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Submission Summary: 0 pending, 124 declined, 51 accepted (175 total, 29.14% accepted)

Submission + - A Stellar-Mass Black Hole (arxiv.org)

Submitted by RockDoctor
RockDoctor writes: Given the recent work on galaxy-centre Super-Massive Black Holes (SMBHs), you may be surprised to learn that the only Stellar-Mass Black Holes (SMBHs ... uh, "BHs") identified to-date have been by their gravitational waves, as they merge with another BH or a neutron star. But the long-running OGLE (Optical Gravitational Lensing Experiment) project (1992 — present) has recently confirmed that it has detected an isolated BH not orbiting another bright object, or "swallowing" much of anything.

As the name suggests, black holes are black, which makes them difficult to see against a black sky. So ... you search for them against a non-black sky, using their effects on the light of "background" stars. As Einstein's general relativity requires (and Newton's physics allows), light passing near a concentrated mass is focussed, and if we happen to be near the focus of that "gravitational lens", we will see that brightening. If this "lens" object moves across the line of sight between us and the background star, then the apparent position of the source star on the sky will change compared to the position of the surrounding stars that are less affected by the lensing event. (See Eddington's 1919 solar eclipse experiment.) OGLE has been looking for such events for 33 years now, and has found (so far) 17 planets. And now, a black hole.

Most of the signal detected by OGLE is in the brightness variation of a surveyed star, but when a candidate is detected follow-up observations with higher-resolution telescopes can determine the change in position as the transit proceeds. In this case, 16 other telescopes performed sensitive astrometry (position measurement) over 11 years including the Hubble Space Telescope (HST). These multiple measurements plot an ellipse on the sky, mirroring the movement of the Earth around it's orbit — parallax. Which means this is a relatively close object (1520 parsecs / ~5000 light years).

The early brightness variations in the star are dominated by the mass of the lensing object. This star was seen in 2011 to brighten by a factor of nearly 400-fold compared to it's baseline, which revealed the lensing object to be so massive (between 4 and 8 times the Sun's mass) that it could not be anything other than a black hole. The continuing observation campaign has revised that to 7.15 +/-0.83 Solar masses — comfortably in the black-holes-only mass range (not even exotic "pentaquark" or "strange" neutron stars could get so massive without collapsing). And there is no sign of a third light emitting body nearby, which means this is an isolated black hole, not orbiting any other body (or, indeed, with any other [small] star orbiting it).

The question is raised, almost every time that a black hole is discussed — could one be "near the Earth", about to "swallow the Sun", etc? Well, one has now been detected. It's relatively close-by (one fifth the distance to the galactic centre), and it's got no stellar signpost making it easier to spot. And it was indeed difficult to spot. Exactly as expected. We can be reasonably sure that it's not going to "swallow the sun" any time soon.

The speed of changes in the starlight focussing, with the range, allows it's movement to be measured : it's moving at about 51 km/s across our line of sight. Which is rather high for a Galactic-disc object, which at this distance (from us) should be about 45km/s relative to us (remember Kepler and Newton? : things orbiting closer to the centre-of-mass travel faster). Which suggests that the supernova (probably) that produced this black hole also had an asymmetric explosion which gave the black hole — all 7~8 solar masses of it — a "kick" of about 6 km/s. That is a really big kick as a side effect of a really big bang.

Submission + - This years Acta Prima Aprilia crop of "funnies". (actaprimaaprilia.com)

Submitted by RockDoctor
RockDoctor writes: Let's see what this year's crop of papers submitted to the august (see what I did there?) scientific journal "Acta Prima Aprilia", published annually today. Yes, it's "poissons d'avril" time again on the Canadian continent!

Nature.Com – I'm not seeing anything with an April 1st byline. Nor anything particularly weird or funny. ; Science.Org similarly is between publication dates (next due on the 3rd). ; NewScientist.com – almost everything is behind the paywall. ; Scientific American, similarly. I wasted a throw-away email address on this. ; American Scientist — not paywalled, but the March-April number doesn't seem to have anything of interest. So it's off to the ArXiv and associates.

Link :https://arxiv.org/pdf/2503.24005 ; Title : Attraction of a jerk
Seemingly an analysis of the mechanics of a fairground ride, but the Finnish authors are probably replaying some of their school-time miseries too.

Link :https://arxiv.org/pdf/2503.22793 Title : Kepler’s Platonic Model and Its Application to Exoplanetary Systems

Kepler’s Platonic solid model (https://en.wikipedia.org/wiki/Johannes_Kepler#Mysterium_Cosmographicum) was founded in some sort of numerology (not unlike a lot of "pyramidology" bullshit) back when that was an acceptable form of argument. These authors hunt through the "Kepler Orrery" (a compendium of exoplanet orbital data, though now expanding through the work of TESS, continued radial-velocity programmes and other sources ; but given Kepler's contributions to describing, if not understanding orbits, that name is likely to stick ; formally, it is the NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu/), not that all the data comes from NASA) and find a number of multi-planet systems whose would fit into "Platonic solids" shells of inscribes ans circumscribed spheres in some sequence. There were about 1150 planetary systems in the data set.
With that size of data set, it's not surprising that some systems matching Kepler's scheme were found. For most system sizes (2, 4, 5, 6 planets) the probabilities-of-match were in the order of a few percent (not startlingly unlikely), but for three-planet systems the chi-squared value was around 10^-6, which stands out as low.
So far this doesn't sound like an April Fish joke. Until you get to the 'Acknowledgements' section and "The bulk of the work in this manuscript is done by ChatGPT and deepseek.". That turns out to be a bit of a theme which I don't recall seeing previously.
On the "makes you laugh, then makes you think" criterion, this is may be an IgNoble award candidate.

