Jeremy,

That is a fascinating paper and Sekanina is very well respected in the
field so carries a lot of weight. Some of the arguments are quite
persuasive but to use "inevitable" in any prediction about a comet is
probably unwise!

It is definitely a testable theory though and that is what science is
all about.

It is another good reason to observe this comet at every opportunity.

Nick.

On 09/07/2024 12:10, Jeremy Shears wrote:
>
> 
> Hmm….perhaps no such a good post-perihelion show…..
>
> https://arxiv.org/abs/2407.06166
>
> Inevitable Endgame of Comet Tsuchinshan-ATLAS (C/2023 A3)
>
> Zdenek Sekanina
>
> Hopes are being widely expressed that C/2023 A3 could become a naked-eye object about the time of its perihelion passage in late 2024. However, based on its past and current performance, the comet is expected to disintegrate before reaching perihelion. Independent lines of evidence point to its forthcoming inevitable collapse. The first issue, which was recently called attention to by I. Ferrin, is this Oort cloud comet's failure to brighten at a heliocentric distance exceeding 2 AU, about 160 days preperihelion, accompanied by a sharp drop in the production of dust (Af\rho). Apparent over a longer period of time, but largely ignored, has been the barycentric original semimajor axis inching toward negative numbers and the mean residual increasing after the light-curve anomaly, suggesting a fragmented nucleus whose motion is being affected a nongravitational acceleration; and an unusually narrow, teardrop dust tail with its peculiar orientation, implying copious emission of large grains far from the Sun but no microscopic material recently. This evidence suggests that the comet has entered an advanced phase of fragmentation, in which increasing numbers of dry, fractured refractory solids stay assembled in dark, porous blobs of exotic shape, becoming undetectable as they gradually disperse in space.
>
> To unsubscribe from this list please go to https://www.simplelists.com/confirm/?u=Aj4vCBHI6JSRpYRB2DWvMTYlWL2vuAnC
>