Talk:Alpha Mensae

Mass/Luminosity discrepancy

Alpha Mensae is a bit of an anomaly. It is about 10% more massive than the sun and slightly older. Therefore, it should be decidedly more evolved. The spectral type is in close agreement here (0.5 classes cooler) but the luminosity is below the solar value. Even if we use the rule of thumb, that luminosity is proportional to m^3.5, and disregard hydrogen depletion, Alpha Mensae should have >1.35 times the sun's luminosity. The imminent giant phase exacerbates that further. Is there any mention of that issue in scientific literature or papers, which could add to the article and explain why alpha Mensae is rather dim? - ¡Ouch! (^{hurt me} / _{more pain}) 15:36, 23 June 2017 (UTC)

You're not comparing like with like. Even though the mass and luminosity (to take two values that you mention) are taken from the same published paper, they are not determined using the same methodology and should not be compared with eachother. The luminosity is a direct observational value, give or take some assumptions about distance, extinction, etc. The given mass is an "isochrone mass", a theoretical mass for a star with the given observed temperature, luminosity, and elemental abundances. Conveniently in this case the same paper also calculates spectroscopic masses, effectively a directly observed mass calculated from the surface gravity and radius. It notes that the modelled "isochrone" masses are systematically 10% larger than the "observed" spectroscopic masses. This sort of result is part of the constant feedback between stellar evolutionary models and observations of real stars. In particular, for α Mensae the isochrone mass quoted in the article is larger than the sun's while the spectroscopic mass is smaller. Lithopsian (talk) 18:41, 23 June 2017 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Alpha Mensae. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20060220180330/http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00493.htm to http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00493.htm

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 19:23, 2 July 2017 (UTC)