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#1

Politics / Re: Duke of Bullshit: "The" Do...

Last post by Recusant - Today at 05:23:46 AM

. . . Not that the US has ever been particularly concerned about international law except when it offers a convenient way of pursuing "national interest." Party to many treaties but not above some covert operations including outright assassinations. In my opinion the current administration has moved past being an unreliable ally, headed more into rogue territory. So it goes.

#2

Science / Re: Black Holes in the News

Last post by Recusant - February 14, 2026, 03:21:29 AM

This one got onto the US's public radio news, and perhaps elsewhere. I'd bet a fiver that it got onto at least Radio 4 from the BBC, if not their television news. So there's a good chance the remaining lucky few here have already heard tell of the vanishing star.

"A Giant Star Vanished, And Scientists Think a Black Hole Is to Blame" | ScienceAlert

One of the brightest stars in the Andromeda galaxy quietly collapsed into a black hole without any of the fanfare of a spectacular supernova.

What makes this startling discovery even more remarkable is that the first signs of the transformation were recorded back in 2014 – data that is crucial for understanding the different ways black holes can form after the death of a giant star.

"This has probably been the most surprising discovery of my life," says astronomer Kishalay De of Columbia University in the US, who led the research. "The evidence of the disappearance of the star was lying in public archival data, and nobody noticed for years until we picked it out."

When a massive star many times heavier than the Sun dies, it's not expected to go quietly. Once nuclear fusion in the core can no longer generate sufficient outward pressure against the inward pull of gravity, the core collapses.

This can send a giant shock tearing outward through the star, triggering a supernova explosion that sends the star's outer material flying, while the core transforms into either a neutron star or a black hole.

However, this is not the only way this transformation can take place. In some scenarios, the outward shock stalls. Instead of ripping the star apart, the explosion fizzles out, and the material ends up falling back onto the newly formed black hole. Because this is a much less dramatic process than a supernova, clear evidence of it is relatively rare.

"Unlike finding supernovae, which is easy because the supernova outshines its entire galaxy for a few weeks, finding individual stars that disappear without producing an explosion is remarkably difficult," De explains.

Only one such event had been documented previously, a star recorded vanishing around 2010 in a galaxy 22 million light-years away. Now, by carefully looking over archival observations of the Andromeda galaxy, De and his colleagues have found another, and it's even clearer than the previous example.

M31-2014-DS1 was a supergiant star that started out about 13 times the mass of the Sun and shone brightly, even across the 2.5 million light-year distance between the Milky Way and Andromeda.

Then, in 2014, NASA's NEOWISE telescope recorded it suddenly shining more intensely in infrared, increasing its brightness by about 50 percent over about two years.

Then, between 2016 and 2022, it dimmed dramatically to the point where, by 2023, it completely vanished from view in optical wavelengths.

[Continues . . .]

The paper is behind a paywall, but I found a revised preprint version. Though I haven't gone into the paper yet, the abstract from the preprint is identical to the published version.

"Disappearance of a massive star in the Andromeda Galaxy due to formation of a black hole" | arXiv

When a massive star reaches the end of its lifetime, its core collapses and releases neutrinos that drive a shock into the outer layers (the stellar envelope). A sufficiently strong shock ejects the envelope, producing a supernova. If the shock fails to eject it, the envelope is predicted to fall back onto the collapsing core, producing a stellar-mass black hole (BH) and causing the star to disappear. We report observations of M31-2014-DS1, a hydrogen-depleted supergiant in the Andromeda Galaxy. In 2014, it brightened in the mid-infrared, then from 2017 to 2022, it faded by factors of ≳ 10⁴ in optical light (becoming undetectable) and ≳ 10 in total light. We interpret these observations, and those of a previous event in NGC 6946, as evidence for failed supernovae forming stellar-mass BHs.

#3

Laid Back Lounge / Re: Multi-Association Thread

Last post by Recusant - February 12, 2026, 03:48:05 AM

Image Credit: Cindy See

#4

Science / Re: Dark Star

Last post by Dark Lightning - February 12, 2026, 03:02:46 AM

Astrophysics is one of those areas where a lot of latitude is still available. What I studied 45 years ago looks Copernican by comparison. 

[Abstract:]

#5

Science / Re: Dark Star

Last post by Recusant - February 12, 2026, 02:46:44 AM

I've been enjoying the abundance of items having to do with dark matter and its nature, not to mention places where it could be. In this instance, an exploration of the possibility that Sagittarius A* (Sgr A*) the supermassive black hole at the center of our galaxy, is actually a dense region of dark matter. Speculate away! I find it gratifying that people are willing to explore ideas about the Universe by looking at the same. This in contrast to the supposed divinely bestowed knowledge contained in collections of old books of mythology.

