Tag Archives: gas

Cosmic wall of gas

NGC 604 is a star-forming region about 1500 light-years across at a distance of about 2.7 million light-years away from us. And the Chandra X-ray space telescope took images of the region to discover a wall of hot X-ray emitting gas dividing the region into two. In the left side of the image below, gas is heated up both by the stellar winds from young stars and the supernovas. But in the right side of the image, hot gas is heated up entirely by the stellar winds from 200 massive stars, implying that the current star formation on that side is much more recent, and the wall of gas between the two sides block much of the energy emitted by the supernovas from the left side.

It's just somehow fascinating to see how gas that is about as dense as outer space around our own planet, in other words pretty much a vacuum to us fragile humans, could have a major effect in cosmic terms. Despite how sparse such gas must be, having light-years worth of the stuff does have an impact.

NGC 604
NGC 604

Mystery of the green blob revealed

One of the objects discovered through the Galaxy Zoo volunteer project, an effort to take advantage of the fact that us humans are far superior pattern-matching machines than modern computers, was a mysterious green blob dubbed "Hanny's Voorwerp". It's a huge irregular cosmic structure nearly the size of a small galaxy, and yet it is suspiciously devoid of stars.

Using radio telescopes, astronomers at ASTRON think they now have a good idea of what it is. They observed an energetic particle stream emanating from the center of a nearby galaxy IC 2497, generated by its supermassive black hole, which slams into the gas comprising Hanny's Voorwerp to make it glow. As for where all the gas comes from? It's probably the gas that was stripped from IC 2497 or another galaxy during a close encounter.

Radio jet (white contours) emanating from the centre of the nearby galaxy IC 2497 headed straight in the direction of Hanny's Voorwerp (green)
Radio jet (white contours) emanating from the centre of the nearby galaxy IC 2497 headed straight in the direction of Hanny's Voorwerp (green)