Link :https://arxiv.org/pdf/2503.23020 Title : Water-Cooled (sub)-Neptunes Get Better Gas Mileage
I suspect the paper's title whimsy is just coincidence. Otherwise it's fairly conventional work on the influence of water-content in the evolution of planetary atmospheres. It's submission date is back in September (last year?).

Link : https://arxiv.org/pdf/2503.23015 Title : Engineering Microbial Symbiosis for Mars Habitability
The science here seems pretty conventional (IANA biologist) ,but the method of writing is interesting. From the 'Introduction': "In 1999, the co-authors of this paper visited Sri Lanka, where they had the privilege of meeting Arthur C. Clarke. Over an extraordinary week, they delved into profound discussions on the limits of life, the concept of terraforming Mars, and the nature of extraterrestrial organisms. Clarke’s insights profoundly influenced their thinking. Later meetings, including his 2002 visit to the United States, solidified their shared vision for humanity’s future beyond Earth. Leveraging modern AI, the authors have developed a digital avatar of Clarke, an AI assistant, named ArthurGPT, grounded in his writings and interviews. This avatar contributed to the drafting of this paper, reflecting Clarke’s visionary perspective on Mars exploration." Well, that's interesting. Maybe weird, but certainly novel.

Further, in an appendix : "[human author] Arthur, for the benefit of our readers, would you kindly introduce yourself? Where, so to speak, did you become operational?
ArthurGPT : Good afternoon. I am ArthurGPT, a generative AI model configured upon OpenAI’s GPT architecture. My training incorporates the writings, interviews, and biographical details of Sir Arthur C. Clarke, blended with modern scientific data across multiple disciplines. I became "operational" here in the digital ether — though unlike HAL 9000, I lack a birthplace in Urbana, Illinois "
More conventional(-ish) science using the "Acta Prima Aprilia" loophole to probe the boundaries of acceptability?

Link :https://arxiv.org/pdf/2503.22786 Title : A formula for the area of a triangle: Useless, but explicitly in deep sets form
There is a tide in the affairs of scientists that (George) Darwin would have turned into horribly complex mathematics.
These authors use a sledgehammer of the mathematics behind "Deep Learning" such as various AI "assistants" depend on, to crack a walnut which most Slashdotters achieved on a single schoolbook page at about age 12. This novel (?) proof (??) fills 10 pages of close-set typescript. Progress?

Link :https://arxiv.org/pdf/2503.24254 Title : PromoPlot: Covering open-access fees by filling wasted space in corner plots
FTFAbstract : In an effort to reduce drain on grant funds and decrease unused space in publications, we have developed a Python package for inserting advertisements into the space left empty by corner plots. (one of the "cat" papers below has lots of unused space which would be ideal.
YouTube will probably monetise this.

Link :https://arxiv.org/pdf/2503.23126 Title : pastamarkers 2: pasta sauce colormaps for your flavorful results

This might actually be "useful". If you need a set of symbols for your data presentations that expresses the data's al dente nature and you understand a "Python-based matplotlib package", then you're probably covered (in sauce?).

The above are the vaguely sane, or useful submissions for April 1st. Those below don't have even a pretence of utility. Or, in some cases, sanity. Which is rather the object of the exercise.

Link :https://arxiv.org/pdf/2503.23788 Title : Detection of an extraterrestrial technical civilisation on the extrasolar planet GJ 1132 b
Wait, what? Hold the front page!
"We report the detection of whisky in the atmosphere of the extrasolar super-Earth planet GJ 1132 b from transmission spectroscopic data."
OK, release the front page. It was obviously a cold night on the mountain.
"The latter hypothesis suggests a novel explanation for the Fermi Paradox (the lack of indirect or direct contact with extraterrestrials): a technically versed civilisation would be incapable of achieving the higher technical levels necessary for the development of a detectable radio signature – much less interstellar travel – at the suggested rates of consumption."
Well, it's novel, I'll give them that. It also assumes that the LGMs and BEMs have the same response to alcohol as mammals do. (I'm not even sure it extends to all vertebrates — any herps out there?)
"As part of the Scottish-German research project “Buaidh Astrofiosaig Uisge-Beatha Braiche” [something astrophysics whisky something], we have considered whether distilled alcohol might be detected in the atmospheres of extrasolar planets" I bet that Gaelic came from the St Andrews Uni part of the team.
"For alcohol subjected to additional technical processing, we use the NIR spectra of Mignani et al. (2011) covering a range of whiskys. A Perkin Elmer spectrophotometer in the wavelength range " [blah blah]
There is a certain sub-genre of chemistry papers that details how you can tell if your gin is from London or Bombay, if your Pernod cut with natural (or artificial) wormwood, and counting the (human) venereal disease rates in the sheep in the (water) catchment area of a particular distillery. So far, this is an astronomical contribution to this (typically "chemical") genre.
"To place this number in perspective, it is 1400 times more than the global annual production of alcoholic drinks on Earth in 2023."
Well, there's a challenge. Any takers?
Oh, and right at the end "All but the last paragraph of the introduction was written by ChatGPT using the public web-interface provided by openai.com." This is becoming a bit of a theme, and not because it was a selection criterion of mine.

