B Which star is the closest red giant to Earth according to The Guardian?

[Vanadium 50]

So you are saying that journalists should know this fine distinction?

Why not? First, it's not that fine a distinction, Second, there are plenty of science journalists around who know this. Third, they got into this mess by changing what was in the paper they sourced, and even a non-science journalist should have known better. And finally, they could have fact-checked the final product.

Further, I expect the PF membership to be interested in learning this, if they don't already.

 

[Ken G]

Stellar classifications are indeed a bit of a mess, because the words can mean so many different things. We probably have to be a bit forgiving.

If one looks at the size and color of the primary star in Capella, it occupies a place in the Hertsprung-Russell diagram that is pretty close to the red giants, just a little hotter and smaller (so is sometimes called a yellow giant, since its spectral type is K0 so almost a G star). But it is much more useful to classify stars based on their evolutionary phase than their size and color, and there the Capella primary is something of an impostor as a red giant-- it is actually a "red clump" star, which means it has started to fuse helium in its core (whereas true red giants have inert degenerate helium cores, so the Capella primary is in a later stage than that, while the Capella secondary is in an earlier stage where it has not yet reached the red giant branch).

So Capella has two main stars that are both close to the red giant branch but one has left and the other hasn't gotten there yet, hence when someone calls Capella a "yellow giant", they are covering a lot of interesting physics about what those stars have done and will do! (On the other hand, calling Betelgeuse a red giant is just wrong, it's nowhere near the right place in the H-R diagram for that, and it is not of the type of star that makes red giants, so it's good that this has been corrected to red supergiant.)

 

[EventHorizon]

Maybe they used out-of-date references, or AI just hasn't updated to that levelyet.