Beyond Chandrasekhar

Five years ago I noted large dwarf ZTF J1901+1458, pondering if it be metastable. One way out might be spin. But stars also have magnetic fields; neutron stars on the other side certainly do, and black holes at least have charge. So here is a study showing what magnets do to WDs.

The Chandrasekhar Limit thereby is an ideal: for the nonmagnetic star, or maybe a 'dwarf whose collapse (from the red giant) scrambled its dynamo. Thing is, I don't think that ever happens. So the Limit of an existent dwarf needs to take into account its gausses and/or teslas.

This suggests a sub-type-2 supernova. Take the starved overlarge dwarf. It never gobbles sufficient matter at once to light that ("standard") Type I candle. It might, however, nibble lightly. As it ages and the dynamo drops too low, and the mass increases: implosion.

The Syrian canon of Ignatius

Dan Batovici got "Four New Syriac Witnesses to the Middle Recension of the Ignatian Corpus" published in 2020, which you may read in Google Books since he's posted only the first page on Academia.edu. The title is a misnomer. In detail-of-fact, Batovici argues their witness for a canon florilegium: taken from six of the saint's letters. Ephesians, Magnesians, Trallians, Philadelphians, Smyrnaeans, and to Polycarp. This is relayed in west-Syrian canons (we may assume, Miaphysite).

The Greeks preserved a recension of all six letters in full plus one to the Romans. Those intersect with a collection of three: Polycarp, Ephesians - and Romans. Romans, further, is relayed in full in the Acts of this holy martyr. In Coptic (Sahidic, I think) survive fragments translated from all but Magnesians, adding Romans and one to Hero; such a collection exists also in Syriac.

The Syrian canon preserves some deviations, especially in the paratext. Some are startling: what is known from the Greeks as Trallians is, here, to "Titilians".

One variant perhaps shouldn't startle: the letter to the Smyrnians is generally "Church of Asia". We may be seeing an echo of that ancient Smyrna / Ephesus rivalry. We know that the Ephesians forced their name upon Paul's letter thereto, which in the MSS does not mention Ephesus and whose paratext for Marcion went to Laodicea. As to the Ignatian collection(s): pro-Ephesians perhaps insisted that their fellow Greeks restrict that other letter to Smyrna, alone. If so, I for one side with the Ephesians. This letter names Smyrna and I don't think it's a manuscript intrusion. It is written from Troas, and the Ephesians are called brothers to the letter's recipients.

One less textbook

If your kid's college is assigning Emmanuel Saez: pull him out. Honest economists (who exist) have been trying to refute Saez and his cowriter Piketty for almost a quarter-century but got stonewalled. AI is denting this wall.

Gabriel Zucman seems to be aware of the grift to which he's attached himself, since he is hurriedly blocking his comments.

It's the same phenomenon noted with Loonybins Johnson: mistakes happen, and sometimes they're neutral or even contrary to the thesis; but overall the mistakes trend toward the same direction. This is strong evidence of Tendenz.

When it happens in the medical sciences, we call in an auditor for suspected fraud. When some obvious ideologue (like Johnson) does this, we laugh him out of the classroom. But in economics? we just pat the scholars on the head, those lovable scamps. Shenanigans!

55 Cancri Ad

Paul Fellows, who runs one of the more informative space channels on the Youtube, is looking at the 55 Cancri system. He touches B at the end; today we're back to A, which star some want to name "Copernicus". The accepted planets are b, c, e, and f; e is the famous one, and b is almost a transit. Inclination is generally considered near-edge. Last September, Xiao's Chinese team mooted that binary systems trend coplanar.

The planet-candidate d is a Jupiter-Plus. It orbits a little eccentric, but not by much. From 4600 days, the radial-velocity method takes a while to confirm. Also, a dynamic study from last year mooted that the A system doesn't need a planet in the gap between Af and the B system. The candidate d got punted to astrometry. Xiao seems to think astrometry has nailed d down, to the expected 5.4 AU. NAMD might not apply for binaries.

Around a 62% luminosity star at only 41 ly, I wonder if we might even see it directly - when it's not in front or behind. The companion B is known to be 8.6 Gy old and the same is assumed for A. Therefore, for A's planets. The light it gets from the star is less than Jupiter gets, but it should have retained more ancient heat than Jupiter has. Or we could constrain d out like for 70 Oph.

The safe-edgy to inclusion pathway

Frankie Fey is a tool. But at least she's holding a fleshflashlight to a real phenomenon in Western corpocracy. Conquest of Cool, 2020s-edition.

Say you have a product which is becoming kinda lame. Ho boy, are M&Ms lame.

M&Ms are run by Mars (Inc.) - still. They used to be chocolate. I believe their mass-market products are now "chocolatey", as Colbert (in an off moment of being good) would say of "truthy". There may still be cacao in there, but no more cacao oil (don't call it "butter" plz - this is important). And even the cacao tends to be "cocoa" which looks like a placeholder for not being chocolatl of any sort. Right now Mars, further, harvests what cacao it does use in conditions most of us in the West would never tolerate.

Back in the 2000s the millennials and GenX hipsters wanted better chocolate, and they weren't wrong. To keep people (okay: us) from shifting from their low-margin product over to real chocolatiers, Mars made their mascots fun! and EDGY!!. So we, watching movie-previews mostly, got this green nugget with high heeled shoes. Glimpse of stocking!

