Interstellar objects function as seeds for planet formation predominantly around high-mass stars

The discovery of 1I/Oumuamua and 2I/Borisov showed that significant numbers of interstellar objects (ISOs) populate interstellar space. Their omnipresence means that ISOs also reside in protoplanetary discs, which are the reservoir for forming planets. There, ISOs could kick start planet formation by overcoming the 1-m barrier present in the standard model of planet formation (Grishin et al. 2019, Pfalzner & Bannister 2019, Mara-Martin & Norman 2022).  

However, not all stars seem equally likely to capture TNOs in their discs. Simulations of the capture of ISOs in molecular clouds indicate that ISOs are predominately captured by massive stars or in star cluster environments (Pfalzner et al. 2021). 

Exoplanet statistics show considerable differences between the planetary systems around high-mass and those around low-mass stars. Main-sequence FGK stars host more larger planets than low-mass stars, whereas M dwarfs host about a factor of three more small planets
 (Mulders et al. 2021). However, the mass is not simply redistributed into more smaller planets. Surprisingly, the average heavy-element mass decreases with increasing stellar mass. Thus, despite M star discs containing ten times less mass, they are nearly 20 times as efficient as F stars in converting the disk’s heavy-element content into planetary material. Besides, high-mass stars have, on average, much shorter disc lifetimes (1-3 Myr) than low-mass stars (5-10 Myr). Thus, giant planets have to form on extremely short time scales. 

We investigate the potential connection between the observed short disc lifetime around massive stars and the different probabilities of capturing ISOs in the discs. 

References
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Moro-Martin, A. & Norman, C. 2022, ApJ, 924, 2, 96. 
Pfalzner, S., Paterson, D., Bannister, M.T., et al. 2021, ApJ, 921, 2, 168. 
Mulders, G.D., Drkazkowska, J., van der Marel, N., et al. 2021, ApJL, 920, 1, L1.