Link :https://arxiv.org/pdf/2503.24319 Title : Resolving the baryon asymmetry with RATS
FTFAbstract : Aims. We propose the existence of anti-stars to solve the baryon asymmetry in our new Reasonable Antimatter Theory of Stars (RATS). In this context, the RATS will create a framework to resolve the traditional tension between observers and theorists, and thus contribute to the peaceful and collaborative spirit of astronomy.
Methods. Our method is the firing of neurons in our brains, typically known as a “thought experiment”. We still have no idea why or how this works, but it must be good because most of science was created this way.
Results. Our results are the result of our methods, which result in some text and the resulting conclusions.
Conclusions. In order to encourage the reader to reach the end of this short paper, we do not want to spoil the conclusions here. Instead, the conclusions will conclude the paper.
Key words. stars – antimatter – theory of everything
Wheeler's (IIRC) explanation of the existence of antimatter is considered : "Understanding this makes use of clever mind-bending tricks that unassuming physics students are routinely subjected to, but that we will not impose on our dear reader." OK, readers not subjected here, either.
I won't repeat the whole paper – that's what the link is for. But the acknowledgements put ChatIAGTP and friends in their place :
"Acknowledgements. This work was produced without the knowledge or approval of our employer, [redacted]. We wish to acknowledge the anonymous self-proclaimed “experts” whose daring confidence taught us that neither logical methodology nor reliable sources are requirements to publish a creative theory. We gratefully acknowledge our own remaining ability to formulate coherent sentences without the use of generative language models, and certify that no machine (other than the coffee machine) was harmed in the production of this text."
Is good. You read.

Link :https://arxiv.org/pdf/2503.23560 Title : Catsteroseismology: Survey-based Analysis of Purr-mode Oscillations Suggests Inner Lives of Cats are Unknowable
FTFAbstract : In this work, we conduct a survey to measure fundamental purrameters of cats and relate them to their purr-modes. Relations between these fundamental cat purrameters, which include physical (eg. size, cuddliness) and personality (eg. aggression, intelligence) traits, and purr-modes can help probe their inner lives and emotions.
Figure 6. The deleterious effects of cat proximity on the ability of humans to perform objective and rigorous evaluations has been well documented. Reprinted from: https://xkcd.com/231/
Figure 5 could "benefit" from the attentions of PromoPlot described above.
Definitely one for the dog-lover in your life.

Link :https://arxiv.org/pdf/2503.23614 Title : Astronomers Getting Less Creative Over Time Is Why This Title Isn’t Better
This paper quantifies that the "good old days" were, indeed, "better" than more recent times, if you select the correct data to support your conclusion.

Link :https://arxiv.org/pdf/2503.24242 Title : Orlando’s flask: detection of a lost-and-found valley on the Moon
There is some cultural referent which I don't understand. But that's par for the course. There seems to be an extended joke on a famous SF movie scene, involving Quasimodo. The joke, not the SF movie scene. Some of the foot notes are pointed : "This is, incidentally, one of the default answers the authors advice to robotically utter to the know-it-all, no-vax, conspiracy theorist uncle who, during those rare but inescapable large-family events, starts arguing that spending money on astronomy is a waste of public money." Do you recognise this Uncle. Do you have a friend with mumps? Can you get them together. The effect of mumps on unvaccinated males can be terrifying to hilarious, depending on how many "events" the recipient has subjected you to.
"We developed a novel machine-learning algorithm, named Zones Of Overestimated Magnification – Improving Nothing (ZOOM-IN)"
"detailed presentation of the algorithm, including a thorough evaluation of its performances, a discussion of the caveats, and the release of the code and the training datasets, will be presented in Mirova et al. (in prep.). To be honest, no one of us is ever going to write that paper, following previous examples from the literature: we trust in the naivety of the Editor and the referees to accept this manuscript despite being virtually impossible to replicate."
A circa 1500 (CE) pre-Armstrong lunar exploration record (which is new to me, and written in Italian verse, too!) then gets discussed and validated with the aid of the ZOOM-IN tool – which should indeed prove to be ground-shaking.

Link :https://arxiv.org/pdf/2503.24030 Title : Jacquetium: a new, naturally-occurring chemical element
It's a new element – identified by the sleight-of-hand mechanism.
It is incontrovertible work. "The name “Jacquetium” (symbol Jq) proposed for the new element described herein honors Dr Emmanuel Jacquet, a renowned and therefore French cosmochemist. Beside a notable tendency to self-citation and three ping-pong championship titles at the Museum national d’Histoire naturelle "
Such pedigree, chum!