That non-troversy having run its course, and a new customer base locked in, now comes the next phase. Where the HR and PR drones murble their murblings about inclusivity and bringing the old problematic ways to a new pluraliszzz sorry, nodded off. Tucker Carlson is here, to complain about not being able to goon to the "old" green candy mascot anymore. Frankie Fey is there, to point at a widely-derived hate figure and mock it.

Safe-edgy brought the customers. Inclusion keeps the investors.

Meanwhile can we all agree that the candy is bad and hasn't been good since, I dunno, the 1960s? or so they tell me. I wasn't alive then. Probably wasn't good then either.

Aerogel NERVA's last progress-report

Back in 2023 I noted a fission-fragment rocket engine - in passing, frankly. I had left to the linked article what this was, mainly because I (1) didn't know much and (2) didn't care to look it up. It had a few unsolved problems which made it not worth my while. Ryan Weed founded something called "Positron Dynamics" for this...

... and then fled the place, shifting to fusion propulsion at AeroFuse. Weed gave up on this too and is now fronting something called Eos Atomics. This is for fusion sparking, compact plasma heating. So the whole aerogel/fission scheme looks dead. Let's autopsy the corpse.

ToughSF links today that Weed was addressing some of these problems in that banner year 2024, in collab with Sandeep Puri et al.

Classical "atomic rockets" are nuclear-thermal, including NERVA. Heat a gas, offer a hole for escape, vroom at very-many m/s. That last is specific-impulse; I_sp opens up new delta-V routes. Among its (many) constraints, is the ability to force the temperatures into vrooming the gas and to control its plasma. The ideal plasma here was the proton, aka hydrogen. Other solutions exist out there to afterburn the hydrogen, like with some oxidiser or even to fuse it; we're not getting into that today.

Because Weed proposed to restrict the propellants: to the fission-chain's fragments. Much of the energy in fission actually doesn't go directly to heat; it goes to moving the fragments, like neutrons or (for uranium) iodine-135. Elsewhere alpha-decay should count as Nature's most common process. I think most fission-thermal solutions let the fragments bounce around to turn their bouncing into heat. Chernobyl enjoyers will recall, for 2-2.6% U-235 LEU, the fragment I-135. This becomes Xe-135 leading to Xenon Poisoning, gobbling neutrons meant for the reaction. As a heat-generator it's all very indirect so inefficient, and some capitalist reactionaries might consider it somewhat dangerous as well.

Aerogel comes in as a matrix to hold the fissile elements in a fine dust at some mutual distance. The notion is that the aerogel would not interfere with the runaway radioactive iodine (or whatever). These frags are ions, iodine in particular being quite reactive, so Weed added a honkin' magnet to run the ions toward the exit. That redirected iodine might not be the fraction of lightspeed that the sail's helium was, but it is still one hefty I_sp. As for the exhaust: this can decay into Xenon or whatever, far from the reactor. Thrust ain't great so it's for robots, as I noted at the time. This is similar to the T-FINER sail proposal.

Puri's crew chose fissile Americium, here -241 rather than -242m, I guess because this isotope could be handled in reasonable times in a lab. Opposite from NΘP they wanted to reduce attenuation into that Θ. For them a graphene matrix worked best: at 900 microns (μm) they wasted only 7.5%.

Aaaand that is where Weed left us. Radioactive critical-mass aerogel is expensive to manufacture, and difficult to justify launching into LEO. In the low-mass high-delta-V mission space generally, by 2024 several competitors were coming to press (if not to prod).

Over-dense planets

On topic of strange (in every sense) white dwarfs, Zim has something on J132800.85–145019.95, and the gaps in the cloud orbiting same. The star, being a WD, is basically Earth-sized. Its cloud(s) can be measured in fractions of the solar-volume: the inner planetesimal must be located between 0.14 R_⊙ and 0.34 R_⊙ and the outer one between 0.54 R_⊙ and 1.93 R_⊙ (pdf). The former 0.14 might be better expressed as 15.27 Earth radii, or 97.4 Mm.

Usually a ring-cloud with gaps implies some gravitational-exerting mass. They don't see the planets.

To that, a WD is not Earth-heavy. It's still a good fraction of the star it was in life, which was probably A or F. Paper estimates 0.47 ±0.09 solar. That point mass should be exerting a wider Roche than 2 R_⊙. Most planets in here should be sheared, to join the rings. The paper has some large estimates for density, which Zim is showcasing, although these only apply if the bodies lack internal strength (see below).

On the assumption that Young Modulus in fact exists, the outer planet could be rocky, they say minimum 3.5 g/cm³. Earth for contrast is 5.513; Psyche 16 isn't as dense, because it's considered to be fractured. So it could be a dwarf planet like those we have here (an expanding family, I hear).

Back to J1328–1450, the inner one is the problem. It would have to be 45-172 km in diameter. That is if it is pure iron and unfractured.

If internal strength is taken away, densities rise to beyond-possible levels... for normal matter. We do, however, have some papers venturing into abnormal matter. Abudushataer Kuerban et al. proposed such in 2019, in a paper taken more-or-less seriously since. The reasoning was that if quark stars exist, quark planets might also exist. GP Com[ae Berenices] b is mooted along with some others.