To celebrate the 19th anniversary of the Hubble Space Telescope this week, a stunning picture of two galaxies merging has been released. The merging galaxies are in the upper parts of the image, and they have an impressive trail of blue star-forming regions. Remarkably, the galaxy in the bottom of the picture is not merging with any of the galaxies in the upper part of the picture: it just happens to be in the background. This would have been hard to tell without the resolution of the Hubble Space Telescope, which reveals dust clouds around the trail that obscures the galaxy in the background.
The Six-Degree Field Galaxy Survey has completed the most detailed survey of the nearby universe so far with 110,000 galaxies. This should help us figure out how matter is distributed on a large scale, and it should also reveal how galaxies move in respect to the rest of the universe. But it's still only a tiny portion of the observable universe surveyed: a hundred thousand down, a hundred billion more to go ...
Using a giant radio telescope in Germany, water molecules have been detected in a galaxy about 11 billion light-years away. This means that there was already detectable amounts of water in our universe when it was only less than four billion years old, which also means that there must have already been enough supernovas by then to create plenty of oxygen.
Like many other cosmological objects from the far past, the detection was aided thanks to the gravitational lensing provided by a foreground galaxy. Detection was also aided by the fact that the water effectively acted as a gigantic laser powered by the supermassive black hole in the center of the galaxy, except that radio waves are emitted instead of visible light.
I don't get it. Why do so many news outlets such as the BBC talk as if there had been any uncertainty in the existence of a supermassive black hole in the center of the Milky Way Galaxy? We already had direct evidence of its existence by observing how stars rapidly swing by it in their orbit around the center of the galaxy for years.
While the recent observations and corroboration are exciting in their own right, as it refines previous measurements and make things even more certain, I don't understand the slant a lot of the news media has been putting on the news. Am I missing something?
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.