Catching up with Publications of the Astronomical Society of Japan (PASJ), not printing every month. In vol. 77 #4, some worthy papers:
Miura, H. Yasuda, T. Thermal evolution model from cometary nuclei to asteroids considering contraction associated with ice sublimation P. 785 psaf048
Hasegawa, H. Tsumura, M. Watanabe, S-i. et al. The 2023 July outburst of comet 12P/ Pons-Brooks: Observations and modeling of dust coma and arc structure P. 934 psaf066
It is assumed, for generations now, that some amount of non-Main-Belt asteroids are actually extinct comets. After all, only the Main Belt is stable for the age of the Solar System; Mars-crossing asteroids and NEOs are only stable for a small fraction of that. This means replenishment by another source; a handy assumption is that some comets circularize orbits, all the while depleting themselves and looking asteroidal. But is this assumption valid? Miura et al. tackle it from one angle.
Tying into a (still a bit controversial) paper (Miura et al. 2022, The Asteroid 162173 Ryugu: a Cometary Origin) that claims (162173) Ryugu is such an extinct comet, Miura et al. forward-model the depletion process. They then test their depletion parameters against real Solar System bodies, like Phaethon, Main-Belt comets, and for good measure, 67P/Churyumov-Gerasimenko as a non-extinct but well-studied example.
Hasegawa et al., on the other hand, is far less speculative. Comets are difficult to study, because their extreme orbits make it hard to send spacecraft to them. Even from the ground, comae obscure the nucleus, and most comet gases do not have spectral features in visible light. We generally need costly infrared, ultraviolet, etc. scopes to say more about comet compositions. Still, Hasegawa et al. are doing what they can to move Pons-Brooks closer to the “well-studied” category.