Have to get back into the habit

/styles

Bloody hell, pushing 3 months since I touched this. Got to get back into this. 6 weeks visiting Dad didn't help, but I've got to get back into the habit.

So, what other things are in today's (well, yesterday's) list from Arχiv ?

• Another MOND publication. An interesting topic, but primarily because the Internet Kook Department loves a conspiracy theory, and the (bullshit) "suppression of heterodox opinion" by the Illuminati, the Physics Orthodoxy, and Uncle Tom Cobbley is high on the list of popular idiocies. I've been tracking this for a while, mostly to piss-off the conspiracy wingnuts (TL;DR version - the field remains a moderate, but minor part of science publication). But in a random pick from Arχiv, there it is. [Distant sound of deflating Internet wind-bag. Or maybe not.]
• Ultrashort Recurrence Time Nova M31N 2017-01e "Recurrent novae" are rare beasts. So it shouldn't be a great surprise to see that at least one has been spotted in the Andromeda Galaxy ("Messier 31", "M31" in the object's designation) because we can see most of the disc of that galaxy and half of the core, compared to under 1/3 of our galaxy. Which should remind me to check the status of the famous "T" variable in Corona Borealis ("T Cr B"), which has been observed to erupt twice, and which was predicted - with good clear reasoning - to erupt in May 2024 ± 6 months. Which prediction period we're getting to the end of. And it hasn't "gone" yet. Regarding the pattern-matching which constituted that "good, clear reasoning", it looks as if there is another cycle of the binary star's orbit to go before it goes "bang". That's the difficulty of making predictions, particularly regarding the future.
  It'll almost certainly go bang ; but when? That's the problem of dealing with small data sets - in this case a single recurrence after the original nova.
  What is this paper about? Prior to this report, the star had 4 known eruptions (discovery in 2017-01 ; a pre-covery in 2012-01, and subsequent observations in 2019-09 and 2022-03 ; see previous comment about datasets of 1) ; with an additional two eruptions the estimated timing has improved to 924 ± 7 days. Which is oddly consistent for a process that should have a significant random component to it. A 900-day recurrence time implies a very high accretion rate of material onto the (inferred) white dwarf. So, a potentially important system.
• Narrowing down the Hubble tension to the first two rungs of distance ladders. OK, I'm not going to introduce the "Hubble Tension" here. But I bet @Dr_Becky covers this on her YouTube channel of "Night Sky News this week. Which reminds me of something else to do tonight. Long story short - because they had a large (and increasing) data set, they could divide the data into smaller groups where the derivation of distance had been done by different methods. And they found that the values of H₀ derived with different distance estimate techniques show a discontinuity where there is a change from stage 2 (Cepheids-bearing host galaxies for SNe, z <e; 0.03) to stage 3 (using SNe as standard candles, 0.02 <e; z <e; 2.3) of the "cosmic distance ladder". Which suggests a systematic problem in one or other of stage 2 or 3. Which is pretty much what most people had been hoping to find, to resolve the "Hubble tension". The problem isn't solved - yet - but this is a pretty big step forward.
  What does Dr_Becky have to say? Well, she's back from holiday. Ah, bollocks - I forgot that youTube had started a new round of whack-a-mole against video downloaders. But since it's a Thursday paper, when she produces her videos, it hasn't made it into this week's NSN.
• "Limits on planetary-mass primordial black holes from the OGLE high-cadence survey of the Magellanic Clouds" Pretty much does what it says on the tin. Almost any discussion of astrophysics or astronomy, even accompanying a well-based repoting set-up such as @Dr_Becky's (above) will almost inevitably have someone chiming in in the comments section, "What if Planet 9 were a black hole?" or "What if a runaway black hole were to come into the Solar system tomorrow?" While they're perfectly fair questions, the askers generally don't seem to know that we've been taking a census of such non-incandescent material in the Milky Way (and the part of it's halo towards the Magellanic Clouds), and (this is what upsets them) there's not a lot of it about. Not enough to solve Vera Rubin's early-1970s discovery of "flat" galactic rotation curves. Not enough to have a credible chance of ex-President Trump being head-shot by a primordial black hole.
  Such non-glowing conventional matter is present - but not in sufficient quantities to make long standing cosmological problems go away.
  Worse - we've known this since the first reports from such occultation programmes in the mid-1980s (I personally remember reading the reports in between lectures, over a cup of tea in the Student's Union.) They're a nice idea to solve various problems - but there are not enough of them about, and several whole (academic) generations of astronomers have known they're an insufficient solution to observational problems. Sorry, guys!
• In-situ crystallographic mapping constrains sulfate deposition and timing in Jezero crater, Mars. That's a very geological one. Ca-sulphate minerals (they're careful to not say "gypsum" nor "anhydrite", so they plainly mean something else) have been reported from Mars for a while. Studying the crystallinity of these materials reveals some veins/ deposits were deposited more than 80m below then-current surface (so ... 80+m of erosion since then, to breing them to the present surface), while other veins were deposited much closer to the surface. Both types of rock sample are already cached for sample-return. Fun stuff, but it doesn't make Mars any the more habitable.
• Anything from the oldest collection that I haven't thrown away yet? All the way back to June 30th.
• A transiting multi-planet system in the 61 million year old association Theia 116 It's only 2 planets, but it's a very young system - possibly as young as when Earth suffered it's "Moon-forming impact. At 3.6 and 6.2 days orbital period, it's going to be a very different system to the Sun's.
• An ancient Indian Solar eclipse recorded in myth. The Rig Veda (hindu holy book ; one of several) records an eclipse "vanquished" by Invisible Sky Fairies (&TM;). Based on "the eclipse [...] having occurred when the Vernal Equinox was in Orion, and three days prior to the Autumnal Equinox [... the authors] identify ‘Atri’s eclipse’ as the one that occurred on 22 October 4202 BC or on 19 October 3811 BC." There are considerable uncertainties when looking back this far (6000-odd years), not least of which is that the tidal friction of the Moon (well, the sub-lunar ocean bulge) starts adding up to thousands of seconds, or hours of Earth rotation, which is a substantial fraction of the sub-solar point's travel through the regions of Central Asia where the ancestors of the Hindu aristocracy were inhabiting in the time interval. The several centuries of time uncertainty also allow for up to 30°ree; of longitude variation between eclipses that would have been visible near the Iranian-Kazakh border (today), or sites as far east as the modern Afghan- Pakistan-China border.
• What's this, Lassie? From the Aug 5 collection, "On Interstellar Quantum Communication and the Fermi Paradox"- sounds fun!
  Well, it does sound fun. Someone (the author) obviously thought "what sort of apparatus would be needed to transmit (and to receive) quantised data structures called "QuBits". Which, yes, fair enough question. Maybe the old stand-by of throwing "quantum" at a problem, like the Fermi Paradox ("where is everyone?") could result in a solution, sweetness, light and the odd Nobel gong for the lucky thinker.
  Tough luck : between Earth and Proxima Centauri, you'd need telescopes around 100km in diameter. Not going to happen soon ; may never happen. But worth feeding the guy while he scratches symbols on the blackboard.

And that's enough for this effort.

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