The Southern Crab

He2-104An unlikely pair of stars may have created this oddly-shaped nebula resembling nesting hourglasses. Images taken with Earth-based telescopes show the larger, hourglass-shaped nebula, but the Hubble telescope, reveals a smaller nebula embedded in the center of the larger one. See the insert The entire nebula is called the “Southern Crab Nebula” (He2-104) because it looks like the body and legs of a crab as seen from ground-based observatories. The likely source of the the larger and smaller nebulae is a pair of aging stars buried in the glow of the tiny, central nebula. One of them is a red giant, a bloated star that is exhausting its nuclear fuel and is shedding its outer layers in a powerful stellar wind. Its companion is a hot, white dwarf, a stellar zombie of a burned-out star.

Image Credit: NASA

V404 Cygni

On June 15, the Swift satellite caught the onset of a rare X-ray outburst from a stellar-mass black hole in the binary system V404 Cygni. In that system a stream of gas from a star much like the sun flows toward a 10 solar mass black hole. Instead of spiraling into the black hole, the gas accumulates in an accretion disk around it. Every couple of decades, the disk changes state, sending the gas rushing inward. The result is a new X-ray outburst.

Video Credit: NASA

A Day on Pluto

nh-pluto-day_1As it approached Pluto last July, the cameras on the New Horizons spacecraft captured Pluto rotating over the course of a full “day.” Pluto’s day is 6.4 Earth days long. The best available images of each view of Pluto taken during approach have been combined to create this montage of a full rotation.

Image Credit: NASA