Dead Stars, Dead Galaxies, Dense Fog

 

February 22 Dead Stars, Dead Galaxies, Dense Fog

Artist's concept of a white dwarf star. They are the small and dense cores of once-active stars like our sun. Astronomers believe 97% of stars in our Milky Way will someday become white dwarfs. Image via Miriam Nielsen/ The Verge.

A habitable zone planet for a dead star? We know 4,000+ exoplanets orbiting distant stars in our Milky Way galaxy. Some orbit cool, dim cores of former sun-like stars called white dwarfs. Such stars are slowly cooling, fading embers. But can there be planets in the habitable zones of such stars? And could those planets have life, even as the host star slowly dimmed? An international group of astronomers might have an answer to the 1st question. They have evidence of a still-intact planet in a white dwarf's habitable zone. Why so many dead galaxies in this galaxy cluster? Stars form in a range of colors, from blue to red. The most massive stars are blue and very hot, but they live only a few hundred million years, in contrast to billions of years for stars like our sun. So when astronomers see lots of hot, young, massive blue stars, they know they're seeing a place where stars are actively forming. And indeed, when they look far out into space (and therefore far back in time), astronomers do see many active, blue star-forming regions. But a newly analyzed protocluster, or newborn galaxy cluster, bucks that trend. It appears to exist in the early universe. But it looks old, red and dead.  Winter fog in Willamette Valley, Oregon Check out this NASA satellite image of Oregon’s Willamette Valley. It shows a long, dense stretch of fog blanketing the valley: the result of a temperature inversion. NASA satellites have viewed three extended periods of Willamette Valley fog this year. They happened on January 14-17, January 22-29, and February 8-12. Read more and see the image.