NAMD

Here is another mathematic constant for you, dear readers: Turrini-Zinzi-Belinchon's normalized angular momentum deficit (2020). This takes a solar-system for which we may account for every planet in it: semimajors and masses - only (for now). We calculate that ideal's whole angular momentum. Then we consider the eccentricities and inclinations and run the calculations again. The eccentricity and inclination, which we'll remember from Kozai von Zeipel oscillate, turn out to lower the momentum of the total. Therefore the deficit reflects how messy the system.

This works for systems where we own those statistics, of course.

Mostly they'll be transits such that multiple planets here will not be mutually inclined. Those will be tight orbits. Einstein starts wrangling Newton for Mercury's orbit. Further-in, tides should be raised on the star, which where eccentric Kepler teaches to undercut the planet's momentum from ideal i.e. increase the deficit. If the planets be resonant, their mutual planetary (and, internally, tidal) interactions are non-Keplerian; making "eccentricity" into a moving target. Rather, we see from the Jovian system that a resonant system should lose energy: here through Io, literally disintegrating over time and radiating heat.

On the high end, sometimes - for systems closer to ours, or very young - we can image the planets directly. Or, the dynamics have been studied to stick some constraints upon eccentricity and inclination both. Which together lower a ceiling upon momentum.

Their map marks our system's NAMD to two thousandths: 0.002, or 2 x 10^-3. "Thanks" to Velikovsky, others have done enough dynamics to declare this as longterm stable, although we'll not live to see what Gliese 710 shall do unto us.

Turrini, Zinzi and more - Polychroni and Danielski were media-available - have posted a followup from their model. Evan Gough (h/t toughsf) summarises: 0.002 is a mean and median for sub-G stars with their outermost planet ("Pout") rolling around in less than a Venereal year. Our system's longest year, for such as matter, is Neptune's at 1.648 x 10² years.

"Pout" year, NAMD, and stellar-mass all correlate at heavier G on-up. Pout and starmass should indeed correlate - with age. Those smaller systems (like GJ 710) brush against larger (like us) with the outermost former planets being less-bound. But.

I mentioned that our system has a Neptune. Such giants are sometimes visible for us in younger systems, still emitting infrared maybe even still red. High-mass systems are all younger. Up to now I could imagine little reason, oh, a Neptune-mass at a Saturn-like decades-long orbit cannot exist around a midage K. We're simply unlikely to find them soon (for GJ 710 I suppose we'll find out). So we could well be missing available data for Gs and Ks.

Danielski predicts that sliding some older K systems now Pout ~0.5 over to Pout ~5 won't budge their models: selection effects acted as the tip of the iceberg, revealing the existence of much deeper structural diversities between these systems. To that, I see one smaller star with a Jovianlike Pout - ~8 years - and its NAMD is high. One suspects it already did get tugged at by a flyby but retained that planet in a wonky orbit. So I may need to recalibrate my imagination.

Polychroni pipes in for the higher-masses: The greater abundance of material from which planets form around their host stars causes them to be born too large, preventing the system from remaining stable.

For skiffy worldbuilders, this suggests constraints on K "goldilocks" stars' systems. Where they have an ice giant or a super earth outside the HZ, it either formed wonky or else got wonked by "now" (4.5 Gy after first carbon 'stroids). Such has already scattered viable mass in the HZ into uninhabitability. I get the impression this happens a lot. So your constructed K system shouldn't have long-period superearths-on-up.

Small reactors have problems

This blog was jumping with my joy when I first heard we were to approve some modular fission-reactors, in the runup to Trump 1. Six years later, Prof. Sabine Hossenfelder, (now) sponsored by the IEEE, is delivering a report-card. For a third of the advertised gains.

She would be going short. - if she were allowed to invest, which journalists shouldn't be (I know, stop laughing).

So far the record shows that the main investors today, as they were in the 1950s, aren't plebs. In the past six years, when a nuclear company has sought non-government investments, the monies aren't enough to float payroll. If Amazon or other data-facilities be ordering these, they're subsidised. The 1990s called and are calling it corporate-welfare.

Her source is Marisol Garrouste, Brendan Kochunas, Max Vanatta & Michael T. Craig from August. As well-known, economies of scale apply to nuclear physics. Small reactors produce less energy per the waste generated; this isn't like stacking rocket-engines for additional thrust. And every reactor requires its own slate of safety and environmental reviews.

We might dodge some environmental concern by using reactors in the middle of Nevada, or the vast outbacks of Canada or of Australia, or isolated mining valleys. Such could bypass some of that since they sometimes figure that revenue and labour trump already-remote and -barren environments. "First-Nation" sovereign lands with their own laws might get in on this one.