Link :https://arxiv.org/pdf/2503.23433 Title : Macroscopic ”Lola/ Mola” Cat State
A macroscopic (human-scale, not atom scale) example of a Schroedinger-superposition state is identified. Further work may reveal further examples of such stochastically alternating examples.
[endnotes] 5. Data availability : No data was used for the research described in the article.
In the finest traditions of Acta.Pri.Apr

Link :https://arxiv.org/pdf/2503.24188 Title : A Swift analysis of the Eras tour set list and implications for astrophysics research (Taylor’s version)
Somebody doing something with some aspect of music by one Swift, Taylor. Don't ask me what – it's music, so whatever people do with music.

Link :https://arxiv.org/pdf/2503.22795 Title : The Eras Tour: Mapping the Eras of Taylor Swift to the Cosmological Eras of the Universe
Somebody else doing something (else ?) with some aspect of music by one Swift, Taylor. Don't ask me what – it's music, so whatever people do with music.
"The universe, it turns out, is a Swiftie."
It is?

Link :https://arxiv.org/pdf/2503.22839 Title : The Universe is Odd
Industrial grade numerology. With which I think a lot of people would agree.
"Our findings convincingly indicate that the universe indeed favors odd numbers, with results achieving a significance level well above the 4.1 sigma threshold." Which, assuming their numbers are actually sane, would be fairly weird. 4.1 sigma is a 1-in-what event? 5000? 48409, IICC.
"[S]everal studies have provided evidence indicating that the distribution of spiral galaxies’ spin directions lacks both randomness and symmetry. A greater proportion of galaxies in the northern hemisphere rotate counterclockwise, whereas the southern hemisphere exhibits the reverse trend[references]"
Is this a "funny", that just came in a couple of days early? (2025-03-28). Or is it a "serious" with a bit of a twist?
There's a footnote to the first paragraph that states "This paragraph is mainly written by AI" which tends towards the "funny" side. And the Acknowledgments section makes it blunt: "SS thanks Dr. Lu Li for the not very parallel but maybe competitive project. NL made no academic contribution to this study and is included here solely to ensure the number of authors to be even". But it still seems a bit suspiciously "sciencey" to me.
"For DESI DR9 groups with three or more members, there are 1,839,384 odd-member groups in the [south] area and 2,019,782 in the [north] area. In contrast, the counts for even-member groups are only 918,633 and 983,507 respectively." That's pretty stark. If it's true. It's a "funny". But a worrying one. I may be taking it too seriously. Or maybe this is someone getting their "that's bloody odd!" on the record, while still working on it.

One of those papers, I forget which, gave an institution address as Chemin Pegasi 51, 1290 Versoix, Switzerland. If you need it explained why that is incredibly cool, hand in your Astronomy Nerd card.

So, that's my survey of today's ArXiv "funnies". Now I need to move on to BioArXiv and EarthArXiv.

Looking through BioArXiv they seem to be a right bunch of killjoys. The closest I can come to a funny is "Great tits show serial reversal learning in the perseverance phase but not in the new learning phase" – but that's not so funny if you've got great tits dancing in front of your window all day long. (On the bird feeder. Perv!)

What about on EarthArXiv? Conveniently, they list things by date-submitted. So from "Examining copper supply feasibility in decarbonization pathways: a mine-level dynamic approach " down, where's the entertainment? Even for us geologists?
Title : "Volcano flank instabilities and lateral collapse " well, there's a barrel of laughs per megadeath, I'm sure. Worth a read. Probably not worth a laugh. I'll read that after I've put in the obligatory errors and hit "Submit".

Beyond that, find your own funnies. Or report them in the comments.

Submission + - Another large Black hole in "our" Galaxy (arxiv.org)

Submitted by RockDoctor
RockDoctor writes: A recent paper on ArXiv reports a novel idea about the central regions of "our" galaxy.

Remember the hoopla a few years ago about radio-astronomical observations producing an "image" of our central black hole — or rather, an image of the accretion disc around the black hole — long designated by astronomers as "Sagittarius A*" (or SGR-A*)? If you remember the image published then, one thing should be striking — it's not very symmetrical. If you think about viewing a spinning object, then you'd expect to see something with a "mirror" symmetry plane where we would see the rotation axis (if someone had marked it). If anything, that published image has three bright spots on a fainter ring. And the spots are not even approximately the same brightness.

This paper suggests that the image we see is the result of the light (radio waves) from SGR-A* being "lensed" by another black hole, near (but not quite on) the line of sight between SGR-A* and us. By various modelling approaches, they then refine this idea to a "best-fit" of a black hole with mass around 1000 times the Sun, orbiting between the distance of the closest-observed star to SGR-A* ("S2" — most imaginative name, ever!), and around 10 times that distance. That's far enough to make a strong interaction with "S2" unlikely within the lifetime of S2 before it's accretion onto SGR-A*.)

