Backlog after the Mars paper.

More backlog.

Still catching up with the backlog. for a change, I'm looking at my most-recent listing.

• Planet Formation Mechanisms (https://arxiv.org/pdf/2410.14430) - a book chapter for something that hasn't come out yet. (Is it a proceedings volume/ review collection from Protostars and Planets VII, April 10th – 15th of 2023, Kyoto, Japan ? Lots of links on that page to recordings of the conference proceedings, such as "The Solar Neighborhood in the Age of Gaia" - now that looks a valuable seam to mine, once the current problems with downloading from YT are fixed.) Quick read ... disk-instability versus core-accretion models (which are end-members of a continuum). It all happens quickly - order of a million years, and in the middle of a dusty nebula, making it inherently hard to observe. (More data, extending into the thousands of exoplanet, improves the chances of finding examples in that 1-in-5000 time period for the Solar system analogues.) All in, that looks a very valuable resource. Time for me to watch some YT, while making supper.
  [Later] Lots of stuff over my head, so far concentrating on aspects of assembling matter into protostars. (Well the conference was titled "Protosatars and Planets", and as presented on YT, the conference seems to have worked systematicay from interstellar space down to assembling planets. So, more watching to do. Worth the investment - and when YT's download blocks are broken again, I'll be back to DL them. Probably worth it's own posting, when I've got recordings that I can pause/ rewind.
• "Projections of Earth’s technosphere. I. Scenario modeling worldbuilding, and overview of remotely detectable technosignatures." - a bit difficult to asssess this one. The astronomical point of view is that looking into the future like this helps sharpen the focus on potential bio- and techno-signatures we could find in the atmospheres of exoplanets. Worth doing. Not sure how to assess this though. Interesting, and not terribly optimistic that their Abstract sums up the results as "Our scenarios include three with zero-growth stability, two that have collapsed into a stable state, one that oscillates between growth and collapse, and four that continue to grow. Only one scenario includes rapid growth that could lead to interstellar expansion."
  I'm not sure how to assess their methodologies, but it's one for the "futurologists" to consider (if they do anything other than navel-gazing and tea-leaf reading).
• "The Accelerating Decline of the Mass Transfer Rate in the Recurrent Nova T Pyxidis" This just caught my eye and reminded me to check on how "T CorBor" is going (Magnitude 10.2 ; Error - JD 2460607.194 ; Calendar Date - 2024 Oct. 23.69400; Magnitude 10.2; Filter Vis.; Observer MQA. It hasn't gone yet.) In comparison to T CorBor, "The recurrent nova T Pyxidis has erupted six times since 1890, with its last outburst in 2011," - 20-odd years, which compares to the 80-year recurrence (one recurrence!, poised on tenterhooks for the second) of T CorBor ; "[...] indicates that T Pyx must have a massive white dwarf accreting at a high rate." Well, it does if there is any validity to the accreting WD model - which I've heard no serious counter-proposals against. "the magnitude decline of T Pyx from ∼ 13.8 (before 1890) to 15.7 just before the 2011 eruption" Ah, that would explain why it's less well known - you need ... at least a 150mm (six-inch) telescope to see that and do any meaningful measurements on it. In the context of T CorBor being around a month "late" for it's bookings as a TOO (Target Of Opportunity) for just about ever professional telescope in the northern hemisphere, the complexity of this stars varying recurrence rate makes the delay in recurrence all the more understandable.
  This star is inferred to have at least one feedback system, where the heat of material transferring onto the WD component inflates one side of the companion star to increase the transfer rate ... leading to more complex behaviour. T Pyx' recurrence intervals of 12, 18, 24, 23, and 44 years suggests there is a lot more complexity to it's behaviour than implied for T CorBor.
  T Pyx is a bit odd. If Wiki is right (an important "if"), then the WD has a mass of 0.7 M_☉ while the companion has a mass of 0.13M_☉. Which puts it down in the brown dwarf margin. And the total mass of the system is 0.87 M_☉ - which is well below the Chandrasekhar limit (about 1.4 M_☉. So the big concern is ... ? Whatever things T.Pyx has up it's binary sleeve, a type 1A supernova isn't among them. [Checking the references for that mass estimate … Uthas et al (Mon. Not. R. Astron. Soc. 409, 237–246 (2010)) do give that figure, but in a context of a WD:donor mass ratio of 5:1. That still leaves the donor as being very small, for feasible WD masses (≤ Chandrasekhar), and the total mass marginal for producing a SN.
  Odd system. Big can of worms. (I also see that Schaeffer - the guy who was headlining the "T CorBor is gonna blow!" story - has a long history publishing in the recurrent nova field. As one would hope. The data densities for nova records from the 1920s to [recent] are instructive - dozens of photometric measurements increasing to hundreds per eruption.) Moving on.
• A cosmic formation site of silicon and sulphur revealed by a new type of supernova explosion. Everyone knows the "onion" model for nucleosynthesis in (massive) stars. Less well-known is the existence of "stripped" stars where hot massive stars lose their hydrogen-dominated envelopes, revealing a He-dominated core (Wolf-Rayet stars, particularly sub-type WN). Digging deeper (ejecting more of the envelope, one gets the carbon/oxygen shell exposed (Wolf-Rayet WC/WO stars) and their corresponding type 1_CN supernovae, with their unusual sets of emission lines. This paper reports a supernova whose spectrum implies stripping all the way to expose the sulphur/silicon layer of the core. SN 2021yf is proposed to show such a star's destruction with lines of multiply ionised silicon, sulphur, and argon (Si_III-IV, S_III-IV, and Ar_III with an absence of lighter element lines. Which they interpret as being the detonation of such a core stripped back well into the S-Si shell.
  Nice find. I was aware thaat W-R stars were stripped, and hot, bright (so, short-lived) stars. But I hadn't realised they were - at their extremes - taking their own cores apart. "Die young, stay pretty", on a stellar scale.

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And that's another couple of days worth skim-read.

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