Luminous blue variable stars showcase a spectacular and rare unstable stage in the death of massive stars. These supergiant stars can rapidly and unpredictably change both their brightness and spectra in outbursts that can last for decades. Some giant eruptions produce nebula that surround the star. Although known for centuries, the identification of the underlying physics remains elusive, and new behaviors continue to be discovered. Long programs of periodic monitoring have produced important pieces of this, as yet, unsolved puzzle. Understanding this dramatic phase will help complete the sequence of massive star development and delineate the progression to the final stellar death as a supernova explosion.... Read More إقرأ المزيد | Share it now!
On this episode of Dirt Every Day presented by Tire Rack, Fred Williams and Dave Chappelle are going to figure out if, with a few modifications, a military surplus Humvee is a great desert machine, or an awful off-roader. After getting a ratty veteran of a 4×4 from GovPlanet, the guys take it home to build it up into a more capable rockcrawler and then head to Johnson Valley, California, to see if their mods worked.... Read More إقرأ المزيد | Share it now!