Given the above, Garrouste's quartet actually consider/s SMR a good bet if they are only delivering high heat, directly. So they could be used in endothermic smelting near those mines. They also might be used in breaking hydrogen off of water, but that too is a government project dependent upon "green energy goals". Where they don't much help, at their small scale, is in electricity generation, even to supply the remote miners' towns.

To check in on SpaceNukes: they're selling to a prototype rocket and to a prototype waterbearer. It seems however that most of their income is coming out of DARPA.

Cracked rock is a poor insulator

In more thermodynamic news, as of last March we know why Bennu (and Ryugu) don't hold heat well - has low thermal inertia. It's because Bennu's bigger rocks are cracked. Similar should hold for Ryugu and maybe Polana.

Apparently cracked geometry conducts heat more than just being porous. Porous rock would be analogous to cement, or to... C type meteorites, fused by the process of landing upon us.

The new cements we hope to make on Lunar bases will of course be more like S type meteorites, but the same porosity should apply. So, better sift out pebbles when making the cement.

Keyhole news

That conference last week further proposed bringing asteroid-bits into cislunar orbit. Joel Sercel has a map. I think the idea is to pull it to STL2, then yank it at the moon, which - by the Jacobi keyhole - ends up flung into a high Lunar orbit. That can touch upon various Earth-Lunar cyclers, the 3:1 being illustrated here.

This fits well with another thesis mooted a few days ago, on Galactic-Solar Lagrange; from the "space journal of Asgardia" page 72. I vaguely recall some skiffy about that maybe ten years ago. Assuming no nearby other heavy stars, our gravity meets the Galactic Core's gravity at 3.8 ly. During those periods, a slow moving body even up to Jupiter mass should be able to slide into a long-period Solar orbit. Which, if eccentric, will pose Problems.

To be sure, this is not one of those times. The Alpha Centauri system is something like twice our system's mass which means our mutual balance is a good deal within 2 ly of us, which should swamp our L's. But - stars move around all the time. Between the Scholz flyby 60skBC and 20kBC, we didn't have anything special near to us. Anything nabbed in L1 or L2 could be on its way toward us, still.

Tint

Me mum sent me this last week: Mark A Hollands, Boris T Gänsicke, Pier-Emmanuel Tremblay, Detlev Koester "Any colour you like: the diverse chromaticities of white dwarfs". This alludes to, and reverses, the famous Model T quote: most of these stars-in-retirement are white, median #F9F5FF to be precise. That would correspond to 6504 K / D65 white point.

That #FF is indeed in the B part of RGB, but they deem the blue negligible, correcting most textbooks. I take it that the blue stars are simply the brighter ones we've historically seen from further away.

Most white dwarf stars fall on a boring logarithmic-like curve by temperature, as one might expect. Sabine is saying our own Sun would be on the green side but all that yellow-to-red swamps it out.

However: outliers exist. These are metal-polluted. I don't find overlap between the two papers. Something like 080843.15 + 464028.64 should be WD J0808+4640, la?

Which is a pity. The "metals" here seem to skew toward lithium and stellar gas, not rocky planet mantles.

WD J1330+6435 is the one making the news at #DDFFB8. That #FF is in the G part of RGB. When I was a kid I asked my dad if green was possible in stars and he said that some elements look green in a fire.

Since then, uh. The Starflight game had some green stars but, by that age, I knew better. There was also Alastair Reynolds with his "green-fly" Dyson swarm, turning some stars green. Mind, both were main-sequence.

So, at last, this paper illustrates what my dad was trying to say, with an example he didn't have on-hand, because none of us did. (Green stars'd make more sense in the Starflight sequel which happens where the solar flares already happened.)

Other outliers are such as might look blue but are cooler than 6000 K. WD J2356–2054 in Draco shines only 4000 K. Here is strong Na[trium] (sodium) pollution.

Don't vote for Vivek

Mr Vivek Ramaswamy (hence, "Vivek" - because it's shorter) has mooted an advert although as far as I know not yet in television syndication, bringing Dr/Mrs Amy née-Stearns Acton's mother Donna Stearns-then-Arthur to testify against Amy.

Yeah. Her own daughter. This gon' get ugly.

Ms Laura Loomer is gung-ho on Vivek's side. Loomer is generally pro-Indian and pro-Republican, in this year's races anyway. I can understand being pro-both: seriously, despite this guy and his razixweeterz. I have long been unsure that Vivek is the right Indian or the right Republican to be daring a statewide race - anywhere, in the US or in India. But here we are discussing his opponent. Whom Vivek through surrogates down to mommy-dearest is accusing of dishonesty.

