From: Brent Meeker <meekerdb@verizon.net> The luminosity of KIC 8462852 is about 4.5 to 5 times that of the sun and its mass is 1.45 solar masses. This means the star has a lifetime of 2 to 2.5 billion years, which is short for the evolution of intelligent life. SETI pointed their radio telescopes at it, but saw no signal. I'd guess the most likely explanation is some chaotic behavior of the nuclear reactions in the star. It's massive for an F-class star, close to being a B-class star and low in metals; so it's plausible that some kind of instability may occur in its radiative zone. Brent
--intelligent life if any may have evolved faster than on earth's 4 Gyr. Or it might be, e.g. Von Neumann machine from a different star. --Even if all nuclear reactions turned off instantly, the outside of the star would not notice for a long time? Cooldown time scales should be 1000-1000000 years? Not 1 day for 20% dimming. --Only certain kinds of stars brighten and dim, this kind is not one of them. It seems to be pretty normal F3-type star, and those just do not do this. Compare with other F3 low-metal stars. No others have ever been seen that do this. Cepheid variables, enormous stars that are extremely bright (100K sun) extremely huge fusion rates, extremely high radiative losses, and extremely short lived (10^6 years) pulsate with periods 2-110 days. The prototype "Delta Cephei" has period=5.4 days, surface temperature oscillates from 5500 to 6600 K, diameter changes about 15%, and its brightest is about 1.9 times its dimmest. --If it really were the star, then its spectrum should change quite noticeably during a dimming event. This if so (or if not) is going to become clear soon because they're pointing spectroscopes at it. https://en.wikipedia.org/wiki/Variable_star discusses. There are many kinds of variable stars in that article, mainly A- and B-type. The only F-types among them are "delta-scuti variables", which this isn't, periodic with rapid period of 15 minutes to 4 hours, whereas KIC 8462852 is very unperiodic and irregular. Further, no star has ever been noticed to have timescales of 100 years for some 20% brightness change, which Schaeffer found for KIC 8462852 by examining old photographic plates at Harvard library. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)