Black Hole Feedback


The evolution of a galaxy is related to the growth of the supermassive black hole at its center. During the galaxy’s quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. This animation illustrates how black-hole feedback works during that phase. Dense gas and dust in the center simultaneously powers the black hole and hides it from view. The black hole’s radiation wind drives huge outflows of cold gas causing a shock wave that clears gas and dust from the central galaxy.

Video Credit: NASA

A Young Protostar


hops383The four infrared images on the left are from instruments at Kitt Peak National Observatory and the Spitzer Space Telescope. They show the outburst of HOPS 383, a young protostar in the Orion star-formation complex. The background image is a wide view of the region taken from a Spitzer false color infrared mosaic. Click the image to embiggen it; depending on your browser, a second click may be worth it.

Image Credit: E. Safron et al.
Background: NASA / JPL / T. Megeath (U-Toledo)

Ganymede


This video shows a map of Ganymede based on images from the Galileo orbiter. The U. S. Geological Survey has classified the surface of Ganymede into various types of terrain. The regions shown in brown are those that are heavily cratered and much older than the light shaded regions that are smoother with few craters. The lighter shaded regions were likely formed by flooding of the surface with water coming from faults or cryo-volcanos that has occurred over billions of years. Tectonic processes may be at work with some crustal ice sheets being forced downward by the emergence of newer icy material. The best models of Ganymede from the Galileo data suggest a deep ocean under a thick ice crust.

Video Credit: NASA / USGS