Scouting around the place, the accusation against Amy Acton's stepfather came from Amy Acton's biologic father. He leveled a charge of molestation against Mr Cledith Arthur, the non-biologic. Arthur got arrested and a grand jury found this to be credible. Arthur then fled Ohio taking the missus in tow, alighting in Pennsylvania. Ohio's legal system subsequently put Amy into the custody of her biologic father.

This brouhaha has, as of poasting, united both National Review (which at heart has been a pro-immigration rag, so aligned with V.R.) and the Huffington Post.

Ohio didn't forget the Arthur family and attempted to toss some warrants into Pennsylvania in 1981 and even in 1987, they say. That Arthur remained - per Ms Loomer - never convicted and never stood trial is indeed the best kind of correct... for Arthur.

Amy Acton's brother Mr Philip Stearns (note: no "Mr Arthur") is siding with Dr Acton. Other snippets of evidence include that Acton has suffered some slips into drunkenness and anger, which most healthy women might not suffer.

This all smells like Philip and Amy have honest memories of what happened, at least that Amy suffered something horrid at a too-young age from someone. Donna failed to protect from this to the extent she lost custody. What directly caused the damage? - at the time, Mr Arthur had a low estimation of his abilities to win his case in court. Also nobody was questioning Amy's story in 2019. It follows that Philip and Amy are honestly pinpointing the culprit, specifically.

At the very least Vivek's team was extremely unwise to dig this dirt into the media. So's Loomer. Stephen "Vodkapundit" Green is simply exercising tactical cowardice, like Vivek himself. Can't speak highly of Ace. And as of now I'm seeing at least seven Instacommenters raising the false-flag (as usual, it's not, if it were, Vivek would have disavowed this by now).

If you are an Ohio conservative, and we know from election results many of these exist, I suggest going downballot but putting the Constitution candidate for governor. Like I did here in Colorado, stuck with another terrible Republican who doesn't deserve a political career.

Joel's Zionism

This blog hasn't much looked in on the prophetic oracles of Joel - directly. It is in CBH excepting six examples of the "LBH" second-Temple cant of the Chronicler. It may or may not cite 'Abd-JehovahObadiah. To this end, John Dunne may offer a helpful project, looking in on the synopsis with Amos (pdf).

Joel looks forward to a new Eden, flowing with wine, focused upon Zion and her Temple. Amos, which is an elder text, has about the same except here the focus is on David's tent. Now: Amos is assuredly a northern text with Amos 6 being in dialect. But "David" as totem shows up in the words of outside opponents: in the north (Dan stele, of Hazael) and against the north (Moab stele, of Mesha). Tents, we should note, are mobile. Also Dunne argues that Amos bears real eyewitness reports of the earthquake in Jeroboam II's time.

We're not really here for Amos. We're just placing him early. He was a popular prophet in the CBH-speaking world, Isaiah and Jeremiah both using his work as to apply to the Jerusalem area. Dunne would add to that list, Joel; as another citer of Amos.

The Old Greek order of Prophets follows that scheme, where Joel "reflects" back on Amos. The MT has rather the order Joel-Amos; so promoting Joel as the prequel, if you like. (Also the Greek merges MT Joel 2+3.) For those who deem 4 Ezra to be originally Hebrew (and based on its connexion with the Pseudo-Philo, I'm one of those): the MT order seems debatable up to Bar Kokhba.

In Old Greek also, Amos himself was interpreted, where David's tent is David's σκηνή which is "built", comparable to Moloch's σκηνή earlier in that book and also to the LXX-Torah tabernacle. In the Greek Tobit 13:10/11 also-also, the Lord has a σκηνή to be "built". I've suspected the Greek project to translate the Prophets was generally a priestly project, in Isaiah's case by exiled dissidents and in Ezekiel's case by Zadokites. Tobit had been composed in the first place by the "Aramaic Levi" crew, which stands to reason would be translated by sympathisers.

Dunne contrasts Joel, Greek-Amos, and Greek-Tobit on the one side; with the late-antique Targum on the other. On the latter side, Amos was still read as referring to David's dynasty. The Damascus Document, in the same lineage as Aramaic Levi and the Zadokite version of Ezekiel, and a citer of Joel 2, takes a third path: that David's tent is now the qahal - soon to become the Qumran yahad community. (On this much, I'll ding Dunne, because his footnote does not support that this be regal, especially given how equivocally Qumran understands "messianism".)

For Dunne, Joel should be read alongside this Greek priestly translation project before the Damascus Document. Dunne would stick this composition before all of that. Since here he doesn't argue the point, I'll give it a go: it was not "back-"translated from Greek to Hebrew, and it's low in the "LBH". Early second-Temple seems safest, like 2 Isaiah.