We got axion [lack of] news from red giant Betelgeuse late last month. It tugged at some of my neurons that this star has been better constrained last year but I couldn't remember exactly. Luckily we now have Meridith Joyce's more-formal paper on that. Which is paywalled but more-luckily points to the arXiv.
Because Betelgeuse is bigger and redder than the Devil's arse in South Park it's long been foisted on schoolkids that this horror has a 5 AU radius, and is/was 600 light years away. Over the past few years from our perspective the star has been getting dimmer. This has caused many astronomers to wonder what is happening over there/then.
It turns out that we are not dealing with a normal red giant. It isn't burning hydrogen; it is burning helium, and not for all that long either. This reaction can keep going for another 100000 years. The helium burn implies more central gravity; so the star isn't as big as we thought it was. The mass is 16.5 to 19 solars; radius, 750 solars which is 3.5 AU. (Might still be about as hot as they'd thought, though.) Since it isn't as intrinsically bright it isn't as far away, neither. It's 530 light years out, not 600 and certainly not the 650 assumed by the axion study.
They do find pulsations: two periods of 185 (±13.5) days and approximately 400 days
. That year-2020 dimming wasn't among them. So the dimming was probably a shadow - a dust cloud. And if Betelgeuse is not prenova then, well, we shouldn't expect its axions (if any) to be emitting in the X band as predicted.
I don't know if Betelgeuse was ever on the main-sequence; Beta Centauri is supposedly over 10 solar masses but still smaller than this guy. This guy is (rather, was) more like Saiph and Rigel on the other side of Orion. Saiph is still marked 200 parsecs = 650 light years away from us; it too is a post-hydrogen supergiant but hasn't gone red... yet.
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