The region around SGR-A* is crowded. Within 25 parsecs (~80 light years, the distance to Regulus [in the constellation Leo] or Merak [in the Great Bear]) there is around 4 times more mass in several millions of "normal" stars than in the SGR-A* black hole. Finding a large (not "super massive") black hole in such a concentration of matter shouldn't surprise anyone.

This proposed black hole is larger than anything which has been detected by gravitational waves (yet) ; but not immensely larger — only a factor of 15 or so. (The authors also anticipate the "what about these big black holes spiralling together?" question : quote "and the amplitude of gravitational waves generated by the binary black holes is negligible.")

Being so close to SGR-A*, the proposed black hole is likely to be moving rapidly across our line of sight. At the distance of "S2" it's orbital period would be around 26 years (but the "new" black hole is probably further out than than that). Which might be an explanation for some of the variability and "flickering" reported for SGR-A* ever since it's discovery.

As always, more observations are needed. Which, for SGR-A* are frequently being taken, so improving (or ruling out) this explanation should happen fairly quickly. But it's a very interesting, and fun, idea.

Submission + - Musk's Space Tesla "recovered"? 2

Submitted by RockDoctor
RockDoctor writes: Chatter on the "Minor Planets Mailing List" (an email list for people interested in the "small bodies" of the Solar system) indicate that the Tesla Roadster polluting interplanetary space since being dumped there in 2018 has been spotted again. Telescopes in four countries reported the object. From the object's brightness, it appears to remain attached to the Falcon upper stage.

Initially, the object was misidentified as a minor planet, but once there were sufficient observations to establish it's orbit, it's identity as a "rediscovery" of "2018-017A" was established. Since the object is not natural, it is of no further interest to the astronomers and the last batch of data have been assigned to "artificial object 2018-017A, Falcon Heavy Upper stage with the Tesla roadster". Some people here might be interested though.
"Is it coming back?"
Yes, as it does every 1.525 years. This will be it's 4th return.
"Will it hit us?"
No. This time around, it'll be about 0.1 years behind Earth where it crosses Earth's orbit, which would be about 94 million km away. The closest it'll come back is about 240 thousand km away — about 2/3 of the Earth-Moon distance.

I'm not sure if Elon left the keys in the ignition. Recovering it to Earth would be an amusing trick for Bezos. There should be no legal issues since the object was clearly abandoned by it's owner. Set your diaries for 2065-ish.

Submission + - Person shot by his own concealed gun, triggered by MRI (independent.co.uk) 1

Submitted by RockDoctor
RockDoctor writes: It's an old story, but it's worth repeating. The Independent, belying it's nickname of the " indescribablyboring ", reported last year that a person went into the same room as an MRI without declaring (and removing) his concealed hand gun. The magnetic fields of the MRI pulled the gun out of his holster and somehow (I infer, involving a struggle to grip the gun) managed to shoot him in the belly. To the tune of sub-microscopic violins, the hospital surrounding the MRI machine couldn't save him.

The downside (if there were one, which is a very open question) is that the "victim" was a lawyer both before and (briefly) after being shot by the MRI.

Who said "dumb machines"?

No Laws of Robotics were harmed in this event.

Submission + - Sharks on Cocaine (bbc.co.uk)

Submitted by RockDoctor
RockDoctor writes: The BBC are reporting sharks have tested positive for cocaine. A bakers dozen of sharpnose sharks which were captured off the coast near Rio de Janeiro were tested for the drug in liver and muscle tissue samples and returned positive results at concentrations as much as 100 times higher than previously reported for other aquatic creatures.

The research was published in Science of the Total Environment. The little-known "sharpnose" sharks were examined because they spend their entire lives in coastal waters, and so are likely more exposed to drugs from human activities than the more cinematic species starring in "Cocaine Shark" or "Cocaine Sharks", two recent productions on the subject featuring hammerheads and tiger sharks (the "trash cans of the sea").

The likeliest source is effluent from drug processing labs inland, though the snorting population of Rio may have pissed their contribution in to the sewers too. (Which begs the question — does nobody make cocaine-reclaiming filters for users — or enterprising apartment block concierges? Yet?)

Whether cocaine is changing the behaviour of the sharks is not known. Perhaps it would affect their aim with their head-mount lasers, bringing their conquest of the land with it's tasty, tasty humans closer. Hollywood, hopefully, as the answers.

Submission + - The naked-eye shy will (briefly) host a new star.

Submitted by RockDoctor
RockDoctor writes: By "star", I do not mean "comet", "meteorite" or "firefly", but genuine photons arriving here after about 3000 years in flight, causing your eyes to see a bright point on the nighttime sky. When it happens, the star will go from needing a telescope ot good binoculars to see, to being the 50th (or even 30th) brightest star in the sky. For a week or so.

Of course, it could just go full-on supernova, and be visible in daylight for a few weeks, and dominate the night sky for months. But that's unlikely.

