The three August “issues” of MNRAS (Monthly Notices of the Royal Astronomical Society) are now online and complete:
Volume 541, Issue 2, August 2025
Attree, N. Gutiérrez, P. Schuckart, C. et al. Constraints on the ejecting-crust activity model on comet 67P/Churyumov–Gerasimenko Pgs. 771 staf1040
Lin, Z-Y. Cheng, C-C. Bolin, B. et al. Asteroid phase function parameters and taxonomic constraints from the Zwicky Transient Facility Pgs. 1472 staf960
Bykov, N. Y. Zakharov, V. V. Tonkov, D. N. et al. Ejection velocities of dust particles from the near-surface layer of a cometary nucleus Pgs. 1782 staf382
Volume 541, Issue 3, August 2025
Zivithal, S. Macher, W. Kargl, G. et al. Sublimation front and sinter layer formation on cometary surfaces: modelling the desiccation process from mixtures of ice and refractory materials Pgs. 2651 staf1091
Volume 541, Issue 4, August 2025
Lewis, Z. M. Stephenson, P. Beth, A. et al. Cometary ion dynamics at 67P: a collisional test-particle approach with Rosetta data comparison Pgs. 3590 staf1162
Four explicit comet papers, and a general (no particular specialty…) paper. Lin et al. consider use of phase information (looking at “full” or “high noon” on a Solar System body, vs. dawn/twilight or even crescent views) to tell us of that body, even if all we see is a dot in the sky. Aside from the “full” phase being brighter than a (unresolved) crescent, bodies can be brighter or dimmer than one would have expected, compared to strictly geometric models of full vs. crescent. The difference between expected vs. measured phase brightnesses can tell us of low-albedo (darker) bodies, like C-type asteroids.
Attree et al. and Bykov et al. write of comet activity- an open question that the Rosetta probe was sent to study. We still don’t really grasp what happens, in what order, and at what comet depth, when a nucleus approaches the Sun and warms up. Simply saying “it sheds” doesn’t cover it.
Zivithal et al. try the micro view: one of the things we’re confident is that comet nuclei are fluffy piles of dust particles, frost crystals (of multiple volatiles), and empty space. As the frost warms up and boils off, some dust is carried along, but the remaining solids deposit into a “lag”. What does this process look like? Given what we know so far, Zivithal and coauthors try to complete the picture.
And why did Rosetta not complete the activity picture? Well, one was the underperformance of the Philae lander (but we’ll get to that…). Another was that the Rosetta science team included plasma physicists; per some reports, these plasma scientists diverted observation time (and even spacecraft maneuvers) to favor their investigations, short-changing other goals like nucleus imaging and closeups of dust/jetting. In any case, we did get plasma and fields data from the 67P coma, and its interaction with the heliosphere. Lewis et al. test our understanding, vs. what Rosetta actually saw.