Just for a larf, indulging my curiosity I checked in with the Christians to find what they have to say about dark matter. You have to be in the right mood but if you are, there are some amusing items. I admit I can be a sucker for desperate tap-dancing. 


"Something Far Darker Than a Black Hole Could Hide in The Heart of The Milky Way" | ScienceAlert

There's no denying that something massive lurks at the heart of the Milky Way galaxy, but a new study asks whether a supermassive black hole is the only possible explanation.

All measurements taken of the galactic center to date are consistent with a highly dense object around 4 million times as massive as the Sun. According to the new paper, though, if you squint just a little, all that evidence can also apply to a giant, compact blob of fermionic dark matter, without an event horizon.

We currently don't have the observational precision to tell the difference between these two models. However, a dark matter composition of the galactic nucleus would give astronomers a new tool for interpreting the dark matter structure of the entire galaxy.

"We are not just replacing the black hole with a dark object; we are proposing that the supermassive central object and the galaxy's dark matter halo are two manifestations of the same, continuous substance," explains astrophysicist Carlos Argüelles of the Institute of Astrophysics La Plata in Argentina.

[Continues . . .]

The paper is open access:

"The dynamics of S-stars and G-sources orbiting a supermassive compact object made of fermionic dark matter" | Monthly Notices of the Royal Astronomical Society

Abstract:

Surrounding Sgr A*, a cluster of young and massive stars coexist with a population of dust-enshrouded objects, whose astrometric data can be used to scrutinize the nature of Sgr A*. An alternative to the black hole (BH) scenario has been recently proposed in terms of a supermassive compact object composed of self-gravitating fermionic dark matter (DM). Such horizon-less configurations can reproduce the relativistic effects measured for S2 orbit, while being part of a single continuous configuration whose extended halo reproduces the latest GAIA-DR3 rotation curve.

In this work, we statistically compare different fermionic DM configurations aimed to fit the astrometric data of S2, and five G-sources, and compare with the BH potential when appropriate. We sample the parameter spaces via Markov Chain Monte Carlo statistics and perform a quantitative comparison estimating Bayes factors for models that share the same likelihood function.

We extend previous results of the S2 and G2 orbital fits for 56 keV fermions (low core-compactness) and show the results for 300 keV fermions (high core-compactness). For the selected S2 data set, the former model is slightly favoured over the latter. However, more precise S2 data sets, as obtained by the GRAVITY instrument, remain to be analysed in light of the fermionic models.

For the G-objects, no conclusive preference emerges between models. For all stellar objects tested, the BH and fermionic models predict orbital parameters that differ by less than 1 per cent. More accurate data, particularly from stars closer to Sgr A*, is necessary to statistically distinguish between the models considered.

#6

Music / Re: What are you listening to?

Last post by Recusant - February 10, 2026, 06:10:40 AM

Such a beautiful, brave soul. It's not just like anyone said it would be. It's decidedly awful.

That was her BBC debut appearance I think. I remember when she first broke into a wide audience--I was impressed with the emotion and power in her music. Fame didn't do her any favors though.

There was a science fiction writer or two of the 20th century who imagined a USA that turned to Christofascism. I'd agree though that the particulars of the ongoing dumpster fire weren't detailed.

#7

Music / Re: What are you listening to?

Last post by Icarus - February 09, 2026, 04:02:20 AM

Here's one with a lot of percussion, it fits the theme .  Find a quiet place, relax, close your eyes and absorb this passionate but dynamic piece.

#8

Music / Re: What are you listening to?

Last post by Icarus - February 09, 2026, 03:02:50 AM

Music that achieves temporary popularity is exceedingly heavy on loud drum beats.  It would seem that percussion has become the lead in mod "musical" groups..  Ms O'conner does not demonstrate a voice that is more talented than a bullfrog in the pond. One wonders whether she can actually sing in a soothing way. The apparent musical tastes of the day apparently does not need smoothness nor any demonstrated vocal skill.

 

#9

Philosophy / Re: Critical thinking?

Last post by Recusant - February 08, 2026, 05:32:00 PM

The video was OK, but his prescriptions for leaders seemed rather unrealistic given the normal process of politics.

[The Magic Pudding..]

#10

Politics / Re: Duke of Bullshit: "The" Do...

Last post by Recusant - February 08, 2026, 05:29:02 PM

I respectfully disagree Rec. We need not be diplomatic nor bother with polite deception.  I believe that the multi millions of angry demonstrators are not much interested in being polite or diplomatic, not now. We have damned well had very close to all that we can peacefully tolerate.

We have given up on the hope that space aliens will kidnap the mentally and morally disabled Trump. 

Yes for those of us in the belly of the beast, steadfast opposition is definitely preferable to cowed acceptance.

It seemed to me that The Magic Pudding.. was thinking more about how democratic nations that have been longtime allies of the US can safely put some distance between themselves and a country that's become an overt threat to peace and stability, blatantly using its power to violate international law.