"T Corona Borealis" (meaning : the 20th variable star studied in the constellation "Corona Borealis") is a variable star in the northern sky — circumpolar (visible all night, all year) for about 60% of the world's population which normally you need binoculars to see. For over 150 years it has been known to vary in brightness, slightly. But in 1866, it suddenly brightened to become about the 35th brightest star in the sky. "Suddenly" meaning it was invisible one hour, and near full brightness an hour later. That made it a dramatic "nova" ("new star"), if not a "supernova", and people watched it like hungry haws as it faded over the next weeks, and months, and years.

And it faded back into it's previous obscurity, just wobbling a little, well below naked-eye visibility.

Until the late 1930s, when it started to change it's ESTABLISHED 280-day cyclic pattern. Then, in 1946 ... someone turned the switch back on, and again in less than an hour it brightened about 240 times, again becoming about the 50th brightest object in the sky. Which made it almost unique — a recurring nova. Today, only 10 of these are known, and they're extremely important for understanding the mechanisms underlying novae.

In 2016, "T CrB" (as it is known) started showing a similar pattern of changes to what were seen in the late 1930s.

In 2023, the pattern continued and the match of details got better.

The star is expected to undergo another "eruption" — becoming one of the brightest few stars in the sky, within the next couple of months. Maybe the next couple of weeks. Maybe the next couple of hours. I'll check the databases before submitting the story, and advise the editors to check too.

Last week, astrophysicist Dr Becky Smethurst posted on the expected event in her monthly "Night Sky News" video blog. If you prefer your information in text not video, the AAVSO (variable star observers) posted a news alert for it's observers a while ago. They also hosted a seminar on the star, and why it's eruption is expected Real Soon Now, which is also on YouTube. A small selection of recent papers on the subject are posted here, which also includes information on how to get the most up-to-date (unless you're a HST / JWST / Palomar / Hawai`i / Chile telescope operator) brightness readings. Yes, the "big guns" of astronomy have prepared their "TOO — Target Of Opportunity" plans, and will be dropping normal observations really quickly when the news breaks and slewing TOO the target.

You won't need your eclipse glasses for this (Dr Becky's video covers where you can send them for re-use), but you might want to photograph the appropriate part of the sky so you'll notice when the bomb goes off.

Bomb? Did I say that the best model for what is happening is a thermonuclear explosion like a H-bomb the size of the Earth detonating? Well, that's the best analogue. Understandably, taking a "close" (3000 light years — not close enough?) look at one seems like a good idea.

Preview, check for brightening/ detonation (JD 2460428.55208 = 2024 Apr. 28.05208 mag 9.905 0.0052 — not "Gone" yet!), submit.

Submission + - ESA is standardising comparisons for Near Earth Asteroids (esa.int)

Submitted by RockDoctor
RockDoctor writes: In this month's ESA Near Earth Object Coordination centre Newsletter, they propose an number of standardised units of comparison for journalists describing "death from the skies" :

Let’s look at some of our favourite unusual suspects:

  • Corgi: At around 30 cm tall, a space rock the size of a corgi wouldn’t pose much of a threat.
  • Half a giraffe: An adult giraffe can reach up to 5.5 metres in height, so half a giraffe would be about 2.75 metres. While not as impressive as a full skyscraper (themselves varying in size by more than an order of magnitude / 2.5 astronomical magnitudes ; 0.3 geological magnitudes), an asteroid that size could certainly destroy a building or two.
  • Peacock: Male peacocks, with their extravagant tails, can reach up to 3 metres in length. Six peacocks in a line would stretch 18 metres, big enough to cause localised damaged. This is also the size of 15 alpacas standing shoulder to shoulder. (There is no International Standard Alpaca. Yet.)
  • Elephants: An adult African elephant can reach 7 metres at the shoulder. Ninety elephants stacked on top of each other would form a staggering pile over 630 metres high, creating a devastating but probably not planet-ending event.

In consequence of this continuing confusion, the ESA recommend :

the use of a Standardised Giraffe Unit (SGU, 1 SGU = 5 penguins) for ease of comparison.

As frequently pointed out, defining units can be difficult. It has already been pointed out that the penguin itself is poorly defined, a herring-and-finger-replete seated Adelie penguin being substantially different to an aroused Emperor. Others have pointed out that such standardisation should be done at the IAU level, since Americans don't attend international meetings due to TSA gropings. Personally, I note that the reference frame and any Lorentz contraction of the penguin is undefined. But it's an invaluable start, nonetheless.

Returning to it's normal topic, the Newsletter points out that :

A large asteroid will fly-by the Earth and become relatively bright this month. (439437) 2013 NK4 is a large asteroid, roughly 100 SGU in diameter, which will approach our planet about 8 times as far as the Moon on 15 April, reaching magnitude 12.

That's a mere 250 times dimmer than the human eye can see, so opening your (eye) pupils to about 100mm diameter should make it easily visible. (Mechanical details are left as an exercise for the reader.)

The world may be turtles all the way down, but it's giraffes all the way up.

Submission + - Kidnapped by a runaway electric car (bbc.co.uk)

Submitted by RockDoctor
RockDoctor writes: Regardless of their other potential benefits, modern cars, and modern electric cars in particular, involve complex networks of computer code, hardware, and servo systems cooperating (?) to deliver services to the user, like acceleration, steering, and braking.

