[astroH]

As an expert in this space, I can confidently tell you that nothing about this observation is conclusive about the presence of the "First Stars" or what we call "Pop. III" Stars. By definition, the first stars are nearly completely devoid of elements heavier than hydrogen and helium. The spectra shows absolutely booming emission from Oxygen III ions at 5007A so there are heavy elements in the system and at best there is a mix of Pop III stars and more normal stars. The lifetimes of the stars are very short, ~3 Myr, so the chances of seeing them are very low which is likely the limiting factor (along with their brightness) and thus there is a strong Bayesian prior against seeing them with a narrow field of view. The mass of the system at 10^7.35 solar masses is much greater than what we expect from theoretical models that form Pop. III stars and you must ask how it's possible to not have any metals pollute the gas. The main piece of evidence for Pop III stars is HeII emission at 1640A which is a prediction of Pop. III stars, but you can also get this in many other ways, for example X-ray binaries. We see this plenty in the local Universe and we fully expect this to happen elsewhere. So to me this is headline chasing with little conclusive evidence.

[dang]

Thanks! I've replaced the overstated title with what seems to be a better phrase from the first paragraph. If there's a better (more accurate and neutral) title, we can change it again.

[perihelions]

The "isotope" part is a mistake in the article. The writers heard "He II" and very reasonably wrote down "helium-2", and added some exposition about that (hypothetical) nuclear isotope. But they're in fact unrelated things: "He II" in this context is an ionization state of helium (the +1 state) -- not an isotope. What the research is observing is high-energy radiation from stars stripping electrons from helium atoms. No rare isotopes in sight!

[dang]

Thanks! I've revised the revision (which, for those who care, was "Light from a rare state of helium in a distant galaxy"). Does it work now?

[mikewarot]

well... that makes a lot of sense

I came here wondering how they knew the spectra of an isotope with a half life of 10^-9 seconds

[skykooler]

Also, spectra don't vary significantly by isotope - even with deuterium the difference is fractions of a nanometer of wavelength, which is not something detectable in astronomical spectra.

[astroH]

I think this is perfect! If only we can convince the author of the article...

[omnicognate]

Or the author of the headline at least. The article itself is detailed and gives most of the caveats you did.

[not2b]

Yes, authors of articles rarely get to choose the headline, at most, they can suggest one. The editors choose the headline and often their motivation is to maximize clicks.

Ars Technica in particular sometimes uses A/B testing, randomly giving readers one of two headlines to see which one generates more clickthroughs (they've been transparent about that, there was an article describing it).

[jonnywithoutanh]

Hello! Author here (for real). Yes I didn't have much say in the headline but I'm fine with it, it's technically what the authors of the paper I covered were saying.

And thanks, hope you enjoyed the article! Regardless of whether this result stands up to scrutiny, I think this was a nice jumping off point to explain Pop III stars, and some of the interesting work JWST is doing here that people are probably not aware of (eg the programs mentioned at the end of the article).

[LarryMullins]

> "First Stars" or what we call "Pop. III" Stars. By definition, the first stars are nearly completely devoid of elements heavier than hydrogen and helium.

I thought Pop III stars initially formed with only Hydrogen and Helium, but they promptly created heavier elements up to Iron within themselves through fusion.

[astroH]

Indeed, but we define their "metallicity" (mass fraction of elements heaver than helium) typically by the gas that they formed from. And the key point is that since they form from metal-free gas, you don't expect to see emission lines from metals which come from the star illuminating the surrounding gas with radiation.

[LarryMullins]

It makes sense to me that these stars would lack planets, and metallic gases around them and whatnot. But wouldn't you still get metal emission lines from the star itself? Or can those emissions not escape the star because the heavier elements are deep inside it?

[soiler]

I interpret

> the star illuminating the surrounding gas with radiation

to mean that we're looking at the spectra of the gas around the star, or at best the corona or maybe the surface of the star. I think it's very difficult for photons in the core of a star to reach the surface, so we probably don't see light from the heavier interior elements often or at all.

[martincmartin]

Inside the star, or even on the surface, there is a lot of energy, so you won't see the light that specifically comes from a single electron, in the first excited state with a well defined energy, that then decays to the ground state.

At least that's my guess, I'm not an expert.

[dguest]

They create most of the heavier stuff when they blow up. But that's a pretty small fraction of their lifetime, even for stars with a relatively short lifetime (a supernova takes minutes, these things live for millions of years).

[jwuphysics]

Agreed, thanks for saying this. I'm also another astronomer by trade and I'm very surprised that Quanta ran with this title. I like the work that Xin Wang has done, and I'm usually a fan of Quanta Magazine reporting and Simons Foundation work -- I'm currently organizing a conference at the Flatiron Center for Computational Astrophysics -- but this is really lowering the bar for science journalism.!

[phkahler]

This isn't literally an observation of a single star at that distance is it? If they only lasted a few million years then it will be unlikely to see a cluster of them devoid of other 2nd generation stars. It's doubtful (to me) that they all formed at the same time so as to not co-exist with other types.

[UI_at_80x24]

>~3 Myr

Just curious, when you mentally say that do you pronounce it: ~3 MEGA-years or ~3 MILLION-years

I realized that I keep flipping it back and forth and I can't settle on the 'correct' version. Like saying data vs data. =)

In addition, thanks for the comment. The information on Pop. III stars was great!

[JumpCrisscross]

> mass of the system…is much greater than what we expect from theoretical models that form Pop. III stars

I would have thought the mere presence of a solar system excludes a star from Population III. Is that inaccurate?

[hinkley]

You’re saying a lot of things here, but is one of them that an event could be detected far away because it’s old, or because it’s such a rare event that the chances it happens near us are vanishingly small?

[astroH]

These systems are very far away because you are looking more than 13 billion years back in time. The argument is JWST has a small field of view and these Pop III stars are like flashes in comparison to the age of the galaxy. So the probability of catching one that is bright enough to be detected is just super low. Which is why there is a strong prior that the HeII could be from other physics that is relatively well understood. But really the OIII emission is the biggest sign that this isn't a "primordial galaxy"

[xtreme]

Pop 3 stars were formed in the very early universe and have been long gone. So there is no way for us to see the light they emitted without looking at the most distant galaxies.

[Natsu]

Why do the populations seem backwards? You'd think the first stars would be Pop. I, then the next Pop. II, then III, and maybe someday we'd get to IV. Instead they seem to work backwards?

[LeifCarrotson]

Because the names were determined by when they found those groups of stars, rather than when the stars they found were formed. They only later realized that their distinct groupings based on observed metal content were caused by stellar formation processes.

Regrettably, the stars didn't show up in their telescopes with labels and histories attached.

[soiler]

Same problem with categorizing star luminosity... I wish we could make a shift to these cumbersome categories, but cultural inertia is tough to overcome

[dylan604]

Yeah, seeing stars with negative luminosity seems weird. Negative? Are they removing light? =) Scales are fun when the index is arbitrary to the data.