA’s New Horizons spacecraft in 2019, are particularly interesting (Grundy et al. 2020). Read more about Arrokoth and the New Horizons mission here.
CONTACT MECHANICS ON MICROSCOPIC SCALES
In order to understand and predict the outcome of individual collisions between solid particles in any environment (e.g., do they stick together, bounce of each other, or even shatter), a detailed understanding of the contact forces between the dust particle constituents is required. I have worked on improving the theory describing these forces by comparing analytical models to a suite of existing laboratory experiments (see Krijt et al. 2013; Krijt et al. 2014; and Güttler et al. 2012). The new force model has a large impact on the collisional behavior of macroscopic dust particles, generally making them more resilient (Seizinger, Krijt & Kley 2013).
N-BODY DYNAMICS & OTHER PROJECTS
I have also had fun investigating the effect of migrating planets on planetesimal belts (Krijt & Dominik 2011), the efficiency and speed of impact ejecta exchange in the TRAPPIST-1 system (Krijt et al. 2017), and thinking about collisional cascades in debris disk systems (Krijt & Kama 2014).