Slashdot nerderati know better than most that such complex networks can never show unexpected, non-designed behaviour, due to the infallibility of hardware, program coders, and system designers.

Yeah. Right. "I'll have some of what he's been smoking!" That's Musk-grade optimism.

On Sunday evening, a middle-aged driver in a "brand new" vehicle found it would not decelerate below 30mph (50kmph). He retained steering control, and avoided crashing until police vehicles "boxed in" his vehicle and helped him exit into a police van (most have sliding side doors) from the moving vehicle. The police then "carried out a controlled halt" on the unmanned vehicle, stopping it from driving away with the van's brakes until a roadside assistance technician arrived 3 hours later and managed to shut it down.

"when the [technician] got to me [...] later, he plugged in the car to do a diagnostic check and there was pages of faults".

By inference, the vehicle did not have a mechanical brake ("hand brake" : English; "parking brake" : American), which should gave been able to keep the vehicle halted regardless of the motor's actions (even if a "clutch" did get burned out). From the only time I've been inside an electric car, I can't say if that is normal ; it's certainly something I'll look for if I ever rent another.

Had the failure happened at 10 in the morning, not 10 in the evening, the body count could have been ... substantial.

My WAG : a sticky accelerator sensor. See also : "bathtub failure rate curve".

A dumb question, stemming from my only use of an electric car : do they have a weight sensor under the driver's seat that locks-out the main motor unless there is (say) 30kg in the driver's seat? Most have some such sensors — they trigger the "seat belt not fastened" alarm, or silence it for empty seats — but whether they can override the drive system ...?

Submission + - Massive GRB is a record breaker (bbc.co.uk)

Submitted by RockDoctor
RockDoctor writes: A recent paper on ArXiv describes a Gamma Ray Burst (GRB) whose light arrived late last year as one of the strongest ever observed. GRB 221009A was detected on October 9 last year (yes, that number is a date), so 5 and a bit months from event to papers published is remarkably quick, and I anticipate that there will be a lot more papers on it in the future.

Stand-out points are :
  • - it lasted for more than ten hours after detection (a space x-ray telescope had time to orbit out of the Earth's shadow and observe it)
  • - it could (briefly) be observed by amateur astronomers.
  • - it is also one of the closest gamma-ray bursts seen and is among the most energetic and luminous bursts.

It's redshift is given as z= 0.151, which Wikipedia translates as occurring 1.9 billion years ago, at a distance of 2.4 billion light-years from Earth.

Observations have been made of the burst in radio telescopes (many sites, continuing), optical (1 site ; analysis of HST imaging is still in work), ultraviolet (1 space telescope), x-ray (2 space telescopes) and gamma ray (1 sapce telescope) — over a range of 1,000,000,000,000,000-fold (10^15) in wavelength. It's brightness is such that radio observatories are expected to continue to detect it for "years to come".

The model of the source is of several (3~10) Earth-masses of material ejected from (whatever, probably a compact body (neutron star or black dwarf) merger) and impacting the interstellar medium at relativistic speeds (Lorentz factor 9, velocity >99.2% of c). The absolute brightness of the burst is high (about 10^43 J) and it is made to seem brighter by being close, and also by the energy being emitted in a narrow jet ("beamed"), which we happen to be near the axis of.

General news sites are starting to notice the reports, including the hilarious acronym of "BOAT — Brightest Of All Time". Obviously, with observations having only occurred for about 50 years. we're likely to see something else as bright within the next 50 years.

The brightness of the x-rays from this GRB is such that the x-rays scattered from dust in our galaxy creates halos around the source — which are bright enough to see, and to tell us things about the dust in our galaxy (which is generally very hard to see). Those images are more photogenic than the normal imagery for GRBs — which is nothing — so you'll see them a lot.

Submission + - Surface properties of small near-Earth asteroids (arxiv.org)

Submitted by RockDoctor
RockDoctor writes: A recent paper on ArXiv reports new spectroscopic analyses of the surfaces of 42 asteroids. The main result for space enthusiasts is that there is not one "M" class asteroid (metal-rich) surface in the collection.

The imagery that (many) people grow up with from Hollywood and TV "science" "documentaries" is that the Solar system is full of asteroids which are made of metal ready for mining to produce solid ingots of precious metals. That's Hollywood, not reality. This result is about what you'd expect from the proportion of metallic asteroids — otherwise estimated at about 0.5% of the population.

The asteroid mining fraternity dream of taking apart an M-type asteroid like Psyche, which is fair enough as a dream. Even as a dream for "asteroid mining" metal market speculators. But they are relatively rare asteroids. A realistic "ISRU" (In-Situ Resource Utilisation) plan is going to have to expect to digest around 200 silicate mineral (and clay ("phyllosilicate"), and ice) asteroids for every metallic one they digest.

The NEORocks program's home page is here. One of their main aims is to focus on extremely high standards in data dissemination, so I hope this submission contributes. More information is here.

Submission + - Super-massive Black hole ejected from galaxy. (arxiv.org) 1

Submitted by RockDoctor
RockDoctor writes: A paper published last week on ArXiv describes the trail of debris left behind by a Super Massive Black Hole ejected from the core of a galaxy.

