Talk:Betelgeuse

Pre-fading magnitude

The lede describes Betelgeuse as (usually) the 11th brightest star, but the section on recent fading describes it as having been the ninth brightest star (before recent months). The Washington Post and National Geographic sources cited in the fading section (not all accessible to me) might be the source of this inconsistency. Attic Salt (talk) 15:13, 21 January 2020 (UTC)

It's variable, irregularly, so there isn't really an average. The press reports generally talk of "in the top 10" quoting more or less directly from The Astronomer's Telegram. I have adjusted that section to match and given the reference directly. List of brightest stars gives Betelgeuse as 11th brightest at its "average" level, with the Sun at #1. Given that five of those top 10 (other than the Sun) are variable, there is lots of scope for picking a number. The Astronomer's Telegram is again much clearer than the Chinese Whispers, stating that at its average maximum it is within the top ten. Lithopsian (talk) 15:45, 21 January 2020 (UTC)

Axis of rotation

This star is in the news, which should be welcome to astronomers — funding! — but the ignorant tabloid stuff might be less welcome. I’ve come from The Economist, and neither that nor Wikipedia mention anything about the axis of rotation.

I.e., is it pointing at us?

A rotation speed is listed, so something might be known about its direction. And if nothing is known, please could at least that be said? JDAWiseman (talk) 19:22, 1 February 2020 (UTC)

The axis of rotation is thought to lie about 20° away from us. Lithopsian (talk) 21:25, 2 February 2020 (UTC)

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"Distance measurements" subsection needs cleanup

Several of the reported measurements are garbled so that they are unreadable. Ishboyfay (talk) —Preceding undated comment added 17:57, 15 February 2020 (UTC)

There's a problem with the nested {{nowrap|{{pi}} = {{val|5|4|u=mas}}}} template. I've removed the "pi =" as it renders unreadable. Someone with more experience with nested templates should take a look at a permanent fix. --mikeu ^talk 16:16, 17 February 2020 (UTC)

My fault. Probably better without the πs anyway. Lithopsian (talk) 17:54, 17 February 2020 (UTC)

For an amateur such as myself, an explanation of why it's especially difficult to measure the parallax of Betelgeuse would be a helpful addition to the article. I have in mind this sentence from an EarthSky article: "Measuring the distance to Betelgeuse has been particularly difficult because it is a variable star." As an amateur, I don't feel confident enough to explain further. Ishboyfay (talk) 18:25, 15 February 2020 (UTC)

Lots of reasons, but simply having a diameter ten times bigger than its parallax makes things tricky. Add in pulsations, starspots, and having an irregular silhouette. Well, you get the idea. Specific to Gaia, Betelgeuse is brighter than its sensors can handle so it isn't possible for the normal scan sweeps to identify the position of the star. Special observing runs and analysis techniques have been developed which may allow Gaia to provide a parallax 1-2 orders of magnitude better than anything before, perhaps to better than a parsec. Lithopsian (talk) 18:09, 17 February 2020 (UTC)

This is a great answer. If it's possible to include some of it in the article, I recommend doing so. Ishboyfay (talk) 22:18, 17 February 2020 (UTC)

Needs reliable sources. I'm sure they're out there somewhere. Lithopsian (talk) 17:54, 20 February 2020 (UTC)

Marcel?

I followed the Wikisky coordinate link which for me shows up in the top-right of the article… Some joker has fiddled Wikisky so that this star seems to be named "Marcel". Searching for "marcel" on Wikisky nets me three results, including α Ori. Am I missing some astronomical in-joke or should someone be told about this? TIA HAND —Phil | Talk 11:22, 6 March 2020 (UTC)

That looks like vandalism to me. I'm not a WikiSky editor myself, so wouldn't know how to fix it without learning how. It needs to be changed. Well done for spotting that and alerting others. TowardsTheLight (talk) 11:59, 6 March 2020 (UTC)

Too soon?

How long before the recent dimming can be consigned to a short paragraph in the body and no more than a sentence in the lead? The news hype is over and the brightness is clearly recovering. Nothing went bang. Might be nice to have a slightly longer light curve for that section showing the whole dip and rise in context now that the brightening is so clear. 176.251.70.30 (talk) 15:05, 14 March 2020 (UTC)

New (Oct. 2020) Info

Joyce, et. al. published new estimates of several physical parameters. I am not clear on whether their paper has actually been published or is still in peer review, but based on claims of the university's PR department, it has been published. Standing on the shoulders of giants: New mass and distance estimates for Betelgeuse through combined evolutionary, asteroseismic, and hydrodynamical simulations with MESA by Meridith Joyce, Shing-Chi Leung, László Molnár, Michael J. Ireland, Chiaki Kobayashi, Ken'ichi Nomoto v5: published in the Astrophysical Journal:The Astrophysical Journal, Volume 902, Number 1, 2020. I only read the abstract. R is revised to 764(-62/+116)Solar radii, M to 16.5-19.0 Solar M, and distance to 168 (-15/+27)pc [equivalent to about 550 (-50/+90)ly. I assume this also changes its estimated absolute magnitude.98.17.180.195 (talk) 09:38, 16 October 2020 (UTC)