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tkdguy

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11 hours ago, Starlord said:

 

Misinterpretation of old news.

 

The uncertainties in the evolutionary track age are still large enough to include the Planck spacecraft cosmic microwave background age result (and its uncertainties).  So ... HD140283 is quite old, among the oldest demonstrable stellar ages, but the star's age is still consistent with the Universe's age.

 

(HD140283 is an old friend of mine, in multiple senses.)

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Well, the luminosity class IV means it has already begun its post-main-sequence evolution: in the very center, hydrogen is exhausted or nearly so, and the star's energy is being generated in a fairly thick shell around the center.  But the core is not yet degenerate, and the envelope has not yet turned fully convective.  For higher-mass stars this subgiant phase doesn't last long, and there are relatively few stars seen in that transition from main sequence to the giant branch.  For lower-mass stars ... less than 1.4 solar masses or so ... the thick-shell-burning phase takes longer.  HD 140283 is in that stage, *and* it's an extremely metal poor star to boot.  With an apparent magnitude of just over 7, it's a long-known and often studied star.

 

I got a spectrum of it back in the early 1980s and was stunned to find a clear lithium line.  (Lithium is very easily destroyed by exposure to high-temperature protons, so any sort of mixing between stellar atmosphere and interior "astrates" the lithium and reduces its abundance; this has already happened in the Sun, where it is just barely detectable, and has been reduced by a factor of a hundred or so from its initial level.)  My advisor didn't urge me to pursue that because a Nature paper by Francois and Monique Spite was in press, where they'd looked at a number of these extremely metal poor dwarfs and subgiants, analyzed them for lithium, and found a more-or-less constant value.  They interpreted this as cosmological in origin: that "ceiling" for lithium in the old stars is Li from the Big Bang, which made hydrogen, helium, and a trace of lithium.  The proportions of those depend on the mass of the Universe and the baryon fraction.  The level they got was consistent with a density less than the critical value, a result the observational cosmologists had found (with substantial uncertainty) by other means earlier.  This came out of left field: it had not been realized that this ancient tracer was observable, and to find a completely independent (and unambiguous) sign that there was not enough ordinary matter in the Universe to make for a critical density was a shock.

 

The Inflationary Hypothesis was formulated a couple of years later; Rubin & Ford's incontrovertible results for unseen matter dominating the rotation curves in spiral galaxies had been out for 5 years or so; and the conclusion that ordinary baryonic matter made no more than a couple of percent of the content of the Universe was slowly gaining grudging acceptance.

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On 7/18/2019 at 5:29 PM, Cygnia said:

Among the dead is Yasuhiro Takemoto, director of the popular series Lucky Star and Miss Kobayashi's Dragon Maid. A second season of the latter was in the early stage of production when the arson happened, and the storyboards, character art, and all the other things that go into the making of an animated film went up in the smoke and are gone forever.

 

The studio's owner has talked about tearing down what is left of the studio building, putting a monument there, and moving production work to a secondary location.

 

 

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Man, Saturday Evening Post and Indianapolis.  Thirty-plus years ago both of those despised RPGs and gamers like we were illiterate, malodorous, Satan-worshipping, child-sacrificing sociopaths who were working to corrupt the young and bring about the end of the world.

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1 hour ago, Cancer said:

Man, Saturday Evening Post and Indianapolis.  Thirty-plus years ago both of those despised RPGs and gamers like we were illiterate, malodorous, Satan-worshipping, child-sacrificing sociopaths who were working to corrupt the young and bring about the end of the world.

 

What is that now inaccurate?  Do I need to change my business cards?

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3 hours ago, Cancer said:

Man, Saturday Evening Post and Indianapolis.  Thirty-plus years ago both of those despised RPGs and gamers like we were illiterate, malodorous, Satan-worshipping, child-sacrificing sociopaths who were working to corrupt the young and bring about the end of the world.

 

Don't worry, it's VIDEOGAMES now that turn us into monsters.  Folks play Mario and get the urge to shoot places up.

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