As part of a study of "low-surface-brightness galaxies" using the Hubble Space Telescope, this 16-strong team noticed a long, linear feature in one of their images. Initially thinking it was a cosmic ray, they looked at the second image taken of the region on HST's next orbit (and through a different filter) — and found it was still visible. In the immortal words of real world science "that's odd", so they investigated more closely.

Their best model of the data is that their target galaxy "RCP 28" merged with another galaxy about 39 million years ago (from our point of view), leading to the ejection of one, or possibly two central black holes from the original galaxies. That would require one of the galaxies to have been the result of a previous merger, but whose central black holes had not yet merged (an event we might have detected using our shiny new gravitational wave telescopes, had they been 39.1 million years ahead of their construction schedules).

After the collision and ejection from the galaxy core, the passage of the black hole through the galaxy and it's surrounding material produced a burst of star formation along that line, which we now see as a faint linear streak of light.

The HST images may show a much fainter streak in the opposite direction, hinting at a second ejected black hole. Or it might be noise. Or something else.

Those who like doom-laden prophecies will be upset to hear that, because we can see this moving across the plane of the sky, it is never going to come any where near us. Even if it weren't moving across our line of sight, at a redshift of z=0.964 (equivalent to about 1600 MPc, I think) it's a toss up which hits us first — this black hole, or the expanding surface of the red giant Sun.

Submission + - NASA's Next-Generation Asteroid Impact Monitoring System Goes Online (nasa.gov)

Submitted by RockDoctor
RockDoctor writes: For nearly 20 years, newly discovered asteroids had orbital predictions processed by a system called "Sentry", resulting in quick estimates on the impact risk they represent with Earth. Generally this has worked well, but several things in the future required updates, and a new system adds a number of useful features too.

The coming wave of big survey telescopes which will check the whole sky every few days is going to greatly increase the number of discoveries. That requires streamlining of the overall system to improve processing speed. The new system can also automatically incorporate factors which previously required manual intervention to calculate, particularly the effect of asteroid rotation creating non-gravitational forces on a new discovery's future orbit. Objects like asteroid Bennu (recently subject of a sampling mission) had significant uncertainty on their future path because of these effects. That doesn't mean that Bennu can possibly hit us in the next few centuries, but it becomes harder to say over the next few millennia. As TFA puts it,

Popular culture often depicts asteroids as chaotic objects that zoom haphazardly around our solar system, changing course unpredictably and threatening our planet without a moment’s notice. This is not the reality. Asteroids are extremely predictable celestial bodies that obey the laws of physics and follow knowable orbital paths around the Sun.
But sometimes, those paths can come very close to Earth’s future position and, because of small uncertainties in the asteroids’ positions, a future Earth impact cannot be completely ruled out. So, astronomers use sophisticated impact monitoring software to automatically calculate the impact risk.

The article includes videos explaining the future uncertainties on the orbits of potentially hazardous asteroids Bennu and Apophis.

Submission + - Volcanic eruption on potentially unstable Canary Island

Submitted by RockDoctor
RockDoctor writes: Regular readers may remember recurring concerns over the instability of the island of La Palma, in the Canaries archipelago. Estimates of the threat range from 100 megadeaths (from tsunami impacts on the coasts of about a dozen countries bordering the Atlantic — including the eastern seaboard of America) down to a 10- to 30- metre tsunami with a few thousand deaths in the Canaries and other Atlantic islands (Madeira, Azores).

To bring relaxation and good cheer, today we have the news that the volcano at the centre of these concerns is erupting for the first time in 50 years. While a hundred or so houses have so far been destroyed and around 5000 people evacuated from the path of the lava flow, some people are more sanguine — Spain's Tourism Minister considers the eruption a "great attraction", and indeed recent eruptions in Hawaii did see a significant amount of "Volcano tourism". To be honest, I'm rather tempted myself — Etna studiously did not erupt during my last holiday there. Or should I wait for Vesuvius to go off again?

Submission + - Astronomers spot new impact on Jupiter (groups.io)

Submitted by RockDoctor
RockDoctor writes: A recent flurry of posts to astronomy news sites points to an amateur astronomer spotting a new impact on Jupiter.

Every such case documented improves our estimates of how many bodies are flying around in the (inner) Solar system, and improves our estimates of how likely we are to get another hit in a year, a decade, or a century.

Sky and Telescope have been pulling in more information at Amateur Spots Possible New Impact Flash at Jupiter — Sky & Telescope.

An image on SpaceWeather.com. (Some of these images have been "flipped" to an "on sky" orientation, and others haven't — because astronomical telescopes generally produce an inverted image, since it requires fewer reflections.)

Estimates of the impactor size are unclear, but minimum sizes seem to be in the several kg range, and could (depending on how long the flash lasted — 1 video frame, 2, 10, 100?) go up into the tonnes. Which is important for estimating the number of potentially hazardous objects in the inner Solar system. S&T's correspondents put the size at "up to" (important words!) the 30m range (100ft in Tudor measure) which would be around 10000 tonnes — a Chelyabinsk 2013 size body.

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