The three issues of MNRAS (Monthly Notices of the Royal Astronomical Society) for May are now out:
Volume 539, Issue 1 May 2025
Ali-Dib, M. Walton, C. Protoplanetary cores drove chondrule formation P. 127 staf505
Anslow, R. J. Bonsor, A. Todd, Z. R. et al. The atmospheric entry of cometary impactors P. 376 staf507
Królikowska, M. Kankiewicz, P. Wajer, P. Future evolution of 12P and other Halley-type comets in near-polar orbits P. 590 staf492
Volume 539, Issue 2 May 2025
Wesołowski, M. The flux-nuclear mechanism as the cause of cometary outbursts – a solution to an old problem P. 939 staf551
Moreno, F. Goetz, C. Aceituno, F. J. et al. Dust environment of long-period comet C/2023 A3 (Tsuchinshan-ATLAS) P. 949 staf552
Volume 539, Issue 3 May 2025
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Chondrules: little blobs of rock that are crucial to meteoritics (and thus, accretion into asteroids and planets), yet we still don’t know what exactly the deal is. Were chondrules melted by lightning in the protosolar nebula? Volcanic spray that cooled? Molten ejecta that cooled? The quest continues. Ali-Dib and Walton propose a bold new hypothesis: chondrules were always part of planetesimals, where they formed. While molten, they escaped by boiling off the surface. We have a new contender in the ring.
Anslow et al. consider the opposite: how did primitive (unmelted) objects (here, comets) contribute their crucial volatiles (like organic compounds) to the young planets, satellites, etc.? We have lots of documentation on the Chelyabinsk meteor, but less so for larger objects, and comet-like (fluffy and weak) bodies. Anslow et al. attempt to replicate such impacts, and survival of their contents.
But before comets can impact us, they have to reach us. What are the dynamics of comets, whose orbits cross the orbits of the planets? A little imagination will tell you that crossing the orbits of Earth, Jupiter, etc. repeatedly is a suicide mission. These bodies cannot be stable for the life of the Solar System, are eventually lost, and have to be replenished. Along the way, strange things like the Kozai mechanism produce weird orbit states. Królikowska et al. walk us through the strange way.
All the while, comets lose material (“activity”) when warmed by enough sunlight. What, specifically, is the origin and process of this mass loss? Wesołowski et al. consider some of the implications for one process, filtering of volatiles through (yes, flow through pores) a comet’s nucleus.
On a more objective level: Moreno et al. describe the activity of one comet, the recent Tsuchinshan-ATLAS. Every comet with well-described activity numbers is one more piece of the puzzle.