Dark Star

[Recusant]

After a site search, and specifically the Science board, it seems that the term dark star is practically absent here. The term itself has been around since at least the 1800s though I imagine it was probably used in astrology or in a metaphorical sense at that time. In pop culture, off the top of my head I note that it's the title of a somewhat bleak science fiction film, and a Grateful Dead song. I haven't heard it in science before that I can recall.

This item could go in the cosmology thread, but right now it seems more like a specific bit of science exotica. I don't know how recently scientists started speculating about a star at least partially composed of dark matter, but it's something I hadn't considered. Dr. Ilie, quoted in the article, appears to be pretty certain they exist.

"JWST May Have The Best Evidence Yet of a Bizarre 'Dark Star'" | Science Alert

JWST might have spotted the 'smoking gun' of a hypothetical object called a dark star in the distant Universe. If confirmed, this discovery could solve several mysteries of physics.

A dark star may sound like an oxymoron, but it would still emit light and energy. It wouldn't be powered by nuclear fusion like a garden-variety star, however – it would be running on a core of interacting dark matter particles.

"Supermassive dark stars are extremely bright, giant, yet puffy clouds made primarily out of hydrogen and helium, which are supported against gravitational collapse by the minute amounts of self-annihilating dark matter inside them," says Cosmin Ilie, an astrophysicist at Colgate University in the US.

Now, researchers have found the best evidence so far for the existence of dark stars. While studying four of the most distant objects ever observed, the team found that all are consistent with a dark star explanation.

Most intriguingly, though, one of the objects showed a particular light absorption feature at the wavelength of 1,640 Angstrom. This is considered a sure sign of dark stars, which arises from singly ionized helium in their atmospheres.

"While the signal-to-noise ratio of this feature is relatively low, it is the first time we found a potential smoking gun signature of a dark star. Which, in itself, is remarkable," says Ilie [University of Texas press release].

Soon after JWST fired up in 2021 and began peering farther back in space and time than humans ever had before, it caught some unexpected sights. Near the dawn of time sat what looked like huge galaxies at a moment when there shouldn't have been enough time (literally) for them to have grown so big.

Astrophysicists quickly came up with a possible explanation for some of these: Dark stars, which could contain as much as a million Suns-worth of mass, would look similar to galaxies from this distance.

[Continues . . .]

The paper is open access:

"Spectroscopic Supermassive Dark Star candidates" | Proceedings of the National Academy of Sciences

Abstract:

Dark Stars (DSs), i.e., early stars composed almost entirely of hydrogen and helium but powered by Dark Matter (DM), could form in zero metallicity clouds located close to the center of high redshift DM halos. In 2023, three of us identified (in a PNAS work) the first three photometric DS candidates: JADES-GS-z11-0, JADES-GS-z12-0, and JADES-GS-z13-0.

We report here our results of a follow-up analysis based on available NIRSpec JWST data. We find that JADES-GS-z11-0 and JADES-GS-z13-0 are spectroscopically consistent with a DS interpretation. Moreover, we find two additional spectroscopic DS candidates: JADES-GS-z14-0 and JADES-GS-z14-1, with the former being the second most distant luminous object ever observed.

We furthermore identify, in the spectrum of JADES-GS-z14-0, a tentative feature (S/N ~ 2) indicative of the smoking gun signature of DSs: the He II 1640 absorption line. In view of ALMA's recent identification of a probable O III nebular emission line in the spectrum of JADES-GS-z14-0, the simple interpretation of this object as an isolated DS is unlikely.

If both spectral features survive follow-up observations, it would imply a DS embedded in a metal rich environment, requiring theoretical refinements of the formation of evolution of DSs, which in previous studies were assumed to form in isolation, without any companions.

[Dark Lightning]

That's wild stuff!

[The Magic Pudding..]

I like the CSNY Darkstar, it used to be on the end of 45/90 minute tape.
If an album didn't fill up a side a good song from a weak album often got added.